(Blasgow

lpce8entc&

4 %^(o O

PRESENTED BY THE COUNOJL CMp
THE ROYAL COLLEGE OF 8UKQtL.M3 OF £140

DESCEIPTIVE AND ILLUSTEATED CATALOGUE

OF

THE PHYSIOLOGICAL SERIES

OF

GOMPAEATIVE ANATOMY

CONTAINED IN

THE MUSEUM

OF

THE ROYAL COLLEGE OE SURGEONS OE ENGLAND

VOL. III.

SECOND EDITION.

LONDON:
PRINTED FOR THE COLLEGE;

AND SOLD BY

TAYLOR AND FRANCIS, RED LION COURT, FLEET STREET.

MDCCCOYII.

PEEFACE

TO THE

THIRD VOLUME.

The third volume o£ the Catalogue o£ the Physiological
Series comprises descriptions of the remainder of the specimens
in Section D [the Nerves of Vertebrates], and also of those in
Section E [the Organs of Special Sense]. The latter are
arranged in order of increasing complexity, namely, Touch,
Taste, Smell, Hearing, and Seeing. These are followed by
undoubted sense-organs which as yet have not had their
function certainly ascertained.

Section E has presented special difficulties as many of the
preparations of sense-organs were very delicate and had become
so injured as to require replacement ; it was also necessary to
add largely to the section, which probably will even yet long
require numerous additions.

This volume of the Catalogue should be justly considered as
the work of the Anatomical Assistant in the Museum, Mr. R. H.
Burne, who has carried out my wishes to my fullest satisfaction.
Professor C. S. Sherrington, F.R.S., has most kindly read the
proof-sheets and furnished me with many valuable suggestions.

C. STEWART,

Conservato)':

1 June, 1907.

CONTENTS.

VOL. III.

D.

NERVOUS SYSTEM {continued).

VERTEBRATA.
NERVES.

Cranial Nerves. Nos.

PISCES D809-D813

AMPHIBIA D 814

AVES D 815

MAMMALIA D 816

Spinal Nerves.

PISCES D 817

REFTILIA D818

MAMMALIA D 819— D 821

Limb Plexuses.

Bracliial Plexus.

PISCES D 822-D 823

EEPTILIA D824-D826

AVES I> 827— D 828

vi

CONTENTS OF VOL. III.

Nos.

D829— D 831
D832

D 833— D 834
D 835 —D 836
P837
D838
D839

D 840— D 842

MAMMALIA.

MONOTREMATA
MARS UPI ALIA
EDENTATA .
UNGULATA .
RODENTIA .
INSEOTIVORA
CHIROPTERA .
PRIMATES

Pelvic Plexus.

PISCES D843

AMPHIBIA I> 844— D 845

^VES D 846— D 848

MAMMALIA.

MONOTREMATA I> 849— P 850

MARSUPIALIA D 851— D 852

EDENTATA D 853— D 854

UNGULATA D 855

RODENTIA D 856

INSEOTIVORA D 857— D 858

CHIROPTERA D 859

PRIMATES D860-D862

Sympathetic System.

PISCES D863

AMPHIBIA 864

llEPTILIA D865-D866

j^YES D 867— D 868

MAMMALIA D 869— D 872

CONTENTS OF VOL. III. VU

E.

ORGANS OF SPECIAL SENSE.

TACTILE ORGANS.

INVERTEBRATA. Nos.

CCELENTEEATA El— E4

ANNELIDA E5

ARTHEOPODA.

CRUSTACEA E 6

INSECTA E 7

MOLLUSCA E8— ElO

VERTEBRATA.

PISCES,

Tactile organs on the head.

GANOIDEI Ell— E 12

TELEOSTEA E13— E16

Tactile organs -on the pectoral fins.

TELEOSTEA E 17

Tactile organs on the pelvic fins.

TELEOSTEA E 18

AMPHIBIA E 19

AYES E20— E21

MAMMALIA.

MONOTREMATA E22— E23

MARSUPIALIA E 24— E 27

EDENTATA E28— E29

UNGULATA E 30— E 34

RODENTIA E35— E36

PINNIPEDIA E37— E44

CARNIVORA E 45— E 49

INSEOTIVORA E50— E51

CHIROPTERA E52— E53

PRIMATES E54— E72

viii

CONTENTS OF VOL. III.

GUSTATORY ORGANS.

VERTEBRATA. jj^g,

PISCES E 73

MAMMALIA E 74— E 81

OLFACTORY ORGANS.

INVERTEBRATA.

ARTHROPODA E 82

MOLLUSCA E 83— E 84

VERTEBRATA.

Olfactory Chamber.
PISCES.

CYCLOSTOMI E 85— E 86

ELASMOBEANCHII E 87— E 90

GANOIDEI E91— E92

TELEOSTEA E 93— E 99

AMPHIBIA E 100— E 101

REPTILIA.

LACERTILIA E 102— E 104

OPHIDIA E 105— E 106

EMYDOSAURIA E 106 a

OHELONIA E 107— El 11

AVES E 112— El 22

MAMMALIA.

MONOTEEMATA E 123— E 124

MAESUPIALIA E 125— El 29

EDENTATA E 130 -E 132

CETACEA E 133

UNGULATA E 134-E 142

EODENTIA E 143— E 145

PINNIPEDIA E 146 — E 153

CAENIVOEA E 154— E 162

CHIEOPTERA E 163

PEMATES E 164— El 75

CONTENTS OF VOL. HI. ix

Parts accessory to the Olfactory Organ. j^^g

PISCES E 176

REPTILIA E 177

AVES E 178— E 184

MAMMALIA.

MONOTREMATA E 185

CETACEA E 186— E 192

UNGULATA E 193— E 200

CAENIVOEA E 201— E 203

CHIEOPTERA E 204— E 206

PRIMATES E 207— E 212

AUDITORY AND EaUILIBRATING ORGANS.

INVERTEBRATA.

ARTHROPODA.

CRUSTACEA E 213— E 214

INSECTA E 215— E 220

MOLLUSCA E221

VERTEBRATA.

PISCES.

CYCLOSTOMT E 222

BLASMOBEANCHII E 223— E 249

HOLOCEPHALI E 250

GANOIDEI E 251— E 253

TELEOSTEA E 254— E 279

DIPNOI E 280— E 281

AMPHIBIA . . E 282— E 286

REPTILIA.

RHYNGHOCEPHALIA E 287

LACERTILIA E 288— E 290

EMYDOSAURIA E 291— E 294

CHELONIA E 295— E 301

AVES E 302— E 306

VOL. III.

X

CONTENTS OF VOL. HI.

MAMMALIA.

Middle and Internal Ear. j^oa^

MONOTREMATA E 307— E 308

CETAOEA E 309— E 324

TNGULATA E 325— E 328

EODENTIA E329

CAENIVORA E330

PEIMATES E 331 — E 336

External Ear.

MONOTREMATA E 337— E 340

MARSUPIAL! A E 341— E 344

EDENTATA E 345— E 346

CETACEA E 347— E 348

UNGULATA E 349— E 360

RODENTIA E 361— E 371 a

PINNIPEDIA E 372— E 373

CARNIVORA E 374— E 383

INSEOTIVORA E 384 — E 385

CHIROPTERA E386

PRIMATES E387-E407

OTOLITHS, OSSICULA AUDITUS, AND BOKTY LABYRINTHS.
PISCES.

GANOIDEI E 408

TELEOSTEA E 409— E 485

AMPHIBIA.

URODELA E 486— E 487

ANURA E488-E492

REPTILIA.

RHYNOHOCEPHALIA
LACERTILIA . .
OPHIDIA . . •
EMYDOSAURIA
CHELONIA . . .

E498

E 494— E 501
E 502— E 503
E 504— E 507
E508— E511

CONTENTS OF VOL. III. xi

AVES. Nos.

EATIT^ E 512— E 513

CAEINATiE.

TiNAMIPOEMES E 514

Galmfoemes E 515— E 522

COLUMBIFOKMES E 523 — E 525

Eallieormes E 526

Peooellabiifokmes E 527

Laeifoemes E 528

Chaeadkiifoembs , E529 — E532

Aedeipoemes E 533 — E 534

Anseeifoemes E 535 — E 536

Pelecanifoemes E 537

Cathaetidifoemes E 538

AccipiTEiFOEMES E 539 — E 550

Steigifoemes E 551 — E 553

PsiTTACIFOEMES E 554 — E 555

C0EACIIF0EME3 E 556 — E 560

Teogones E 561

PiciPOEMEs E 562

Passeeifoemes E 563 — E 585

MAMMALIA.

MONOTEEMATA E 586— E 588

MAESUPIALIA.

POIYPBOTODONTIA E 589 — E 601

DiPEOTODONTIA E 602 — E 619

EDENTATA.

Xbnaethea E 620— E 633

LoEicATA E 634— E 641

NoMAETHEA E 642— E 649

CETAOEA.

Odontoceti > . E 650— E 676

Mtstacoobti E 677 E 682

SIEENIA E 683— E 691

UNGULATA.

Hteaooidba E 692— E 694

Peoboscidba E 695— E 700

Peeissodacttla E 701 E 711

Abtiodacttla E 712 E 783

xii

CONTENTS OF VOL. III.

RODENTIA. Nos.

SciuROMonritA E 784 — E 797

Myomobpha E 798 — E 818

Hystricomori'iia E 819 — E 834

Lagomorpha E835-E840

PINNIPEDIA E 841— E 80 1

CARNIVORA.

Akcxoidea E 862 — E 892

Cynoidba E 893— E 906

AiLimoiDEA E 907— E 941

INSECTIVOEA.

Insectivora vera E 942 — E 960

Dermoptera E 961— E 962

CHIEOPTERA E 963— E 975

PRIMATES.

Lehuroidea E976-E998

Anthbopoidea E 999 — E 1065

VISUAL ORGANS.

INVERTEBRATA.

MOLLUSCA E1066-E1080

ARTHROPODA.

CRUSTACEA E 1081

ARACHNOIDEA E 1082

INSECTA E1083-E1087

VERTEBRATA.
The Eyeball.
PISCES.

ELASMOBRANCHII E 1088— E 1095

GANOIDEI E1096-E1097

TELEOSTEA E 1098— E 1112

AMPHIBIA E1113

REPTILIA.

LACERTILIA E1114-E1120

OPHIDIA E1121-E1122

CHELONIA E1123-E1126

AYES E1127-E1142a

CONTENTS OF VOL. I!I. xiii

MAMMALIA. Nos.

MARSUPIALIA E a 1143

OETAOEA E 1143— E 1156

TJNGULATA E 1157 —E 1173

EODENTIA E 1174— E 1178

PINNIPEDIA E 1179— E 1181

OAENIVORA E 1182— E 1185

INSECTIVOEA E 1186— E 1187

PEIMATES . . . . E 1188— E 1201

Parts accessory to the Organ of Vision.
PISCES.

ELASMOBEANOHII E 1202— E 1213

GANOIDEI E1214

TELEOSTEA E 1215— E 1223

AMPHIBIA E1224--E1225

EEPTILIA.

LACEETILIA E 1226— E 1230

OPHIDIA E 1231— E 1232

EMYDOSAUEIA E 1233— E 1237

OHELONIA E 1238— E 1241

AYES • . .. . E 1242— E 1252 a

MAMMALIA.

MONOTEEMATA E 1253

MARSUPIALIA E 1254

EDENTATA E 1255— E 1257

CBTACEA E 1258— E 1263

SIEENIA E 1264

UNGTJLATA E 1265— E 1287

EODENTIA E 1288— E 1293

PINNIPEDIA E 1294— E 1296

OAENIVOEA E 1297— E 1300

INSEOTIVOEA E 1301

• OHIROPTEEA E 1302

PEIMATES E 1303— E 1310

SENSE-ORaANS OP UNKNOWN FUNCTION.
Organs of the Lateral Line.

PISCES E 1311— E 1319

VOL. m. c

DESCRIPTIVE CATALOGUE

OF THE

PHYSIOLOGICAL SERIES.

D

[continued).
NERVOUS SYSTEM.

NERVES.

John Hunter, Animal (Economy : A description oE the nerves
which supply the organ of smelling, Works of Hunter,
. Palmer, vol. iv. 1837, p. 187.
Croonian lecture on Muscular Motion, No. 1, 1776, ibid.
vol. iv. p. 212.

' Lectures on the Principles of Surgery, ibid. vol. i. p. 260.
Essays and Observations, edit. R. Owen, vol. i, p. 163.

Cranial Nerves.

Cole, Liverpool Mar. Biol. Committee Memoirs, viii.

[Pleunmectes) p. 110.
Merritt, Jour. Anat. & Physiol, vol. xxxix. 1905, p. 199.

The cranial nerves take their origin Erom the brain and supplv
the muscles, skin, and sense-organs of the head, the mucous
membrane o£ the mouth and pharynx, parts of the viscera and,
in low aquatic Vertebrates, special sense organs distributed over
the surface of the trunk.

For convenience sake they are grouped according to their
superficial origin from the brain into ton pairs in lower Verte-
brates, or twelve i)airs in the higher, although this arrangement
in the case of the majority has no correspondence with their

VOL. III. 1.

PUYSIOLOGICAL SERIES.

true centres o£ origin. The individual nerves of this series,
with the exception of the olfactory and optic, are not, in fact,
morphological unities, but each is composed of several kinds oL
lihres, that differ in histological features, arise from distinct
centres in the brain, and have each a peculiar distribution and
function. In all, five of these "components" have been
reco«»nized :— (1) General cutaneous sensory, distrdnited b.y
the tdgeminus (v.) and to a less degree by the glossopharyngeal
(IX.) and vagus (x.) to the skin, but not to specialised sense
„roans. These fibres are similar to the sensory fibres of the
dorsal roots of the spinal nerves and like them are in connection
with special ganglia— the Gasserian and jugular. (2) Special
cutaneous sensory (acoustic and equilibrating). This in lower
Vertebrates composes not only the auditory nerve (vill.), but
also branches of the facial (vii.) and vagus that innervate the
sense organs of the lateral line (vestibulo-laterahs system).
C^) Somatic motor, confined to the nerves of the eye-muscles
(III IV vi.) and to the motor nerve of the tongue-the hypo-
glossal (XII.). (4) Visceral sensory : distributed to the taste-
h-uls and the mucous membrane of the mouth and pharynx,
and in Fishes to special sense organs of the skin other than ^
those of the lateral line. This component (communis system) is
found mainly in the facial (forming the chorda tynipam and
palatine branches), in the glosso-pharyngeal (ix.) for the mnei-
tation of taste-buds, and in the vagus. Its centres in the
b..ain are often conspicuous superficidly as lie facnal lobe and
the sensory lobe of the vagus (Brain, Nos D. G8, D. 85, D. 0.)
(.5) Visceil motor, present in the trigeminus for the supply of
the muscles of mastication, and in the facial, glosso-pharyngeal,

FroTthe trigeminus backwards the cranial nerves, and more
particularly the hinder members of the series show signs o
^t^ir primitive relation to visceral arches in the separation o
he nerve-trnnk into three bran ches-pr.- and post-branchia
,nd visceral. With the loss of the gilb, the vagus which is
'e sei^l ra eomp^ of several independent branchial nerves
t^hl<Ml character, becomes more and more condensed
td extends its range further down the trunk ; at the same
r Vus posterior part which even in Fishes innervates the
;:;:!:sCa^^ ^ and, m combination with a root from the

NERVOUS SYSTEM. — VERTEBRATA.

3

spinal cord, forms the spinal accessory (xi.). Meanwhile,
the liypoglossus, which is a derivative of several spinal nerves,
and in lower forms belongs clearly to Ihe spinal series, becomes
included within the cranium. The facial — the nerve of the
hyoid arch — also shows signs of considerable evolutionary
change. With the loss of aquatic life, it loses its lateral-line
branches and becomes greatly diminished, particularly in
Eeptiles and Birds ; in Mammals it receives a new importance
owing to the relatively great development of the cutaneous
muscles of the hyoid region. The trigeminal (the general
sensory nerve of the face) gradually increases in importance
in the ascending series, particularly as regards the branches
of its maxillary division distributed to the muzzle.

PISCES.
HOLOOEPHALI*.

D. 809. Head of a Sea Cat (^Cldmcera monstrosa) with the brain
and cranial nerves exposed on the left side. The optic
nerve has been cut short. The oculo-motor (ill.) and
trochlear (iv.) nerves have respectively the distribution. to
the ocular muscles usual in Vertebrates : to the inferior
oblique, inferior, superior, and internal recti, and to the
superior oblique. The sixth nerve is not shown. The
trigemino-facial (v., vii.) complex, which in all low aquatic
Vertebrates is accompanied by a number of the nerves that
supply ihe organs of the lateral line, and in Fishes is
further confused by the blending of its roots, occurs in
Cliimcera in a relatively simple condition. In this specimen
the roots of the buccal and hyomandibular branches of the
lateral-line system have been cut to expose the underlying
roots of the trigeminal. The roots of the lateral-line
branches are better shown in D, 85. The nerves marked
VII. belong for the most part to the lateral-line system, and
comprise (a) the superficialis ophthalmicus vii. — a largo
trunk running along the dorsal border of the orbit and
supplying the supra-orbital canal, Qi) the buccal branch of
VII,, for the innervation of the infra-orbital canal, and (c)

* Placed bufore the ElasniobrRnclis owing to the greater simplicity of tho
cranial uerves.

B 2

I'llVSlOlXKilCAL SICltlKS.

tlie liyoni:in(lH)u!;ir division for the liyoiiiiiiulibiiinr canal.
This hitter nerve is closely bound up lor the first half of
its course with the true facial. The first (ophthalmic)
division ot' the trigeminal (v.) consists of two parts : a
minute ophthalmicus suf)erficialis that runs upwards with-
out joining the ophthalmicus superficialis vii. to the skin
covering the top o£ the head, and a relatively large ophthal-
micus profundus, that runs horizontally forward through
the orbit and joins the ophthalmicus superficialis Vll. to be
ultimately distiibuted to the snout. The maxillary and
mandibular divisions of the trigeminal are united for the
first part of their course, but can be seen diverging towards
the lower part of the orbit undercover of the buccal lateral -
line nerve. The facial (vil.) shows the essential characters
of a branchial nerve, in having three chief branches — a
post-branchial, accompanying the hyomandibular lateral-
line nerve to the operculum, a smaller prse-branchial
passing to the inner aspect of the mandible (this possibly
represents the chorda tympani of the higher Vertebrates),
and a visceral distributed to the palate. The glosso-
pharynge:d (ix.) and the first three trunks of the vagus
supply the gills and each gives off pree- and post-branchial
and visceral branches. The last (fourth) trunk of the
vagus innervates the oesophagus and stomach. The several
roots of the vagus retain their individuality far more com-
pletely than in any other Vertebrate. Crossing the roots
of IX. and x. from before backwards is a powerful nerve
(lateralis vagi) belonging to the lateral-line system ; it
arises in the brain in common with the other branches of
this system alid with the acoustic nerve, and supplies the
organs of the lateral line upon the trunk.

Cole, Trans. Soc. Edinburgh, vol. xxxviii. 1897,
p. 631.

ELASMOBRANCHII.
Ewart, Proc. R. Soc. vol. xlv. 1889, p. 524.
D. 810. Head of a Tope (Galeus communis) with the brain, and
the cranial nerves of the left side, exposed. The nerves
have the same general arrangement as in Ckimcera. The
union of the roots of the cephalic lateral line nerves with

KEUVOUa SYSTEM.

— VEKTEIiliATA.

5

tliose of the trigeminus and facial is however more intimate,
and the relative importance of the two ophthalmic branches
of the trigeminus is reversed, the ophthalmicus superfi-
cialis V. being in this case a nerve of considerable size which
soon after its exit from the skull blends with the ophthalmic
lateral-line branch of vil., whereas the ophthalmicus pro-
I'undus V. is quite small. Black paper has been inserted
between the buccal lateral-line branch of vii. and the
maxillary and mandibular divisions of the trigeminus, and
nearer the brain, between it and the true facial. The post-
spiracular branch of the facial is strongly developed and
consists of a union of fibres of the true facial with the hyo-
mandibular branch of the lateral-line system. The prae-
spiracular branch is minute, but the visceral (palatine)
is well developed. The glosso-pharyngeal is in a very
generalised condition, with prse- and post-branchial,
^isceral, and dorsal branches. The lateralis vagi and the
several divisions of the vagus are more intimately blended
in their passage through the skull wall, than in Chimcera.
The pigmentation of the neurilemma of the superficial
ophthalmic and fourth nerves is worthy of remark,

TELKOSTBA.

D. 811. The head of a Cod (Gadus morrhua) with the brain and
the cranial nerves shown from the left side. The blending
of the roots of the trigeminus, facial, and cephalic lateral-
line branches is even more complete than in the previous
specimen. Nerve trunks essentially similar to those seen
in CJuiiicera and Galeus, but differing much from them in
details and in relative importance, spring from the common
mass formed by the roots and ganglia of thi's nerve complex.
The ophthalmicus superficialis v. is completely separate
from the superficial ophthalmic lateral-line branch of vil.
There is no ophthalmicus profundus v. The lateral-line
branches in general, and particularly the buccal, are less
developed than in Galeus ; but, on the other hand, the
maxillary and mandibular branches of the trigeminus are
remarkably large : from the latter a strong branchlet
.supplies the barbel on the chin. The true facial is

rilYSIOLOGICAL SERIES.

accompanied by nerves belonging to the lateral-line system;
it is itscll: divisible into palatine, prae-spiracular, and post-
spiracular (hyoid) branches. The glosso-pharyngeal, on
its exit from the skull, divides into two trunks ; the anterior
of these gives origin to palatine and pra3-branchial branches.
From the palatine branch a slender filament passes towards
the combined roots of v. and vii. and enters them in con-
junction with the cephalic sympathetic cord at the point
of emergence of the palatine branch of the facial ; this
is the first appearance of the anastomosis of Jacobson.

Roots of V, Vll, IX cranial nerves of Oadus moirhua, showing
the anastomosis of Jacobson.
V VII IX The several cranial nerves. AN.J. Anastomosis of Jacobson.
' PAL. Palatine branches. SY. Sympathetic cord. SO. Superficial
ophthalmic branches.

The lateralis vagi and vagus nerves leave the skull as a
common bundle and at once separate into lateral Ime,
branchial, and gastric branches. An interesting nerve
(ramus accessorius lateralis) arises by two roots from the
dorsal parts of the trigemino-facial complex and vagus.
Its chief root, which is derived from the facial, runs directly
upwards towards the skull roof and after receiving the
smaller, vagus, root passes backwards along the sides of the
body for the innervation of special sense-organs situated
chiefly upon the fins. Blue paper has been placed beneath
the cranial portion of the sympathetic cord, which enters
into connection with the ganglia of the trigemmo-facial

NEUVOUS SYbTEM. VEUTEBRATA.

7

complex, and of the glosso-phaiyngeal, vagus, and fii\<t
spinal (hypo-glossal) nerves. The chief cranial nerves arc
distinguished by numbers. 0. C. 1380 B a.

Cole, Trans. Linn. Soc, vol. vii. 1896-1900, p. 115.

D. 812. A Whiting {Gadus merlangus) with part o£ the skin of
the trunk removed to expose a system o£ cranial nerve
branches (ramus accessorius lateralis and lateralis vagi)
that supplies special sense organs upon the body and fins.
The organs are o£ two kinds — end buds similar in structure
to the taste buds that occur in the mouth cavity and
pharynx and upon the lips. These are innervated by the
ramus accessorius (marked by black paper). The other
organs form the trunk part of the lateral-line system. The
nerve-fibres that supply them belong to the somatic sensory
component and aiise in common with the auditory nerve in
the acoustic centre, but leave the brain in connection with
the vagus. In the specimen they are marked by blue
paper.

Merritt, Jour. Anat. and Physiol., vol. xxxix. 1905,
p. 210.

D. 813. The head and anterior part of the trunk oE an Eel
(Anguilla longirostris) in which the commencement of
the lateralis branch of the vagus is shown on the right
sitle. 0. G. 1385. Hunteriaiu

AMPHIBIA.

Strong, Jour. Morph., vol. x. 1895, p. 101.

D. 814. The head of a Bull-Frog (iia/ia catesbiana), with the
brain and the cranial nerves of the left sidfi, exposed. The
rio-ht half of the brain has been removed to show the nerve-
roots of that side and the cranial portion of the sympathetic
system. In comparison with Fishes and aquatic Amphibia,
the facial and vagus nerves have undergone reduction iu
size and importance owing to the loss of the gills and of
the organs of the lateral line. The trigeminal is thc'
largest of the cranial nerves. Two trunks arise from its
Gasserian gangliui^ — a superficial oi)hthalmic, that passes

8

rilYfflOLOG'ICAL SERIKS.

forward beneath the roof of tlio orbit and is distributed to
the nasal chambers and to the surface of the snout; and
a large conjoint inaxillo-mandibular trunk that shortly
divides into maxillary and mandibular branches.

The facial is a relatively small nerve. It emerges from
the brain in close contact with the auditory nerve by a
sinole root and leaves the skull beneath the Gasserian
ganglion. Outside the skull it divides into palatine and
hyomandibular branches. The former runs forward along
the floor of the orbit and near its anterior border is con-
nected by a transverse anastomosis (marked by black paper)
to the ramus maxillaris trigemini. The hyomandibular
trunk passes behind the columella auris, and is joined by
the prEE-branchial branch of the glosso-pharyngeal. The
compound nerve that results from this union redivides
behind the outer end of the squamosal into three branches —
an external mandibular (shown by Strong to be composed
in the Tadpole of glosso-pharyngeal and lateral-line fibres)
distributed to the skin around the angle of the mouth ; an
internal mandibular (the prje-branchial division of the facial
which possibly represents the chorda tympani of mammals)
that runs parallel to the ramus mandibularis trigemini
along the inner surface of the lower jaw ; and a hyoid
branch (the post-branchial division of the facial) composed,
according to Strong, of fibres derived partly from the
glosso-pharyngeal and partly I'rom the facial. The lateral-
line branches associated with the facial in Fishes are
absent. The glosso-pharyngeal emerges from the skull in
company with the vagus. Besides the above-mentioned
prze-branchial branch, it has also a visceral (pharyngeal)
and a post-branchial. The latter runs along the floor of
the mouth to the tongue. There is no anastomosis of
Jacobson. The vagus arises by two roots. Outside the
skull it forms a single trunk, that later divides into laryn-
geal, cardiac, pulmonary, and gastric branches ; there is no
lateralis vagi. The first spinal nerve (hypoglossal) supplies
the muscles of the neck, hyoid region, floor of the mouth
and tongue.

In this specimen the anterior part of the sympathetic
system is also shown. Behind the skull it lies outside the

NERVOUS SYSTEM. — VEUTEBRATA.

9

vertebral column, enlarging opposite tlie first vertebra and
beneath the second spinal nerve to form large pigmented
ganglia. Anteriorly it enters the skull alongside the vagus,

Fig. 2.

Roots of tlie cranial nerves and intracranial sympathetic cords of
Eana catesbiana, enlarged.

11, III, IV, V, VI, VII, VIII, IX, X. The cranial nerves.
SY. ISynipathetic cord.

and can be seen (on the right side) as a delicate double
strand passing forwards behind the roots of the auditory
and facial nerves to join the Gasserian ganglion.

Ecker's Anat, des Frosches, 2« Aufl., Graupp, Abt. 2,
p. 128.

AVES.

D. 815. The head of a Swan [Cygnus olor) dissected from the
left side to show some of the chief trunks of the cranial
nerves. The most notable feature is the great size of the
branches of the trigeminus. At the posterior part of the
skull can be seen the glosso-pharyngeal, va^us, and hypo-
glossal.

MAMMALIA.

D. 816. Head and fore-part of the trunk of a Rabbit {Lepus
cuniculus) showing the cranial nerves of the left side. The
nerves of the eye muscles diifer in no essential from those
of lower Vertebrates. The trigeminal is divisible into
three main trunks — (a) the oi)htlialmic, separated inio

rHYSIOLOGICAL SEUIKS.

several branches, for the innervation of the skin of the
foreliead and the eyelids ; (/>) the maxilUuy, a strong nerve
bundle that crosses the floor of the orbit, passes internal to
the alveoli of the upper molars and traverses the maxilla
through the infra-orbital foramen to reach its final distri-
bution in the skin of the muzzle. It supplies the upper
teeth and the vibrissse and skin of the upper lip; and
(c) the mandibular, which leaves the skull by the foramen
lacerum medium some way behind the point of exit of the
other two trunks and close in front of the auditory bulla.
Within the foramen it divides into two branches — an
anterior branch or rather bundle of nerves that enters the
orbit and supplies the muscles of mastication and the
buccinator, and a large postei'ior division. This latter,
after a course of about 6 mm., subdivides into mandibular,
lingual, and mylohyoid branches. The lingual is shortly
joined by the chorda tympani (the prje-spiracular branch
of the facial) and passes external to the hypoglossus to
the lateral parts and tip of the tongue for the inner-
vation of the rnucous membrane. The mandibular trunk
enters the lower jaw to supply the teeth. In the specimen
the jaw has been removed as far forward as the mental
foramen, through which the nerve regains the external
surface for its ultimate distribution to the chin. The
facial in comparison with that of lower land Vertebrates
is relatively large, owing to the increased importance
of the skin-muscles of the face. It emerges from the
skull behind the auditory meatus through the stylo-
mastoid foramen. Its proximal part only is shown.
Close to its exit from the skull it gives ofE an anterior
branch— the chorda tympani— which passes through the
tympanic chamber and as just mentioned joins the
lingual branch of the trigeminal. The glosso-pharyngeal
is small ; its chief distribution is to the mucous membrane
of the pharynx and the taste- organs of the circumvallate
and foliate papilla of the tongue. The vagus is repre-
sented by a single trunk, which 10 mm. below its exit
from the skull enters a large ganglion (g. nodosum).
Further down it gives off the superior laryngeal nerve and
an extremely delicate filament (depressor cordis) that ruus

NEltVOUS SYSTEM. VEHTEDRATA.

11

down tlic neck to the heart to exert upon it an inhibiting
influence in opposition to the cardiac branches of the
sympathetic system. On a level with the aortic arch,
the main trunk of the vagus gives off another (recurrent)
laryngeal nerve, that passes inwards through the arch of
the aorta close behind the vestigeal ductus arteriosus, and
supplies the trachea and larynx. The further distribution
of the vagus to the lungs and stomach is not shown. The
spinal accessory nerve leaves the skull close behind the
vagus ; it runs backwards, joins the fourth spinal nervo
and is distributed mainly to the trapezius. The hypo-
glossal is strongly developed ; it crosses the vagus just
proximal to the ganglion nodosum, and gives off a small
descending branch (Kamus doscendens noni of Human
Anatomy), which after forming connections with two of
the spinal nerves innervates the sterno-hyoid muscles.
The main trunk of the nerve runs forward above the hyoid
and external to the hyo-glossus, to tlie base and sides of
the tougue. It supplies the tongue muscles. In this
specimen the cervical and anterior part of the thoracic
portions of the sympathetic system are also shown.
W. Krause, Anat. des Kaninchens, 1868, p. 224.

Spinal Nerves.

The spinal nerves, like the cranial, are made up of several
components. These are somatic sensory and motor for the
innervation of the skin and the muscles of the body- walls
and limbs, and visceral sensory and motor. The latter form
the rami communicantes with the sympathetic system ; the
motor set enter via the sympathetic vertebral ganglia into
various spinal nerves as vaso-motor and pilo-motor (to hairs)
fibres. The two roots of 'a spinal nerve probably represent
what at one time were two independent nerves, and in existing
Vertebrates they actually vary much in the extent to which they
are separate — the union tending to be more and more close
the higher the position of the animal in the vertebrate scale.
Gaskell, Jour. Physiol., vol. vii. 1886, p. 1.

12

I'lIVblOLOOlCAL SHUIES.

PISCES.

D. 817. Portion of the trunk of a Tope {Galeus communis),
sliowiiig the origin and cljief branches of three spinal
nerves. The proximal parts of two isolated spinul nerves
are mounted above. The dorsal and ventral roots of each
nerve are given off from the spinal cord at different levels —
the ventral root in front of the dorsal. Immediately upon
emerging from the neural canal, the ventral (motor) root
sends out a dorsal branch ihsi unites with a similar branch
irom the dorsal (sensory) root to form a mixed nerve for
the innervation of the muscles and skin of the back. The
ganglion of the dorsal root lies just outside the vertebral
column. It gives off a small outwardly directed branch
which is later joined by a twig from the dorsal branch of
the ventral root. The dorsnl and ventral roots unite at
some distance from the vertebral column and give off a
few minor branches that accompany the ribs. The com-
bined trunk perforates the intercostal membrane and
proceeds outside the peritoneum to the ventral surface of
the body.

REPTILIA.

D. 818. Part of the trunk of a Python {Python sebcc), showing
the distribution of several of the spinal nerves, and (upon
the anterior surface of the specimen) the roots of one pair
of nerves, the position of the spinal ganglia, and the mode
of origin of the chief branches.

Each spinal ganglion lies in the space between the
zygapophyses of successive vertebrse, at the point of union
of the dorsal and ventral roots of the spinal nerve. From
its distal parts dorsal and ventral nerve-trunks are given
off. The former passes upwards amongst the muscles of
the back. The ventral trunk runs downwards between
the ribs and emerges upon the inner surface of the body-
wall between the costo-vertebralis inferior muscles. It
shortly divides into dorsal and ventral branches. The
dorsal branch innervates the latero-ventral muscles external
to the ribs. The ventral branch is finally distributed to
the muscles of the ventral shields.

NERVOUS SYSTKM. — VERTEBRATA.

13

MAMMALIA.
UNGULATA.

D. 819. Part of the cervical region of the spinal cord of a Colt
{Equiis cahalhts), showing the origins of the second to the
fifth spinal nerves. On the right side the rootlets of the
dorsal roots have been cut away to show the corresponding
ventral rootlets and the spinal root of the accessorius. The
latter arises from the spinal cord at a shghtly lower level
than the hinder end of this specimen, and runs towards
the head between the dorsal and ventral rootlets of the
spinal nerves receiving in its course reinforcing filaments.

The rootlets of the dorsal and ventral roots enter and
emerge from the cord at the dorso- and ventro-lateral
furrows respectively, and those belonging to each metamere
converge to form the dorsal and ventral roots. The dorsal
root just before it unites with the ventral to form the
mixed spinal nerve bears a large ganglion.

PRIMATES.

D. 820. Proximal part of a Human spinal nerve, showing the
roots internal to the investments of the spinal cord, the
reflexion of the dura mater upon thciir surface as ihcy
leave the neural canal, and the swelling at their point of
coalescence due to the ganglion on the dorsal root. At a
spot proximal to the ganglion the two roots have been
forcibly separated by the insertion of a bristle between
them. 0. C. 1378 H.

D. 821. Portions of two Human intercostal nerves unravelled at
their lower ends to show their component bundles.

0. C. 1379. Himterian.

Limb Plexuses.

Sherrington, Jour. Physiol., vol. xiii. 1892, p. G21 ; also

Phil. Trans., vol. 190 B, 1898, p. 93.
von Ihering, Peripherische Nervensystem der Wirbelthiere,

1878.

The ventral branches of those spinal nerves that supply the
limbs are united by their perineural investment to form plcxuecs,

14

PHYSIOLOGICAL SERIES.

situated between their exit from the neural canal and their entry
into the limb. Althougli, no doubt, meclianical causes, such as
the crowding that takes place as the nerves converge to enter
the limb, or that due to the backward extension of the gill-
arches in Fishes, have had much to do with the formation of
these plexuses, the constancy of their occurrence and the intricate
interchange of nerve-fibres that takes place within them, indicate
that they probably have some important physiological meaning.
What this meaning is, has been a matter of much discussion.
However, there is probably some truth in the suggestion of
Panizza that the plexuses have for one of their uses the protection
of the muscles from excessive fatigue ; for as the nerve to each
muscle is composed of fibres arising in different parts of the
cord, the entire muscle need not be called into play during any
one coordinate movement, and thus while one part of the muscle
is in action, the rest is in repose, and the liability to over-
fatigue of the whole is much lessened. But to whatever extent
this may be the function of the plexuses, it seems certain from
Professor Sherrington's experiments that " by [their] instrumen-
iality nerve-fibres passing through a number of si)inal roots from
an extended line of origin in the cord are sorted and collecfed
in such a way that all those destined for one particular muscular
organ .... finally exist gathered together in one and the same
nerve trunk " (Jour. Physiol., vol. xiii. p. 712). The arrange-
ment affords anatomical evidence that the group of motor cells
to such muscles extends longitudinally through not one but
several segments of the spinal cord.

A very constant feature in the arrangement of the plexuses is
the separation of their individual roots into dorsal and ventral
divisions, and the distribution of the nerves derived from the
combination of the members of each series of these divisions, to
the muscles and skin of the dorsal and ventral surfaces of the
limb respectively. This constancy is to be referred to the mode
of development of the limbs : to the early separation of the
originally unbranched limb nerves into dorsal and ventral
branches, following the separation of the muscle-sheath of the
limb-bud into dorsal and ventral sheets. The further sub-
division of these dorsal and ventral sheets into muscle groups
of increasing complexity and the direct rehitionshi[) that exists
between the individual muscles of lower forms and complex

NERVOUS SYSTEM. — VBRTEBRATA.

15

series of mnscles in tliose Ligher in the scale, is reflected by tlie
approximate similarity in the various classes in the distribution
ot: the chief nerves given off irom the plexus.

Brachial Plexus.

PISCES.
ELASMOBRANOHII.

Braiis, Jena. Zeits., Bd. xxxi. 1808, p. 239.
D. 822. The fore-part of the trunk, including ihe posterior half
of the skull, of a Tope {Galeus communis), showing the
cervical and brachial plexuses and the spino-occipital nerves.

rig. 3.

The spino-occipital nerves of Galeus communis.
I, IT, in, IV, V, VI. Iloota of the first six spinal nerves.

The first four spinal nerves (spino-occipital) arise from
the medulla within the cranial cavity, and, with the fifth,
which lies between the skull and the vertebral column, are
more or less vestigeal, being small and without dorsal roots.
They increase regularly in size from the first, which leaves
the skull in front of and below the root of the vagus
and is so small as to }>e almost invisible. The sixth and
succeeding nerves are formed by the union of dorsal and
ventral roots in the ordinary way. The ten anterior spinal

IG

PHYSIOLOGICAL SERIES.

nerves (including the spino-occipital) join together between
their exit from the cranio-spinal cavity and the posterior
limit of the branchial apparatus, to form a single trunk
(cervical plexus) that innervates the hypo-glossal region,
and also gives off' a large branch that traverses the pectoral
arch to its outer side for tlie innervation of the fin. The
four succeeding spinal nerves unite on a level with the
lateral vein to form a brachial plexus, from which branches
are given off to the ventral trunk muscles and to both dorsal
and ventral surfaces of the fin. Posterior to this, each
spinal nerve remains distinct although seven of them take
part in the innervation of both surfaces of the limb.

Black paper has been placed beneath the spino-occipital
nerves after their exit from the skull, a red glass rod is
inserted into the subclavian artery, and the branches of
the brachial spinal nerves to the body-wall have been cut
short and lifted to distinguish them from the branches
distributed to the fin. The lateralis vagi has been exposed.

TELEOSTEA.

D. 823. The right pectoral fin and part of the skull and vertebral
column of a Gurnard ( Trigla liirundo) , ^\wvi'mg the brachial
plexus and the distribution of nerves to the fin. An isolated
specimen of the roots of the last two cranial and the first
five spinal nerves is also shown, in which the boundary
between the cranium and spine is marked by a red line.
The first and second s[)inal nerves are fused together ;
they have two dorsal roots, that arise respectively in the
two anterior enlargements of the spinal cord (c/. D. 755),
and three ventral roots. The first nerve supplies the swim-
bladder and the muscles of the throat, and unites by a
strong branch with the second and third nerves to innei-
vate both surfaces of the fin. The fourth spinal nerve has
one immense dorsal root derived from the fourth and filth
enlargements of the cord, and a single small ventral root.
It breaks up into five strong sensory branches for the
supply of the free tactile fin-rays— one to the first and two
to each of the others, and also gives rise to motor branches
for the inner superficial muscle-sheet of the fin and for the
muscles of the tactile fin-rays.

NERVOUS SYSTEM. VEKTEBRATA.

17

BEPTILIA.

Fiirbringer, Jena,. Zeits», Bd. xxxiv. 1900, p. 3G4.

D. 834. Right fore-limb and part of the trunk o£ a Monitor Lizard
( Varanus varius), showing the brachial plexus and the dis-
tribution of the chief nerves given off from it. The four
roots of the plexus (of which the middle two are by far the
strongest) are derived from the seventh to the tenth spinal
nerves. At the point of union of the two anterior roots a
bundle of dorsal nerves (analogous to the supra- and sub-
scapular of Mammals) is given off to the subcoraco-
scapularis and supracoracoideus. The second root prior to
its union with the first divides into dorsal and ventral
divisions. The former joins a similar dorsal division of the
combined posterior roots of the plexus to foi*m a nerve
trunk with a distribution approximately similar in the
upper arm to that of the circumflex and musculo-spiral
of Mammals, but restricted in the forearm to the head of
the extensor communis and the skin for a short distance
below the elbow. Nerves for the latissimus dorsi arise
from the proximal parts of the dorsal divisions of the
plexus. The ventral division of the second root unites
with that of the combined third and fourth roots to form
the chief nerve of the limb — the brachialis longus inferior.
Between the axilla and the elbow this nerve gives off
branches to the pectoralis, to the flexors of the elbow, to
the humero-radialis (supinator), and to the sldn on the
inner side of the elbow. In the bend of the elbow it
divides into trunks analogous to the median and ulnar of
Mammals. These supply the flexors of the forearm and
hand, and, by branches of the median trunk that pass
through the interosseous membrane, the humero-meta-
carpalis medialis (ext. comm. digit.), the epicondylo-meta-
carpalis ulnaris (ext. carp, uln.), the back of the hand
and the skin on the extensor surface of the distal end of
the fore-arm : parts that should be supplied by nerves
derived from the dorsal division of the roots.

D. 825. The brachial plexus and nerves of the left fore-limb of
the same individual, isolated. The distribution of the
VOL. III. c

18

PHYSIOLOGICAL SERIES,

several nerves is indicated by figures as follows : — (1)
Supracoracoideus. (2) Subcoracoscapularis. (3) Skin of
fore-arm, humero-radialis, and humero-carpalis. (4) Dorso-
scapularis, scapular head of anconeus, and skin of shoulder.
(5) Latissimus dorsi, (6) Subscapular part of subcoraco-
scapularis, (7) Anconeus and head of extensor communis.
(8) Coraco-brachialis longus. (9), (10) Coraco-ante-
brachialis (biceps) and humero-antebrachialis inferior
(brachialis internus), (11) Coraco-brachialis longus, and
skin on inner side of elbow. (12) Coraco-brachialis brevis.
(13) Pectoralis. (15) Pronator teres, humero-radialis
carpalis. (16) To i-adial surface of thumb. (17) Pro-
nator quadratus, and back of the hand. (18) Palm of
hand. (19) Extensors, and skin of fore-arm. (20), (21),
(22) Flexor profundus. (23) Flexor carpi ulnaris. (24)
Palm of hand. C, indicates cutaneous branches.

D. 826. Left brachial plexus of a Chameleon {Cliamceleon
vulgaris), isolated, together with the right half of the head
and shoulders of the same individual with the ])lexus iu
position. The plexus lies relatively far forward, including
the third to the sixth spinal nerves. The two middle roots
are the strongest.

AVES.

Fiirbringer, Morph. Jahrb., Bd. v. 1879, p. 324.

D. 827. The right wing and part of the trunk of a Ki-Wi
{Apteryx oweni) showing the brachial plexus. The plexus
is formed bv the last three cervical nerves but one ; the
three components being fairly equal in size. Before joining
to form the plexus, each bifurcates into dorsal and ventral
divisions. The ventral divisions unite to form a cord that
supplies the pectoralis and biceps. The dorsal divisions of
the two anterior roots unite and give rise to the axillaris
(analogous to the circumflex of Mammals) for the innerva-
tion of the deltoid and outer aspect of the shoulder. The
main cord due to their union then joins the dorsal division
of the third root to form a trunk (musculo-spiral of
Mammals) for the supply of the extensors of the upper- and
fore-arm. The nerves are very feeble beyond the elbow.

NERVOUS SYSTEM. — VERTBBRATA.

19

D. 838. Right wing and part o£ the vertebral column of a
Heron {Ardea cinerea) showing the brachial plexus and the
nerve-supply of the limb. The plexus lies at some distance
from the vertebral column. It is formed by the last three

Fig. 4.

Brachial Plexus of Ardea cinerea.

AX. Axillaris. C.BK.P. Coraco-tracLialis posterior. I.D. First dorsal
nerve. D.T. Dorsal trunk. P. Brancli to pectoralis. P.TH. Posterior
thoracic. SC. Branch to surpra-coracoideus. V.T. Ventral trunk,

cervical and the first thoracic nerves, the two middle roots
being the strongest. The two anterior roots, before joining,
give rise to the posterior thoracic nerve for the serratus.
At their point of union a large nerve is given off for the
supra-coracoideus and just beyond this the combined roots
divide into ventral and dorsal divisions that respectively
unite with the third root and with its dorsal division. Two
chief nerve trunks arise from the plexus — a ventral trunk,
corresponding to the musculo-cutaneous and median' of
Mammals, which, after giving off branches to the pectoralis
and coraco-brachialis posterior, passes down the inner
surface of the arm, innervates the biceps, and in the hollow
of the elbow bifurcates to form median and ulnar branches.
The median supplies the pronators and flexors of the fore-
arm (except the flexor carpi ulnaris which receives its
nerves from the ulnar branch). The other chief trunk
represents the musculo-spiral of Mammals. Before innervat-
ing the triceps, it gives of? the axillaris to the deltoid and

c 2

20

PHYSIOLOGIOAl, SKUIES.

the shoulder-joint. In the middle of the upper arm it
passes to the oiiter surface of tlie limb and is ultimately
distributed to the extensors of the fore-arm and to the skin
on its extensor surface.

MAMMALIA.

Paterson, Jour. Anat. & Physiol., vol. xxi. 1887, p. 611.
MOIsOTREMATA.

D. 829. Right fore-limb and part of the vertebral column of
a Duck-billed Vlatyytus {OrnithorhyncJius anatinus), showing
the brachial plexus and the innervation of the limb. The
plexus involves seven spinal nerves — the last five cervical
and the first two thoracic ; the first and" last roots are,
however, quite insignificant. From the point of union of
the first and second roots a nerve is given off to the supra-
coracoideus (c/. Heron, Vara7ius, D. 828 & D. 824). Sub-
scapular blanches spring from the union of the second and
third roots, and, by the combination of the dorsal divisions
of the second, third, and fourth roots, a large trunk is
formed that agrees in its distribution to the circumflex and
radial nerves of other Mammals. The musculo- cutaneous
is formed by the union of the ventral divisions of the third
and fourth roots. It at once gives off several branches to
the flexors of the elbow and passes on to join the main
trunk of the median. The fifth and combined sixth and
seventh roots of the plexus unite and also receive dorsal
and ventral 'contingents from the fourth. The resulting
trunk, after giving origin to a large anterior thoracic nerve
for the supply of the pectoralis and skin muscles, divides
into internal cutaneous, ulnar, and median branches. A
large nerve is also given off from its dorsal surface between
the ulnar and median branches, which supplies the extensor
antebrachii, coils round the outer surfiice of the humerus
and is distributed finally to the extensors of the fore-arm,
thus agreeing in its area of innervation with the musculo-
spiral and posterior interosseus of Man. This apparent
origin of what should be a dorsal nerve from a ventral trunk
is deceptive, as the stem from which it originates is

NERVOUS SYSTEM. — VERTEBKATA.

21

derived clearly IVom both dorsal aud ventral divisions of
the plexus.

Westling, Bihang Kgl. Sven. Akad. Haudlingar, Bd. ix.
1884-5, p. 27.

D. 830. Distal part of the right fore-limb of a Duck-billed
Platypus {Ornithorhynchus anatinus), showing the dis-
tribution of the median, ulnar, and musculo-spiral nerves in
the fore- arm. The cut ends of these nerves have been
.separated and arranged in a line just above the elbow. The
extensor carpi radialis receives its chief nerve-supply from
the radial extension of the circumflex. All the other
extensors of the fore-arm are innervated by the musculo-
spiral. The branches of the radialis have been cut short.

D. 831. Right fore-limb and pai-t of the vertebral column of
a Spiny Anteater (^Tachyglossus \_Ecliidna] aculeatus),
showing the brachial plexus and the innervation of the
limb. The formation of the plexus and the course and

Fig. 5; Fig. 6.

Fig. 5.— Brachial plexus of Tachi/glossus aculeatus.
Fig. 6. — Brachial plexus of Ornithorhynchus anatinus.

A.TH. Anterior thoracic. CIRC. Circumflex. I. CUT. Internal cutaneous
M. Median. M.CUT. Musculo-cutaneous. M.SP.* Musculo-spiral.
S.COR. Supra-coracoid. UL. Ulnar. Dorsal nerve-trunks dotted.

distribution of the nerves are essentially the same as in
Ornithorhynchus, but the musculo-spiral which in Ornitho-
rhynchus, as mentioned in the description of D. 829, appears
to be a branch of the common trunk of the median, internal
cutaneous and ulnar nerves, and thus to be a nerve of the

22

PHYSIOLOGICAL SERIES.

ventral series, is hei-e formed clearly by the union of the
dorsal divisions of the fourth and of the combined fifth
sixth and seventh roots of the plexus. The last mentioned
dorsal division is, however, combined for some considerable
distance with the common trunk of the median, internal
cutaneous, and ulnar nerves.

MARSUPIALIA.

D. 832. The left fore-limb and part of the trunk of a Wallaby
{Petrogale penicillata) , showing the brachial plexus and the
nerve-supply of the limb. The plexus is formed by the last
four cervical and the first thoracic spinal nerves. The first
two roots unite and the resulting trunk splits into dorsal
and ventral divisions. The dorsal division gives off" supra-
and sub-scapular nerves and unites with the dorsal divisions
of the third and fourth roots to form a plexus from which
arise the circumflex^ musculo-spiral and subscapular nerves.
The ventral division in a similar way forms a plexus with
the ventral divisions of the third fourth and fifth roots,
which gives origin to the anterior thoracic, musculo-
cutaneous, median, ulnar, and internal cutaneous nerves.
. The arrangement of the nerves within the limb is essentially
the same as in Man, but the innervation area of the radial
nerve is mainly supplied by a branch of the median
(indicated by a green rod) given oJBF in the hollow of the
elbow.

Parsons, Proc. Zool. Soc, 1896, p. 708.

EDENTATA * .

D, 833. Right fore-limb and part of the vertebral column of a
Sloth {Bradypus tridactylus), showing the brachial plexus
and the innervation of the limb. The plexus is very large,
being formed by seven roots derived from the last four
cervical and first three thoracic nerves. The first two roots
unite and give off the suprascapular nerve. They then join
the third and fourth roots and the resulting trunk divides
into a dorsal and a ventral division. In a similar way
dorsal and ventral divisions are formed from the coalescence

* The brachial nerves of Myrmecophaga are shown in C. 145.

NERVOUS SYSTEM. — VEETEBRATA.

23

of the last three roots of the plexus. The two ventral
divisions unite and give origin to the musculo-cutaneous,
median, ulnar, and internal cutaneous nerves, and
from a similar union of the dorsal divisions arise, as
usual, subscapular, circumflex, and musculo-spiral nerves.
The musculo-cutaneous is given off from the trunk of the
median half way down the humerus and below the origin
of the ulnar and internal cutaneous.

D. 834. The brachial plexus of a Two-toed Sloth (Choloepus
didactylus). The plexus is not so extensive as in
Bradypus. It includes five roots derived from the last
four cervical and the first thoracic nerves. Allowing for
the smaller number of roots the chief nerves of the limb
take their origin from the plexus in a manner similar to
those of the Three-toed Sloth,

UNGULATA.

D. 835. Part of the vertebral column of a Cape Hyrax [Procavia
capensis), showing the roots of the brachial plexus. These
are derived from the last four cervical and the first thoracic
spinal nerves. The anterior root is slender, but the rest,
in correspondence with the great muscularity of the limb
(c/. C. 147 a) are peculiarly stout.

George, Ann. des Sci. Nat., ser. 6, T. i. 1874, p. 156.

D. 836. Left fore-limb of a Goat {Capra hircus) with part of
the vertebral column, showing the brachial plexus and the
nerve-supply of the limb. The plexus is formed by the last
three cervical and the first thoracic spinal nerves. The
second root at its point of separation into dorsal and
ventral divisions is joined by the relatively insignificant
first root and gives origin to a large* suprascapular
nerve. The dorsal divisions of the last three roots,
after giving off short and long subscapular nerves, unite
to form a cord that soon branches into musculo-spiral
and circumflex nerves for the innervation of the extensor
surface of the limb in the usual way. The ventral division
of the second root joins a compound ventral division
derived from the two hinder roots, and in conjunction with

24

PHYSIOLOGICAL SERIES.

it gives rise to the musculo-cutancous, median, ulnar, and
internal cutaneous nerves for the supply of the flexor
surface of the limb. The musculo-cutaneous perforates
and innervates the coraco-brachialis and enters the biceps.
The brachialis internus receives its nerve-supply from the
median. It should be noticed that the roots of the dorsal
(extensor) plexus are considerably stouter than those of the
ventral (flexor) plexus.

RODENTIA.

D. 837. Right fore-limb and part of the vertebral column of a
Hare {Lepits europceus), showing the brachial plexus and
the distribution of nerves to the limb. The plexus is
formed by the last three cervical and the first thoracic
nerves. The first root gives off the suprascapularis and
separates into doi'sal and ventral divisions which unite
with the corresponding divisions of the second root to give
origin respectively to the subscapularis and circumflex, and
to the musculo-cutaneous nerves. The musculo-cutaneous
sends a branch to the pectoralis and is united by a slender
anastomosis to the main trunk of the median nerve through
which its fibres are transmitted to the biceps and brachialis
internus. The other nerves of the ventral series are formed
by the union of the ventral divisions of the last two roots.
The dorsal divisions of these roots unite together and with
part of the dorsal division of the second to give rise to
the musculo-spiral nerve.

Krause, Anat. des Kaninchens, 1868, p. 245.

INSEOTIVORA.

D. 838. Right fore-limb and part of the trunk of a Hedgehog
{Erinaceus europceus), showing the brachial plexus and the
distribution of nerves in the limb. The plexus receives
roots from the last four cervical and first two thoracic
spinal nerves. The first and second, and fourth, fifth and
sixth roots respectively unite before dividing into dorsal
and ventral divisions. The suprascapular nerve arises
at the union of the first and second roots. The three
dorsal divisions of the conjoint first and second, of
the third, and of the conjoint fourth, fifth and sixth

KERVOUS SYSTEM. — VEUTEBRATA.

25

roots, form a plexus from whicb arise circumflex, musculo-
spiral, and subscapular nerves. The three corresponding
ventral divisions also form a plexus which gives origin to the
musculo-cutaneous, median, ulnar and conjoint anterior
thoracic and internal cutaneous nerves. The latter is very
strongly developed and innervates the cutaneous muscles o£
the trunk and the pectoralis {cf. Monoi remes) . The
musculo-cutaneous nerve is united to the median by an
ansa, passing in front of the coraco-brachialis longus.
Distally the musculo-cutaneous extends to the extensor
surface of the hand.

CHIROPTERA.

D. 839, Part of the vertebral column and the riofht arm of a
Bat (Fteropus edwardsi), with, the brachial plexus and
nerves of the limb displayed.

The plexus is compounded of roots derived from the
last three cervical and first tw^o thoracic spinal nerves, the
last root being very minute. The usual mammalian nerve-
trunks are given off from the plexus — the supra-
scapular from the first root at its point of division into
ventral and dorsal branches ; the musculo-cutaneous from
the ventral divisions of the first and second roots ; the
median from the ventral divisions of the second, third and
fourth roots, and the ulnar from the fifth root and the
ventral division of the fourth. Of the chief dorsal nerves,
the circumflex is derived from the dorsal divisions of roots
one and two, and the musculo-spiral from those of roots
two, three and four.

The ulnar nerve unites with the median in the fore-arm.

PRIMATES.

J). 840. Left arm and part of the trunk of "an Orang-utan
{Simia satyrus), showing the brachial plexus and the nerve
distribution in the limb. In this specimen, the union of
the ventral divisions of the first three roots of the plexu&
to form an outer cord from which arise the musculo-
cutaneous nerve and the anterior component of the median,
and the similar union of the ventral divisions of the two
posterior roots to form an inner cord from which the

26

PHYSIOLOGICAL SERIES.

internal cutaneous and ulnar nerves and the posterior
component of the median are given off, is more definite
than in the Chimpanzee, and even more closely resembles
the condition typically found in Man. The distribution
of the peripheral nerves is essentially the same as in Man.
There is no blending of the median and ulnar nerves as
seen in the Chimpanzee. Elaborate descriptions of the
brachial plexus and limb nerves in the Anthropoid Apes
and comparisons between them and those of Man will be
found in the following papers.

Saberton, Stud. Anat. Univ. Manchester, Young, vol. iii.
1906, p. 166.

Sperino, Anat. d. Chimpanz^, 1898, p. 401.

D. 841. Left arm and part of the trunk of a Chimpanzee
(Anthropnpithecus troglodytes), showing the brachial plexus
and the nerves of the limb. The plexus, as in Man and
most other Mammals, is derived from the last four cervical
and the first thoracic spinal nerves. The mode of com-
bination of the dorsal and ventral divisions of the roots to
form the plexus, and the further distribution of the nerves
difier in some particulars from the condition most usually
found in Man. The three anterior roots divide into dorsal
and ventral divisions before uniting. Their ventral
divisions, together with that of the combined fourth and
fifth roots, after having given origin to the anterior thoracic,
musculo-cutaneous, ulnar, and internal cutaneous nerves,
unite to form the median nerve, but there is no definite
formation of inner and outer cords, as in Man. The dorsal
roots in a similar way combine to form the musculo-spiral
after having given off the subscapular and circumflex
nerves from^the point of union of the dorsal divisions of
the two anterior roots. It should be noticed that a large
nerve, with a distribution similar to that of the flexor
branches of the ulnar in Man, is formed in the hollow of
the elbow by the union of two cords derived respectively
from the median and ulnar nerves (of. C. 170). A con-
nection of an apparently similar character is found in
other Primates and is of frequent occurrence in Man.
Gruber, Arch. f. Anat., 1870, p. 501.

NERVOUS SYSTEM. VEllTEBRATA.

27

D. 842. Nerves of the left fore-arm of a Chimpanzee (^Anthro-
popithecus troglodytes), isolated and spread out to show in
a diagrammatic fashion the connection between the median
and ulnar nerves and the distribution of their various
branches.

Pelvic Plexus *.
PISCES.
ELASMOBEANOHII.

Braus, Jena. Zeits., Bd. xxxi. 1898, p. 319.

D. 843. Part of the trunk of a Tope [Galeus communis)
including the right pelvic fin. The nerves to the fin have
been exposed. The plexus is of a slight and extremely
simple character. The several limb nerves split into dorsal and
ventral divisions which are distributed to the muscles and skin
upon the corresponding surfaces of the fin and are united at
its base by a few feeble connections. At the anterior end of
the plexus the dorsal nerves are connected by a longitudinal
trunk that runs forward to the fourth spinal nerve in
advance of the plexus and there vanishes. This " collector "
nerve is regarded by some as a vestige indicating the path
of a backward migration of the limb.

AMPHIBIA.

D. 844. The right hind-limb and part of the trunk of a Bull-
Frog {Rana cateshiana), showing the pelvic plexus. The
plexus is formed by the coalescence of the seventh^ eighth
and ninth spinal nerves — the last of which emerges from
the neural canal between the sacrum and urostyle. These
nerves unite at some distance from the vertebral column and
immediately give off a nerve (indicated by a black bristle)
that breaks up into ilio-hypogastric and>crural branches.
The latter supples the rectus femoris anticus, ilio-psoas,
pectineus, and adductor longus, thus combining in part

* The following specimens also show the pelvic plexus, or nerves of the
leg:— C. 179, C. 180, Crocodilus; C. 187, Apteryx ; C. 188, Pauxi; C. 190,
Dendrocygna ; C.lQl, JButeo; 0.192, Cathartes; C.l^Z, Buceros; C.207a,
Dasyurus; C. 209, Myrmecophaga ; C. 216, Elephaa; C. 232, 0. 233,
llylohates; C, 242, Anthropopithecua troglodytes.

28

PHYSIOLOGICAL SERIES.

the distributions of the anterior crural and obturator
nerves o£ higher Vertebrates. The main trunk derived
from the plexus forms the sciatic nerve, and passes to the
outer side of the leg behind the ilium. Its distribution is
shov\rn in the next specimen.

D. 845. Left hind-limb of a Bull-Frog [Rana catesbiana), with
the distribution of the nerves shovv^n. The whole mus-
culature of the limb, with the exception of the muscles
mentioned in the description of the previous specimen as
being supplied by the anterior crural trunk, is innervated
by branches of the great sciatic nerve. The chief trunk of
this nerve passes down the thigh between the biceps and
the semimembranosus. Its branches to the thigh muscles
(adductors, extensors and flexorsj are given off soon after
its passage into the limb. At the lower end of the thigh
it divides into two main trunks, that pass respectively
on either side of the tendon of insertion of the biceps.
The outer of these (peroneal nerve) supplies the skin on
the outer surface of the knee and the extensor muscles of
the shank and foot. Below the knee it divides into two
branches that again unite, after passing one on either side
of the flexor tarsi posterior, to form a common trunk from
which are given off the nerves for the extensor surface of
the foot. The inner trunk subdivides in the hollow of the
knee into tibialis and suralis nerves. The latter innervates
the gastrocnemius and is distributed to the skin of the
shank and sole of the foot. The tibialis runs within the
substance of the tibialis posticus and is finally distributed
to the flexor muscles of the foot. A delicate commissure
unites the tibialis and suralis nerves across the point of
the heel.

Ecker's Anat. des Frosches, 2* Aufl. Gaupp, Abt. 2,
p. 191.

AVES.

In groups higher than the Amphibia, the pelvic plexus can be
subdivided into three distinct parts— a crural plexus from which
nerves are distributed to the extensor muscles ot the thigh ; a
sciatic plexus for the innervation of the flexors of the thigh
and the muscles of the shank; and a pudendal plexus for the

NERVOUS SYSTEM. VERTEBRATA.

29

supply of the perineal region. The boundaries between these
several parts are marked in each case by a divided root that
contributes a branch to either plexus. The nerve that shares
thus in the formation of the crural and sciatic plexuses, is known
as the furcal, that which stands in a similar relation to the
sciatic and pudendal, as the bigeminal.

The separation of the roots of the plexus into dorsal and
A^entral divisions from which respectively the extensor and
flexor aspects of the limb receive their nerve-supply, is less
clearly marked in the pelvic than in the brachial plexus. The
obturator, by which the adductors are innervated, is however
always unmistakeably a derivative of ventral divisions, and the
crural trunk almost as clearly of dorsal.

D. 846. Part of the body and right hind-limb of a Ki-Wi
[Apteryx oioeni), showing the crural and sciatic plexuses
and the distribution of some of the nerves that arise from
them. The crural plexus is composed of the anterior
branch of the furcal nerve and three whole roots ; the
sciatic plexus of the posterior branch of the furcal nerve
and five whole roots. The nerves given off from the
plexuses are, so far as shown, essentially similar in their
origin and distribution to those of the Heron (D, 847).

D. 847. Part of the vertebral column and of the right hind
limb of a Heron (Ardea cinerea), showing the crural,
sciatic, and pudendal plexuses and the distribution of the
nerves of the limb. The crural plexus is composed of three
whole roots (the anterior of which is very small) and of
the anterior branch of the furcal nerve. It gives off a
bundle of branches for the innervation of the extensor
cruris, sartorius, and skin on the outer side of the thigh,
and from its lowest part a nerve (peculiar, it is said, to
Birds, Crocodiles, and Monotremes) that passes between
the femur and the ilio-femoralis internus, supplies that
muscle, and is ultimately distributed to the knee-joint and
skin on the inner surface of the shank. It is marked in
the specimen by black paper. The obturator nerva arises
by two roots from the ventral surface of the second and
. third components of the crural plexus; within the pelvis it

30

PHYSIOLOGICAL SERIES.

innervates the obturator muscle, but in this specimen its
further distribution to the accessorins obtnratoris and pubi-
ischio femoralis is not shown. The sciatic plexus consists
of the posterior branch of the furcal nerve and four whole
roots; it has apparently no connection with the pudendal
plexus. The sciatic nerve before passing through the pelvis
gives off branches to the ilio-fibularis (biceps), caudi-ilio-
flexorius (semimembranosus), and ischio-flexorius (semi-
tendinosus), and to the skin of the back of the thigh.
External to the pelvis it divides into two trunks. The
upper of these passes through the sling of the biceps in the
hollow of the knee, and after giving off small branches to
the extensors of the shank, continues, as two cords (marked
by a red rod) , to the foot. The lower trunk subdivides,
about the middle of the thigh ; its upper branch passes
through the sling of the biceps and beneath the outer head
of the deep flexor, to the outer malleolus ; its ultimate
distribution to the foot is not shown. The lower branch
divides in the hollow of the knee into numerous branchlets
that supply the gastrocnemius and superficial and deep
flexors of the shank.
D. 848. Eight hind-limb and part of the vertebral column of
a Hornbill (Buceros sp.), showing the crural, sciatic, and
pudendal plexuses and the distribution of the chief nerves
of the limb. The plexuses include remarkably few spinal
nerves. Two whole roots and the anterior branch of the
furcal nerve combine to form the crural plexus, and the
posterior branch of the furcal nerve three whole roots and
the anterior branch of the bigeminal, the sciatic. The
obturator nerve arises by two roots given off respectively
from the distal and proximal ends of the anterior arm of
the furcal nerve. The nerve distribution to the muscles
of the limb is essentially the same as in the Heron.

MAMMALIA.
MONOTREMATA.

D 849. Part of the vertebral column of a Duck-billed Platypus
(OrnithorliyncKus anatinus), showing the crural and sciatic
plexuses. Both are remarkably small, including together
only four spinal nerves-the two last thoracic and the two

NERA'^OUS SYSTEM. — YERTEBRATA,

31

lumbar. The crural plexus is formed by two whole roots
and the anterior branch of the furcal nerve. The obturator
nerve is derived from the crural plexus only, although a
delicate anastomosis passes outwards from its root to the
furcal nerve. The sciatic plexus has only one whole root.
Westling, Bihang Kgl. Sven. Vet.-Akad. Handlingar,
Bd. ix. 1884-5, p. 36.

D. 850. Right hind-limb and part of the vertebral column of a
Spiny Anteater {Tachyglossus [EcUdnd] aculeatus), show-
ing the crural and sciatic plexuses and the distribution of
the nerves arising from them. The plexuses are far larger

Fig. 7.

The pelvic plexus of Tachyglossus aculeatus.

A.CR. Anterior crural. I.SPH. Internal saphenous. L. Lumbar vertehrce.
OBT. Ohturator. S. Sacral vertebrae. SC. Sciatic. TH. Thoracic
vertebrae.

than in Ornithorhynchus, including altogether seven spinal
nerves — the last two thoracic, three lumbar, and the first
two sacral. The second lumbar nerve is the furcal. The
four roots of the crural plexus combine two and two to
form two cords that later unite and give origin to a large
bundle of crural nerves. The obturator nerve is derived
by three roots from the two anterior components of the
crural plexus. The sciatic plexus is formed by the posterior
branch of the furcal nerve, two whole roots, and the anterior
branch of the bigeminal nerve.

.'52

PHYSIOLOGICAL REIUES,

MARSUPIALIA.

D. 851. Part of the vertebral column with the right hip and
thio-h of a Wallaby [Petrogale penicillaia) , showing the
pelvic plexus. The crural part of the plexus has two roots
derived from the third lumbar and the furcal nerves.
Each root gives off a ventral division for the formation of
the obturator. The cutaneous branches of the anterior
crural nerve are shown on the inner surface of the thigh.

The sciatic plexus is composed of the minute posterior
branch of the furcal nerve, two whole roots (the fifth and
sixth lumbar nerves), and the anterior branch of the bige-
minal (first sacral) nerve. The second and third lumbar
nerves give origin to genito-crural and external cutaneous
branches.

Parsons, Proc. Zool. Soc. 1896, p. 710.

D 852. Left hind-limb of a Wallaby (Petrogale penicillata),
showing the distribution of the anterior crural and sciatic
nerves." The muscular branches of the anterior crural to
the extensors of the knee are more clearly shown than in
the previous specimen ; they are numerous and well deve-
loped The sciatic nerve during its passage past the sciatic
notch gives off a strong bundle of nerves to the hamstring
muscles. The main trunk passes behind the great tro-
chanter as a single cord, and then shortly divides into
three branches-short saphenous, for the supply of the skm
upon the outside of the leg and of the fifth toe, and
internal and external popliteal, the former for the inner-
vation of the calf muscles, the latter for that of the ex-
tensors of the leg and of the dorsal surface of the foot. It
should be noticed that in correspondence with the absence
of the first toe there is no anterior tibial branch.
Parsons, Proc. Zool. Soc. 1896, p. 710.

EDENTATA.

D 853 Right hind.limb and part of the vertebral column of a
Three-toed Sloth (Bradr/pus tridactylus) , showing the
iral and sciatic plexuses and the distribution of the chief

crui

NERVOUS SYSTEM. — VEETEBRATA.

33

nerves of the limb. The crural plexus (seen best on the
left side of the specimen) is formed by roots derived from
the second, third, and fourth (furcal) lumbar nerves. A
ventral branch from its last whole root joins a branch from
the posterior (sciatic) division of the furcal nerve to form
the obturator nerve. The sciatic plexus consists of four
roots — the posterior division of the furcal nerve, two whole
roots (the first and second sacral nerves), and the anterior
division of the bigeminal (third sacral) nerve. The further
course of the sciatic nerve is shown on the reverse side of
the specimen. In the thigh it innervates the flexors in-
cluding the praesemimembranosus, and then divides in the
hollow of the knee into external and internal popliteal
branches. Thfe latter innervates the flexors of the shank
and foot ; the former subdivides into short saphenous,
peroneal and musculo-cutaneous, and anterior tibial nerves
that respectively innervate the soleus and the skin on the
outer side of the foot, the peronei and the dorsum of the
foot, and the extensors of the shank.

D. 854. The pelvis with the hinder end of the body of a Two-
toed Sloth (Cholcepus didactylus), showing the pelvic plexus.
This differs from that of Bradypus in the inclusion of an
extra root: the crural plexus being formed by the first
three lumbar nerves, and the sciatic by the third and fourth
lumbar and the first three sacral. The third lumbar nerve,
and not as in Bradypus the fourth, is the furcal nerve.
The origin of the obturator is essentially the same as in
Bradypus.

UNGULATA.

D. 855. The left hind-limb and part of the trunk of a Goat
{Capra hircus), showing the pelvic plexus and the nerve-
supply to the limb. The plexus is formed by the last three
lumbar nerves and the first two sacral, the last lumbar
bemg the furcal nerve. The obturator arises by two roots
derived respectively from the united whole roots of the
anterior crural and from the stem of the furcal nerve.
The branches of the Bciatic to the hamstring muscles and
VOL. HI. - ^

34 I'HYSIOLOGICAL SERIES.

its internal and external popliteal divisions are shown by
the removal o£ parts of the gracilis, semimembranosus, and
adductors.

RODENTIA.

D. 856. Part of the trunk and right hind-limb of a Rabbit
(Lepus cuniculus), showing the pelvic plexus. The anterior
crural nerve is mainly derived from the sixth lumbar, it
receives a small root from the fifth lumbar, but no con-
tingent from the furcal (seventh lumbar) nerve. The
sciatic nerve has only one whole root-the first sacral
nerve. This feature is general among Rodents. The
obturator, as usual, has two roots derived respectively from
the anterior crural and the furcal nerves.

Krause, Anat. des Kaninchens, 1868, p. 252.

INSECTIVORA.

D 867. Left hind-limb and part of the vertebral column of a
Hedgehog (Erinaceus europceus), showing the pelvic plexus
and the course of the chief nerves of the Hmb. The crural
plexus results from the combination of two whole roots (the
second and third lumbar nerves) with the anterior division
of the furcal nerve (the fourth lumbar). The sciatic plexus
consists of the posterior division of the furcal nerve, two
^hole roots (the fifth and sixth lumbar nerves), and a minute
branch of the bigeminal (the first sacral) nerve. The
obturator is derived from the posterior division of the furcal
nerve and from the two whole roots of the anterior crural.
Isolated specimens of the plexuses of another individual are
mounted at the side to show more clearly than in the entire
specimen the relations of the furcal nerve to the crural and
sciatic plexuses and to the obturator nerve.

D 858 Right hind-limb and part of the trunk of a Golden Mole
( Chrysochloris trevelyani) , showing the pelvic plexus. This
s smaller than in the Hedgehog, and consists of only five
roots-a whole root (second lumbar nerve) and the anterior
division of the furcal nerve forming the crural plexus, and

NBRYOUS SYSTEM. VERTEBRATA.

35

the posterior division of the furcai, two whole roots, and
the anterior division of the bigeminal (second sacral), the
sciatic.

Ptilvio piexus of Chrysochloris trevelyani,

A.CR. Anterior crural. OBT. Otturator. SC. Sciatic. Dotted : the
obturator root from the anterior crural. Horizontal lines: lumbar
vertebrsB. Vertical lines ; sacral vertebrae.

CHIROPTEEA.

D. 859. The posterior end of the vertebral column, with the
pelvis and left hind-limb of a Fruit Bat {Pteropus edwardsi),
showing the pelvic plexus. The last lumbar but one is the
furcai nerve. It gives off roots to the anterior crural (visible
with difficulty and only on the right side) and to the ob-
turator. The anterior crural is also derived from the two
lumbar nerves above, and the sciatic from the last lumbar
and first sacral. Upon the left side the branches of the
sciatic nerve have been exposed.

PEI MATES.

L. 860. The left leg and hip of an Orang-utan {Simia satyrus),
showing the distribution of the nerves that arise from the
pelvic plexus. In comparison with the same system in
Man, it may be noted that, the anterior crural divides up

D 2

3G

PHYSIOLOGICAL SERIE3.

into its several main branches while yet within the pelvis,
the middle cutaneous being given off while the nerve is still
under cover of the ileo-psoas muscles, and the combined
internal saphenous and pectineal branch leaving the main
trunk some 2 inches (5 cm.) within the brim of the pelvis.

The great sciatic, as it passes the trochanter gives off a
large branch for the hamstring muscles ; later it divides
in the usual way into internal and external popliteal
branches. Elaborate descriptions of the plexuses and
limb-innervation in the Anthropoid Apes and detailed
comparison with the same structures in Man will be found
in the following papers : —

Bolk, Morph. Jahrb., Bd. xxv. 1898, p. 305.

Saberton, Stud. Anat. Univ. Manchester, Young, vol. iii,
1906, p. 166.

Sperino, Anat. d. Ohimpanse, p. 434.

D. 861. Right half of the posterior end of the vertebral column
of a Chimpanzee (Anthropopithecus troglodytes), showing
the pelvic plexus. The anterior crural nerve is formed
by the union of the second and third lumbar nerves with
branches from the first and fourth. The posterior division
of the fourth lumbar (f ureal) nerve combines with the first
«acral and with the anterior division of the second sacral,
to form the sciatic nerve. The obturator arises by three
roots, derived respectively from the two whole roots of the
anterior crural and from the furcal nerve. This plexus
closely resembles that of Man except for the presence of
only one whole sciatic root.

D 862 The left leg and hip of a Chimpanzee (Anthropopithecus
troglodytes), showing the distribution of the nerves that
arise from the pelvic plexus. The main branches of the
anterior crural and sciatic nerves closely resemble in their
general disposition and mode of branching those of Man,
and apparently show none of the peculiarities noted m the
previous specimen of the Orang-utan.

NERVOUS SYSTEM. — VBUTEBRATA.

37

Sympathetic System.

The sympathetic is a portion of the cerebro-spinal system set
apart for the innervation of the viscera and the control oi: the
blood-vessels, glands, and involuntary muscles. The nerves
that compose it consist of visceral motor and to a less extent
of visceral sensory components. Branches of the spinal and
also in most caseSj of the cranial nerves, containing both afferent
and efferent fibres, form connections (rami communicantes)
with a series of ganglia (vertebral sympathetic ganglia) . From
these ganglia fibres, more numerous than those that enter by
the rami communicantes, are given off for the innervation of
the visceral and vascular system either directly or through the
mediation of secondary (prevertebral) sympathetic ganglia.

An anatomically separate sympathetic system has not hitherto
been discovered in the Dipnoi, and in Cyclostomes it is ex-
tremely rudimentary ; but in the other classes of Vertebrates it
is always present, sometimes only in the trunk region (Elasmo-
branchs), though usually extending from the trigeminal to the
hinder end of the body or even (Teleostea, Urodeles) to the tip
of the tail. In Mammals it consists of a cranial part which is
derived from certain fibres in the 3rd, 7th, 9th, and 10th cranial-
nerves, and of a spinal part which is wholly derived from the
thoracic and anterior half of the lumbar spinal nerves : the other
spinal nerves not contributing to it at all. Behind the head,
the vertebral ganglia are arranged on either side of the mid-
line in linear series united by longitudinal connectives, the
whole being known as the sympathetic cord. The nerves that
spring from these ganglia are chiefly gathered together at
certain points to form plexuses and ganglionic masses, from
which are given off nerve filaments for the various visceral
regions. Thus in Mammals^ where these nervou'5 concentra-
tions are most definite, cardiac, solar, and hypogastric plexuses
can be distinguished for the supply of the thoracic, abdominal
and pelvic viscera. Sympathetic fibres are also distributed to-
the blood-vessels and the sweat-glands and the arrectores of the-
hairs of the skin.

Jaquet, Arch, des Sci. Med., I. v. 1900, p. 163.

GaskcU, Jour. Physiol., vol. vii. 1886, p. 1.

38

rilYSlOLOGICAL SERIES.

PISCES.
ELASMOBRANCIIII.

D, 863. Part of tbe trunk of a Hay {Raja clavata), showing
portions of the sympathetic nervous system stained with
osmic acid. The most anterior sympathetic ganglion is
intimately united with the foremost adrenal body. It Kes at
the side of the oesophagus close behind the " diaphragm,"
and receives a large number of rami communicantes
from the anterior spinal nerves (seven are visible in this
specimen). From its medio-ventral border a number of
anastomosing branches follow the coeliac and superior
mesenteric arteries to the abdominal viscera.

Other sympathetic ganglia lie within the mesentery, either
free or in connection with the adrenal bodies. The latter
receive connectives from the spinal nerves and are con-
nected longitudinally by an irregular netw^ork of fibres,
which spreads downwards over the mesentery and there
enters into connection with the above-mentioned isolated
ganglia. A minor splanchnic nerve formed by the con-
centration of the general mesenteric network accompanies
the inferior mesenteric artery.

Chevrel, Arch. Zool. Exp., t. v bis, 1887, p. 56.

AMPHIBIA.

D. 864. A Frog {Rana temporaria) with the sympathetic system
shown from the ventral aspect. Within the head, the
sympathetic cord extends forward to the trigeminus
{cf. D. 814) and passes backwards from this point across
the median surface of the periotic capsule to the root of
the vagus, with which it leaves the skull.

From the ganglion of the vagus it runs back closely
applied to the ventral surface of the hypoglossal (first
spinal) nerve and to the roots of the brachial plexus.
From this point to its termination upon the posterior root
of the sciatic plexus, the cord lies at some distance ventral
to the spinal nerves but is connected to each by a long
slender ramus communicans. The point of union of each
ramus with the cord is marked by a pigmented ganglion.

NERVOUS SYSTEM. VERTEBEATA.

39

In this specimen the cranial, spinal, and limb nerves are
also shown. 0. C. 1311 h.

Ecker's Anat. des Frosches, 2nd Aufl. Gaupp, Abt. 2,
p. 214.

REPTILIA.
EMYDOSAUEIA.

D. 865. Head and trunk of a young Alligator {Caiman sclerops)
with the sympathetic system exposed from the ventral
aspect- The cervical part of the system is- stated to be
double and to consist of superficial and deep cords. In
this specimen the deep cord only is shown passing back-
wards within the vertebral canal. The cord is connected
with each spinal nerve as it passes it, but shows no sign of
ganglionic enlargement except at the hinder part of the
neck in the region of the brachial plexus, where ganglia
are well marked. Several of the cervical ribs have been
removed to expose this part of the system more clearly.
A double connective embracing the transverse process of
the vertebra unites the last brachial with the next following
ganglion.

On a level with the seventeenth to the twentieth vei tebrs©
several large branches are given off from the sympathetic
cord to form the chief visceral plexus of the body. Beyond
this point the cord is not shown.

Jaquet, Arch, des Sd. Med., T. v. 1900, p. 18ff.

CHELONIA.

D. 866. Head, neck, and body of Sternotherus derbianus, showing
portions of the sympathetic system. In the neck, the
sympathetic cord accompanies the vagus, and shows in the
specimen three small ganglionic enlargements, the last of
which is situated opposite the anterior roots of the brachial
plexus. This is succeeded by two ganglia lying upon the
posterior roots of the plexus, and from that point back-
wards the sympathetic chain is represented by a delicate
cord, closely adherent to each spinal nerve.

Jaquet, Arch, des Sci. Med., T. v. 1900, p. 187.

40

FHYSIOLOGICAL SERIES.

AVES.

Th(^bault, Ann. Sci. Nat., s6r. 8, T. vi, 1898, p. 1.

D. 867. The vertebral column and neighbouring parts of a Wild
Duck (Anas boscas), showing the ganglionated cords of the
sympathetic system and the origin of the splanchnic nerves.
In the cervical region the sympathetic cords lie within the
rertebral canal closely united by a series of ganglia to the
successive spinal nerves. A superficial cord (not shown in
this specimen) is stated to accompany the vagus from the
anterior cervical sympathetic ganglion to the brachial plexus.
On a level with the brachial plexus the ganglionic chaiu
leaves the vertebral canal and lies upon the ventral surface
of the spinal nerves close to the vertebral column, united
to each by a large ganglion. The primary ganglia in the
trunk are connected by a single nerve strand that passes
dorsal to the ribs. An additional connective occurs ventral
to the ribs between the three anterior thoracic ganglia. The
great splanchnic nerve is formed by the union of branches
derived from the second, third, fourth, and fifth thoracic
ganglia. Branches from the three succeeding ganglia
combine to form the lesser splanchnic. In the abdominal
region the sympathetic cords are less developed and the
ganglia are further removed from the spinal nerves, being
connected with them by long rami communicantes.
Marage, Arm. Sci. Nat., ser. 7, T. vii. 1889, p. 16.

D. 868. The rectum of a Wattled Brush-Turkey {Catheturus
latlmmi), with its mesentery, showing the intestinal cord
of the sympathetic system. This nerve-cord runs in the
mesenteiV parallel to the rectum at about 10 mm. distance
from it, and gives ofF numerous minute branches to the
gut-wall. Anteriorly it is continuous with a less conspicuous
sympathetic cord (removed in the specimen) that follows
the course of MeckeFs loop and arises in the gastric plexus.
Posteriorly it receives several strong branches from the
hinder end of the abdominal sympathetic and spreads out
on the cloaca.

The cord is double in its posterior half, and shows here
and there indistinct ganglionic enlargements.

NERVOUS SYSTEM. VERTEBRATA.

41

MAMMALIA.
Jaquet, Arch, des Sci. Med., T. v. 1900, p. 203.

UNGULATA.

D. 869. Head and trunk of a Goat (Capra Jiircus), with the
sympathetic system shown from the left side. The general
arrangement of the sympathetic cords is very similar to
that of the Cat (D. 871). The combined posterior cervical
and anterior thoracic ganglion is, however, relatively not so
large, and has rami communicantes to the last two cervical
and the first thoracic spinal nerves only. The ramus to the
seventh cervical is, however, continued forward in a series
of loops (indicated by black bristles) from nerve to nerve
within the vertebral canal, where it goes by the name of
the vertebral nerve. This nerve occurs in several Mammals,
but not in Man, and may extend forward as far as the
cranium. The close union of the free part of the cord
between the anterior and posterior cervical ganglia with the
vagus trunk is well shown. The posterior cervical and the
first, fifth, and sixth thoracic ganglia contribute to the
cardiac plexus. Splanchnic nerves for the solar plexus
arise from the twelfth, thirteenth, fourteenth, and fifteenth
thoracic ganglia, and branches are given off opposite the
kidney to form the hypogastric plexus.

D. 870. One of the semilunar ganglions of a Horse (Equus
cahallus). 0. G. 1383. Hunterian.

CAENIVORA.

D. 871. Head and axial parts of the trunk of a Cat [Felis
domestica), showing the sympathetic cords from the ventral
aspect together with some of the branches and plexuses
given off from them. Within the neck, the cord stretches
free between an anterior cervical ganglion (on a level with
the ganglion nodosum of the vagus) and a small middle
cervical ganglion situated opposite the last cervical vertebra.
Branches are contributed from both these ganglia to the
cardiac plexus. The middle cervical ganglion is connected
by two cords to the combined posterior cervical and anterior
thoracic — a large compound ganglion united by rami com-

42

rHYSIOLOGICAL SERIES.

municantes to the last two cervical and first three thoracic
spinal nerves, from which a strong branch is contributed to
the cardiac plexus. Between this ganglion and the dia-
phragm, the cord is represented by a chain of small ganglia,
each connected by a ramus communicans of variable length
to a spinal nerve. The ganglia on the confines of the
thoracic and lumbar regions supply splanchnic nerves to
the solar plexus and semilunar ganglion. Behind the
diaphragm, the ganglia of the chain become somewhat
larger and the cords approximate to the axial line.

PRIMATES.

D 872. A human semilunar ganglion, showing its great size in
comparison with that of the Horse. 0. C. 1382.

Hunterian.

OEGANS OF SPECIAL SENSE.

43

E.

ORGANS or SPECIAL SENSE,

John Hunter, Croonian Lecture on Muscular Motion, No. 1,
1776. Works of Hunter, Palmer, vol. iv.
p. 198. Lectures on the Principles of Surgery,
ibid. vol. i. p. 261.
Essays and Observations, edit. R. Owen, vol. i.
p. 165.

Retzius, Biol. Untersuch. N. F. iv. 1892, p. 49.

All living matter is in a general way responsive to alterations
in the condition of the media in which it exists. But apart
from this general sensitiveness, in Metazoa certain cells either
belonging to or derived from the integument are modified in a
definite manner to respond to particular kinds of stimulation only^
and so form specific organs of sense. Thus, there are special
organs of touch affected only by alterations in pressure, organs of
taste and smell for the discrimination of certain chemical properties
of matter when in solution, organs of hearing for the apprecia-
tion of material (sound) vibrations, organs of vision and light-
perception responsive in an analogous way to etherial (light)
vibrations, special organs of equilibration (response to altera-
tions in the position of the body) which usually are combined
with the auditory organs, and, in the lower Vertebrates and in
Invertebrates, certain sense organs of unknown function.

Besides these special sense organs, examples of which are
included in this section, mention must also be made of sense
organs for the perception of temperature variations, and of the
muscular sense by which the amount of the coAtraction of the
muscles is gauged, although in the absence of any concentration
of the minute end organs concerned upon special modified parts
of the body, they cannot be represented in this collection.

The mechanism for the reception and transmission of sensory
stimuli consists in its simplest terms of an epidermal senso-
neural cell, provided distally with a process which is directly
acted upon by the exciting cause, and drawn out proximally

41

VHYSIOLOGICAL SERIES.

into a conductive filament (afferent nerve-fibre) that conveys
the stimulation to a nerve centre composed of the aggregation
of similar afferent fibres with motor and connecting nerve
elements. It seems probable (Retzius) that during tlie course
of evolution the senso-neural cells which, in simple animals
{e. g. Annelida), retain their primitive position in the epidermis
and may even still be found there in the highest animals in
special sense organs {e. g. the nose), have gradually migrated
into the body towards the central nervous system, where they
form the sensory ganglia upon the cranial and spinal nerves,
and at the same time retain their connection with the integu-
ment or sensory epithelium of the special sense organs by
filiform processes (aff"erent nerve-fibres) that end either freely
between the cells of the epithelium or in contact with particular
cells which have been secondarily developed to form the special
receptive end organs for the various senses.

TACTILE ORGANS.

John Hunter, Oroonian Lecture on Muscular Motion, No. 1,
1776. Works of Hunter, Palmer, vol. iv.
1837, p. 198.
Essays and Observations, edit. E. Owen, vol. i.

p. 182.

INVERTEBRATA.

Although in the simpler Metazoan Invertebrata the restriction
of each sensory end organ to response to one particular form of
stimulation is probably not complete, in the majority certain
sense-cells which are chiefly concentrated upon feelers or similar
appendages are solely or pre-eminently tactile. These cells he
in the surface-epithelium when the integument is soft and moist,
and are thread-like with a terminal process or tuft of processes
projecting freely into the surrounding medium ; b"t when the
body is covered with a hard cuticle {e.g. Arthropods) they he
deeper, and are stimulated indirectly by the movements of
special cuticular setse.

ORGANS OF SPECIAL SENSE. — IN VEUTEBRATA.

45

CCELENTERATA.

E. 1, The oral disc with tlie surrounding tentacles of a Sea
Anemone (Actinia sp.). The tentacles, which, in addition
to their offensive, defensive, and food-capturing functions,
may be regarded as tactile organs of a very simple cha-
racter, are hollow processes of the body-wall, and are the
special seat of sensory cells. The epithelial sense-cells in
the Actiniae are stated (Hertwig) to be elongated in form,
with a median or basal nucleus, and to be produced super-
ficially into one, or at most two, fine hair-like processes
and to give off from their deeper surface a number of fibrillae
that join the meshwork of nerve-fibres situated between
the outer epithelial and muscular layers of the body-wall.

0. C. 1386. Hunterian.
0. & R. Hertwig, Jena. Zeits., Bd. xiii. 1879, p. 478.

E. 2. A Sea Anemone {Anlhea cereus) with its crown of
tentacles extended.

E. 3. A craspedote Medusa {Olindias miilleri). The margin of
the umbrella is beset by a number of long flexible tentacles,
which, because of the large proportion of sensory cells in
their epithelial covering, are no doubt simple touch organs,
although they are also the special seat of nematocyst
batteries and are actively used in the pursuit of prey.
Between every two tentacles are small pear-shaped bodies
of unknown function, which may possibly be immature
stages of prey-catching tentacles ; or perhaps organs of
equilibration.

Miiller,. Arch. f. Naturgesch., Bd. xxvii. 1861, p. 314.

E. 4. An acraspedote Medusa (Pelagia noctiluca) . The umbrella
edge is divided by sixteen indentations, alternately shallow
and deep, into a series of sensory folds. Eight long (30-
40 mm.) tactile tentacles arise from the margin in the deeper
clefts, and within the shallower clefts, enveloped in processes
of the sensory folds, are peculiar sense-organs (rhopala) of
unknown function, though possibly they may be in some
sense equilibrating organs, A typical rhopalon consists

46

PHYSIOLOGICAL SERIES.

of a minute finger-shaped process containing at its free
end a mass of crystals embedded in the cells of the endo-
derm, and with its base surrounded by a pad of elevated
sensory epithelium. Upon the upper margin of the speci-
men two rhopala have been displayed by removing the
greater part of the sensory folds ; they have the appearance
of two black specks. The other rhopala can also be seen,
though with more difficulty, deeply buried between the
sensory folds.

0. & R. Hertwig, Das Nervensystem u. Sinuesorg. der
Medusen, 1878, p. 109.

ANNELIDA.

Jourdan, Ann. Sci. Nat., ser. 7, T. xiii. 1892, p. 227,
Retzius, Biol. Untersuch., N. F. iv. 1892, p. 1 ; vii.

1895, p. 6; viii. 1898, p. 94 ; ix. 1900, p. 85 ; x. 1902,

p. 25.

E. 5. The anterior part of a Marine Worm {Marphysa sanguinea).
The head region is provided with five straight tactile ten-
tacles, situated upon the prostomium and innervated (c/.
D. 5) from the mid-brain. Small conical tactile cirri occur
also upon each body segment, one at the base of each
neuropodium and notopodium. These though minute are
distinctly visible in the region of the body anterior to the
gills.

ARTHROPODA.
von Rath, Zeits. f. Wiss. Zool., Bd. Ixi. 1896, p. 499.

CRUSTACEA.

von Rath, Zool. Anz., Bd. xiv. 1891, pp. 195, 205.
Retzius, Biol. Untersuch., N. F. vii. 1895, p. 12.
E. 6. The brain and left antenna of a Lobster {Homarus vulgaris).
The antenna consists of a long filament (flagellum) borne
upon three enlarged basal joints. The distal (filamentary)
part is covered with large numbers of tactile hairs and
although very flexible, owing to its cuticle consisting alter-
nately of rings of soft and hard chitin {cf. B. 45), has no
power of movement in itself but can only be directed as a

ORGANS Of SPECIAL SENSE. — INVERTEBTIATA. 47

whole to any desired spot by the action of suitable muscles
upon the three basal joints. The nerve for the antenna arises
from the side of the brain, and until it reaches the base of
the flagellum contains both motor and sensory fibres. From
this point it becomes purely sensory and divides into a
brush of separate fibre bundles.

INSECTA.

E. 7. A Black-beetle (Periplaneta orientalis). The antennse are
long, filiform and flexible, and probably serve chiefly as
organs of touch, although the histology of the brain centres
from which they are supplied (cf. D. 27) and the structure
of some of the end organs upon them suggest that they
possibly also have an olfactory f anction. The brain has
been exposed to show the large antennary lobes upon its
anterior surface from which the nerves to the antennge arise.

MOLLUSCA.

Eetzius, Biol. Untersuch., N. F. iv. 1892, p. 11 ; ix. 1900,
p. 94.

E. 8. The soft parts of a Scallop (Pecten maximus) minutely
injected. The left lobe of the mantle and corresponding
branchiae have been removed showing the muscular organ
called the " foot/' which protrudes from the antero-ventral
surface. It terminates in an expanded disc, which is an
organ of adhesion and (in the young) subservient to loco-
motion as well as touch. Numerous small tentacles or
feelers are arranged along the thickened margin of the
mantle, and the sense of touch is probably further exercised
by the highly vascular fimbriated palps that extend from
either side of the mouth. Their situation is indicated by a
bristle which is placed in the mouth.

0. C. 1388. Himterian.
Eawitz, Jena. Zeitschr., Bd. xxii. 1888, p. 478.

E. 9. A similar specimen in which the blood-vessels have not
been injected.

E. 10. A Cockle {Cardium norvegicum) with the hinder parts of
the valves removed to expose the mantle border in this

48

PHY'SIOLOGICAL SERIES.

region and the siphons. Tentacles, chiefly it would seem
of tactile function, are confined to these parts of the mantle
edge, this being the only part of the mantle expo.^ed in the
ordinary half-buried position of the animal. The mouth
of the incurrent (lower) siphon in particular is guarded by
a fringe of slender tentacles that overhang the orifice.
Drost, Morph. Jahrb., Bd. xii. 1887, p. 163.

VERTEBRATA.

In Vertebrata, as in Invertebrata, the sense of touch is dis-
tributed over all parts of the body surface, but certain areas
are in a higher degree than others the seat of tactile nerve-
endings and are also frequently modified in form to fit them to
act in a special sense as organs of touch.

Amongst the numerous kinds of sensory nerve terminations
that occur in or beneath the skin, it is extremely difficult to
determine which are those specially adapted for the reception of
tactile impressions. In Fishes and aquatic Amphibia the sense
of touch is probably lodged, to some extent, in certain end
organs known as " nerve-buds " which occur in various places
upon the surface of the skin and resemble " taste-buds in
structure (in many Fishes taste-buds with truly chemical,
i. e. gustatory function, are found on the outer surface of the
head, especially in barbules &c.). In the higher, land Vertebrates
the specific functions of the various cutaneous nerve-endings are
most obscure. In Mammals certainly, hairs in all parts of the
body are extremely sensitive to touch and no doubt are particu-
larly well adapted to stimulate, by the movements of their roots,
tactile end organs in the deeper part of the skin. These end
organs, in the case of special bristles, such as the " whiskers "
of Carnivora or the bristle-like feathers at the root of the beak
in some Birds, are most probably the " tactile cells " found at
the base of these structures, but in the case of ordinary hairs
such cells have not been observed, and it must be supposed that
the stimulation is received by the meshwork of nerve fibrill»
that envelopes the hair follicle.

There is also much reason to include amongst organs of touch
the "touch (Meisner's) corpuscles" which occur in great numbers

ORGANS OF SPECIAL SENSE. — VERTEBRATA.

49

in tbe dermal papillaa of the hairless parts of the skin (palmar
and plantar surfaces of Man), and, in Birds, Grandry's corpuscles
and, in Amphibia, the touch spots.

As regards the functions of the other cutaneous sensory norve-
endings — free filamentary nerve terminations. Pacinian cor-
puscles, end-bulbs (Krause's corpuscles), Ruffini's corpuscles, &c.
— very little definite is know^n, but it seems likely that they are
influenced rather by temperature, pain, and muscular sense
impressions, than by touch.

PISCES.

Jobert, Ann. Sci. Nat., ser. 5, T. xvi. 1872, p. 29.
Tactile organs on the Head.

GANOIDEI.

E. 11. A portion of the skin from the lower surface of the
snout of a Sturgeon {Acipenser sturio) including two
tactile barbels. Bristles have been inserted into the
orifices of some of the mucous canals, which are situated
abundantly on this part of the head (see Organs of the
Lateral Line\ 0. C. 1397. Huiiterian

Dogiel, Arch. f. mikr. Anat., Bd. xlix. 1897, p. 769.

E. 12. A portion o£ the lip of the same Sturgeon, showing its
villous surface. This is probably specially sensitive to
tactile impressions. 0. C. 1396. Huntenan.

TELEOSTEA.
Leydig, Zool. Jahrb., Bd, viii. 1895, p. 1.

E. 13. A Bed Mullet (Mullus harhatus). Two white, stifi" barbels,
part of the hyal apparatus, are attached to the chin. They
are constantly used as touch organs when the fish is feeding
on the bottom. When swimming freely in the water, they
are completely concealed in a groove beneath the head.

Preserved in 50 per cent, glycerine.

Jobert, Ann. Sci. Nat., ser. 5, T. xvi. p. 59.

E. li. A Cat-fish {Bagrus docmac). The mouth is surrounded
by eight flexible tactile barbels of different length. On
VOL. in. B

50

PHYSIOLOGICAL SERIES

either side, one arises from the front margin o£ tlie posterior
nostril, one — by far the longest — from the skin covering
the upper jaw, and two from the posterior edge of the
mandible. The Cat-fishes are bottom feeders.

E. 15. The head and fore part of the trunk of a Three-bearded
Rockling {Motella tricirrata). Upon the head there are
three tactile barbels — two formed by a prolongation of the
upper border of the anterior nostrils, and the third upon
the chin. The pelvic fins are also modified, by the elonga-
tion and marked sensitiveness of the two anterior rays, to
act as special organs of touch. They appear to be the
chief agents in the search for food. The way in which
they are used has been described by Bateson ; he says :
" The Rockling searches by setting its filamentous pelvic
fins at right angles to the body, and then swimming about
feeling with them. If the fin touch a piece of fish or other
soft body, the Rockling turns its head round and snaps it
up with great quickness.'^

Bateson, Jour. Mar. Biol. Assoc., vol. i. 1889, p. 214.

E. 16. The head of a Sole (Solea vulgaris). In this fish the
surface of the face, on the blind side, is covered by a
number of small conical sensory papillae, which are used
in the search for food. As the fish crawls over the sea-
floor by means of its dorsal and ventral fin-rays, it pats
about with its head, thus bringing the papilla on its cheek
into contact with all parts of the underlying surface, and
by their means examining and testing any substance likely
to serve as food. As a rule the papillae are grouped in
clusters of five or six upon a common fleshy base. They
cover the whole blind surface of the face, with the ex-
ception of the lips and nostrils, and extend back as far as
the level of the sixth dorsal fin-ray. Behind that line they
occur only over certain areas : along the dorsal and ventral
margins of the head and upon the anterior parts of the
lateral line.

Bateson, Jour. Mar. Biol. Assoc., vol. i. 1889, p. 240.

ORGANS OF SPECIAL SENSE. — VERTEBUATA.

51

Tactile organs on the Pectoral Fins.

TELEOSTEA.

E. 17. An Indian Fisli {Polynemus paradiseus) that frequents
estuaries, feeding near the muddy bottom. The seven
lower pectoral fin-rays on each side are free and greatly
elongated, the upper three being often longer than the
body. They are used as touch organs. 0. C. 1398 b.

Tactile organs on the Pelvic Fins.

TELEOSTEA.

E. 18. A small (^2\icliogaster fasciatus). The pelvic fins

are represented by a pair of long tactile filaments.

O.C. 1398 A.

AMPHIBIA.
Leydig, Morph. Jahrb., Bd. ii. 1876, p. 287.

E. 19. A small part of the body with the right anterior extreraihy
of a Siren {Sirm lacertina). The limb is terminated by
four sti-aight digits which however are mutilated in the
specimen. In the Siren the anterior extremities alone are
developed, and apparently serve more as tactile than as
locomotive organs. 0. C. 1399. Hunterian.

John Hunter, Essays and Observations, edit. R. Owen,
1861, vol. ii. p. 393.

AVES.

E. 20. The cranium and upper mandible of a Spoon-bill {PlataJea
leucerodia), minutely injected to show the great vascularity
of the dilated extremity of the mandible, which in the
natural state is covered with a soft cuticle in which are
lodged numbers of special tactile end organs known as
" Herbst's corpuscles." The beak is thus well adapted to
the office of exploring in mud or sand for the small worms,
molluscs, &c., which constitute the food of this Bird.

0. C. 1402. Hunterian.
Jobert, Comptes Rendus, Ac. Sci., T. Ixxv, 1872, p. 1780.

E 2

52

PHYSIOLOGICAL SERIES.

E. 21. Hoad of a Duck (A7ias hoi>cas), in which some of the
main trunks of the trigeminus have been exposed. The
great size of this group of nerves in the Duck and certain
other Birds is necessary for the innervation of special
sense organs (Gandry's corpuscles), probably of a tactile
nature, that occur in groat numbers along the margins of
the beak and upon the surface of the mouth and tongue.
Ilesse, Arch. f. Anat., 1878, p. 288.

MAMMALIA.

In selecting examples of tactile organs among Mammals it
has been decided to ignore, except in a few cases, the special
tactile function of the ventral surfaces of the fore and hind feet,
for, apart from the hands of Primates, this is not their most
important function, which in almost all cases is locomotion.
The few specimens that haA^e been retained in this section to
show the ventral surface of the fore-feet, have been chosen with a
view to illustrate the arrangement and distribution of the papil-
lary ridges. These were probably at first developed to assist in
locomotion by the prevention of slipping, but among Primates,
and especially in Man, have become important accessories to
the organs of touch, by mechanically stimulating the end organs
in the underlying papillae by their movements due to friction
upon their exposed edges.

Whipple, Zeitschr. f. Morph., Bd. vii. 1904, p. 261.

Klaatsch, Morph. Jahrb., Bd. xiv. 1888, p. 407.

MONOTREMATA.

E. 22. Head of a Duck-billed Platypus {Ornitlxovliynchus
anatinus) with the calvaria removed. It shows the nume-
rous large branches of the trigeminus distributed to the
" bill.-" In the skin of the bill are vertically arranged
cylinders of epithelium (push rods), which can be slightly
depressed, and by thus compressing a group of Pacinian
bodies upon which they rest, initiate a centripetal nervous
impulse. ^- 1380 I.

Poulton, Quart. Jour. Micr. Sci., vol. xxxvi. 1894, p. 143.

E 23. A similar preparation with the lower jaw removed.

0. C. 1380 H.

ORGANS OF SPECIAL SKNSE.

— YEUTKBRATA.

53

MAESUPIALIA.

E. 2i. The right fore- and hind-foot of a Flying Phalanger
(^Petaunis sciureus). In the fore- foot (the left-hand
specimen) upon the ventral surface of the arm close above
the wrist, there is a slight integumentary eminence pitted
by several large hair follicles that during life lodged a
tuft of vibrissas. A similar tuft of relatively large hairs
(indicated by black paper) is present in a corresponding
position upon the ankle. Such tufts of vibrisste (sea
Nos. E. 28, E. 30, E. 31, E. 35, E. 36, E. 47, E. 55,
E. 56), are commonly found upon the wrist in those Mam-
mals whose fore-limbs are not solely used for walking.
The tuft on the ankle is rare. Although the use of these
tufts is not definitely proved, there can be little doubt that
they are special touch-organs comparable to the " whiskers "
of a Cat.

The skin upon the surface of the pads of the fore-foot
can be seen, though not very easily, to be corrugated by
delicate transverse ridges similar to the papillary ridges of
the palmar and plantar surfaces of Man.

♦Beddard, Proc. Zool. Soc, 1902, vol. i. p. 127.
Klaatsch, Morph, Jahrb., Bd. xiv. 1888, p. 407.

E. 25. The fore-feet of a native Cat {Dasyurus sp.). The
palmar surface is naked and is covered with small warty
■ excrescences of the integument except along the central
ridge of each foot-pad, where to (he naked eye the skin
appears smooth. A slight magnification (fig. 9, p. 54),
however, shows that the epidermis upon thege areas is
raised into a series of close-set parallel ridges arranged at
right angles to the long axis of the pad. These are
comparable to the papillary ridges of Primates, and like
them are probably accessories to the organs of touch.

* This specimen and Nos. E. 28, E. 30, E. 35, and E. 47, were selected
from those described by Mr. Beddard ; the rest of the dissections referred
to in his paper are preserved in the College stores.

54

PHYSIOLOGICAL SERIKS.

E. 26. The left fore- and liiiid-foot of an Opossum (Dideljihyt
. marsupialis). The foot-pads are large and prominent in
this species, and are covered all over by papillary ridges,

Fig. 9, Fig. 10.

Yig, 9— The first and second interdigital pads of the fore-paw of
Dasyurus sp.

Fig. 10.— Interdigital pad of the fore-paw of Didelphys marsupialis.

except in the case of the ulnar and last interdigital pads of
the fore-foot, which are smooth. The ridges upon the proxi-
mal pads are transverse in direction as in the Dasyure, but
upon the interdigital and terminal pads are more compli-
cated, being arranged in the first case in concentric loops
around the apex of the pad and in the latter case having
a longitudinal direction, those at the sides passing trans-
versely across the apex of the pad.

E 27. Rio-ht fore- and hind-foot of a Phalanger [Phalanger
maculatus). The system of papillary ridges is more highly
developed than in either of the previous specimens and
covers the whole of the plantar and palmar surfaces to the
roots of the digits, and occurs also upon the terminal
digital pads. In the hand, the palmar ridges are arranged
transversely upon the apices of the foot-pads, becoming
circumferential in the intermediate spaces, and in the
centre of the palm and around its margin being broken up
to form prominences intermediate in appearance between
papillary ridges and papillae. In the foot, fully formed
ridges cover the whole plantar surface, and, except upon

ORGANS OF SPECIAL SENSE. VERTEBRATA.

55

the apex of the fibular pad, are not clearly separable by
their direction into those upon the apex of the pads and
those in the intermediate spaces, but form a continuous
pattern in which the general direction of the lines is at
right angles to the plane of closure of the foot in grasping.
The ridges upon the terminal pads in both feet are arranged
as in the same pads in the Opossum.

EDENTATA.

E. 28. The left fore-arm and foot of a Hairy Armadillo [Dasy-
pus villosus). The skin has been partially raised from the
flexor surface of the limb to show a nerve entering the
skin beneath a tuft of coarse hairs situated upon the radial
side of the wrist. These hairs, although little, if at all,
different from the rest of those upon the fore-arm, from
their position and special innervation should probably be
regarded as an extremely generalised form of carpal tuft.
The foot-pads are not clearly defined and have a perfectly
smooth surface.

E. 29. The skin from the infcermandibular space of a Hairy
Armadillo (^Dasypus villosus) mounted, with the anterior
end uppermost, to show a tuft of. five strong vibrissse im-
planted in a rounded prominence of the skin.

UNGULATA.
HYRACOIDBA.

E. 30. Foot and part of the fore-limb of a Oape Hyrax {Pro-
cavia capensis). The skin has been raised from the under-
lying tissues to show the follicles of the carpal vibrissse.
They are only two in number, one having fallen out.
Mr. Beddard states {I. c. p. 133) that in this specimen no
nerve could be traced to the carpal tuft. The foot-pada
have the normal positions, but are much expanded and
extended owing to the locomotive adaptations of the foot
(see Section H, Locomotive Organs). Their surface is
smooth.

PHYSIOLOGICAL SERIES.

E. 31. Right fore-limb of a liyrax (^Procavia sp.),in wliicli
some of the chief nerves have been exposed to show the
innervation by the internal cutaneous nerve of an integu-
mentary excrescence, in the position of the carpal tuft.

PROBOSCIDEA.

E. 32. Trunk of a foetal Indian Elephant (Eleplias indicus).
The rio-ht side shows the numerous large branches of the
trigeminal and facial nerves. The skin is highly sensitive.
The trunk (nose) is used for prehension, small bodies being
grasped between the dorsal and ventral portions at the tip,
or the trunk being coiled around the object when it is
larger. It is also used in drinking, &c. 0. C. 1379 B.

E- 33. A transverse section through the trunk of a young Indian
Elephant (ElepJias indicus) in which the chief nerves shown
in the previous specimen have been cut at a higher level
than the muscles and skin to show clearly their true position
on either side of the nasal passages. 0. C. 288 o a.

Presented hy A. H. Garrod, Esq.

ARTIODACTYLA.

E. 34. Anterior part of the head of a Sheep (Ovis aries), showing
the distribution of the trigeminal and facial nerves to the
nostril and npper lip. The branches of the trigeminal are
of great size to furnish the necessary nerve-supply to the
tactile vibrissse and highly sensitive muzzle.

The anterior part of the lacrymal canal and two branches
o£ the olfactorius upon the septum nasi, are also shown
in this specimen.

RODENTIA.

E. 35. The right fore-limb of a Squirrel (Ratufa indica). The
skin has been removed from the radial surface to show a
large branch of the ulnar nerve passing directly to the base
of a remarkably well marked tuft of carpal vibrissas. The

ORaANS OF SPECIAL SENSE. — VERTBBRATA.

57

surface of the foot-pads is marked by extremely fine
strife.

Klaatsch, Morph. Jahrb., Bd. xiv. 1888, p. 421.

E. 36. The left fore- and hind-foot of a Grey Squirrel (Sciurus
cinereus) showing a similar tuft of vibrissEe on the ulnar
side of the wrist. As in most Mammals, there is no
corresponding tuft on the ankle. 0. C. 1415.

Hunterian.

PINNIPEDIA.

E. 37. A portion of the skin of the cheek of a Seal (Plioca sp.)
showing the large branches of the trigeminal distributed to
the roots of the vibrissse.

Numerous forms of nerve-ending have been observed in '
and around the roots of these specialised hairs, and although
there is much uncertainty in assigning to each its special
function, there is no doubt that some are tactile.

O.C. 1380 k.
Ksjunin, Arch. mikr. f. Anat., Bd. liv. 1899, p. 403.

E. 38. The skin of the upper lip of a Bearded Seal (Fhoca
harbata) showing the disposition of the whiskers in regular
rows curving outwards and upwards from the mesial line
of the muzzle and margin of the upper lip.

O.C. 1972 a.

E. 39. Three whisvkers from the lip of a Sea Lion (Otariajiibata),
in two of which the root-sheath is shown, and in the third
the root-sheath with the dermal follicle and the nerve
attached to its base. 0. C. 1970. Hunterian.

E. 40. A section of the lip of a Sea Lion, in which the follicles
of three whiskers are exposed and the large nerves which
pass to them dissected out. 0. C. 1971. Hunterian.

E. 41. A section of the lip of a Sea Lion with the sockets of
several of the whiskers laid open. In the uppermost of

58

PHYSIOLOGICAL SKRIRS.

tlicse the blooJ-sinus oE the follicle is pLiinly visible. This
sinus is characteristic o£ tactile hairs of this description,
and forms the upper part of an investment of erectile

Fig. 11.

Longitudinal section of tlie "whisker" of a Cat.
(After Dietl, Sitz. Ak. Wiss. Wien, Bd. Ixiv. pi. i. fig. 2.)

EL.S. Blood sinus. 0. Cavernous tissue. CO. Circumferential cushion.
I.F. Inner layer of follicle. l.K.S. Inner root-sheath. N. Nerve.
O.F. Outer layer of follicle. O.R.S. Outer root-sheath.

tissue that surrounds the lower end of the outer root-sheath.
This tissue serves to erect the bristle when in use.

0. C. 1972. Huntenan.

E. 42. The skin of the upper lip and cheek (including the border
of the nostril and the angle of the mouth) from the right
side of an adult male Elephant Seal (MacrorJiinus leoninus),
showing the large stiff whiskers and the short bristly hair

ORGANS OF SPECIAL SENSE. — VERTEBRATA.

59

which covers the general surface of the skin. The whiskers
are arranged in regular parallel rows as in Plioc.a harhata
(E. 38), but are fewer in number and relatively smaller.

0. C. 1972 B. Presented Inj Capt. R. C. Packe.

E. 43. A section of the lip of a Walrus (Odobcenus rosmarus).
On the left, three follicles and their contained whiskers have
been so cut as to show the follicles, dermal papilla and
blood-sinuses. Within each sinus can also be seen a small
mass of tissue attached to the inner wall. This forms a
projecting ridge around the hair, and is always found in
this position in the blood-sinus of these special tactile hairs.

0. C. 1974. Hunterian.

E. 44. A piece of the lip of a Walrus (Odohcmus rosmarus)
including the follicles of three whiskers. From one of
these the whisker has been withdrawn ; a second is left
entire with the whisker «i situ ; in the third a longi-
tudinal section has been removed from the follicle and root
of the hair exposing the dermal papilla and the root-sheath.
The large nerves of these apparently rude organs of sensa-
tion are distinctly shown. 0. C. 1973. Hunterian.

OARNIVOEA.
ARCTOIDEA.

E. 45. The left fore-foot of a Ratel (MelUvora indica) showing
the naked skin covering the soft foot-pads. The skin of
the palmar surface is raised into small warty processes
that give it a granular appearance. There is no difference
in this respect between the skin of the foot-pads and that
of the rest of the palmar surface. The Ratel uses its fore-
paws for burrowing. 0. C. 1414. Hunterian.

E. 46. The right fore- and hind-foot of a Eacoon {Procyon
lotor). O.C. 1414 a.

Presented hy St. George Mivart, Esq.
Hoggan, Jour, Anat., vol. xiii. 1884, p. 183.

E. 47. Distal part of the left fore-limb of a Coatimundi (^Nasua
nasua) dissected to show the innervation of the carpal tuft
of vibrissje. The palmar integument of the paw shows the

60

PlIVSIOLOGICAI. SKHIKS.

same warty surface as in the Ratel, without any linear
arrangement on tlie foot-pads. This general granulation
of the surface is usual among Carnivora and is also found
among Aplacental mammals in Kangaroos. It is probably
a more archaic condition than the grouping of the papillae
into parallel ridges.

Klaatsch, Morph. Jahrb., Bd. xiv. 1888, p. 41G.

AILUROIDEA.

E. 48. A section of the lip of a Tiger {Fells tigris) exposing the
roots of the whiskers and the dermal follicles in which they
■ are lodged. One of the whiskers has been extracted and the
dermal papilla upon which it rests exposed and made more
visible by a bristle being placed behind it.

0. C. 1966. Hunterian.

E. 49. A section of the lip of a young Lion {Felis leo),
minutely injected, showing the follicles of two whiskers
which are laid open exposing the roots of the hairs. The
large branches of the trigeminus by which the whiskers
are innervated have been exposed a little w^ay below the
opened follicles. 0. C. 1968. Hunterian.

INSECTIVOEA.

E. 50. The head and shoulders of a Mole (Talpa europcea) with
the maxillary trunk of the trigeminal exposed upon the
left side. After passing through the infraorbital foramen
this nerve gives rise to a bundle of large branches (in-
dicated by a black bristle). The uppermost of these runs
directly to the snout disc and there supplies a number of
special tactile papillae which cover its entire surface. The.<=e
organs have been described by Eimer as consisting of
masses of epidermic tissue each perforated by a tube filled
• to within a short distance of the surface with an homo-
geneous substance within which runs a bundle of nerve-
fibrils. Each fibril is connected by a series of knob-like
nerve-endings with the cells that form the walls of the
tube.

The snout is certainly one of the most important of the

ORGANS OF SPECIAL SENSE. — VERTEBKATA.

61

Mole's sense-organs and its extreme sensitiveness is shown
by the fact, apparently well authenticated, that the slightest
blow upon it causes immediate death.

Eimer, Arch. £. mikr. Anat., Bd. vii. 1871, p. 181.

E. 51. A Star-nosed Mole (Covdt/lura cristatd). The snout-
disc is surrounded by a fringe of conical fleshy tentacles.
These are the seat of special tactile papillae, which are
arranged in rows parallel to the axis of the tentacle and
are similar in essential structure to those upon the snout of
Tulpa.

Ayers, Biol. Centralbl, Bd. iv. 1885, p. 356.
CHIROPTERA.

E. 52. The skin of the head of a Leaf-nosed Bat (^Megaderma
frons). The integument of the muzzle is enlarged to form
a leaf-like expansion that surrounds the nostrils and stands
up like the petal of a flower in front of the forehead. This
"nose-leaf'" is said to be innervated by strong fibres from
the ophthalmic and maxillary branches of the trigeminus,
and is probably a highly sensitive touch organ. A similar
expansion of surface, extremely sensitive to touch, is
provided by the enormous development of the pinnae, u^Don
the surface of which numerous small tactile vibrissse are
scattered. 0. 0. 1423 b.

Presented ly G. E. Dohson, Esq.
Dobson, Brit. Mus. Cat., Chiroptera, 1878, p. xvi. "

E. 53. The head of a Horseshoe Bat {Rliinoloplats lucius),
showing a similar but far more complicated nose-leaf than
that seen in the last specimen. The nose-leaf in the
Horseshoe Bats consists " of three disti;ict portions —
anterior, central, and posterior ; the anterior horizontal
portion is horseshoe-shaped, usually angularly emarginate
in front, containing within its circumference the nasal
orifices and the central erect nasal process ; the posterior
nose-leaf is triangular, erect, with cells on its anterior
surface ; the cectral process rises between and behind the
nasal orifices, is flattened anteriorly and posteriorly, sends

62

PHYSIOLOGICAL SERIES,

backwards a vertically laterally compressed process which
is either connected with the front surface of the posterior
nose-leaf or free/' (Dobson, Brit. -Mus. Cat,, Chiroptera,
1878, p. 100.)

Eedtel, Zeitschr, wiss. Zool., Bd. xxiii. 1873, p. 2,54.

PRIMATES.

Whipple, Zeits.f. Morph., Bd. vii. 1904, p. 2G1 {Papillary
ridges).

Schlaginhaufen, Morph. Jahrb., Bd. xxxiii. 190,5, p. 577,
and Bd. xxxiv. 1905, p. 1 {Papillary ridges).

LEMUROIDEA.

E. 54. The skin of the head of Galago dcmidoffii. Above the
inner canthus of each eye is a small w^iitish pimple from
which springs a tuft of long fine vibrissfe. 0. C. 2152 lb.

E 55. Left hand and skin of the wrist of Microcchus coquereli.
There is a well marked tuft of four dark coloured carpal
vibrissse upon the fore-arm above the ulnar foot-pad. The
skin upon the eminences that correspond to the foot-pads
of lower Mammals is covered by papillary ridges that in
the main are arranged concentrically to tlie apex of the
pad, or in the case of the terminal digital pads parallel to
the long axis of the finger. The skin between the pads is
smooth. 0. G. 2152 i.

Bland Sutton, Proc. Zool. Soc, 1887, p. 372.

E. 56. Three specimens of the hand and distal part of the forearm
of Lemur catta : above, the right hand of a foetus ; below,
on the left, the left hand of an adult ; and on the right, the
right hand of a still older example. In all three specimens
there is a tuft of carpal vibrissae. The two adult specimens
also show an area of thickened hairless integument ex-
tending from the ulnar foot-pad upwards towards the radial
border of the arm. The upper part of the patch is some-
what enlarged, and in the older specimen bears upon
its ulnar border a horny spur-like process. This
structure was supposed to be the hardened secretion
of a large aggregation of sweat-glands that underlies

ORGANS OF SPECIAL SENSK. VEUTEBRATA.

63

tlie callous patch (see the reverse of tte specimen), but
latterly it has been shown by Beddard to be a local
development of the corneous layer o£ the epidermis. (See
also in Section F, Integumentary Scries — Galar/o, Equus.)

0. C. 2152ia.

Sutton, Proc. Zool. Soc, 1887, p. 369.
Beddard, Proc. Zool. Soc, 1902, vol. ii. p. 158.

E. 57. The right fore- and hind-foot of a Lemur (Lemur sp.).
The hand is very similar to the oldest shown in the
previous specimen, but the wrist has been so cut as just to
exclude the tuft of carpal vibrissse. Upon both extremities
- the tips of the digits are swollen to form soft pads, which
are probably very sensitive to tactile impressions, although
no doubt their most important use is in enabling the finger-
tip to obtain a firm grip of the branches of trees. The
palmar and plantar skin is much shrunken in this specimen
and in consequence the papillary ridges, which in Lemurs
occur upon certain areas that correspond to the foot-pads
of lower Mammals, are difficult to see.

0. C. 1419. Hunterian.

E. 58. The right fore-foot of a Slow-paced Lemur (Loris tardi-
gradus), showing the dilatation of the finger-tips to form
soft adhesive and tactile pads supported dorsally by flat
broad nails. The first digit is directed laterally so as to
act as an opposable instrument or thumb to the other digits,
The papillary ridges, which in this genus are more uni-
versally distributed over the palmar surface than in Lemur.^
are scarcely visible owing to the state of preservation of
the specimen. 0. C. 1416. Hunterian,

ANTHBOPOIDEA.

E. 69. The hand of a Squirrel Monkey (Chrysotlirix sciureus)
from which most of the epidermis has been removed,
lu the Anthropoidea the papillary ridges are distributed
over practically the whole volar surface. They are un-
fortunately too indistinct to be seen in this specimen, but
their arrangement is shown in the accompanying figure.
The spaces between the pads are covered by irregular

PHYSIOLOGICAL SERIES.

frranular eminences, the surface of many of which show
well-marked papillary ridoes. The extremities of the
throe outer digits are much expanded, as in the Lemurs ;

Fig. 12.

Hand of Callithrix sciureus, showing papillary ridges.

hut the eminences corresponding to the foot-pads of lower
Mammals are less clearly defined than (for instance) in
Microcehus (E. 55). 0. C. 1420. Bunterian.

John Hunter, Essays and Observations, edit. R. Owen,
1861, p. 27.

E. 60. The right hand of an Entellus Monkey (SemnopU/iecus
entellus). The papillary ridges are very strongly marked,
especially over the surface of the palm.

E. 61. The head of a Ch impanzee (^A-nthropopithecu s tv^glodytes^.
The lips, by reason of their great sensitiveness and mobility,
serve as efficient organs of touch.

0. (!. 1424. Hunterian.

ORGANS OF SPECIAL SENSE. — VERTEBRATA.

65

E. 62. The right hand of a Chimpanzee {Anthropopithecus
troglodytes), showing the pahnar surface covered with
papilhay ridges. 0. C. 1421. Hunterian.

E. 63. The lower part of the face of a Human subject, injected,
to show the vascularity of the highly sensitive and delicate
integument of the lips. 0. C. 1425. Hunterian.

E. 64. The left hand of a Woman, injected, and with the epi-
dermis removed. The ends of the digits which are specially
sensitive to touch impressions are pointed and protrude as
soft fleshy cushions beyond the nails, which serve for their
support. O.C. 1431. Hunterian.

E. 65. The left band of a Woman, injected, dried, and pre-
served in oil of turpentine, showing the high vascularity of
the integument. 0. C. 1432. Hunterian.

E. 66. Left hand, supposed to be that of Thomas Beaufort,
second son of John of Gaunt, oUit. a.d. 1424, a^tat. 52,
efoss. Feb. 26, 1772. The interest of this specimen consists
in the state of preservation of the tissues after the body
had been buried about 300 years. The abdominal viscera
had been removed, the body wrapped in cere-cloth, and
enclosed in a leaden coffin in which holes had been made.
It was buried in earth. 0. C. 1437. Hunterian.

Collignow, Phil. Trans., vol. Ixii. p. 465.

E. 67. The right hand of the same bodj, 0. C. 1437 a.

Presented hy Sir Thomas Gcry Cullum, Bart.

E. 68. A Human finger in which the arteries have been in jected
with mercur3^ 0. 0. 1433 D.

Hunterian (Kew Collection, No. 11).

E. 69. The last joint of a Child-'s thumb, injected, and with the
epidermis removed. 0. C. 1433. Hunterian.

E. 70. A longitudinal section of one of the fingers of a Child's
hand with the arteries injected with mercury, dried and
preserved in oil of turpentine, showing the plexus of
vessels at the tactile extremity. 0. C. 1433 c.

Presented by Sir William BUzard.

VOL. III. F

66

PHYSIOLOGICAL SKRIES'.

E. 71. The hand of an Infant similarly propared, showing tlio
rich network of vessels with which the fingers are
surrounded. 0. C. 1433 B.

Presented- hy William Lawrence, Esq.

E. 72. The hand of an Infant, minutely injected. 0. C. 1433 a.

Presented hy Sir William Blizard.

GUSTATORY ORGANS.

John Hunter, Essays and Observations, edit. R. Owen,
vol. i. p. 180.

The organs of Taste and Smell have much in common, both
being concerned in the distinction of certain chemical properties
of matter : the one (Taste) only when the matter is in n liquid
condition, the other usually when it is gaseous.

In Invertebrates, although the skin is sensible of chemical
differences either all over or especially in certain regions, the
sense of taste is apparently very partially developed, and it
is rare to find anatomically distinguishable organs clearly
specialised for the performance of this function. In Arthro-
pods, where the epidermal and cuticular sense-organs have
reached a relatively high state of perfection, certain structures
upon the lips, palate, and mouth-parts have been identified as
taste oro-ans, hwi it is only in Vertebrates that taste organs
are met with suitable for display in an Anatomical Collection.
In Fishes the lips, tongue, mouth-cavity, and pharynx are
covered with aggregations of sense-cells resembling taste-buds,
and similar end-buds (innervated by visceral sensory com-
ponents) occur also on the surface of the head and in some
cases upon parts of the body. In Amphibia and Sauropsida
organs of taste are restricted to the mouth and are developed
feebly, when present at all. In Mammals taste-buds occur
chiefly upon the tongue (upon the fungiform, circumvallate, and
foliate papillae) and to a less degree upon the palate and Malls
of the phar;ynx. These organs are innervated by the glosso-
pharyngeal and by the fibres of the chorda tyn)pani and are
apparently responsive to only a few chemical properties, which

ORGANS OF SPECIAL SENSE. — VERTEBRATA. 67

■give rise to acid, salt, sweet, bitter, and metallic tastes. Other
tastes, or rather flavours, act upon the olfactory organs and not
the gustatory.

VERTEBRATA.

Gottschau, Zool. Cbl., Bd. ii. 1882, p. 298.

PISCES.

Nagel, Biblioth. Zool., Bd. vii. 1894, p. 182.

ELASMOBEANCHII.

E. 73. The floor of the mouth and fauces of a Port Jackson
Shark [Cestracion francisci). The anterior part is slightly
raised to form a fleshy but completely attached tongue,
very like that of a Crocodile, Upon the mucous membrane
covering the tongue and fauces are a number of fungiform
papillae similar in appearance to those of Mammals. They
are most numerous about the centre of the tongue and
lessen in number near the tip and towards the fauces,
extending in the latter direction to about the level of the
penultimate gill-arch. Probably these papillae are the
seat of taste-buds.

Todaro, Cbl. med. Wiss., Bd. x. 1872, p. 227 {Trygou).

MAMMALIA.*
Munch, Morph. Arb., Bd. vi. 1896, p. 605.

E. 74. Part of the base of the tongue of an Elephant {Elephas sp.)
showing four large circumvallate papillte. They are
arranged in pairs on either side of the mid-line, one
behind the other. 0. C. 1490. Hunterian.

Miinch, I. c, p. 641.

* A few examples of the tongue selected to sliow the most mavlied
variations in the position and development of the fungiform, circumvallate
and foliate papillse, are exhibited in this section. The bulk of the collection
is in "Section J, DigestiAe Organs."

F 2

^8

PHYSIOLOGICAL SERIES.

E. 75. The base of the tongue of a Dromedary (Camelus drome-
darius). The circumvallate papilljB have the same linear
type of arrangement as in the Elephant, There are four
on tlie left side and live on the i-i^ht. Tlie second, counting
from in front, is of very great size. In this region of the
tongue the mucous membrane is raised into a sci-ies of
conical processes. 0. C. 1405. Ilunterian.

Miincli, I. c, p. 643.

E. 76. The hinder part of the skull of a Sheep (^Ovis aries) with
the tongue and the right ramus of the mandible, shov^'ing
the nerves that supply the tongue. The lingual branch of
the trigeminus innervates the organs of general sensation,
and also by means of fibres contributed by the chorda
tympani some of the more anteriorly placed organs of
taste. It is of great size and enters the tongue just
external to the genio-glossus in company with the branches
of the equally strongly developed motor nerve (hypoglossus).
The majority of the taste organs are supplied by the glosso-
pharyngeal, which is quite a small nerve and enters the
tongue at its base, p;issing upwards near the surface
towards the foliate and circumvallate papillae upon which
the taste-buds are mainly situated. Upon the right side
the nerves have been separated out and traced as f;ir as
possible towards their final distribution ; upon the left
the relations of their main trunks to the surrounding parts
are retained.

E. 77. The tongue of a Rabbit [Lepus cuniculus). The fungiform
papillae are almost entirely confined to the dorsal surface
and margins of the free end of the tongue, being particu-
larly numerous upon the anterior margin. There are two
circumvallate papillae placed transversely at the posterior
end of the body of the tongue, and laterally to them upon
its sides ai-e two very strongly marked foliate papillae.
Numerous taste-buds occur upon the apposed surfaces of
the leaA'es of which these papillae are composed.

E. 78. The tongue and fauces of a Gibbon ( Hi/Mates st[).). The
papillae on the tongue are very clearly defined. There are

ORGANS OF SPECIAL SENSE. VEHTEBEATA.

69

four circumvallate papillfe, one on either side and two
in the mid-h'ne posterior to them. The lateral parts of
the tongue are covered with scattered fungiform papillae,
and the whole of the dorsal surface is velvety from the
presence of filiform papillfe. Foliate papilliE are present
on either side in front of the anterior pillars of the fauces.
The fungiform, circumvallate and foliate papillae, but not
the filiform, are said to he the seat of taste-buds.

E. 79. The tongue of a nearly adult Chimpanzee {Anthropo-
pithecus troglodytes), showing the arrangement of papillae
upon its dorsal surface. The fungiform papillae are very
conspicuous and are scattered over the dorsal surface of
the whole of the organ in front of the circumvalhite papillae.
There are six of the latter arranged upon the base of the
tongue in the form of a Y, corresponding exactly in position
to the six circumvallate papillae of the Gibbon. Foliate
papillEB are present at the sides of the tongue on a level
with the anterior circumvallate papillae. 0. C. 1523 D.
Miinch, I. c, p. 636.

E. 80. A Human tongue. The fungiform papillae are scattered
OA'-er the dorsal and lateral surfaces of the anterior parts of
the tongue^ but are most numerous along the sides. There
are seven obscure circumvallate papillae arranged in a
V shape upon the base of the tongue. Somewhat in-
definite foliate papillae are also present on either side in the
usual position in front of the anterior pillars of the fauces,
Miinch, I. c, p. 639.

E. 81. A Human tongue, with the hypoglossal and lingual
nerves exposed. The lingual is distributed to the tip and
sides of the tongue. It is not in the main a gustatory
nerve, but innervates the organs of general sensation.
Some of its fibres, which reach the brain by way of the
chorda tympani, do however carry true taste stimuli. The
hypoglossal supplies the muscles of the tongue, entering it
behind the lingual nerve. 0. C. 1380 L.

Zander, Anat. Anz., Bd. xiv. 1898, p. 131.

70

PHYSIOLOGICAL SERIES.

OLFACTORY ORGANS.

John Hunter, A description o£ the nerves which supply the
organ of smelling, Animal OEconomy, Works
of Hunter, Palmer, vol. iv. p. 187.
Essays and Observations, edit. R. Owen, vol. i.
p. 177.

Nagel, Biblioth. ZooL, Bd. vii. 1894-96, pp. 1-63.

The olfactory sense is closely allied to that of taste, both
beina: concerned with the discrimination of certain chemical
properties of matter. In Man and presumably in lower land
Animals the olfactory organ is capable of response to the
stimulation of odoriferous substances only when they are in a
gaseous form, but in Fishes in which the sensitive surface is
actually bathed in water this is obviously not the case, and in
this group the distinction between taste and smell is not very
clearly defined. The acuteness of smell differs enormously in
different animals. The sense is entirely absent in the Toothed
Whales, and in Man and Apes and in most Birds is very weak,
but on the other hand in some Insects and in many Mammals it
reaches a power and delicacy of discrimination of which it is
diflBcult for us to form a conception.

In aquatic Vertebrates its use is apparently confined to the
seeking out and recognition of food only within quite a hmited
area ; but with the greater opportunities offered by the rapid
diffusion of odorous particles in air, its range and sensitiveness
have increased in land Vertebrates till it has become in many
cases the most important of all the senses, giving information of
the whereabouts of mates, friends, enemies, or prey, often at
almost incredible distances, and being used, as we use sight, in
the detailed examination of near objects. The prime importance
of this sense is also suggested by the fact that its nerve centres
were the first to form connections with the cerebral cortex (see
this Catalogue, Vol. II. p. 112).

INVERTEBRATA.

Nagel, Biblioth. Zool., Bd. vii. 1894-96, pp. 67-182;

Little is known of the sense of smell in Invertebrates. In
the lower forms there are probably no organs set apart for this

ORGANS OF SPECIAL SENSE. — INVERTEBRATA.

71

function, but in Worms sensory epithelial areas in tlie nuchal
region, and in Molluscs aggregations of sense-cells upon certain
parts oE the mantle and head, have been thought to be sensitive
in a somewhat special degree to the chemical condition of the
surrounding medium. However, among Arthropods and
especially among the Insecta there is no doubt that the
olfactory sense is extremely keen, the sense organs concerned
being apparently placed for the most part upon the antennae.

ARTEROPODA.

E. 83. The antennule of a Lobster {Homarus vulgaris), with the
cerebral ganglion attached. The nerve for the supply of
the antennule emerges from the anterior surface of the

Fig, 13.

A small part of the exopodite of the antennule of Homarus vulgarit,
showing olfactory setae.

OL.S, 01factor\' setae.

ganglion (arising within it by two roots, one of which
takes origin from a glomerulated mass of neuropile — the
globulus, cf. D. 14. Physiol. Series) ^. Within the basal
part of the appendage the nerve gives off a small branch
to the auditory sac, and then divides into branches for the
exo- and endopodites. The nerves to the exopodite are
partly distributed to a number of delicate tubular processes

* Glomerulation of the neurnpile is, in "Vertebrates, alwaj-s found in the
olfactory bulbs.

PHYSIOLOGICAL SKRIES,

situated along the lower border oE the ramus, towards its
distal end. In the specimen they look like a whitish
coaguluni lodged amongst the longer and stiff.-r tactile
setae. These processes are consiflered to have an olfactory
function ,

MOLLUSCA,
Yung, Arch. Psychol., T. iii., 1903, p. 1.
E. 83. A Whelk {Buccinnm undatum) with the mantle-wall
divided and reflected to either side to show the osphradium
or false branchia. This organ, which is supposed to have
an olfactory function, lies close below and parallel to the
attached border of the gill axis near its anterior end. It
consists of a central axis beset on either side by a series of
triangular pigmented leaflets. The organ is innervated
from the visceral loop through the mediation of a nerve
centre that forms the core of its axis, and from which
delicate branching filaments pass into each leaflet. The
innervation is not shown in the specimen.

Bernard, Ann. Sci. Nat., ser. 7, T. ix. p. 202.

E.84. Head of a Cuttle-fish {Sepia officinalis) dissected from
the posterior (dorsal) aspect to show a pair of integu-
mentary pits, possibly olfactory in function, situated behind
the eyes*. Upon the left side a nerve has been traced
from the base of the pit to a small rounded ganglion npon
the dorsal (anterior) surface of the optic stalk. The nerve
does not terminate here, but passes on into the cerebral
ganglion. Red rods have been inserted into the mouths of
the olfactory pits. 0. C. A 1527.

Jatta, Boll. Soc. Natural. Napoli, vol. i. pp. 30 & 92.

VERTEBRATA.

In Vertebrates the olfactory membrane lines part of a paired
cavity (nasal chamber) that lies in front of or above the mouth,
and may either serve solely for the lodgement of the olfactory
sense organ, or may in addition become either the chief or the

* The olfnctory pit oi KautUua macromphalus is shown in the dissection
of tliat species prepured to sliow the eyes. No, E. 1071.

ORGANS OF SPECIAL SENSE. — VERTEBRATA.

73

only respiratory passage, by the development of a posterior
connection with the mouth-cavity. The liquid or gas in which
the odoriferous substance is difiused can generally be forciblj'-
brought into contact with the olfactory membrane by some
special mechanical means. This may either be by the action of
ciliated cells that line the cavity, by valvular arrangements of
the nostrils to deflect the water into the nasal cavities during
forward progression, by dilatable accessory pouches in con-
nection with the true olfactory chamber, or by acceleration of
the inspiratory air-current.

The end organs peculiar to the olfactory sense closely resemble
the epithelial senso-neural cells of some Invertebrates, each
being an elongated cell terminating distallyin a brush of slender
processes freely exposed upon the surface of the mucous
membrane, and drawn out proximally into an afferent nerve-
fibre that breaks up in neuropile glomeruli in the olfactory
bulbs of the brain. In certain Fishes (e. g. Bdone) the
olfactory cells are grouped to form bud-like organs scarcely
distinguishable from end- or taste-buds, but m other genera
these are more and more coalesced till the type of olfactory
membrane common to most Vertebiates is produced — that is,
an epithelium composed of senso-neural, sapporting, and
glandular cells evenly distributed.

Olfactory Chamber.
PISCES.

Blaue, Arch. f. Anat., 1884, p. 231.
- . Bateson, Jour. Mar. Biol. Assoc., vol. i. 1889, pp,235, 246.

CYCLOSTOMI.

E. 85. The head of a Sea-Lamprey {Petromyzon marinus) in
sagittal section. The olfactory sac is single and median.
It communicates with the exterior by an opening with
prominent lips, situated in the dorsal mid-line slightly ia
front of the plane of the eyes. A short passage leads from
the nostril to a globular olfactory chamber the posterior
wall of which lies close in front of the brain and is
radially pleated to increase the surface covered by the
olfactory membrane. The lower and anterior parts of the
sac are prolonged backwards between the skull and front

PHYSIOLOGICAL SERIES.

end of the notochorJ and tlje pliiirjnx as a blind pouch,
which is tubular and surrounded by cartilage in front, but
behind is dilated and is separated from the branchial
chamber by the narrow oesophagus only. This bulb-like
posterior dilatation shares in the alternate expansion and
contraction of the branchial cavity, and is thus a mechanism
for the production of currents of water into and out of the
olfactory chamber (Bert, Ann. Sci. Nat., s6r. 5, T. vii.
1867, p. 372), The passage of the incoming water through
the olfactory chamber is ensured by a suitably arranged
pair of valves situated at the lower end of the first segment
of the nasal passage.

Fig. 14.

OL. c N

Sagittal section of the nasal region of Vetro^nyzon marinus.
Brain. BR.O. Brancliial chamber. C. Cartilage of skull. CCEC.
Ccecum of nasal chamber extending between the notochord and the
oesophagus, compressed during expiration. N. Nostril. NC. Noto-
chord. OES. (Esophfigus. OL.C. Olfactory chamber. V. Valve
between the respiratory chamber and the mouth-cavity.

A black bristle has been passed from the nostril, through
the olfactory chamber into the csecal pouch. A red rod is
inserted into the respiratory division of the pharynx and
purple rods through the first two gill-openings,

0, C. 1527 a.

Ballowitz, Arch. f. mikr. Anat., Bd. Ixv, 1905, p, 78
{Hist.).

ORGANS OF SPECIAL SENSE. — VERTEBRATA.

75

E. 86. Two specimens showing the olfactory organs of a Hag-
fish {Myxine glutinosa). The organ is siiniL^r to that of
Petromyzon in being single and median, but differs from
it in having an open communication with the pharynx.
The specimen on the left shows the head in sagittal section.

Fig. 15.

N.P o.U

Sagittal section of the nasal region of Myxine glutinosa.

B. Buccal cavity. BE. Brain. NO. Notochord. O.L. Olfactory leaflets.
N.P. Nasal passage. V. Velum.

The nasal passage can be traced from its opening at the
anterior end of the snout to its passage into the pharynx
slightly behind the posterior limit of the brain. The first
part of the passage, owing to the forward position of the
nostril, is relatively longer than in the Lamprey and is
supported by rings of cartilage. Close in front of the
brain the dorsal parts of the passage enlarge to form the
true olfactory chamber occupied by a series of seven plates
arranged longitudinally in the vertical plane. These plates
are covered by olfactory epithelium, and are innervated
(as in the Lamprey) by a pair of nerves that enter the
anterior end of the brain. The posterior part of the nasal
passage runs close beneath the brain-case and opens by
a wide mouth into the pharynx in front of a pendulous
flap — the velum.

In the right-hand specimen the alimentary canal, palate,
and ventral wall of the nasal passage have been longitudi-
nally divided and spread apart to show the roof of the
nasal passage and the arrangement of the plates in the
olfactory chamber, A red glass rod marks out the passage
. of the left half of the buccal cavity into the pharynx. .

76

PHYSIOLOGICAL SKKIES.

ELASMOBllANCIIII.

E. 87. He;id of a Dog-fisli {Acantliias vulgaris), sliowing the
olfactory organ?. Upon the left side, wliere the parts are
undisturbed, is shown the subdivision of the single opening
of the olfactory sac into an outer (inhalent) and an inner
(exhalent) channel by the overlapping of projections from
its anterior and posterior borders. Upon the right side
the ventral half of the olfactory sac has been removed and
the olfactory part of the brain exposed. The sac has an
oval form and is occupied by a series of leaflets that project
from its walls transversely to its length, and are separated
into two series by a fibrous longitudinal axis that extend.?
from end to end of its floor. The middle part of the free
border of each leaflet projects as a tongue-shaped process
into the cavity of the s;ic. The olfactory bulb (see also
D. 71) lies close behind the olfactory sac and gives off for
its innervation three large nerve-bundles of indefinite
outline. Olfactory epithelium is said (Blaue) in Elasmo-
branchsto clothe only the deeper parts of the clefts betw een
the leaflets.

Blaue, Arch. f. Anat., 1884, p. 267.

E. 88. Part of the head of a Skate (Raja batis) including the
right olfactory organ. The cavity has the form of a
transversely elongated depression upon the ventral surface
of the head, partially covered over by a deep overhanging
lip (cf. subsection : Nostrils) , The deeper parts of the cavity
are lined by an olfactory membrane, thrown into a series
of folds arranged at right angles to a ligamentous axis
disposed in the long axis of the pit. The free margin of
each lamella is extended about the middle of its length by
a triangular process. The specimen is mounted with the
posterior border uppermost to allow the cavity of the
olfactory sac to bo seen. 0. C. 1528. Hunterian.

E. 89. A transverse section through the head of a Ray (Raja
clavata), showing from in front the olfactory organs and
their connection with the brain. On the left the pigmented
covering of the nasal sac has been exposed ; ic is continuqus

ORGANS OF SPECIAL SENSE. — VEETEBUATA.

77

with tlie dura mater. On the right, the olfactory sac has
been mesially divided by a section parallel to its long axis, to
show its lateral elongation, the arrangement of the olfactory
lamellte at right angles to a median longitudinal raphe,
the position of the olfactory bulb along the dorsal border
of the sac, the passage of a bundle of nerve- fibres from the
bulb into each olfactory lamella, and the partially closed
gutter leading from the cavity of the sac to the corner of
the mouth.

E. 90. Transverse section through the olfactory organ of a
Skate [Raja hatis). In this specimen a pair of leaflets are
ghown, lying on either side of the central axis and with
triangular processes of their free borders projecting into
the cavity of the sac. The olfactory bulb is cut trans-
versely and on the left side gives off a large bundle of
nerve iilaments (marked by a black bristle] to the corres-
ponding leaflet. The olfactory mucous membrane upon
the surface of each leaflet is pleated at right angles to the
wall of the sac.

GANOIDEI.

E. 91. A portion of the head of a Sturgeon {Aci2')enser sturio)
including the right olfactory organ. The olfactory nerve
(cf. D. 86), which is of large size, is visible on the reverse
of the specimen cut obliquely close to the olfactory pit.
It expands towards lis termination upon the olfactory
membrane, which lines a cavity of hemispherical form
and is disposed in a series of deep but thin semilunar folds
that radiate from a ligamentous centre.

0. 0. 1527. Hunterian.
Dogiel, Arch. £. mikr. Anat., Bd. xxix. 1887, p. 77.

E. 93. Head of Polypterus lapradii, with the olfactory organs
and brain displayed from above. Each olfactory organ
consists of two distinct parts : — (1) a passage that passes
directly between the anterior and posterior nostrils, and
(2) an olfactory chamber in connection with it. The
nostrils lie at a considerable distance apart (14 mm.), the
anterior at the end of a flexible tube, as in many Bony

78

PHYSIOLOGICAL SERIES.

Fishes with keen scent, and the posterior, wliich is slit-
like, close in front of the eye. A narrow opening leads
through the median wall of the passage that connects the

Fig. 16 A.

AN

1

A

Fig. 1(3 B.

Fig. 10 A. — Olfactory organ of Folypterus lap-adii, opened from above.
Fig. 16 B. — Diagram of section through part of the olfactory chamber of
Tolypterus.

A. Axis of olfactory chamber. A.N. Anterior nostril. N. P. Nasal passage.
OL.C. Cavity of olfactory compartment. OL.L. Olfactory leaflets.
OL.N. Olfactory nerve. P.N. Posterior nostril. S. Septum between
two contiguous compartments of olfactory chamber.

two nostrils into the anterior end of a large oval olfactory
chamber built up of a number (about 6) of sausnge-shaped
compartments arranged around a central axis. The partition

ORGANS OF SPECIAL SENSK. VKRTEBRATA.

79

walls between every two compartments are covered by a
series of leaflets arranged at right angles to the long axis of
the organ and filling up the greater part o£ each com-
partment. The olfactory nerves are strongly developed ;
each leaves the posterior end of one of the olfactory chambers
and at the fore end of the brain enters a large pear-shaped
olfactory bulb. Upon the left side, the roof has been
removed from the passage between the nostrils and from
three compartments of the olfactory chamber, showing the
connection between these two parts of the olfactory organ
and the arrangement of the olfactory leaflets. On the right,
the dorsal surface of the olfactory chamber has been exposed
and green rods have been inserted into the nostrils. One
may suppose, from the complexity of the olfactory chamber
and from the size of the olfactory nerves and bulbs, that
the power of scent in this fish is exceptionally great.

Presented hy J. S. Budgett, Esq.
WaldschmidL, Anat. Anzeig., Bd. ii. 1887, p. 308.

TELEOSTEA.

E. 93. Head of a Gar Fish {Belone vulgaris), showing the
olfactory organs. Each olfactory sac is a shallow open
pit of roughly triangular outline and measuring some
7 mm. in diameter, situated at the side of the head
close in front of the eye. From the upper part of its
cavity a smooth club-shaped fleshy mass protrudes slightly
beyond the general surface-level of the face. This repi'e-
sents in a much simplified form the olfactory rosette
characteristic of the olfactory organ of the vast majority
of Bony Fishes. The extremely simple character of the
olfactory oi'gans indicates that the sense of smell is feeble.

The olfactory epithelium in its structure resembles a
collection of end-buds such as occur upon the skin of the
head (Blaue).

Blaue, Arch. f. Anat , 1884, p. 241.

E. 94. Three specimens of the olfactory organ of a Cod (Gadus
morrlma). The olfactory sacs are hemispherical in shape
and lie on either side of the snout about halfway between
its extremity and the orbits. Each sac opens to the

PHYSIOLOGICAL SKUIEP.

exterior by two nostrils— an anterior, which is the smaller
of the two and is bordered by a lip produced behind to
form an upstanding flap by which the water is deflected
into the nostril during the forward progression of the fish,
and a larger posterior nostril of oval form'also bordered by a
low membranous lip. The olfactory sac is almost completely
filled by a series of leaflets attached to its floor and sides
and converging to a longitudinal raph<^ that extends back-
wards from the anterior border of the anterior nostril about
half way along the floor of the sac. The free edge of each
leaflet is prolonged into a tongue-shaped process. Beneath
the median raphe of this rosette of leaflets lies the olfactory
bulb connected by a long slender tract to the brain.

The resemblance in general structure between this
olfactory organ and that of AcanlJiias (E. 87) is very
striking. The upper specimen shows the sac divided
parallel to the axial raphe of the rosette. The lower shows
it in surface view after the removal of the skin. The
middle specimen is the skin removed from the preceding
showing the nostrils.

95. Two specimens of the olfactory organ of a Sea-Bream
(Pagellus centrodontus). The nostrils are in much the
{•ame position as in the Oad. The anterior is circular, the
posterior oval and valved along its hinder margin to
prevent entry to the sac. The rosette is more circum-
scribed than in the Cod and is surrounded above, below,
and behind by a plain area of the olfactory sac. In this
plain area close behind the rosette are two openings that
lead from ihe olfactory sac into two accessoi'y chambers
that lie respectively behind the median process of the prse-
maxillte and behind the maxilla. When the mouth is
closed the accessory chambers are compressed by these
bones, but can freely expand when the mouth is opened.
By their means water can thus be drawn into the olfactory
sac and again expelled following the moA^ements of the
jaws. Water can only enter the sac by the anterior nostril
which lies directly over the olfactory rosette. The upper
specimen shows the nostrils and the compressed condition
of the lower accessory sac when the mouth is closed. In

ORGANS OF SPICCIAL SENSIC. — VEUTEBRATA.

81

the lower specimen the olfactory sac has been opened to
show the rosette, and the accessory sacs are fully expanded,
the mouth being wide open.

E. 96. Head o£ a Conger Eel {Conger vulgaris), showing the
olfactory organs. Upoii the right side green rods have
been inserted into the anterior and posterior openings of
the olfactory chamber ; and upon the left the roof of the
chamber has been removed and the brain and left olfactory
nerve exposed. The olfactory organs are very strongly
developed. Each has the form of a flask-shaped chamber,
opening in front upon the margin of the snout by a short
tube, and behind by a simple opening situated close in
front of the eye ; the two openings being separated by a
distance of 60 mm. The anterior or inhalent orifice leads
into a short vestibule separated from the olfactory part of
the chamber by a valvular projection. The main cavity
of the organ is almost completely filled by flat leaflets, like
gill lamellae, that project in close-set transverse series from
its dorsal and ventral walls, and meet alono- its median
side in a central axis. From the posterior end of the main
cavity a short tube leads outwards to the exhalent opening.
The olfactory nerve leaves the organ by its median border.
It is of great size and is divisible into three bundles. The
olfactory bulb, which is small in comparison with the
nerve, is sessile upon the brain. The olfactory epithelium
is confined to the surfaces of the leaflets but does not
extend to their bases or upon the wall of the chamber
between them (Blaue, I. c, p. 265).*

E. 97. The head of Tetrodon bimaculatus . The floor of the
olfactory pit is only slightly sunk below the general surface
of the skin, but the roof is raised to form a dome-shaped
elevation perforated by large inhalent and exhalent orifices.
Wiedersheim, Anat. Auzeig., Bd. ii. 1887, p. 652.

E. 98. The head of Tetrodon fahaka. The olfactory organ is
represented by a bifoliate tentacle, attached to the surface
of the head by a short pedicle. The olfactory epithelium
covers the apposed surfaces of the leaves. This condition

VOL, III. Q

82

PHYSIOLOGICAL SKRIKS.

has been shown (Regan, Proc. Zool. Soc, 1902, vol. ii.
p. 292) to be traceable to an olfactory pit of the normal
type. It results from the shallowinf;; of the pit, and the
raising and subsequent rupture of the bridge of integument
between the inhalent and exhalent orifices. This and the
previous specimen are examples of stages two and four of
the accompanying scheme.

Fig. 17.

Diagram iUusti'ating the probable course of evolution of the tentacular
olfactory organ in the genus Tetrodon.

L Normal olfactory pit (e. g. T, sceleraius). II. Elevated roof
( T. bhnaculatus). III. Ruptured bridge. IV. Bifohate tentacle
{T.fahaka).

E. 89. A portion of the fore part of the head of a Fishing-Frog
[Lojiliius j^ificalonus), showing the olfactory organs. In
this fish, winch does not actively pursue its prey, the

Fig. 18.

Olf actoi-y tentacle of Lojihiits piscatorius : enlarged.

(). lu- and exhalent openings. O.L. Olfactory leaflets.
O.N. Olfactory nerve.

olfactory organs and brain (cf. D. 100) are reanarkably
small. Each olfactory pit is situated at the extremity of
a short solid pedicle, and opens to the exterior bv

ORGANS OF SPECIAL SENSE. VEUTEBRATA.

83

two apertures (indicated on the right by a red rod) placed
oiic at the extremity of the pedicle and the other upon its
anterior face. Upon the left side, the portion o£ the
olfactory nerve in front of the orbit has been exposed and
the olfactory pedicle longitudinally divided. The surface
of the olfactory pit is increased by the presence of several
delicate olfactory laniellje, projecting from its floor.

AMPHIBIA.
Blaue, Arch. f. Anat., 1884, p. 282.
Seydel, Morph. Jahrb., Bd. xxiii. 1895, p. 453.
Mihalcovics, Anat.-Hfte., Bd. xi. 1898, p. 1 {Jacohsons
orgaii).

With the adoption of a terrestrial mode of life, the nose
becomes a respiratory passage as well as an olfactory organ,
and for this purpose acquires a direct opening into the mouth
through the choanse or posterior nares. At the same time the
nasal cavity becomes more or less definitely divided into olfactorv
and respiratory regions lined respectively by sensory and ciliated
epithelia. The primitive choause lie in the anterior part of the
palate, but in the higher groups of land Vertebrates the respi-
ratory part of the nose cavity is extended backwards beyond
them and opens into the pharynx immediately above the glottis
thus ensuring a practically continuous air-passage -from the
nostrils to the lungs. An increase in the area of the lining
membrane of the nose-cavity necessary for the proper warming
of the inspired air (in warm-blooded animals) and for the full
development of the olfactory sense, is effected by prominences
of the nasal walls. These can be supported by special skeletal
elements, and being then very constant in position though
variable in form, are distinguished from mere fleshy pro-
tuberances of different sorts as " turbinals " (see Mammalia,
Introduction) .

The olfactory membrane is mainly confined to those parts
of the lateral walls and septum of the nose that lie near the
entry of the olfactory nerves, but in many groups a detached
portion of somewhat peculiar structure is lodged in a pair
of cavities in the floor of the nasal chamber on either side
of the septum. These, known as Jacobson's organs, are

Q 2

84

I'll VSIOLOGIOAL SKKllSS.

first recognitiiiblo in tlie Ainpliihiu, where they are simple
divci'ticula of the ireneral cavity opening; near tlie choanae. In
hio-lier groups they boconio more cut oif from the nose-cavity
and open rehitivoly further forward, not into it, but into a pair
of canals or blind pits, the naso-palatine canals, that, when not
degenerate, connect the front part of the nose-cavity with the
mouth and probably represent the original choanse, left behind
in the above-mentioned backward extension of the respiratory
passage. The function of these organs is very obscure, but it
has been suggested that they may serve to test ihe flavours of
food during the act of expiration.

E. 100. Head and shoulders of Necturus maculaius, with the
olfactory organs shown. On the right side the skin has
been removed to expose the external surface of the olfactory
capsule W'ith its supporting skeleton of transverse cartila-
ginous bars. The capsule is an elongated chamber of
sliglitly cresceutic form with the concavity directed out-
wards. It opens to the exterior in front on the margin of
the snout, and posteriorly into the mouth-cavity by a slit-
like orifice lying between the maxilla and the palatine
teeth. The openings are indicated by green rods. On
the left the chamber has been opened from above. The
lining membrane is thrown into numerous transverse pleats
to provide increase of surface, as in the olfactory organ of
most Fishes. The olfactory nerves (marked by black
bristle?) are very large and leave each organ along its
median margin. Their course within the skull and relation
to the fore-part of the brain are shown by removal of the
cranial roof.

In the Urodeles examined by Blaue the olfactory cells
were arranged, as in many Fishes, in bud-like groups
separated by indifferent epithelium.

Wiedersheim, Morph. Jahrb., Bd. ii. 1877, p. 392.

E. 101. The head of a Frog {Leptodaciylus pentadaayhts) in
which the nasal cavities have been opened from the dorsal
aspect. Each cavity is spaceous in the horizontal plane
and opens posteriorly into the mouth by a large round
opening- on the level of the palatine teeth. The lips of this

ORtiAXS UF SPECIAL SliNSE. — VKUTELSUATA.

85

opening do not unite laterally, but cross one another (the
posterior above), and thus give rise to a gutter by which
tlie lateral parts o£ the nose cavity are continued into the
mouth alongside the upper jaw. This gutter is probably a
rudiment of the maxillary sinus and backward respiratory
extension of the nasal cavity of higher forms. From an
opening in the floor of the nasal cavity (marked on the
left by a red rod) a pit or recess extends to the septum.
This recess, which is an antero-median prolongation of
the maxillary sinus, is lined by olfactory epithelium
and probably represents the Jacobson^s organ of higher
Vertebrates.

EEPTILIA.
Solger, Morph. Jahrb., Bd. i. 1876, p. 467.
LACEETILIA.

E. 102. Right half of the head of a Spiny-tailed Lizard {Uro-
mastlx spinipes), showing the cavity of the nose and the
brain. The cavity is short and deep and consists of two
divisions — a vestibule and an olfactory chamber. The
former lies just within the nostril, in front and slightly to
the side of the olfactory chamber, and is occupied to a
considerable extent by a large protuberance of its lateral
wall. Posteriorly it communicates with the olfactory
chamber by a large round opening in the upper and
anterior part of the turbinal that stretches diagonally like
a diaphragm across the nose-cavity from its outer wall
posteriorly to the septum in front, and probably corresponds
to the maxillo-turbinal of Birds and Mammals. The
posterior nares are a pair of slits in the palate that extend
side by side from the level of the septal attachment of the
turbinal (which is seen in the specimen as a cut edge) to
the hinder limit of the nose-cavity. The olfactory mem-
brane is innervated from an olfactory bulb situated above
the orbit close behind the nasal chamber. A long slender
tract connects the bulb to the cerebrum. In this specimen
Jacobson's organ of the right side can be seen in longitu-
dinal section beneath the nose-cavity just in front of the
posterior nares. It is a curved tube (with the concavity
ventral) about 2 mm. in length.

Presented Inj Frofessor G. Elliot Smith.

86

PHYSIOLOGICAL SEinES.

E. 103. A series of sections, five transverse and one horizontal,
through the nose of a Spiny-tailed Lizard (Uromastix
spinipes). The approximate levels of the section surfaces
are shown in the accompanying diagram.

Fig. 19.

Diagram of a sagittal section of the nose of ZTrotnastix spinipes.

AP. Atrial process. M.T. Maxillo-turbinal. OL.B. Olfactory bulb.
P.N. Posterior nares. 1, 2, 3, 4, 5. The positions of the transverse
sections ; an ari'ow passes from the posterior nai'es through the nose-
cavity and anterior nostril.

The first section (counting from above and from left to
right) shows the left anterior nostril ; the second passes
through the protuberance of the lateral wall of the vestibule;
the third shows the septal termination of the turbinal and
the anterior extremity of the olfactory chamber and of the
posterior nares ; the fourth includes the passage from the
vestibule into the olfactory chamber ; and the fifth (seen
from in front) shows the hinder part of the olfactory
chamber and of the vestibule.

In the horizontal section the serpentine form of the
nasal cavity is shown.

Presented hj Professor G. Elliot Smith.

E. 104. A section of the head of an Iguana [Iguana iuherculata)
with the left half of the cavity of the nose exposed. A
bristle is passed from the nostril through the vestibule,

ORGANS Ol!^ SFKCIAL SISNSE. VEUTEBUATA.

87

olfactory chamber, and posterior nares into the mouth.
The vestibule, lies above and to the external side of the
olfactory chamber and communicates with it by a circular
opening. Part of the olfactory nerve has been exposed ;
it is distributed to the greater part of the e})itheliuni of
the olfactory chamber. 0. C. 1531. Hunteriaii,

OPHIDIA.

E. 105. A series of transverse sections through the nose of a
Boa constrictor. The sections are arranged vertically in
pairs with the point of the nose above. In each pair the
left-hand section is seen from behind^ the right-hand from
in front.

The cavity of the nose is relatively simple and extends
forward some little way beyond the nostrils (first pair of
sections). Close behind the nostril a lateral projection
indicates the beginning of a turbinal comparable to the
maxillo-turbinal of Birds and Mammals (second pair of
sections). Further back the turbinal enlarges, assumes a
plate-like form, and shifts its attachment upwards. From
the eighth section backwards its attachment is transferred
from the dorsal wall to the floor of the chamber by the
encroachment of a forward diverticulum of the hinder
part of the nasal cavity. The body of the turbinal is free
at quite the hinder extremity of the cavity and ends in a
blunt scroll (final pair of sections). In this pair of sections
the communication between the nose and the mouth by
the slit-like posterior nares is also shown. In addition to
these points, in the third pair of sections is shown Jacobson's
organ situated between the nose-cavity and the mouth, and
in the fifth pair the position of the olfactory bulbs.

E. 106. Longitudinal section of the head of an Anaconda
(Eunectes murlnus), showing the olfactory organ and the
brain. The nose-cavity and the turbinal in essential^ re-
semble those of the Boa Constrictor, In this view the
position of the turbinal and the contour of its median
surface are shown, but the lateral diverticulum of the
olfactory chamber is concealed behind its posterior end.
The right olfactory bulb is exposed, showing its relatively

88

PHYSIOLOGICAL SEIIIKS.

large size and the nerves given off from its anterior end
to an area of pigmented tissue at the extreme postero-
dorsal part of the olfactory chamber. The position of
Jacobson's organ should be noted in the floor of the noso
about half way between the anterior and posterior nares.

EMYDOSAUEIA.

E. 106a. The head of a young Long-nosed Crocodile (Croco-
dilus catapliractus) in vertical longitudinal section, showing
the right half of the nose-cavity and brain. The posterior
limit of the septum is indicated by the retention of a small
piece of its upper and lower parts. The nasal cavity on
either side is single in front for about half its length, but
is posteriorly divided into an upper olfactory chamber and
a lower respiratory passage by a horizontal septum that
stretches from the side walls to the septum. The single
part of the cavity is partly occupied by a longitudinal
prominence that projects from its roof and probably re-
presents the atrial prominence in the nose of Lizards and
Birds. Within the olfactory chamber are a couple of
turbinal-like prominences. The anterior of these corre-
sponds with the true turbinal of Lizards and Birds, but
the posterior is the projecting wall of a sinus in connection
with the nose-cavity and is comparable to the olfactory
eminence in Birds. The olfactory bulb and tract are of
large size, and in the specimen the olfactory nerves can be
traced owing to the pigmentation of their sheaths beneath
the mucous membrane of the olfactory eminence and tur-
binal. The nerves that supply the corresponding part of
the septum have been cut short.
Solger, I. c, p. 483.

CHELONIA.

Seydel, Festschr. z. Gegenbaur, Bd. ii. 1896, p. 387.

E. 107. Two sagittal sections through the nose of a Turtle
(^Clielone myclas), showing, in the upper specimen, the
septum and, in the lower, the outer wall of the right half
of the cavity. The nostril leads into a tubular vestibule
which is directly continuous with a cylindrical respiratory

ORGANS OK SPECIAL SENSfcl. — VER'i'BBRATA ,

89

seo-ment of the nasal cliainber. At the entry into this it
expands to form a flattened chamber that stretches up-
wards, downwards and forwards, and towards the septum.
The downward extension is compared by some (Seydel) to
Jacobson's organ. Just behind these expansions is a
globuhir diverticulum of the roof of the nasal chamber
which is lined by olfactory epithelium. 0. C. 1534 A.

Presented by G. A. Ring, Esq.

E. 108. A longitudinal section of the anterior part of the head
of a Turtle (Chelone mydas), showing the distribution of
olfactory nerves of considerable size upon the septum and
walls of the olfactory chamber. The section has divided
the septum and exposed the median parts of the vestibular
expansions. The nostril, which can be seen on the reverse
of the specimen, is a simple oval aperture.

0. C. 1532. Hunterian.

E. 109. The opposite half of the same head.

0. C. 1533. Hunterian.

E. 110. A dissection from above of the olfactory organs of a
Turtle (CheloJie mydas). The two olfactory nerves are
shown. The olfactory cavity has been opened on the left
side. 0. C. 1534. Hunterian,

E. 111. The supporting cartilages of the olfactory organs of a
Turtle (Chelone mydas). 0. C. 1535. Hunterian.

AVES.

Gegenbaur, Jena. Zeitschr., Bd. vii. 1873, p. 1,
Hill, ' Nature,' vol. Ixxi. 1905, p. 318.

E. 112. The head of a Ki-Wi {Apteryx mantelli), divided sagit-
tally to show the olfactory organ and brain. The small
nostrils, unlike those of other Birds, open close to the tip
of the beak. In consequence the nasal cavity is elongated
and can be separated into two regions — a long tubular
"vestibule" that extends from the nostril to the base of
the beak and is longitudinally ridged by a delicate atrial
"process"; and a true nasal cavity occupied by several
turbinal prominences and opening into the mouth by the

90

Pll VSl()L()(iICAL SKItlKS,

posterior nares. The tnrbinal system i.s more developed
than in other Birds and superficially bears a strong re-
semblance to that of a Mammal, four mock " ethmo-
turbinals'-' being ranged in series between the maxillo-
turbinal and the cribriform plate. The second of these i.s
a direct continuation of the maxillo-turbinal. The great
development of the turbinal system is accom])anied by a
similar enlargement o£ the olfactory bulb. Tiie division
between this lobe and the rest of the hemisphere is distinct
only below, but roughly the bulb has the size and ap-
pearance of the end of a little finger, the area from which
nerve-fibres are given off to the mucous membrane of the
septum and turbinals measuring in an antero-posterior
direction 9 mm. From the anatomical features of this
specimen, as well as from direct experiment, it is clear that
the Ki- Wi has an olfactory sense far more highly developed
than that of the generality of Birds.

Benham, Nature, vol. Ixxiv. p. 222 {Physiol.).

E. 113. A longitudinal section of the head of a Peacock {Pavo
cristatus), showing the nasal cavity, brain, and olfactory
nerve of the right side. The cavity contains the three
prominences (atrial process, maxillo-turbinal, and olfactory
eminence) characteristic of Birds. The sense of smell,
judging by the size of the olfactory nerve, must be very
slight.

E. 114. A similar section of the head of a Swan ( Cygnus olor),
showing the septum nasi perforated opposite the nostrils
by an oval aperture. This condition is common to An-
serine Birds, and is also met with in OrnitJwrJiynchus
(E. 185). A bristle has been inserted into the Eustachian
tube. Upon the reverse of the specimen the lacrymal
canal (marked by a black bristle) and maxillary sinuses
have been laid open. 0. C. 1530. nvnterian.

John Hunter, Essays and Observations, edit. R. Owen,
1861, vol. ii. p. 318.

E. 115. Median longitudinal section of the head of a Cygnet
[Cygnus olor), with the right wall of the nasal cavity
exposed by the removal of the seplum nasi. The anterior

ORGANS OF SPECIAL SENSK. VKKTICBIIATA . 91

nares open into a vestibular cliaiiiber imperfectly separated
from the rest of the nasal cavity by a prominent ridge —
the atrial process — that runs diagonally from the upper
border of the nostril to the lower part of the septum.
In the post-atrial nasal cavity there are two main pro-
minences— a maxillo-tui'binal, that originates above the
atrial process as a narrow ridge and expands posteriorly.
It separates the upper (olfactory) half of the nasal chamber
from a lower (respii'atory) passage that lies upon the
palate and opens into the month by a pair of slit-like
posterior nares, fringed by several rows of stout conical
papillae. Above and behind the maxillo-turbinal lies the
olfactory eminence, a triangular expansion which is supplied
by the olfactory nerve and is the chief area covered by
the olfactory membrane.

The large ophthalmic branch of the trigeminus, which
in its natural position lies beneath the mucous membrane
of the septum, has been retained, isolated. A black bristle
marks the passage from the nose cavity to the frontal
sinuses, and a red rod has been inserted into the slit-like
opening of the lacrymal duct.

E. 116. Transverse sections through the nose of a Goose [Anser
ferus). The approximate levels of the section surfaces are

Eig. 20.

Diagram of nasal cavity of Cygnus olor.
A, B, 0, D, E, the areas included in the transverse sections.
A.N. Anterior nares. A.P. Atrial process. M.T. Maxillo-turbinal.
O.E. Olfactory eminence.

92

PHYSloLUUlCAL SERIES.

shown on.tlie accoiiipunyiug diagram from E. 115. Sections
A B and E are seen from in front, C and 1) from behind.

The atrial process and the perforation of the septum are
shown in A; the beginning. of the nuixillo-tiirbinal and
the swelling on the septum at the hinder end of the atriiil
process in B ; the scrolled structure of the maxillo-turbinal
and the anterior limit of the posterior nares, in C; the
hinder end of the maxillo-turbinal and the anterior extremity
of the olfactory eminence, in D ; and the olfactory chamber
and its separation fi-om the posterior narial passage by the
hinder attachment of the maxillo-turbinal, in E.

The maxillary sinus, which has no connection with the
nose cavities, is shown in B, C, D, and E.

Green rods have been inserted into the lacrymal duct.

E 116 a. Part of the head of an Albatross (Diomedea exulans) in
sagittal section, showing the brain and the right half of
the nasal cavity.

The brain is remarkable for the large size of the olfactory
bulbs, -which measure 7 mm. in length X 8 mm. vertically,
the length of the rest of the hemisphere being 35 mm.
This strong development of the olfactory bulbs is accom-
panied by a corresponding enlargement of the olfactory
eminence, which lies in a backw^ard extension of .the upper
part of the nasal chamber imperfectly separated from the
rest by a shelf-like process of the sejitum (most of this
process has been removed). Olfactory nerves are distri-
buted to the surface of the olfactory eminence and to the
neighbouring parts of the septum. They are indicated in
the specimen by a faint longitudinal striping of the mucous
membrane. Their cut ends can be seen projecting from the
left olfactory bulb. It seems likely that in this and cei-tain
other aquatic Birds the sense of smell is relatively strong.

The maxillo-turbinal and atrial process are not remarkable.
Upon the free edge of the latter the opening of the duct
of the nasal gland {cf. E. 180) can be seen filled with
black injection. A green rod has been passed into the
lacrymal duct.

E. 117. The head of a Gannet {Sula hassana) in mesial sagittal
section, showing the reduced condition of the olfactory

ORGANS OK SPECIAL SENSE. VERTBBRATA.

93

organ. There are no anterior nares, and the olfactory
chambers are reduced to a pair of dome-shaped pits thai
extend upwards into the skull from the hinder parts of the
palate. The pits are separated mesially by a septum that
terminates ventrally some distance -v\-ithin the common
opening of the posterior nares. The inner surface of the
olfactory chamber is smooth. The olfactory nerve (indi-
cated by black pnper) and bulb are small compared with
those of many Birds. A hair has been inserted into the
duct of the nasal gland. This reduced condition of the
nose, with the absence of the anterior nares^ is common to
members of the Order Steganopodes, all of which are aquatic
Birds.

E. 118. A longitudinal section of the head of a Golden Eagle
lAquila chrysaetus), showing the lateral wall of the left
half of the nasal cavity. The vessels of the maxillo-turbinal
have been minutely injected to show the high degree of
vascularity of the mucous membrane. The maxillary sinus,
situated beneath and to the side of the nasal cavity, has
been opened, and bristles have been passed from the
puncta lacrymalia (see reverse of the specimen) through
the lacrymal duct into the nose. The opening of the duct
lies close behind the hinder end of the atrial process.

0. C. 1538. Hunterian.

E. 119. A similar specimen in which the brain, olfactory bulbs
and nerves, and olfactory eminence are shown.

E. 120. A transverse section through the head of an Erne
{lialiaelus alhicilla) taken through the mid-region o£ the
maxillo-turbinals. The cavities of the maxillary sinuses
are well shown, as also is the position of the lacrymal
ducts (marked by black bristles). Bristles have also been
inserted into the common openiug of the Eustachian tubes,
situated behind the posterior nares. Upon the reverse of
this specimen a dissection has been made of the eyes — the
left eye having been divided to show the pecten, and a
preparation having been made of the muscles of the globe
and of the nictitating membrane on the right side.

0. C. 1539. Ihmtenan.

04

PHYSIOLOGICAL SERIES.

E. 121. The anterior part of the same head, showing the termi-
nations of the maxillo-turbinals and of the lacrymal ducts
(indicated by black bristles), and also the passage of the
maxillary sinuses into the cancellous tissue of the beak.

0. C. 1540. Ilunteriav.

E. 122. The head of a young Rook {Trypanocorax frugiJegus)
in sagittal section, showing the right half of the nose cavity
and brain. The atrial process and maxillo-tiirbinal are
well developed, particularly the latter, which has a swollen
cylindrical form. The olfactory eminence and olfactory
bulb and nerve are, on the other hand, peculiarly small,
showing that the sense of smell is feeble.

MAMMALIA.

Zuckerkandl, Das periph. Geruchsorg. Saugethiere,

Stuttgart, 1887.
PauUi, Morph. Jahrb., Bd. xxvi. 1900, pp. 147, 179, 48H.

In Mammals Ihe respiratory passage occupies the anterior
and lower parts of the nose cavity, and is separated from the
olfactory chamber by the maxillo-turbiual in front, and behind
by a horizontal septum (lamina terminalis) that stretches
forwai'd from the sphenoid bone and is united to the side walls
of the cavity and to the septum. The maxillo-turbinal, which
is chiefly used in warming and filtering the inspired air, is
homologous to the only true turbinal of Reptiles and Birds
and occurs in a considerable variety of forms, due apparently
to the progressive division and scrolling of the free border of
an originally simple plate.

The olfactory chamber is filled by ethmo-turbinals that spring
from the cribriform plate and are also attached to the lateral
walls of the cavity and to the lamina terminalis. An ethmo-
turbinal in its simplest form is a plate (basal lamella) attached
along one margin, and with its free edge thickened or bent upon
itself to form a double or single olfactory scroll. The basal lamella
is usually simple, but it may divide longitudinally and gi^-e rise
to two or more marginal scrolls, or again it may be complicated
by the development of small secondary scrolls upon its sides.
The ethmo-turbinals are divisible into two .series (figs. 22, 23) : —

ORGANS OF SPECIAL SENSE. — VERTEBRATA.

95

(1) Endo-turbinals, whose marginal olfactory scrolls abut on tliG
septum and are visible from the mesial aspect. They are usually
five in number and A^ery constant. (2) Ecto-turbinals, smaller
scrolls attached in varying numbers to the nasal walls between
the endo-turbinals and in mesial view concealed by them.

The first or most dorsally attached of the endo-turbinals
extends forward along the nasal bone, and to distinguish it
from the rest is usually called the naso-turbinal. In most
cases the cavity of the olfactory chamber is further extended

Fig. 21 A. Fig. 21 B.

ST •.

Fig. 21 A. — Second endo-ethmoturbinal of Lepus cumculus.
Fig. 21 B. — Transverse section of the same turbinal.

B.L. Basal lamella. CE.PL. Cribriform plate. EX. Free extremitj^.
L.W. Lateral wall of nasal chamber. OL.SCR. Olfactory scroll.
S.T. Secondary tuibinal.

by the outpushing of recesses and accessory cavities into the
neighbouring bones of the skull. In lower (osmatic) Mammals
some of these spaces form simple outpushings or recesses of the
general nose cavity, and serve for the lodgment of ethmo-
turbinals and for the increased extension of the olfactory
membrane, while others, both in osmatic and anosmatic
Mammals, form vacant pneumatic chambers or sinuses in more
or less open communication with the nose cavity or its recesses *,
In Man the sinuses are almost completely cut off from the nose
cavity, and are known as the anti'um or maxillary sinus, the
frontal and sphenoidal sinuses, and the ethmoid cells, and are
lodged respectively in the maxilla, the frontal bone, the pre-
pphenoid, and the lateral parts of the ethmoid, but the posilion
of these cavities is no true guide to their homology, which c:in
only be determined by their point of connection with the nose

* Specimens of these sinuses are also shown in section A.

PHYSIOLOaiOAL SKHIRS.

cavity. Thus the iiiaxilliiry sinus may frequently extend into
the frontal or sphenoid bones, but its o])ening always lies between
the hinder end of the maxillo-turbinal and the anterior attachment
of the second endo-turbinal. In like manner the frontal sinuses,
whatever their extension, open between the basal lamellae of
the first and second endo-turbinals, and the sphenoid sinus and
ethmoidal cells in different positions between the basal lamellie
of the succeeding endo-turbinals. In the following descriptions
the term recess denotes an open extension of the nose cavity
containing turbinals^ and the term sinus a vacant pneumatic
cavity opening into a recess or into the main cavity of the nose.

The olfactorj^ membrane is chiefly confined to the upper
part of the septum and the ethmo-turbinals, thus the number
and complexity of these turbinuls taken in conjunction with
the size of the olfactory parts of the brain give a rough measure
of the degree of perfection of the olfactory sense.

MONOTEEMATA.

E 123. Sagittal section of the fore part of the head of a Duck-
billed Platypus {Ornitliorhynchus anatinus), showing the
right half of the nasal cavity. The olfactory organ is
degenerate in the Platypus, owing to the unimportance of
the sense of smell to an aquatic animal, and also ditftrs in
form entirely from that of its only near ally — Echidna. The
olfactory chamber, which is not separated from the hinder
part of the respiratory passage by a lamina terminalis, is
occupied by three endo-ethmoturbinals, one of which,
however (Paulli, I. c, p. 170) bears two terminal olfactory
scrolls. The olfactory region of the brain is relatively small
(cf. D. 189), and the apertures of the ci'ibriform plate are
reduced as in some Primates to one on either side. In
comparison v^dth this reduce 1 condition of the olfactory
parts of the nose cavity, the respiratory region is well
developed. The maxillo-turbinal is large and of complex
structure, conforming to Zuckei'kandl's multi-scrolled type.
It arises midway between the nostril and the cribriform
plate, and at once swells to form a large spindle of scroll
svstems filling the nasal cavity. It terminates posteriorly
below the last ethmo-turbinal. The nostril lies upon the
dorsal surface of the snout as in Echidna. It.< orifice is

ORGANS OF SPECIAL SENSE. — VERTEBRATA.

97

valved {cf. E. 185). The floor of the nose just behind the
nostril forms a considerable projection (the anterior end of
the horizontal lamina shown in E. 185), within which lies
the organ of Jacobson. In the specimen the mesial wall of
this organ has been removed, showing the free edge of a
turbinal-like prominence that projects into its cavity.
Symington, Proc. Zool. Soc, 1891, p. 575.

E. 124. Right half of the head of a Spiny Ant-oater {Tacliy-
glofsus [^Echidna] aculeatus), in which the nasal cavity has
been exposed by the removal of the septum. The organ
of smell is remarkably developed. This is shown by the
large size of the cribriform plate {cf., D. 191) and the
great development of the ethmo-turbinals and hinder part
of the septum, which form the chief area covered by the
olfactory membrane. There are seven endo-ethmoturbinals
(Paulli, I. c, p. 171) represented by eight olfactory scrolls,
which are further complicated by numerous secondary
foldings. The root of one of the ecto-ethmoturbinals is
visible between the third and fourth endo-turbinals. The
extent of the olfactory membrane is yet further increased
by numerous turbinal-like outgrowths upon the hinder
part of the septum. These in the natural condition inter-
digitate with the foldings of the four last ethmo-turbinals.
They are shown upon a portion of the septum mounted
beside the main specimen. The maxillo-turbinal is rela-
tively simple. It begins anteriorly at the nostril and for
more than half its length is i-epresented by a simple fold.
Behind, it spreads out to a spindle shape and is grooved by
a deep furrow upon its median surface. It terminates pos-
teriorly beneath the fourth ethmo-turbinal. The olfactory
chamber is separated from the hinder part of the respiratory
passage by a small lamina terminalis, but there are no
accessory cavities. The nostril lies upon the dorsal surface
of the tip of the snout.
Zuckerkandl, I, c, p. 10.

MARSUPIALIA.

E. 125. Head of a Spotted-tailed Dasyure (Dasyurus maculatus)
divided by a longitudinal section to show the extent of the
nasal cavity in the vertical plane and the septum nasi.
VOL. m. H

98

PHYSIOLOGICAL KRKIES.

The septum is free along its lowor Ijorder backwards from
the naso-palatine canal. It is grooved below in its anterior
parts and eml)races an upstanding ridge of the maxillae
but without actual fusion. In its hinder part it is joined
laterally by the two halves of the lamina terminalis. The
extent of this miion (20 mm.) is shown on the section
surface by the cut edge of the lamina.

The size of the cribriform plate indicates a well-developed
olfactoiy bulb (c/., D. 197). The naso-palatine canal of
the left side has been opened.

E. 126, The right half of the head of a Walleroo (Macropus
robiisius), showing the nasal cavit}-- and the arrangement of
the turbinal bones. The cavity is oblong in the sagittal
plane, the fore part being peculiarly spaceous. The large
maxillo-tnrbinal is fluted upon its inner and upper surfaces
hy two deep furrows that limit separate scroll systems.
In addition to the naso-turbinal, which is plate-lilce, there
are four endo-ethmoturbinals somewhat similar to those of
the Sheep in form. The olfactory bulb is fairly large, but
the general anatomical characters of the nose do not
suggest any great development of the olfactory sense. In
this specimen the naso-palatine and part of the nasal branch
of ihe trigeminal are indicated by black bristles ; they are
of considerable size. The cut end of the chief branch of
the olfactorius to the septum is also shown, and part of the
ventral edge of the septum has been retained to show the
point at which it becomes free of the palate.

E. 127. A series of eight transverse sections through the nose
of a Black-faced Kangaroo {Macropus melanops). The
following are some of the chief points shown in the several
sections : — A. The external aspect of the muzzle and the
position of the nostrils. B. The plate-like anterior ex-
tremities of the maxillo- and naso-turbinals, and the
opening of the naso-palatine canals into the moutli. (J. The
middle part of the maxillo-turbinals. This is a good
example of the multi-scrolled type of this turbinal ; it
differs considerably from that of M. robustus (previous
specimen). D. The hinder end of the maxillo-turbinals

ORGANS OF SPECIAL SENSE. — VERTEBRATA.

99

and (on the right side) the anterior conical free-.ond of the
second endo-ethnaoturbinal. The scroll-systems o£ the
maxillo-turbinal are converging together to form its hinder
stalk of attachment. The two walls of the naso-turbinal
are spreading apart and contain between them the anterior
extremity of a cavity that further back becomes the frontal
recess. E. The anterior limit of the opening from the
general nose-cavity into the frontal recess and within the
latter, parts of ecto-ethmoturbinals. F. Tiie frontal ecto-
turbinals are now more complex. The remains of the
naso-turbinal have diminished in size and the anterior
ends of the second and third endo-turbinals have appeared.
Gr. Appearance of the fourth and fifth endo-ethmoturbinals.

Fig. 22.

Diagram of Section G.

I, II, III. IV, V. Endo-etlimoturbinals. EOT. Ecto-turbinala. FR.R.
Frontal recess. LAM.T. Lamina terminalis. SEC. Secondary turbiual.

In this section the relative positions of the endo- and ecto-
turbinals are very clearly shown, especially on the left side
There are three ecto-turbinals between the first and
second endo-turbinals, and one between the third and
fourth. The basal lamella of the second endo-turbinal
gives origin to a secondary turbinal. The lamina terminalis
is now formed. The frontal recess merges into an empty
space— the frontal sinus. H. The frontal sinuses above

II 2

100

PHYSIOLOGICAL SERIES.

are separated by the olfactory bulbs from the sphenoidal
recesses in which lie the fifth pair of ondo-turbinals.

In sections C, D, and E, Jacobson's organs and
Jacobson's glands can be seen at the lower end of the
septum.

E. 128. The nasal septum and two transverse sections through
the nose of a Black- faced Kangaroo (Afacropus melanops),
showing the oi-gan of Jacobson. In tlie upper specimen
the right organ is exposed from the side. It is a long
tube surrounded anteriorly by a scroll-like cartilage, lined by
olfactory epithelium and enveloped, especially posteriorly, by
a mass of gland tissue (Jacobson's gland) and blood-vessels.
It is situated beside the base of the septum, and opens
anteriorly into the naso-palatine canal (black bristle) and
receives numerous strong nerves from the olfactorius, as
well as branches from the trigeminus. A considerable
pnrt of Jacobson's gland has been removed to show the
branches of the olfiictorius going to the organ. The sec-
tions show the opening of Jacobson's organ into the
naso-palatine canal, and the organ in cross section.

Symington, Jour. Anat. & Physiol., vol. xxvi. 1891,
p. 371.

E. 129. Right half of the head of a Phalanger (Trichosurus
vulpecula) with the nasal cavity exposed by the removal of
the septum. The arrangement of the five endo-ethmo-
turbinals is very similar to that of the Kangaroo ; the fifth
is, however, larger and more oblong in outline. Between
the roots of the first and second endo-turbinals can be seen
part of an ecto-turbinal. The maxillo-turbinal is multi-
scrolled .

EDENTATA.

E. 130. Left half of the head of an Ant-eater {Myrmecophaga
jubata), showing the form and extent of the nasal cavity
and the arrangement of the turbinal bones. The wholo
cavity is greatly lengthened. The maxillo- and naso-
turbiiials are simple and differ little from those of the
Sheep. They extend forward to the nostril. The naso-
turbinal, which in front is a simple solid lamina, becomes

ORGANS OF SPECIAL SENSE. — VEKTEBRATA.

101

inflated posteriorly. Including the naso-turbinal, there are
five endo-ethmotnrbiuals, the second of which is continuous
anteriorly with the hinder end of the maxillo-turbinal and
is provided \\ ith two marginal olfactory sci-olls, as in the
Rabbit or the Bat. The roots o£ several ecto-turbinals can
be seen between those of. the endo-turbinals. Ju Iging by
the size of the cribriform plate, the sense of smell is acute.
The lower , edge of the septum has been retained to show
the point at which it becomes free of the palate.

Upon the reverse of this specimen, the muscles of the
lips and snout are shown.

Paulli, I. c, p. 509.

E. 131. A small piece of the other half of the same head showing
in transverse section the maxillo- and naso-turbinals. The
former is composed of two simple scrolls arising from a
common laminn, the latter is a mere plate-like projection.
The section was taken 15 cm. from the extremity of the
snout.

E. 132. Right half of the b ad of a Hairy Armadillo (Dasypus
vdlosus) with the nasal cavity exposed. The olfactory
la'.iyrinth is remarkably developed, and in the arrangement
of the endo-ethmoturbinals has a superficial resemblance to
that of Echidna. The maxillo-turbinal is simple and is
apparently of the double-scrolled type. There are seven *
endo-ethmoturbinals, including the naso-turbinal. The
first and second are much elongated, the first, as usual,
extending to the nostril, the second to the middle of the
maxillo-tui-binal. The remainder are oblong in shape, wilh
their length nearly in the vertical plane as in Echidna ;
they are enclosed in the backward prolongation of the
olfactory chamber (sphenoid recess) that lies above the
lamina terminalis, and are deeply fluted by superficial
corrugations. Above the base of the naso-turbinal a small
piece of the partition wall between the accessory cavities
in the frontal bones has been removed to expose some of
the ecto-ethmoturbinals contained in the frontal recess.

* This may be too liigh a uuniber, as it is not always possible in this view-
to distinguish between true tuibiiials and marginal olfactory scrolls, two of
which may belong to one turbinal.

^^'2 PHYSIOLOGICAL SEKIES.

The cribriform plate is of great size and is separated
into two distinct areas through which respectively pass the
nerves from the turbinals in the frontal recess and from
those in the main cavity and from the septum.

The nostril is guarded by a brush of stiflf papilliform
spines along its lower and outer margin.

Paulli, I. c, p. 511.

CETAOEA.

" The organ of smell would appear to be less necessary in
these Animals than in those which live in air, since some
[the Toothed Whales] are wholly deprived of it ; and the organ
in those which have it is extremely small when compared with
that of other Animals, as well as the nerve which is to receive
the impression." — John Hunter, Phil. Trans., vol. Ixxvii. 1787,
p. 428.

E. 133. A small part of the head of a Piked Whale (Balceno-
ptera acuto-rostrata) including the left posterior narial
opening. This is long and slit-like, slightly curving out-
wards. Upon the right of the specimen the cut surface
shows ]oieces of the ethmo-turbinals and the cavity occupied
in life by the olfactory bulb. This specimen can be better
understood by reference to No. 2759 Osteol. Series, which
is apparently its counterpart, dried.

0. C. 1546. Hunterian.

UNGULATA.
HTRACOIDEA.

E. 134. A sagittal section through the fore-part of the head of
a Cape Hyrax (Procavia capensis), showing the right half
of the nasal cavity. The maxillo-turbinal is peculiarly
small and simple. There are four endo-ethmoturbinals,
with five marginal olfactory scrolls, each of which presents
a perfectly smooth surface towards the septum. The first
(naso-turbinal) is broadened out posteriorly, and its lower
border is prolonged downwards to form the anterior
boundary of a bay in which lies the free end of the second
endo-turbinal. The fourth endo-turbinal and the upper
scroll of the second are broad and IVom this aspect roughly

ORGANS OF SPECIAL SENSE. — VERTEBRATA. 103

triansulai' in outline, the third and the lower scroll of the
second being narrower and more quadrangular. The hinder
part of the sphenoid recess is vacant. There is no frontal
sinus.

George, Ann. Sci. Nat., ser. 6, T. i. 1874, p. 172.

PEiaSSODACTYLA.

E. 135. Right half of the head of a foetal Horse (Equus cahallus),
showing the cavity of the nose. The maxillo-turbinal is
flat and simple in form, terminating in front in a fiair of
ridges, the upper of which (the wingfold) contains the
navicular cartilage, the lower being traversed by the
lacryraal duct (of., E. 196). There are six endo-ethmo-
turbinals, of which the last three lie in the recess above the
lamina terminalis. The naso-turbinal extends as usual
from the nostril to the cribriform plate, but is of remarkable
breadth for almost the whole distance, occupying nearly
half the vertical diameter of the nose-cavity. Its median
surface is deeply grooved towards the anterior end. The
other five endo-turbinals have a very characteristic form,
being short and spindle-shaped and each subdivided by
deep longitudinal folding. Parts of ecto-turbiaals can be
seen between the stalks of attachment of the endo-turbinals.
The lining membrane of a large cavity in the kimina
terminalis (probably part of the maxillary siuns). has been
exposed, and v\ithin the brain-cavity the hinder surface and
stalk of the olfactory bulb are shown.. The dilatation upon
the Eustachian tube (c/., E, 327) has been laid bare, and a
blue rod has been pai-sed into if from the posterior respiratory
passage.

Ellenberger &, Baum, Vergl. An;it.. Hausthiqrq, 190o,
p. 476.

E. 136. A vertical transverse section through the anterior
part of the nasal cavity of a Horse (Eginis cahallus),
showing the naso- and maxillo-turbinals, each of which in
this region consists of a single scroll. The membrane
covering the turbinals is extremely vascular, containing
an extensive venous rete — the plexus venosus concharum.

104

PHYSIOLOGICAL SEIIIKS.

On either side of the base of the septum, Jacobson's
organ can be indistinctly seen in section, ensheathed in a
ecroll-like Jacobson's cartilage. 0. C. 1556 b.

Presented hy Josejih Swan, Esq.

ARTIODACTYLA,

E. 137. The head of a foetal Pig {Sus scro/a) in sagittal section,
showing the brain and nasal cavity — the outer wall of the
left half of the cavity in the lower specimen and the septnm
in the upper.

The maxillo-turbinal is simple, as in other Ungulates.
Instead of the usual five endo-ethmoturbinals there are
seven, the last two of which are however very small. The
second to the fifth resemble those of the Horse in general
shape and are subdivided by folds of iheir surface. The
hinder end of the naso-turbinal is separated from the root
of the second endo-turbinal by a considerable gap, within
which appears part of an ecto-turbinal.

These specimens have been minutely injected.

O.C. 1551b, & 1551 c.

Paulli, I. c, p. 193.

E. 138. A sagittal section of the head of a Sheep (Ovis aries)
exposing the right half of the nasal chamber and brain.
The maxillo-turbinal is of quite simple form though large.
There are five endo-ethmoturbinals with six marginal
scrolls. In this view the olfactory labyrinth has an
extremely simple appearance, the endo-turbinals being
perfectly smooth and of moderate size. In reality the
ethrao-turbinals are very complex and numerous. Part of
the olfactory bulb has been exposed by the removal of the
anterior end of the hemisphere. Most of it is, however,
hidden by the roots of the endo-turbinals.

E. 139. Part of the right half of the head of a Sheep (Ovis
aries) showing the distribution of the olfactorius and tri-
geminus nerves upon the septum nasi. The chief septal
branch of the olfactorius runs downwards and forwards to
be distributed to Jacobson's organ. In the specimen the
branches of (his nerve are indicated by a red rod. A large

ORGANS OF SPECIAL SENSE. VBRTEBRATA. 105

naso-palatine branch of the trigeminus runs forward in the
angle formed by the septum and tlie floor of the nasal
cavity. Other nasal branches of the same nerve can be
seen entering the substance of tlie maxillo-turbinal. The
forward parts of the septum are innervated by a fine nerve
given off from the spheno-palatine ganglion.

E. 140. Six transverse sections taken at different levels through
the nose of a Sheep (Ovis aries), in which the following
points are shown in particular

A (the most anterior section). The cavity is plain in
outline with a prominence — the anterior end of the maxillo-
turbinal — projecting from its lateral walls. The passage
of Jacobson's organ into the naso-palatine canal is shown,
the cavities of Jacobson's organ (red rod) and of the naso-
palatine canal (pui-ple rod) being united by a narrow cleft
upon the section surface. B. The nasal opening of the
lacrymal duct is shown on the right by a green rod, and a
red rod is inserted into the cavity of Jacobson's organ.
C. The maxillo-turbinal has increased in size and has
assumed a double-scrolled form. Above it lies the laminar
anterior part of the naso-turbinal. D. The maxillo-turbinal
is at its largest. Within the naso-turbinal is a cavity that
further back broadens out into the frontal recess. The
antrum is shown in this section. E. Below the anterior
parts of the frontal sinuses lies the olfactory labyrinth
consisting of the endo- and ecto-ethmoturbinals. The
majority of the latter lie in the frontal recess — an out-
pushing of the nose-cavity between the first and second
endo-turbinals. F. The hinder part of the nose-cavity
showing the frontal sinuses above separated by the olfactory
bulbs from the respiratory passages and the recess containing
the lower endo-turbinals.

All the sections with the exception of E are seen from in
front.

E. 141. Two specimens showing the Jacobson's organ of a Sheep
{Ovis aries). This organ, as in other Ungulates, is strongly
developed, and lies alongside the ventral border of the
septum nasi, surrounded by a cartilaginous sheath (Jacob-
son's cartilage). ft has the form of a long laterally

lOG

PHYSIOLOGICAL SERIUS,

flattened tube, blind iind pointed j)o.steriorly and opening
in front by a slit-like aperture into the naso-jtalatine canal.
In cross section the lumen is orescentic, with its concavity
directed outwards. The walls are thick and vascular ;
they are chiefly composed of glandular tissue (Jacobson's
glands) ; the lumen is lined by olfactory epithelium similar
in histological structure to that in the Eeptilian Jacobson's
organ. The organ is innervated from the olfactorius and
trigeminus.

In the upper specimen the relations of Jacobson's organs
to the nose are shown by a transverse section, the lumen of
the right Jacobson's organ being indicated by red glass
rods. In the lower specimen the left organ has been
exposed^ showing particularly its innervation and method
of opening into the naso-palatine canal. Windows are cut
in the canal and in the outer wall of Jacobson's organ.

0. C. B 1559 A.

E. 142. The maxillo-turbinal of a Calf (Bos taurus), isolated.
It is fusiform in shape, and is attached along one side to
the lateral walls of the nasal cavity by a basal lamella,
the cut edge of which is shown in the specimen. The
free edge of the basal lamella is scrolled outwards on
either side, giving rise to the plain rounded form of the
turbinal. 0. C. 1556. Hunterian.

EODBNTIA.

E. 143. Anterior parts of the head of a Canadian Porcupine
(Erethizon dorsaivm), in sagittal section, showing the
cavity of the nose. The cavity has considerable vertical
depth. The hinder part is occupied by the ethmo-
turbiuals, of which there are four in the median row. Of
these the first (naso-turbinal) extends forward above the
maxillo-turbinal nearly to its anterior end. A process
extends downvvards from its lower border in front of the
succeeding ethmo-turbinals, and is attached to the lateral
nasal wall at a point close in front of the lamina terminalis.
The second to the fourth endo-turbinals have a simple
dilated form, and are united together distally by a plate
that posteriorly merges into the lamina terminalis. An

ORGANS OF SPECIAL SENSE. — VERTEBBATA.

107

ecto-ethmoturbiual is very plainly visible between the roots
of the first and second endo-tui binals.

The maxillo-turbinal, unlike that of the Eabbit, is
perfectly smooth mesially. In its posterior segment it is
much flattened and is free only dorsally. One centimetre
within the nostril it is dilated to form a globular pron)i-
nence, in front of which is another that contains a cavity,
suggestive of the false nostril of the Horse (E. 19f)), that
opens into the nose by a small round aperture just within
the nostril. A black bristle has been passed into the
naso-palatine canal. A large pneumatic sinus of tri-
angular form is situated beneath the outer and posterior
parts of the frontal bone. It is shown by the removal of
the anterior wall of the brain-case. At its anterior end it
opens into the nasal cavity behind the downward process
of the naso-turbinal. The passage is shown by a black
bristle. Antero-mesially this sinus is separated by a thin
partition wall from another large sinus situated partly
beneath the frontal bone and partly in the maxilla.

E. 144. The head of a young Crested Porcupine {.Hystrix
cristata) in sagittal section, showing the surface of the
septum. The anterior end of the septum is attached
ventrally to the palate, which in this part is dilated by an
unpaired sinus, that opens from the anterior end of the
posterior respiratory passage just below the thickened
anterior end of the free ventral border of the septum. A
short distance within the opening are a pair of orifices that
lead on either hand into a backwardly directed sinus
(maxillary sinus). The free ventral border of the septum
is strongly arched upwards and is remarkably broad.
Where it spreads out on either side to form the lamina
terminalis, a pair of openings, marked by black bristles,
lead into air spaces within the basul lamellae of the ethmo-
turbinals.

Paulli, Morph. Jalirb., Bd. xxviii. 1900, p. 5! 6.

E. 145. The head of a Rabbit (Lepus cuniculus) in sagittal
section, showing the nose-cavity and brain. The maxillo-
turbinal is multiscroUed, as in many Marsupials and

108

PHYSIOLOGICAL SERIES.

Carnivores. The ethmo-turl)inals are simple and of rela-
tively small size. There arc four endo-ctlimoturbinals, of
which the first (naso-turbiual) is plate-like in f'lont but
inflated posteriorly, the second bears two terminal olfactory
scrolls, and the fourth is partly lodged in a recess in the
sphenoid bone. The sense of smell is probably not very
acute, to judge by the want of complexity of the ethmoid
labyrinth and the comparatively small size of the olfactory
bnlb. There is no naso-palatine canaL
Paulli, I. c, p. 513.

PINNIPEDIA.

E. 146. A sagittal section through the head of a young Wali'us
(^Odohcenus rosmarus), showing the tubular form of the
nasal cavity and the arrangement of the turbinals of the
right side. The cavity of the nose is almost completely
filled by the highly developed maxillo-turbinal. This in
general shape and structure resembles that of the Dog, but
is relatively far larger and shows a most elaborate system
of scrolling. The naso-turbinal is small and does not reach
more than half way to the nostril. The rest of the ethmo-
turbinals are also much reduced and extend forward a very
little way from the cribriform plate. The outlines of the
lower ethmo-tiirbiuals are indistinct. Enough however is
shown in the specimen to make it evident that in com-
parison with the land Carnivora the sense of smell must
be insignificant in the Walrus, and that the nose-cavity is
essentially a passage in which the air is warmed on its way
to the lungs by passing through the interstices of the
maxillo-turbinal. 0. C. 1557. Hunterian.

E. 147. The left maxillo-turbinal from the same Walrus. The
general form of the turbinal is shown, and the cut edge
of its attachment to the lateral nasal wall. It is fastened
along its whole outer aspect, mainly by two broad stalks,
one at either end, which are formed by the convergence
and coalescence of the numberless scrolls of which the
bulk of the turbinal is composed, but also by a narrow
lamina that connects the two terminal stalks, and is in
fact the basal lamella from which tho whole complex

ORGANS OF SPECIAL SENSE. — VBRTEBRATA. 109

scroll-system has grown out. In the specimen the cut oflF
terminal stalks are very plain, but the central lamina is
partially concealed hy the overlapping of the scroll systems
of either side. 0. C. 1558. liunterian.

E. 148. A vertical section of the same head including the nasal
septum. 0. C. 1559. Hunterian.

E. 149. A sagittal section through the fore part of the head of
a young female Bladder-nosed Seal (Cystophora cristata),
showing the nose-cavity. The septum has been retained
in the anterior part of the nose, but removed from the
hinder two-thirds.

The nostril opens into a capacious vestibular chamber of
oblong outline. This represents, in a rudimentary con-
dition, the enormous inflatable air-sac of the adult male.
Posterioily and below, the vestibule opens into the nose-
cavity proper by a constricted mouth bordered above by a
projecting lip. The nose-cavity is almost completely filled
by turbinals. It has roughly a square outline in the
vertical plane. It'< anterior half is occupied by the maxillo-
turbinal, which, as in the Walrus, is large, spindle-shaped,
and an extremely complex variety of the multi-scrolled
type. Its anterior extremity reaches a point just in front
of the dorsal lip of the vestibulo-nasal opening, and its
posterior end to a point below the last ethmo-turbinal.

The endo-turbinals are five in number, with seven
marginal olfactory scrolls, and though short, are consider-
ably developed, with deep pleats upon the surface. The
first (naso-turbinal) extends forward to the posterior
surface of the dorsal lip of the vestibulo-nasal opening.
The cribriform plate is fairly large. 0. C. 1556 c.

E. 150. The anterior part of the head of a male Bladder-nosed
Seal {Cystophora cristata), showing from behind the
vestibular cavities and the opening in the posterior part of
the floor of each by which it communicates with the nasal
chamber proper. These dilatable vestibular chambers are
of enormous size in the male. They lie mainly above the
level of the cartilaginous nasal septum separated from each
other by a partition of soft tissue. Part of the right

110

PHYSIOLOGICAL sEllIR;^

maxillo-turbinal has boen retained, but the left has been
removed. 0. C. 1556 f.

Presented by Capt. David Gray.
Rapp, Arch. f. Anat., 1829, p. 236.

E. 161. Posterior part of the same head showing the hinder
blind extremities of the vestibular chambers and the pos-
terior border of their passage into the nasal chamber.
The latter cavityjis almost entirely filled by the complex
multi-scrolled maxillo-turbinal. 0. C. 1556 G.

Presented hy Capt. David Gray.

E. 162. The right vestibule removed from the skull of an adult
male Bladder-nosed Seal {CystopJiora cristata), showing
the circular form of the nostril, the septum between the
two chambers, and the outline of that of the left side in
the vertical plane. From an animal brought from Green-
land by Mr. Whymper in 1870. The skeleton is Osteol.
Series, No. 1101. 0. C. 1556 d.

E. 153. A portion of the lateral wall of the left sac of the same
individual dissected to show the subcutaneous muscle-fibres
radiating over it. 0. C. 1556 B.

CARNIVOEA.
CYNOIDEA.

E. 15i. Fore part of the head of a Foxhound in sagittal section,
showing the right half of the nasal cavity.

The maxillo-turbinal is spindle-shaped and belongs to
the multi-scrolled type. It is continuous in front with a
fold supported by the navicular cartilage (cf. E. 202) — an
internal process of the lateral cartilage of the nasal wall.
Its middle region is greatly expanded and is broken up by
deep gutters into a number of branching ridges, which are
the superficial parts of a complex system of scrolls springing
on either side from a central lamina. Posteriorly the
scrolls reunite to form a single fold similar to the one in
front, that merges into the lateral wall of the nasal cavity
in front of the lamina terminalis.

The ethmo-turbinals and the olfactory bulb are very

ORGANS OF SPECIAL SKNSE. — VEUTEBRATA.

Ill

strongly developed, though not quite so much so as in the
Cat; the turbinals occupy approximately the hinder hall:
of the entire nasal cavity. There are four endo-ethmo-
turbinals with five olfactory scrolls, which differ from
those of the Cat mainly in being longer and narrower. The
first ethmo-turbinal (naso-turbinal) is plate-like and solid
in front, but dilates posteriorly to form the mesial and lower
boundary of a large frontal recess which is occupied by a
number of ecto-turbinals and communicates with a well-
marked frontal sinus. The anterior end of the second
endo-ethmoturbinal is closely applied to the hinder margin
of the maxillo-turbinal : the two are separated in the
specimen by a row of black bristles. The fifth endo-
turbinal is elongated and extends to the hinder limit of the
sphenoid recess.
Paulli, I. c, p. 489.

E. 155. A series of nine transverse sections through the nose of
a Dog {Oanis familiaris) : sections A and D seen from
behindj the rest from in front, — A. Through the anterior
ends of the naso- and maxillo-turbinals. On the left side
the naso-palatine canal has been opened and a bristle passed
into it through the opening of the organ of Jacobson. —
B. The maxillo-turbinal is slightly grooved. A green rod
is inserted into the opening of the lacrymal duct, a purple
into the naso-palatine canal, and a red into Jacobson's organ.
— C. Through the scrolled part of the maxillo-turbinal.
— D. The naso-turbinal flattens out and contains a cavity
(tbe anterior end of the frontal recess) in which are small
processes — the anterior ends of ecto-turbinals. A large
passage between the hinder extremity of the maxillo-
turbinal and the anterior attachment of the second endo-
turbinal leads into a recess in the maxilla (antrum). The
septal parr of the lamina termiualis is spreading across the
nasal chamber, — E. The frontal recess, which is now
filled with well- developed ecto-turbinals, becomes continuous
with the maxillary sinus and the general nose-cavity. The
second and third endo-turbinals are united together and
to the lateral wall of the nose-cavity above the lamina
terminalis. The lamina terminalis is completed. The

112

rHYSlOLOGICAL SERIES,

Fig. 23 A.

MX.S.

LAM.T.

A diagram of Section E.

Fig. 23 B.

A diagram of Section F.

I, II, III, IV. The Endo-ethmoturbinals. 1, 2, 3, 4. Ecto-turbinals in the
frontal recess. LAM.T. Lamina terminalis. MX.S. Maxillary sinus.
SECT. Secondary turhinal. In Fig. 23 A an arrow is passed from the
main nasal cavity into the maxillary sinus and frontal recess.

ORGANS OF STKC'IAL SIONSK.— VKRTEUnATA. 113

septum loses its connection with the floor of the nose. —
F. Posterior extremity of the maxillary sinus. Second
and third endo-turbinals abut against the septum. Black
paper has been inserted between the second endo-turbinal
and the contents of the frontal recess. — G. Union of the
second and third endo-turbinals with the cribriform plate,
and consequent separation of the frontal recess with its
turbinals from the sphenoid recess containing the fourth
endo-ethmoturbinal. The punctum lacrymale of the
left side is indicated by a green rod. — H. Above : the
hinder end of the frontal turbinals and passage of the
frontal recess into the frontal sinus. Below : the posterior
end of the fourth ethmo-turbinals in the sphenoidal recesses.
In the middle: the olfactory bulbs.— I. The frontal sinuses
and the fore part of the cerebral hemispheres.

E. 156. A sagittal section of the head of a Greyhound (Canis
familiaris), showing the right half of the brain and cavity
of the nose. In this Dog, which has been bred to hunt
entirely by sight and not by scent, the extent of the surface
of the ethmo- and fronto-turbinals, and the size of the
olfactory part of the brain are apparently quite as great as
in the Foxhound.

AILUROIDEA.

157. The head of a Cat {Felis domestica) in sagittal section,
showing the right half of the nasal cavity and of the brain.
Zuckerkandl (L c, p. 48) states that of all the Mammals
examined by him the Cat has the most extensive olfactory
area. This great development of the olfactory organ is
indicated in the specimen by the size and extent of the
ethmo-turbinals and of the olfactory region of the brain.
The maxillo-turbinal is relatively small and is for the most
part hidden from view by the forward extension of the
second endo-ethmoturbinal. There are four endo-turbin:ds
with five marginal olfactory scrolls, the basal lamella of the
second being longitudinally divided. The naso-turbinal is
lamelliform and extends forward nearly to the nostril.
The second, third, and fourth endo-turbinals are triangular
in mesial view, with their free apices directed forward" and

VOL. III. ,

PHYSIOLOGICAL SERIES.

are attached posteriorly to tlie cribriform plate, and ventrally
to the lamina terminalis. The mesial surface of the second
and third is concave, the concavities being respectively
occupied by the free ends of the third and fourih. Behind
the fourth endo-tnrbinal is a vacant recess in the pre-
sphenoid (sphenoid sinus). Above the hinder part of the
naso-turbinal is a large chamber — a recess from the
main nasal cavity — occupied by two scrolled ecto-turbinals.
This frontal recess opens posteriorly into a vacant frontal
sinus.

Paulli, /. ('., p. 502.

E. 158. A series of transverse sections through the nose of a
Cat {Felis domestica). These sections are intended, as in
previous cases, to explain the longitudinal section forming
the previous specimen and should be studied in connection
with it. Sections A G I K are seen from in front, the rest
from behind. — A. The superficial features of the point of
the nose and the nostrils. — B. Passes through the front
part of the maxillo- and naso-turbinals, and includes the
opening of the lacrymal duct (green rod). — C. The maxilio-
turbinal is multi-scrolled, though feebly ; a red rod indicates
Jacobson's organ. — D. Passes through the free anterior
part of the ethmo-turbiuals (they have been removed on
the left side). The depressed position of the maxillo-
tiirbinal due to the large size of the ethmo-turbinals is
shown. The frontal recess begins to appear above the
dorsal wall of the nose-cavity and in the substance of the
naso-tui binal. — E. The frontal recess is larger and contains
pieces of ecto-turbinals. The naso-turbinal begins to flatten
out transversely. — F. Anterior borderof the opening between
the nose-cavity proper and the frontal recess (seen best on
the left). The naso-turbinal is almost completely flattened
out, and gives attachment to a frontal secondary turbinal.
— G. Disappearance of the maxillo-turbinal. Main cavity
of the nose in open communication with the frontal recess.
The antrum (maxillary sinus) is completely separate from
the nose-cavity on the left side, and on the right shows the
anterior margin of its mouth. First appearance of the
lamina terminalis.— H. Disappearance of the antrum

OUGANS OF SPECIAL SKKSB. — VEllTEBRATA.

.115

(reverse of the section). Completion of the lamina tcrmi-
nalis. Union of the second endo-turbinal with the cribri-
form plate. — I. Passaoe from the frontal recess into the
frontal sinus. Third and fourth endo-turbinals join the
cribriform plate. The frontal and sphenoidal recesses with
the posterior respiratory passage are the only parts of the
nose-cavity remaining. — K. The frontal sinuses separated
by the olfactory bulbs from the sphenoidal recesses.

E. 159. A longitudinal section of the head of a Leopard {Felis
pardus), showing the nose-cavity and turbinal bones of the
left side. The general form of the cavity and the arrange-
ment of the turbinals, so far as this rather imperfect
specimen shows, are exactly as in the Cat. 0. C. 1552.

Hunterian.

E. 160. A longitudinal section of the right side of the head of a
Lion {Felis leo). lu the form of the nasal cavity and of
the turbinals the Lion is similar to the Cat in essentials,
but in details difEers from it considerably. The cavity is
more roomy ; the maxillo-turbinal is larger and is not
covered mesially by the free ends of the ethmo-turbinals ;
the ethmo-turbinals are shorter, rounder, and more deeply
corrugated on their mesial surface. The frontal recess
and sinus have been opened. Upon the reverse of the
specimen the attachmenis of the maxillo-turbinal and
frontal ecto-turbinals are shown by the removal of the
outer wall of the nasal chainber. 0. C. 1553. Hunterian.

E. 161. The opposite side of the same head, in which the mesial
walls have been removed from the frontal eclo-turbinals
and fifth endo-turbinal to show the cavities contained
within their scrolls. The greater part of the long naso-
palatine canal is in section. 0. C. 1554. Hunterian.

E. 162. The nasal septum from the same head. Branches of
the olfactory nerve can be seen running beneath the
pituitary membrane towards the thickened base of the
septum, to supply Jacobson's organ. The anterior ex-
tremities of the naso-palatine canal.g are shown. They

,1 2

r'UVSlltl,0(il('AI. SICUIKS.

open neiir llic mid-line close bohinii the median incisors.
In this and the two previous specimens the arteries have
been injected to show the great vascularily of the pituitary
membrane. O.C.I 55f>. Ilunterian.

CIIIROPTERA.
Grosser, Morph. Jahrb., Bd. xxix. 1902, p. 1.

E. 163. Right half of the head of a Fruit-Bat {Pteropus medhin),
with the nasal septum removed to show the cavity of the
nose and its contained turbinals. The maxillo-turbinal i.^;
inconspicuous, being half hidden by the large free extremity
of the second endo-ethmoturbinal. It shows in this view
a plain surface furrowed by one deep longitudinal gutter.
(Sections showthat it is multi-scrolled, though compai'atively
simple. In the hinder part of the cavity are four olfactory
scrolls, which belong to the second, third, and fourth endo-
turbinals. The upper two are both attached to one basal
lamina and at their anterior end unite in a large flat
triangular expansion, which covers the upper and hinder
part of the maxillo-turbinal, and is continuous below with
the lamina terminalis. The first endo-ethmoturbinal (naso-
turbinal) is scarcely visible, being also to a large extent
covered by the anterior expansion of the second endo-
tnrbiiial.

PRIMATES.

Seydel, Morph. Jahrb., Bd. xvii. 1891, p. 44.

E. 164. The head of a Lemur (Lemur catta) in sagittal section,
showing the brain and the right half of the nasal chamber.

The ethmo-turbinals have the same arrangement and
appearance as in non-primate Mammals, but are relatively
somewhat small. The degenerate condition of the olfactory
organ is also shown by the rudimentary condition of the
ecto-turbinals (tw^o only are said to be i)resent) and by the
comparatively small size of the olfactory bulbs.

The maxillo-turbinal is double-scrolled. There are four
endo-turbinals, including the naso-turbinal, the second of
which has two olfactory scrolls and is prolonged forwards
above the maxillo-turbinal in a free point of unusual length.

OHGANS Ol!' SPECIAL SE\SR. — VEUTIiRKATA.

117

The third and fourth endo-turLinnls are small and lie at
the anterior end of a deep sphenoid sinus.

Piirt of an ecto-turbinal can be seen between the roots
of the naso- and second endo-turbinals.

Sejdel, Morph. Jahrb., Bd, xvii. 1891^ p. 5(5.

E. 164 a. Right half of the head of a Sooty Mannabey (Cerco-
cehus fuliginosus), sliowing the brain and nasal cavity in
sagittal section. The slight importance of the olfactory
sense in compai'ison with that of lower Mammals is indi-
cated by the small size of the olfactory bulb of the brain
and the simple character of the ethmo-turbinals. In place
of the complex olfactoiy labyrinth of quadrupeds there are
but three vestigeal ethmo-turbinals — a minute naso-turbinal
and a pointed plate-like second and a minute third endo-
turbinal. The maxiilo-turbinal is also of very simple
character. Frontal and sphenoidal sinuses are absent.

E. 165. The right half of the anterior portion of the face of a
Gibbon (Uylobates sp.), showing the nose-cavity and the
nasal cartilages. The turbinals occupy a considerable
proportion of the nasal chamber, but are very simple in
form. The ethmo-turbinals are represented by a single
plate-like expansion, with very definite anterior and ventral
borders. A deep indentation in the anterior border
separates a forwardly directed process of the plate, which
represents the naso-turbinal, from the main part, which is
probably a fusion of the middle and superior turbinals of
Man — the homologues of the second and third endo-
turbinals of lower Mammals. The maxiilo-turbinal (inferior
tnrbinal of Man) is prominent and formed of a double scroll.
The sphenoid sinus is spacious. There is no frontal sinus.
The lateral cartilage af the nose is considerably overlapped
by the nasal bone, as in Man. The annular cartilage is
small and simple,

Zuckerkandl, I. <7.-, p. 67.

E. 166. Sagittal section of the face of an Orang,utan {Simia
satyrus), pa,ssing through the left half of the nasal cavity.
The turbinals are more reduced even than in Man. The

lis

PHYSIOLOGICAL SKftlKS.

iiaso-turbinal is absent, or more probably included in the
middle turbiniil and represented by a small process of its
anterior border. Tiiore is no superior turbinal. The entire
area of the nose-cavity and cribriform plate are also
relatively smaller than in Man (compare with E. 174, a
Human specimen of about the same size). These characters
indicate an extremely weak power of smell. Bristles have
been [)assed into the opening to the antrum in the middle
meatus, into the mouth of the lacrymal duct below the
maxillo turbinalj and into that of the Eustachian tube.

0. C. 1550 D.

E. 167. Tlie right side of the face of a young Orang-utan
(^Shnia sati/7'iis), in which the maxillary sinus is exposed
by the removal of its outer wall. This cavity is remarkably
spacious, and corresponds in position to a combination of
the antrum and the sphenoidal sinus. A blue rod has
been passed through its opening into the nose-cavity. In
this specimen the nostrils and the cartilages of the nose
are also shown. The lower laferal cartilages are large, in
accordance with the great breadth of the tip of the nose.

Presented hy E. J. Steegmann, Esq.

Paulli, I c, p. 527.

E. 168. The two halves of the head of a Chimpanzee {Anthro-
popilhecus troglodytes), showing the nose-cavity and the
sinuses in connection with it. In the upper specimen (the
right half) the nasal chamber and the cartilages of the
nose have been ex[)osed. The ethmo-turbinals are more
separated by ethmoidal fissures than in Man. Three
separate prominences can be distinguished, a lower, middle,
and upper, which respectively correspond to the second,
third, and fourth endo-turbinals of quadrupeds, or to the
middle, superior, and suprema conchse of Man. A naso-
turbinal is not defined. The maxillo-turbinal is double-
scrolled. In the lower specimen the antrum and sphenoidal
sinus have been opened. The former is very extensive ; a
blue rod is passed through its passage into the nose-cavity.
The sphenoid sinus is small. In both specimens its opening
is marked by a green rod. There ir^ \w frontal sinus in
this young sjiecimen.

ORGANS OF SPECIAh SENSE. — Y lillTEDK ATA .

119

E. 169. The heads of two Infants at birth divided in the longi-
tudinal and transverse vertical planes to show the vestigeal
organ of Jacobson. In the sagittal section the opening of
the organ into the nose-cavity just above a deep pit that
represents the naso-palatine canal is marked by a bhick
bristle. Bristles have also been inserted into the ducts of
Jacobson's organs in the transverse section. They have
the usual mammalian position, one on either side of the
septum. 0. 0. 1550 F.

Presented hy S. G. Shattock, Esq.

E. 170. A longitudinal section of a Human face, minutely
injected, showing the septum nasi covered by the pituitary
membrane, through which the filaments of the olfactory
nerve may be faintly seen radiating from the cribriform
plate. The frontal and sphenoidal sinuses have been laid
open ; and behind the septum the opening of the Eustachian
tube, marked by a small quill, is seen boi dered by thick
swollen lips. The relative positions of the tongue^ soft
palate and uvula, pharynx, epiglottis, larynx, and sacculus
laryngis are also well displayed in this section.

0. C. 1547. Hunterian.

E. 171. A longitudinal section of the upper part of the face,
including the septum nasi and portions of the turbinal
bones of the right side. The specimen has been steeped
in an acid and shows several branches of the olfactorius
leaving the cribriform plate and distributed to the mucous
membrane. This preparation is described and figured in the
' Observations on Certain parts of the Animal (Economy,'
2nd ed. 1792, p. 259, pis. xvii, & xviii., and served to
demonstrate to Hunter that, of the nerves that supply the
nose and other organs of special sense, some are solely
concerned with the conduction of the special sense stimuli,
others being "only for the common sensations of the part
and other purposes answered by nerves."

0. C. 1550. Hunterian.

E. 172. The Human septum nasi minutely injected, dried, and
preserved in oil of turpentine, showing the great vascularity

.120

VHTSIOLOGICAL SKRIEs',

of the pituitary monibraiie covering that jiart, and the
mode of ramification of the hlood-vessels.

0. C. 1551. lJunterian.

E. 173. The opposKe side of the same head as E. 170, showing];
the three turbinal or spongy bones dividing the nasal
cavity into three passages or " meatuses." The superior
meatus is the smallest ; it is situated between the middle
and superior turbinals which represent the second and
third endo-turbinals of Quadrupeds. Bristles are passed
from it into the posterior ethmoidal cells and into the
sphenoid sinus. The middle meatus lies between the
middle and lower (maxillo-) turbinals ; a portion of
the former has been removed to expose the small opening
that leads into the maxillary sinus or "Antrum of
Highmore " ; the frontal sinus is also in communication
with this meatus, and a bristle is passed from one to the
other. The inferior meatus, which is situated between
the inferior (maxillo-) turbinal and the roof of the mouth
and forms the chief respiratory passage, receives the
termination of the lachrymal duct. In order to show this
opening a portion of the inferior turbinal has been raised,
and a bristle inserted into the orifice of the duct.

The Eustachian tube communicates with the nasal cavity
about 20 mm. behind the posterior extremity of the
maxillo-turbinal. A quill is placed in its opening.

In Man as in other Primates, the turbinals are quite
vestigeal. This is particularly the case with the ethmo-
turbinals, which are the chief area innervated by the
olfactorius.

To judge only from this and from the minute size of the
olfactory bulbs, the sense of smell in Man can bear no
comparison in its importance in the general life oeconomy
with that of most of the lower Mammals. 0. C. 1548.

Huntenan.

E. 174. A sagittal section tlirough the nose similar to that
shown in the previous specimen, but with the turbinals
undisturbed. Bristles have been passed into the openings
of the antrum, lachrymal duct, and Eustachian tube.

ORGANS OF SPECIAL SENSE. — VERTEBRATA,

121

Upou the reverse of the specimen the cavity of the antrum
and the ocuhir end of the lachrymal duct have been
exposed. 0.0. 1550 b.

E. 175. A transverse section through the nasal cavity and
mouth, showing the turbinals and the meatuses between
them, the septum nasi, the ethmoidal cells, and the hinder
part of the antrum. In this specimen the fauces including
the hinder part of the tongue, the soft palate, uvula and
tonsils are also well seen. 0. C. 1549. Hunterian.

Parts accessory to the Olfactory Organ.
PISCES*.

E. 176. Head of a Ray {Raja clavata), showing the nostrils and the
cartilages that support them and form the olfactory capsule.
On the right side the in- and exhalent openings of the
olfactory sac are shown. They are formed by overlapping
processes of the borders of the sac, in a manner similar to
that seen in Acanthias (E. 87), but in this case the process
of the anterior border is greatly enlarged and forms the
median boundary of a deep gutter leading from the inner
end of the olfactory sac to the corner of the mouth. Upon
the left side the cavity of the olfactory sac has been
exposed, and the cartilages that support the borders of the
sac left in position. The largest and most important of
these lie within the lips of the channel leading to the
mouth. The deeper part of the olfactory sac U
encapsuled in the actual cartilage of the skull.

IlEPTILIA.

E. 177. A sagittal section through the right nostril of a
Crocodile {Crocodilus americanus) . The nostrilj which ia
surrounded by a boss-like elevation of the integument, is
crescentic in form with the concavity facing backwards,
and opens into a narrow vertical nasal passage that soon
dilates and turns backwards. The lips of the nostril are

* Nostrils of Teleostca are shown in E. 94, E. 95, E. 96, and of Folyptems
in E. 92.

122

rilYSlOLOGICAL SERIES.

said to contain ii spliincter of unstriped muscle by which
they can be closed. In front of the vertical^ dilated part
of the nasal passage is a rounded mass of erectile tissue
continuous with ths vascular layer that underlies the
mucous membrane of the floor of the nasal cavity.

AVES.

E. 178. Heads of two Ptarmigan [Lagopus mutus). The nostril
is protected, as seen in the upper specimen, by feathers of
ordinary structure that grow around its margin. In the
lower specimen the feathers have been cut off short to
show the large oval nostril and the arrangement of their
roots around it.

E. 179. The head of a Petrel {Pufnus sp.). In members of
this group the nostrils are situated at the forward ex-
tremities of a pair of integumentary tubes, that run
forward along the dorsal surface of the beak for a variable
distance from its base. In this specimen they are 10 mm.
long.

E. 180. Part of the head of an Albatross {Diomedea exulans)
dissected to show the nasal gland of the right side.
The gland is of great size and occupies a deep groove in
the bones above the orbit. From its anterior part a duct
(marked by a black bristle) runs directly forward in the
frontal bone and beneath the mucous membrane of the nose
to open finally upon the free edge of the atrial process a
short way within the nostril. The opening of the duct is
shown in E. UG a. The gland is lobulated upon the
surface, and has a peculiarly hard compact appearance
due to the density of the connective tissue that forms its
framework. The nasal gland is found in most Birds,
but differs much both in position and in degree of develop-
ment. It secretes a watery fluid.

E. 181. The head of a Kagu {Rhinochetus jubatus). In this
bird the nostril is a long slit, bordered below by a slight
lip, and overhung by an arched flap of integument. This
flap, which projects 5 mm. from the surface of the beak,

ORGANS OF SFBCIAL SENSE. — VERTEBRATA. 123

protects the nose from the entry o£ foreign matter when
the bird digs for its food. Its action is thus described by
Dr. Murie : " As the nostril approaches the ground and is
touched, its anterior part having a plough-share formation
or scroll-like contour sends the earth upwards or over it.
The springy semi-elastic lid, from in front to behind, is
pressed down and inwards, finally completely closing the
aperture as the beak is thrust deep into the earth in search
of its living prey." (Trans. Zool. Soc, vol. vii. 1872,
p. 486.)

E. 182. The head of a Gannet {Sula bassana). In the Gannels
and several allied genera there are no anterior nostrils
(c/. E. 117). In this specimen [)art of the left side of the
head has been removed to show the nasal gland, which has
the same hard lobulated appearance as in the Albatross,
but is far smaller, globular in shape, and is situated in the
maxillary sinus in front of the orbit close against the wall
of the nasal cavity. The opening of its duct is shown in
E. 117. A black bristle has been inserted into the
lacrymal duct.

Ewart, Jour. Linn. Soc, vol. xv. 1881, p. 455.

Pycraft, ibid., vol. xxvii. 1899, p. 207.

E. 183. Head of a Falcon {Falco sp.), showing the nostrils.
In Birds of Prey the olfactory sense is comparatively keen
and the nostrils are large. They have in this specimen a
circular form, but are partly occluded by a knob-like
prominence that projects downwards from the dorsal
border. This prominence is the free end of the greatly
developed atrial process.

E. 184. The head of a Raven (Corvus coraco). The nostrils,
though large and widely open, are protected from the
entry of foreign matter by a thick covering of stiff bristle-
like feathers, that grow forward along each side of the
beak from the skin immediately behind the nostrils. On
the left side these feathers have been in part removed to
show the nostril.

124

PI-IYSIOLOGIICAL SERIES.

MAMMALIA,

Spurgat, Moi'ph. Arbeit., Bd. v. 1896, p. 555 (cartilages).
MONOTREMATA.

E. 185. Two specimens of the snout of a Duck-billed Platypus
(Oi'nitkorhyiicluis dnalmus), showing the nostrils — in the
lower specimen from the dorsal aspect, in the upper in
sagittal section. The nostrils are oval in shape, and lie, as
in the Echidna, upon the dorsal surface o£ the snout close
together, about 15 mm. from its extremity, and with
their long axes transverse and slightly inclined backwards
from the mid-line. Just within the nostril (see upper
specimen and left side of lower specimen) the roof and
floor of the nasal cavity are reflected forward to form
a pair of valves that would effectually exclude mud from
the nose cavity, though it is difficult to see why they
should not also impede the entry of air unless it be that
they are too stiff to be put into action by a gentle pressure.
In the lower specimen the central part of the dorsal valve
has been removed and black paper has been placed beneath
the ventral one. The fore-part of the nasal cavity has also
been exposed to show a connection through the lower part
of the septum between the two nasal chambers (compare
with the Anseriform Birds, E. 114 and E. 116), and a
horizontal membrane projecting from the septum and
partly dividing the anterior end of the nose cavity into
two. The opening of the naso-palatine canal beneath the
anterior end of this membrane is shown by a black bristle
in the upper specimen.

CETACEA.

John Hunter, Phil. Trans., vol. Ixxvii. 1787, p. 420.

E. 186. A portion of the upper part of the head of a Piked-
Whale (Balanoptera acuto-rostrata) showing the external
oritices of the nasal passages, or blow-holes. These are
paired, unlike the blow-hole of the Toothed Whales, and
have the form of two longitudinal clefts, approximated at
their anterior ends, but diverging posteriorly. Between
them the skin of the head is denply creased longitudinally.

ORGANS OK SPECIAl. SENSE. — YKHTEBRATA.

125

The left blow-hole has been opened by the reii oval of its
lateral wall, showing that the nasal passage is a direct
prolongation of its anterior half. At a depth of some
15 cm. the axis of the passage changes from longitudinal
to transverse and is here blocked by a large round boss,
projecting from its anterior wall. This swelling is mainly
composed of muscle-fibre.s, that run forward and outward
and by their contraction serve to open the nostrils.

0. C. 1545, Hunterian.

Delage, Arch. Zool. Exp., T. iii. Us, 1885, p. 108.

Carte & Macalister, Phil. Trans., vol. clviii. 1868, p. 238.

E. 187. A piece of the integument from the upper part of the
head of a Porpoise (Phocana phomna), including the
external oriSce of the nasal passages, or blow-hole : it is
single and of a crescentic form with the concavity turned
forwards. 0. C. 1541. Hunterian.

E. 188. A longitudinal vertical section of part of the head of a
Porpoise {Phoccena pJioccena) passing just to the left of
the external nostril through the left praenasal sac. The

Fig. 24.

Sagittal section of the nasal passage of Phuccena phoccena.

A.N. Anterior nares. L.F.V. Lower frontal valve. PN.S. Left prm-
nasal sac. PN.V. Prsenasal valve. S. Septum nasi. U.F.V. Upper
frontal valve. V. Vestibule.

preparation includes the whole of the valvular apparatus
for closing the nasal passage. The nostril, through which

126

PHYSIOLOGICAL SERIKS,

a quill has beeu passed, leads into a transversely expanded
' unpaired vestibular chamber connected anteriorly with a
pair of large " prasnasal " sacs that extend forward on either
side of the nostril close beneath the skin. The floor of each
prtenasal sac is thick and thrown into irregular transverse
folds (seen in section upon the surface of the specimen), but
the roof is unpleated and quite thin. Just above the separa-
tion of the nasal passage into two by the septum nasi, the
anterior wall of the vestibule is thickened to form a pair
of transversely disposed eminences (prsenasal valves). The
posterior wall of the vestibule is smooth, but projects close
above the level of the prsenasal valves to form a pair of
eminences (upper frontal valves) that correspond to the
praenasal valves and, when the walls of the vestibule are
apposed, fit above them. Below the upper frontal valves
are a pair of deep indentations for the lodgment of the
prsenasal valves, and these are again succeeded by a pair
of large rounded prominences (the lower frontal valves)
that complete the vestibular locking mechanism by fitting
below the prsenasal valves.

In this specimen the septum that divides the nasal passage
from the level of this valvular apparatus downwards, has
been cut through and the interlocking valves separated.

0. C. 1544. Buntp.rian.

Eawitz, Internat. Jour, Anat., vol. xvii. 1900, p. 296.

E. 189. Part of the head of a Porpoise {Phoc(Bna phocana)
including the anterior border of the nostril, the front
wall of the vestibule, and the prsenasal sacs. The roof of
the left prsenasal sac has been retained showing the natural
orifice of communication between the sac and the vestibule.
On the right the roof has been removed to expose the
transverse folds of the floor and front walls of the sac and
to show its extent in a lateral direction. The prsenasal
valves are shown at the lower edge of the specimen.

0. C. 1543. Hunterian.

E 190 A corresponding specimen of the hinder border of the
nostril and the posterior wall of the vestibule, showing
the two pairs of frontal valves. 0. C. 1542. Hunterian.

OKGANS OF SPECIAL SICNSE. VERTEBRATA.

127

E. 191. Part of the head of a Dolphin {Lagenorhjnchus albi-
rostris) inchiding the blow-hole, the vestibule of the nasal
passage and the sac-like cavities in connection with it.
The nostril as in the Porpoise is transverse and crescentic

Fig. 25.

Vestibular part of the nasal passage of Lagenoi-hynchus albwostris,

seen from behind.

F.S. Frontal sac. PAR.N.S. Paranasal sac. PMX.S. Premaxillary sac
PN.S. Praenasal sacs. PN.V. Prsenasal valve. U.F.V. Upper frontal'
valve. Rods are passed on the left from the vestibule into the
frontal sac and from the latter into the paranasal sac, and on the right
from the frontal sac into the cavity situated in front of the vestibule
(see text).

with the concavity directed forward. Close within the
nostril the vestibule opens on either side into a prsenasal
sac (maxillary sac, Murie), which differs from that of a
Porpoise in being without deep transverse folds upon its

128

rilYSIOLOOICAT. SriUlRS,

floor. On the left tliis sac has been fully exposed and
a window cut in its wall^ on the right it is seen in section.
The prsenasal valves are similar in position to those of the
Porpoise, but are relatively somewhat larger. They have
been exposed from behind and are seen to lie at the upper
end of a pair of large bluntly conical nasal sacs (pre-
maxillary sacs, Murie), both of which have been opened in
the specimen. The posterior wall of the vestibule has been
removed below the level of the upper frontal valves.
Through these the vestibular cavity opens into a pair of small
frontal sacs (naso-frontal sacs, Murie), lying transversely
just beneath the skin. On the left side the lateral ex-
tremity of this sac communicates by a small hole with
another of oval shape (paranasal sac). A corresponding
sac is not present on the right but just above the upper
frontal valve the vestibular cavity is continued laterally
into a large sac that bends round in front of the vestibule
across the mid-line. 0. C. 1544 B.

Presented by J. W. Clark, Esq.
Murie, Jour. Anat. & Physiol., vol. v. 1871, p. 123
(^Grampus),

E. 192. The skin from the middle of the upper surface of the
head of a young Gangetic Dolphin (Platanista gangetica),
showing the longitudinal linear single nostril or "blow-
hole " which characterises this genus. 0. C. 1544 A.

Presented hy Sir Joseph Fayrer, K.C.S.I.

UA"GULATA.
PROBOSCIDEA.

E. 193. The terminal portion of the trunk of a female African
Elephant {Mephas africanus). The nostrils are circular in
form and lie within a transverse cleft at the extreme end
of the trunk separated by the free edge of the nasal septum.
The nasal passages are protected from the entry of foreign
matter by a number of coarse stiff hairs that project in front
of the nostrils from the inner walls of the transverse cleft.
The upper lip of the cleft is prolonged to form a finger-
like process that can be apposed to the lower lip, forming

ORGANS OF SPECIAL SENSE. — VERTEBRATA. 129

an efficient grasping organ. This piece of trunk was
accidentally torn off by the animal itselE in the Zoological
Society's Gardens, August 1875. 0. C, 288 p a.

Presented hy the Zoological Society.

PEEISSODACTYLA.

E. 194. The proboscis and fore-part of the head of a Tapir
(Tapirus ainericanus\ showing the nostrils, the muscles of
the snout and the accessory nasal diverticula. The levator
labii superioris proprius and the caninus are clearly defined
and have much the same characters as in the Horse. The
other muscles of the snout are indistinct and much matted
together. A lateral indentation on either side between
the nasal and frontal bones is occupied by a scrolled
diverticulum of the nasal cavity. This is enclosed by a
tubular extension of the lateral cartilage of the nose and
lodges an offshoot of the maxillo-turbinal. The roof of the
nose has been laid bare, showing upon the right side
the lateral nasal cartilage with its scrolled hinder pro-
longation resting upon the dorsal surface of the nasal and
frontal bones. On the left the nose cavity has been opened
to show the continuity of the diverticulum with the main
cavity and the extension of the maxillo-turbinal within it.
This accessory pouch resembles in some ways the false
nostril of the Equidse, but opens into the nose cavity very
much further back. A similar pocket is found in the
Rhinoceros (Treves & Beddard,Proc. Zool. Soc. 1889, p. 11).

Upon the reverse of this specimen, the nostrils can be
seen. They are a pair of transversely elongated oval
openings surrounded and separated by an area of hairless
corrugated integument. 0. C. 1556 B ha.

Murie, Jour. Anat. & Phys., vol. vi. 1872, p. 138.

E. 195. The anterior part of the face of a Horse ( Equus
cahallus) dissected to show the nostrils with their muscles
and supporting cartilages, the false nostrils, and the opening
of the lacrymal duct.

Upon the right side (the reverse of the specimen) the
skin has been removed except around the nostril ; the
VOL. III. ic

130

PHYSIOLOGICAL SERIES.

superficial muscles of the upper lip and nostril and the
surface of the false nostril (diverticulum nasi) have been
thus exposed. The false nostril is conical in form and
stretches back from the upper part of the true nostril
along the lower border of the levator labii superioris pro-
prius. The most important muscles shown on this side
are : — the levator labii superioris proprius, the tendon of
which unites with that of its fellow in the mid-line between
the nostrils to pass along the centre of the upper lip ; the
upper part of the trausversus nasi, passing towards the
dorsal mid-line from the plate of the alar cartilage ; and
the caninus and levator naso-labialis, running backwards
from the posterior and lower border of the nostril and false
nostril. The three last-named muscles dilate the nostril.
Upon this side of the specimen a white rod has been
inserted into the mouth of the lacrymal duct, in the median
■wall of the nostril. (For the lacrymal duct of the Donkey
and other Mammals see Section E : Parts accessory to the
organs of vision.) Upon the left side a deeper dissection
has been made showing the alar cartilage, the ca\dty of
the false nostril and its connection with the nose cavity
proper, and the part of the transversus nasi in connection
with the cornu of the alar cartilage. 0. C. 1556 B a.

Ellenberger & Baum, Handbuch der Vergl. Anat. der
Hausthiere, 1903, pp. 219, 474.

E. 196. The extremity of the nose of a Horse [Eguus cahallus)
showing the cavity from behind, and the relation of
Jacobson's organ to the naso-palatine canal.

Upon the left side the section passes just in front of the
posterior border of the passage from the nostril cavity to
the false nostril, so that these two cavities are continuous.
The upper lip of this passage is inturned and scrolled
forming the "alar fold,'' supported by the navicular
cartilage— a derivative of the lateral cartilage of the nose.
The alar fold is continuous posteriorly with the maxillo-
turbinal. Below it, is a vascular swelling of the lateral
nasal wall also continuous posteriorly with the maxillo-
turbinal. The centre of this is occupied by the lacrymal
duct, into which on the right side a rod is inserted. The

ORGANS OF SPECIAL SENSE. — VBRTEBRATA.

131

anterior opening of the duct can be seen at tlie riglit side
o£ the specimen.

In the floor of the nasal cavity, on the left side, are two
round openings. The outer of these is the naso-palatine
cnnal, the inner, which is surrounded by a cartilaginous
tube, the duct of Jacobson's organ. On the right, sufficient
of the floor of the nasal cavity has been removed to show
the connection between these two ducts. 0. C. 1780 b.

E, 197. The left side of the fore part of the face of a Donkey
(Equus asinus), showing the nostril, the false nostril, the
alar cartilage, and the opening of the lacrymal duct.

The alar cartilage and the false nostril are very similar
to those of the Horse. The lacrymal duct, however, opens
into the nostril, not on the median, but on the lateral side.
Its opening is indicated by a white rod. 0. C. 1556 B b.

Presented by Henry Poiver, Esq,

AETIODAOTYLA.

E, 198. The skin of the snout of aPig (Phacoclmrus cetMop{eus{?))
showing the form of the nostrils. They are small and
nearly round, and are set very far apart. The broad flat
area of skin that surrounds them and forms the point of
the snout is highly sensitive. Its upper margin is, however,
tough and horny. 0. C. 1546 0.

E. 199. The snout of a Pig (Sus scrofa) with the nasal cartilages
exposed. The dorso-lateral cartilages are continuous with
the upper edge of the septum. They are covered for fully
half their length by the nasal bones (that of the left side
has been removed), and in this part show signs of reduction,
in the separation of irregular plates of cartilage from their
ventral borders. The anterior end of each is partly sepa-
rated from the rest as an alar cartilage, by a slit that
extends from the free edge to within 7 mm. of the septum,

The anterior extremity of the septum and alar cartilages
is greatly thickened to form the support of the snout disc.
The ventro-lateral cartilage is small and carries at its
anterior end a sickle-shaped cartilage accessoria for tho
support of the lateral walls of the nostril.

Spurgat, I. c, p. 562.

K 2

132

PHYSIOLOGICAL SERIES.

E. 200. Two specimens of the anterior part of the nose of a
Sheep {Ovis aries), showing its supporting cartilages. The
dorsal and ventral lateral cartilages are continuous with
the dorsal and ventral margins of the septum. The dorsal
lateral cartilage is considerahly reduced, more so than in
JS^asua (E. 201), in that its central parts are replaced by
a large membrane-covered space. The alar cartilage is
not separated from the anterior end of the lateral cartilage
although it is clearly marked off from it by a depression ;
ventrally, it is prolonged into a narrow bar that bends
outwards and terminates in a cross piece — the appendicular
cartilnge. In the tipper specimen the cartilages are seen
from without, in the lower from the inner side. In the
latter case the intimate connection between the navicular
cartilage and the maxillo-turbinal can be seen. Red rods
have been placed in the naso-palatine canals and black
bristles in the ducts of J acobson's organs.
Spurgat, I. c, p. 568.

OARNIVORA.

E. 201. The fore part of the head of a Coatl-Mundi {Kasua
nasua), showing the cartilages of the snout.

The chief parts of these cartilages lie in advance of the
prsemaxillse and form a double tube consisting of the
septal cartilage and its dorsal and ventral wings. Pos-
teriorly the basal part of the septal cartilage is jointed to
a cartilaginous bar that runs back along the base of the
septum to the prse-sphenoid, but the upper part of its
hinder border is separated by a sheet of membrane from
the perpendicular plate of the ethmoid. In the same way
membrane is interposed between the hinder border of the
dorsal lateral cartilages and the nasal bones. The snout
thus has great mobihty, particularly in the horizontal plane.
Its dorso-ventral movements are restrained by a rod of
fibro-cartilage that stretches from the nasals to the hinder
margins of the cartilages of the snout.

In detail, the whole of the dorsal and the anterior part
o£ the ventral margins of the septal cartilage are reflected
outwards to form the dorsal, ventral and lateral walls of
a pair of tubes. Where the lateral cartilages meet along

ORGANS OF SPECIAL SENSE. — VERTEBRATA.

133

tlie sides of each tube, the ventral one is inturned to form
a ridge (navicular cartilage) continuous posteriorly with
the maxillo-turbinal. An alar cartilage is not separated
off from the front end of the dorsal lateral cartilage. The
anterior edge of the septal and dorsal lateral cartilages are
inturned to support the borders of the nostrils. The
ventral part of this reflection bears at its end a small free
cartilage (c, accessoria).
Spurgat, I. c, p. 576.

E. 202. Anterior part of the snout of a Dog (Cams familiaris"),
showing the nose cartilages. The dorsal and ventral
lateral cartilages are direct prolongations of the upper
and lower margins of the septum. The dorsal lateral
cartilage forms the greater part of the side wall of tbe
nose, its lower part (preserved on the reverse of the
specimen) is however imperfect and is separated from
the rest of the cartilage by a narrow membranous space.
The ventral lateral cartilage is inturned, as in Nasua, to
form the navicular. A large cartilage accessoria for the
support of the lateral gutter of the nostril is attached by
fibrous tissue to the anterior and lower process of the
ventral lateral cartilage and also by an attachment, which
has been separated in the specimen, to the anterior end of
the lower part of the dorsal lateral cartilage. Ou the left
side the lower part of the dorsal lateral cartilage has been
removed to show the inturned navicular cartilage. As in
Nasua a considerable area of membrane intervenes between
the nasal and premaxillary bones and the lateral cartilao-es,
giving a large amount of play to the tip of the nose.
Spurgat, I.e., p. 581.

E. 203. The snout of a Dog (Canis familiaris), showing the
nostrils and the area of hairless finely granulated skin
around them. This bare area is richly supplied with
sensory nerve terminations, and in the Dog and many
other keen-scented Mammals is kept continually moist by
abundant secretion. It has been suggested (Exner) that
it may act as an accessory to the sense of smell by giving

134

PHYSIOLOGICAL SERIES.

information of tlie direction of air currents. The lowering
of the temperature due to the impact of a current of air
being much increased by the quickened evaporation of the
moisture upon the surface. A familiar application of this
principle in detecting otherwise imperceptible air currents
is to moisten a finger, hold it up, and notice which side
becomes cold. The importance to such animals as the
Deer of a delicate instrument of this kind by which to
determine the direction from which a smell proceeds is
obvious.

The Dog, however, does not scent its prey from a distance,
and in this case it would seem that the wet sensitive nose
is of use in helping it to always work into the wind when
hunting over any tract of country.

Exner, Zeitschr. f. wiss. ZooL, Bd. xl. 1884, p. 557.

Botezat, Morph. Jahrb., Bd. xxix. 1901, p. 439 (nerve
endinys).

CHIEOPTEEA.

E. 204. The skin of the head of a Bat (Pteropus vampyms),
showing the nostrils and the scroll-like projection of the
skin around them— see also E. 52, E, 53, and E. 386.

The ears, which also are shown in this specimen, are
small and pointed and without any of the remarkable
developments characteristic of many Bats.

O.C. 1551D.

E. 205. The skin of the head of a Bat (NocliUo lepor'mus). The
nostrils are small and oval in outline. They are situated
close together at the end of a pair of short tubes that form
a projection overhanging the upper lip.

The ears in this specimen are narrow and pointed. The
tragus forms an upstanding lamina, toothed along its upper
and outer margins. The lower part of the outer margin
of the conch is abruptly bent inwards to form the anti-
tragus, from the lower end of which a cutaneous ridge
rune's to the angle of the mouth. 0. C. 1607 a a.

Presented hy J. E. Hartwg, Esq,

ORGANS OF SPECIAL SENSE. — VBRTEBUATA.

135

E. 206. Skin o£ the head o£ a male Hypngnatlms monstrosus.
The snout is greatly distended and hammer-shaped, termi-
nating in a roughly quadrangular hairless disc. The
nostrfls lie near the upper border of the disc, surrounded
on their upper, mesial and lower sides by a scroll-like
projection of the integument which merges below into the
lateral parts o£ the upper lip. The central part of the
disc between the nostrils is irregularly sculptured and,
along the actual border o£ the lip, papillate.

O.C. 1551 E.

PRIMATES.

E. 207. The skin o£ the anterior part of the face o£ an old male
Baboon {Papio anubis), showing the external form of the
nose. Upon the left side the nasal cartilages have been
exposed. The lateral dorsal process of the septal cartilage
is extremely small, being only 4 mm, in breadth. It
occupies a position at the upper part of the nose, where
that organ begins to project from the general surface of
the face. On the other hand, the annular cartilage forms
an immense scroll situated upon the median, dorsal, and
lateral surfaces of the nose from the level of the middle of
the lateral cartilage to the tip. Its lower lateral margin
is inturned to form the navicular cartilage. No ventral
lateral process of the septum is apparent. The nostrils, as
in Man, are inclined outwards from the tip of the nose.
Their lateral border is strongly impressed by the prominence
due to the navicular cartilages. 0. C. 1546 D.

E. 208. The skin of the head of a male Proboscis Monkey
(jyasalis larvatus), showing the nose-like snout. This
proboscis differs much in form and size according to the
age and sex of the individual, and undergoes a process of
development superficially comparable to that of the Human
nose. In the foetus it is short, with the nostrils directed
forwards, but gradually the dorsal parts enlarge (not
however by the growth of the nasal bones), and in
old age a pendulous hooked-nose is formed. The nostrils

13G

PHYSIOLOGICAL RKIilKS.

are situated upon the under surface of the proboscis and
as in animal snouts he near the tip. 0. C. 1546 E.

VViodersheim, Zeits. f. Morph. u. Anthrop., Bd. iii.
]y01,p. 300.

E. 209. Tlie sldn of the head of a Gibbon {Iltjhhates leuchcus),
showing the form and position of the nostrils. The nostrils
are narrow and have a vertical position, sloping obliquely
towards the mid-line of the upper lip. They are set close
together. 0. 0. 154G r.

E. 210. The sl<in of the head of a Gorilla (AnfJiropopithecvs
gorilla), showing the nose and nostrils. The nose is broad
and flat; the nostrils set almost horizontally.

E. 211. A section of the nose and upper Hp of a Man, showing
the short crisp hair which grows from the inside of the
nostril and defends the entrance of the nasal cavity.

0. C. 1932. Bnnterian.

E. 212. A human nose and part of the upper jaw, showing the
nasal cartilages. In comparison with the cartilages of the
Goati-Mundi, which approximate to the continuous double
tube that was probably the original condition, the cartilages
in Man are veiy degenerate. The dorsal lateral processes
of the septal cartilage are overlapped to a certain extent
by the nasal and maxillary bones. Posteriorly they are
still organically continuous with the septal cartilage, but
distally are free from it, and are not prolonged so far
forward as is the septum itself.

On either side of the distal end of the septum lie the an-
nular cartilages, completely separated from the dorsal lateral
processes of the septal cartilage from which they are
derived. They form on either side a ring, incomplete
below, for the support of the margins of the nostrils. The
extremity of the outer limb of the ring is separated off in
the form of small irregular plates (sesamoid cartilages) .

O.C. 1550 E a.

Spurgat, Anat. Anz., Bd. viii. 1893, p. 228.

ORGANS OF SPECIAL SENSE.

137

AUDITORY AND EaUILIBRATING ORGANS.

John Hunter, Essays and Observations, edit. R. Owen,
vol. i. p. 171.

Many Invertebrate and all Vertebrate Animals have special
organs for the perception of alterations in the position of the
body in space (equilibration) and for the appreciation of
vibrations in the surrounding medium (audition). Although
these functions are at first sight so distinct, they both as a
matter of fact depend upon the stimulation of fundamentally
similar sense-organs, in which the special sensory cells are
provided with relatively long and stiff hair-like processes
which may be acted upon either by the movement of fluids or
of hard adventitious bodies (otoliths) in contact with their free
ends following any alterations in the position of the organ, or
by the vibration of the fluid in which they are bathed. This
similarity of structure in the receptive mechanism, together
with the curiously conflicting evidence derived from direct
physiological experiments, makes any sure discrimination
between the two sets of organs extremely difficult even in
higher Animals *, where probably a definite part of the ear is
set apart for the performance of each function ; but in Inver-
tebrates it is doubtful if any such distinction should be made,
for probably the whole organ is sensitive both to changes in its
position and to auditory vibrations, and is in truth an un-
differentiated equilibrating and auditory organ with probably
a preponderance of the equilibrating function. In the percep-
tion of sound it is possible to distinguish two degrees of
refinement : simple audition — the mere sensitiveness to sound
vibrations, without any analytic appreciation of the qtialities of
the vibrations other than degrees of loudness, and a more
refined tonal sense by which the various qualities of a mixture
or series of vibrations can be recognised and appreciated. The
first is common probably to all conditions of auditory organs
and is difficult to distinguish from the mere feeling of jar ;
the second only to organs of peculiar structure (chordo-tonal
organs) which occur in Insects and the higher Vertebrates
(cochlea).

* This difHculty is especially apparent in reading the work done on the
ear of Fishes, c/. for instance the papers by Kreidl, Lee, and Ayers (quoted
below under " Vertebrata,"

138

PHYSIOLOGICAL SEIIIES,

INVERTEBRATA.

LuLbock, The Senses of Animals, 1888, p. 77.
Engelmann, Zool. Anz., Bd. x. 1887, p. 439 {Physiol).

Sense organs, in the form of a pit, sac, or hollow prominence,
lined, at least in part, by cells bearing long peripheral sense
hairs, and generally containing hard adventitious bodies, occur
in most of the chief Phyla of the Invertebrata. Such are the
tentaculo-cysts auditory vesicles and rhopala of Coelenterates,
the otocysts of some Platodes Polychaste Worms and Molluscs,
the auditory sacs and vesicles of some of the higher Crustacea,
and the otocysts of Holothuria and the sphseridia of Echinids.
In spite of the various names by which these several organs are
known, many of which imply an auditory function, they may
probably all be classed together physiologically as equilibrating
organs at least as regards their chief function. In Insecta,
however, there are organs of an entirely different form which
there is every reason to believe are truly auditory in the
highest sense.

AETHROPODA.
CEUSTACEA.

E. 213. The antennules of a Lobster {Homarus vulgaris). In
the basal segment of the protopodite of each antennule is
an auditory or more probably an equilibrating organ
formed by a sac-like involution of the dorsal integument
of the segment. The sac is in communication with the
exterior by a small aperture near the inner margin of the
dorsal wall, protected by a close fringe of setse springing
from its outer and posterior borders. A semicircular area
of the ventral wall of the sac is specially modified to
receive sense impressions ; internally it bears a number of
long vibrissa, which support minute sand grains inten-
tionally introduced after each moult. The ventral wall of
the basal segment of the left antennule and the outer
wall of that of the right have been removed to show the
auditory sac. On the left the area of the sensitive
membrane can be seen, and on the right a bristle has been
inserted into the orifice of the auditory sac.

Numerous independent experiments leave little doubt
that the "auditory organs" of Crustacea are statocysts,

PI I

J.Green lith.

PLATE I.

Fig. 1. A single chordo-tonal organ from the subgeniial organ
of Dediciis verruchoriis, x 360 *.

Fig. 2. Tibial chordo-tonal organs o£ Decticus vemicivorus seen
from the outer side, x 95.

Fig. 3. Transverse section through the upper part of the
auditory organ of a nearly adult Locusta viridissima,
X 90.

Fig. 4. Distal termination of a chordo-tonal organ froiTi
Siebold''s organ of Decticus vemicit'onis, x 540.

Figs. 1, 2, and 4, after Schwabe j. Fig. 3, after Graber.

c, the membrane coverinp^ Siebold's organ ; c.c, capj)ing- cells [ = cliorclo-
tonal ligaments (Graber)] in which the end organs are plunged;
c.c,', fibrous prolongation of the capping cells attached to the integu-
ment ; e., epidermis of the body-wall ; e.c, enveloping cells in
which the terminal parts of the senso-neural cells lie; e.o., end
organs of the senso-neural cells ; (/., senso-neural ganglion cells ;
f/r., groove between the anterior and posterior tracheal dilatations ;
I.O., intermediate organ ; n., distal prolongations of senso-neural
cells ; 0., operculum ; s.o., subgenual organ ; t., tympanic mem-
brane ; t.7i., nerve to tympanal organ ; t.n'., its branch to Siebold's
organ; to., tracheal (Siebold's) organ; tr., tracheal dilatations.

« This figure has been substituted for that of a larva (Graber, Arch,
mikr. Anat. xx, PI. 31, fig. 8) referred to in the text,
t Zoologica, Bd. xx., 1906.

btiuI » io JfliiJ 'lui Jj'jj
> -tri} «i b-^ i

ougans of special sense. — invertebrata.

1H9

concerned in equilibration and hardly if ever (e. g., Mysis,
Hensen, Zeits. wiss. Zool., Bd. xiii. p. 393) possess any
marked auditory function. The most striking results were
perhaps those obtained by Kreidl (Sitz. Ak. wiss. Wien,
Bd. cii. Abth. 3, p. 149) from experiments upon PalcBinon,
in which movements designed apparently to restore a
supposed loss of equilibrium resulted from the action of
an electro-magnet upon iron filings introduced into the
auditory sac in place of the sand normally present there.

0. C. 1559 A a a. Presented hj Mr. R. Burton.
Beer, Arch. f. Physiol., Bd. Ixxiii. 1898, p. 1, &
Bd. Ixxiv. 1899, p. 364.

E. 214. The right antennule of a Crawfish {Palinurus vulgaris).
A portion of the ventral wall of the basal segment of the
protopodite has been removed to show the small flattened
auditory sac. A bristle has been inserted into its orifice.

0. C. 1559 a a.

INSEOTA.

*Graber, Arch. f. mikr. Anat., Bd. xx 1882, p. 506 ; &
Bd. xxi. 1882, p. 65.
Nerve end organs of a special character and probably truly
auditory in function occur in all orders of Winged Insects,
and are disposed upon the most various parts of the body.
They are known as chordo-tonal organs and in their simplest
form, as found in many Larvse (PI. I. fig. 1), consist of senso-
neural cells, enclosed either singly or in bundles within a fibrous
tube (chordo-tonal ligament) which is stretched between tM^o
mutually stationary points of the inner surface of the exo-
skeleton. The seuso-neural cells terminate distally in stiff
semichitinous rods or auditory hairs and are connected
proximally wilh a peripheral ganglion of the nervous system,
which is situated usually at some distance from either end of
the chordo-tonal ligament.

E. 215. A New Zealand Cricket (JDeinacrida Jieteracantha,
Fam. Locustidse). In each fore-limb, on the outer and
inner surfaces of the tibia close to its articulation with

* A good summary will be found in Lowne's ' Anatomy .... of the
Blow-riy,' 1893-1895, yoI. ii. p. 595, or in Lubbock's ' Senses of Animals,
p. 94.

uo

PHYSIOLOGICAL SERIES.

tlio femur, the integument is thin and colourless over an
oval area. In the interior of the limb in relation .to this
area is a special dilatation of a tracheal tube and a special
nerve termination (chordo-tonal organ).

Among the Orthoptera tympanic auditory organs o£
this kind occur in several families either on the legs or
abdomen. The chordo-tonal oi'gans in connection with
them are more complex than that shown in PI. I. fig. 1,
although with the same fundamental structure. They lie
either near the margins of the drum membrane (MUUer's
and Graber's organs) or between the drum membrane and
the tracheal dilatation (Siebold's organ). In this latter
modification (PI. I. figs. 2, 3, 4) the details of the histo-
logical arrangement are especially suggestive of a refined
auditory function, for the chordo-tonal organs are arranged
in linear series and regularly diminish in size from one
end of the line to the other, while a corresponding
regular alteration is noticeable in the size of a row of
cubical cells within which the auditory hairs are imbedded.

O.C. 1559 Ac.

Graber, Deukschr. Akad. wiss. Wien, Bd. xxxvi. 1876,
p. 1.

E. 216. A specimen of Eenvacrida sp. The structure of the
auditory organ is essentially the same as in the previous
specimen, but in the centre of each drum-membrane is a
longitudinal dark streak. 0. C. 1559 a h.

E. 217. A female example of Pseudopliyllus sp. On either side
of the tibia of each fore-leg are thmriiH^s of tliG cut c g
similar to those seen in the two previous specimens ;
but in this case they are protected by an opercular
forward growth of the thick integument of their posterior
margins. Access to the drum membrane is through a
narrow slit-like opening beneath the anterior edge of the
operculum. Black paper has been inserted into these
openmgs on the left leg. 0. C. 1559AtZ.

E. 218. A Locust {Pachjtylus migratorius, Fam. Acridiidre),
dried. A red arrow points to a thin membranous area
forming the front wall of a pit on the upper lateral surface

ORGANS OF SPECIAL SENSE. — INVERTEBRATA.

141

o£ the first abdominal segment. A chordotonal organ is
connected with this area of the integument.

0. C. 1559 A /.

E. 219. An example o£ Rliomalea gigantea, in spirit, showing a
similar structure. The drum is however not sunk
. beneath the general surface of the body. 0. C. 1559 A e.

E. 220. A Crane-fly (Tipida gigas). Behind the wings are a
pair of knobbed appendages, which represent the hind
wings in a highly modified condition. Each of these
organs (known as Halteres or Balancers) consists of a
slender stalk attached to the side of the metathorax by
a thin triangular plate (scabellum) and terminates distally
in a pear-shaped knob (capitellum).

Halteres are found in almost all Diptera and probably
act as organs o£ equilibration and hearing. They are
supplied by a peculiarly large sensory nerve and are
provided at their base with large numbers o£ complex
chordotonal organs. Their partial or complete removal
disturbs or destroys the power of flight.

Lowne, Anatomy of the Blow-fly, 1893-95, vol. ii.
p. 603.

MOLLUSCA.

E. 221. Two specimens o£ the statocysts o£ a Cuttle-fish {Sepia
officinalis). The cartilaginous cranium has in each case
been transversely divided to show the statocysts in section,
in the upper specimen from in front and in the lower from
behind. The section surface is as nearly as possible upon
the same level in each.

The statocysts are a pair of rectangular chambers buried
in the cartilage of the skull beneath the visceral ganglia.
Their cavities are partly occupied by blunt processes (very
constant in number and position) that project inwards
from all sides and apparently serve to prevent the statolith
which lies within the cavity of the cyst from touchino-
the sensory areas of the lining membrane. The nerves
to these areas appear to arise from the pedal ganglia,
but in reality have their true origin, as in other Molluscs,
in the cerebral ganglia.

U2

rilYSIOLOGICAL SERIES.

Fig. 26 A.

Fig. 26 B.

CR.

The right atatocyst of Sepia officinalis in transverse section.

A, seen from in front ; B, seen from behind (the positions of the masulae
inserted from Hamlyn-Harris).

CR. Crista statica. M.NA. Macula neglecta anterior, M.N.P. Macula
neglecta posterior. M.P. Macula princeps. V.Gr. Visceral ganglion.

The statocyst in Sepia is stated (Hamlyn-Harris) to be
lined by a low columnar epithelium, modified only in
certain places to form sensory areas. These are four in
number — three level areas (maculae) upon the anterior
wall and a ridge (crista) that runs almost horizontally
from the inner margin of the anterior wall, along the
outer and posterior walls, turning sharply upwards
before its termination. The sense cells are large and
columnar in form and appear to be seuso-neural— i.
directly continuous proximally with an afferent nerve
fibre. Distally they bear a number of short sense hairs.

From the experiments of Delage, there seems little
doubt that the statocyst in Cephalopods is an organ of
equilibration ; the statocyst of A'autilus is shown in
IQjl 0. C. 1559 B.

Delage, Arch. Zool. Exp., s^r. 2, T. v. 1887, p. 3
(^Physiol.).

Hamlyn-Harris, Zool. Jahrb., Bd. xviii. 1003, p. 327
{A7iai.).

ORGANS OF SPECIAL SENSE. — VEllTEBRATA.

143

VERTEBRATA.

Lee, Jonr. of Physiol, vol. xv. 1894, p. 311 ; and
A^ol. xvii. 1895, p. 192 ; and American Jour, Physiol.,
vol. i. 1898, p. 128.

Kreidl, Arch, £. Physiol., Bd. Ixi. 1895, p. 450.

Ayers, Jour, of Morph. vol. vi. 1892, p. 1.

Retzius, Das Gehororgan der Wirbelth., Stockholm,
1881-1884.

The organ of hearing and equilibration is developed as an
integumentary inpushing on either side o£ the head behind the
eyes, and probably has a common origin with the organs of the
lateral line of aquatic forms. The originally simple invagina-
tion sinks into the tissues and becomes differentiated to form
the various parts of the membranous labyrinth. Except among
Cyclostomes where its form is somewhat peculiar, the general
plan of the labyrinth is the same in all classes (cf. figs. 28, 31,
39, 40, 41). The main part consists of two chambers, the
utricle above and the saccule below, which generally open into
each other. Above and upon the outer side of the utricle and
opening at either end into it are three semicircular canals
disposed roughly one in the horizontal and the other two in the
vertical planes of the head, the two latter lying in planes at
right angles to each other and at angles of about 45° to the
transverse plane of the head. Each canal has an enlargement
(ampiiUa) near one end, situated in front in the case of the
anterior and horizontal canals and behind in that of the posterior
canal. The saccule, which only in Elasmobranchs retains an
open connection with the exterior by means of the ductus endo-
lymphaticus, is almost universally separable into two divisions
— a saccule proper and a lagena. The latter in animals higher
than Fishes forms the basis of the cochlea, and is gradually
replaced by it.

The membranous labyrinth lies in the walls of the skull within
a lymph-containing space which from the Amphibia upwards is
a very definite chamber (perilymphatic space) lined by peri-
osteum and in communication by the ductus perilymphaticus
with the brain-cavity. The membranous labyrinth itself is
filled with a fluid (endolymph), whose movements, due to

14i

PHYSIOLOGICAL SERIES.

alterations in the position of the head, or to vibrations, stimulate
sensory cells upon certain special areas of the lining membrane
and give rise to static, dynamic, and auditory sensations. These
sensitive areas occur in the ampullas of the canals (cristse) and
upon certain parts of the utricle, saccule and lagena (macula?),
and in a very special form in the cochlea of Mammals (organ
of Corti).

The auditory nerve, by means of -which the sensitive areas
are connected with the brain, belongs to the same system as
those that supply the organs of the lateral line. In the lowest
groups, though usually divided into anterior and posterior rami
for the innervation of the anterior and external ampullae and
the recessus, and of the saccule and posterior ampulla respec-
tively, it is a single trunk, but in man and probably also in all
vertebrates in which the cochlea or its rudiment is present,
another independent nerve (ramus cochlearis) is added to it
(Streeter, Am. Jour. Anat. vol. vi. 1907, p. 154). The trans-
mission of vibrations to the labyrinth is frequently aided by
various special modifications of the neighbouring parts of the
body : in many Fishes by connections of different kinds with
the swim-bladder, and in higher Vertebrates by a special
oscillating (tympanic) apparatus developed in relation to the
second visceral cleft. In most Mammals and some few Birds
trnmpet-shaped external ears further serve to concentrate sound
vibrations upon the drum membrane of this apparatus, and
to aid in locating the direction from which a sound proceeds.

Many points in the physiological action of the ear have yet
to be explained. There is not much doubt that the organ
combines two functions of which that of hearing is the latest
to rise to importance, the other-equilibration— being its chief
and almost only use in Fishes. Experiments (Lee) tend to
show that in them all parts of the labyrinth, except probably
the lagena and macula neglecta, are concerned in this function
—the semicircular canals being the agents in dynamic equilibra-
tion (L e., response to alterations in direction and position when
in motion), and the maculae in the recessus and saccule in
static equilibration (t. f., response to change of position when at
rest). The same functions are also probably performed by the
semicircular canals and vestibule in other groups. Hearing in
Fishes is apparentlv confined to perception of vibrations without

ORGANS OF SPECIAL SENSE. — VERTEBRATA.

145

an)-- powers of discrimination between their different qualities ;
although, from the experiments of Pieper and Hensen upon
Teleosts, it seems highly probable that they do hear in the
strict sense, though imperfectl3^ The presence of a pars
basilaris lagense or cochlea which first appears amongst
the lowest terrestrial Vertebrates seems, however, to be always
accompanied by the power of true hearing, and probably also
carries with it a certain capacity for the analysis of sound. In
its highest development this part of the labyrinth becomes a
chordotonal organ of extreme delicacy by which the musical
qujilities of complex sounds can be analysed, often with
astonishing accuracy, and transmitted to the brain.

PISCES.

John Hunter, An Account of the Organ of Hearino; in
Fishes, Pliil. Trans, vol. Ixxii. 1782, p. 379 ; also,
Works of Hunter, Palmer, vol. iv. p. 292.

OYOLOSTOMI.

E. 222. Head region of a Sea Lamprey {^Petromyzon mar'ums).
The brain and spinal cord have been exposed from above,
and on the left side the dorsal wall of the periotic capsule has
been removed to show the membranous labyrinth within.
In the River Lamprey (which probably in the structure

Fiir. 27.

Eight membranous labyrinth of Petromyzon JIaviatilis (after Retzius),
A. Ventral aspect. B. Dorao-lateral aspect.
A.C. Anterior canal. A.T. Ampulla trifida. 0. Commissure. G. Gan-
glion. O.A. Opening from ampulla to vestibule. O.VC. Opening
from vestibule to commissure. P.O. Posterior canal. S. Saccular
appendage. S.O. Its opening into the vestibule. V. Vestibule.
(A.C. & P.C. .siioitld bo transposed.)
VOL. III. L

U6

PHYSIOLOGICAL SRRIES,

of its auditory organs resembles in essentials the Sea
Lamprey) the membranous labyrinth consists of a single
main chamber (vestibulum) and of two semicircular canals
that correspond apparently to the anterior and posterior
canals of other Vertebrates. The vestibule is partially
divided into anterior and posterior halves by a prominent
ridge (crista frontalis) and communicates above with a
rounded chamber (commissure) into which open the upper
ends of both semicircular canals. The canals are closely
applied to the surface of the vestibule, and run outwards in
anterior and posterior directions respectively towards its
ventral surface. Below, each canal swells to form a
trilobed ampulla, which opens into the lower parts of the
vestibule. The floor of the vestibule is also dilated to
form an asymmetrical pocket (saccular appendage). The
auditory nerve divides into two main branches that run ante-
riorly and posteriorly to the ampulise and saccular appendage
to which they are mainly distributed. 0. C. 1559 c.

Eetzius, Das Gehororgan der Wirbelthiere, Bd. i. p. 13.

ELASMOBRANCSn.
Retzius, Das Gehororgan der Wirbelthiere, Bd. i. p. 105.

The membranous labyrinth (figs. 28, 29, 30) is completely
buried withiu the cartilage of the skull, but still in most cases
retains an open connection with the exterior through the ductus
endolymphaticus, which sometimes (e. g., Acanildas, Rldna) is
wide enough to allow the passage of sand into the saccule.

The utricle consists of two completely separate divisions — a
utriculus anterior in connection with the anterior and horizontal
canals and (by the ductus utriculi) with the recessus utriculi ;
and a utriculus posterior continuous at either end with the
posterior canal. Each utricle opens into the sacculus either
directly by the canalis utriculo-saccularis anterior and posterior
(Sharks) or sometimes (in the case of the anterior utricle)
indirectly only, through the recessus and the canalis recessu-
saccularis (Rays). Upon the canalis utriculo-saccularis posterior
lies a small macula neglecta— a similar nerve-ending marks the
posterior limit of the single utriculo-sacculine canal in Chhncvra
and many Teleosten. The maoulix} upon the walls of the recessus,

ORGANS OF SPECIAL SENSE. — VERTEBUATA.

147

saccule, and lagcna are covered by loose masses oE otoconia,
embedded, at any rate as regards the saccule, in endolympb of
gelatinous consistency.

Among tbe different groups and genera, variations are chiefly
found in the amount o£ separation between the ascending arms
of the utriculi, in the mode and extent of communicatioQ between
the utricules and the saccule^ and in the size and form of the
saccule and lagena.

E. 223. The right membranous labyrinth of a Skate [Raja hatis)
with a portion of the dorsal cranial wall and skin of the
head. The anterior utricle is in connection with the anterior
and horizontal canals. Ventrally it is joined by a narrow

Fig. 28.

Right membranous labyrintli of Jiaja batis.

A. Anterior and posterior ampulliE. C.A., C.E., CP. Anterior, external,
and posterior semicircular canals. C.US.P. Canalis utriculo-saccularis
posterior. D.E. Ductus endolymphaticus, D.U. Ductus utriculi.
C.RS. Canalis recessu-saccularis. L. Lagena. R.A., E.L., R.N ,
R.n., R.S. Ramus ampullae, lagenae, neglectus rece-ssus, sacculi.
R.U. Recessus utriculi. S. Sacculus. S.E. Saccus endolymphaticus.
U.A. Utriculus anterior. U.P. Utr'culus posterior.

ductus utriculi (indicated by a red rod) to a rounded sac-
like chamber — the recessus utriculi, which in turn opens

148

rHYSIOLOGICAL SERIES.

by a small orifice (canalis recessu-saccularis), which is not
shown in this specimen, into tlie sacculus. There is no
direct connection between this utricle and the saccule.
The posterior utricle, like the anterior, is a delicate thin-
walled tube. It crosses the inner surface of the saccule
and is continuous at either end with the posterior semi-
circular canal, forming with it a complete ring, at the
lower part of which lies the ampulla of the canal. Near
its upper extremity it communicates with the saccule by
a fine tube indicated by a green rod (canalis utriculo-
saccularis posterior), close to the saccular opening of which
lies the macula neglecta.

The sacculus is a large pear-shaped chamber, with its
pointed upper extremity continued to the surface of the
head as the ductus endolymphaticus. This duct lies be-
tween the ascending portions of the two utricles, and after
traversing the skull dilates slightly and bends sharply
forwards and backwards before opening to the exterior.
At the hinder end of the saccule is a small oval appendage
— the lagena.

The trunk of the auditory (vestibular) nerve divides into
two chief branches, the anterior of which supplies the
cristre in the ampullje of the anterior and horizontal canals
after sending a large bundle of fibres to the macula of the
recessus. The posterior branch innervates the macula of
the saccule and gives off branches to the macula lagenae and
to the crista in the ampulla of the posterior canal. From this
latter branch a small ramulus runs to the macula neglecta.

O.C. 1570 c.

Eetzius, I. c, p. 138.

E. 224. Part of the cranium of a Ray including the left
auditory organ. The outer cranial walls have been cut
away and the labyrinth filled with a black injection to
show the natural position of the auditory organ within the
skull and the perilymph cavities within which its various
parts are suspended. The three semicircular canals lie,
respectively, one in the horizontal and two in the vertical
plane. The latter are set at right angles to one another
and each at an angle of 45° to the transverse i)lane of the

ORGANS OF srECIAL SENSE. — VEUTEBRATA. 149.

head. The saccule is ahnost horizontal, its broad outer
and inner surfaces facing approximately upwards and
downwards, and its free border outwards. The otoconia
contained in the saccule and recessus utriculi show clearly
in contrast to the dark injection.

On the reverse of the specimen the cranial cavity is
shown. It is completely cut off by cartilage from the
perilymph cavities in which the labyrinth is contained,
except at the point of passage of the auditory nerve.

A black bristle is inserted into the ductus endo-
lymphaticus. 0. G. 1570. Hunterian.

E. 225. The right membranous labyrinth of a Ray, filled with
black injection. A bristle has been inserted into the
external orifice of the ductus endolymphaticus. 0. C. 1571.

Hunterian,

E. 226. The right membranous labyrinth of a White Shark
(Carcharias lamia) with part of the skull and overlying
skin. When compared with the labyrinth of the Skate,

Fig. 29.

Ricrht membranous labyrinth of Carcharias lamia.
C.RS Oamili3 vecessu-saccularis. CCiP. Oaualis iilriculo-saccularis
posterior. R.N. Kamulus neglectus.

150

PHYSIOLOGICAL SKlilES.

apart from a broad general reseinljlance, there are many
important differences in detail. The recessus utriculi is set
at some distance in front of the saccule owing to the great
length of the horizontal portion of the anterior utricle.
The posterior utricle is quite slender, and is xmited to the
saccule by a relatively short canalis utriculo-saccularis
posterior, which is narrow at its saccular end, but is
inflated above, where it opens into a similar dilatation of
the utricle. These two enlargements are innervated by a
peculiarly lai'ge double ramulus maculae neglectae, whicli us
usual is given off from the nerve that supplies the crista of
the posterior ampulla. The saccule is of great size and has
a definite lagena at its posterior end, separated from it by
a slight constriction. The extra-cranial part of the ductus
endolymphaticus is long and is bent acutely npon itself —
the anterior end of the bend being also slightly convoluted.
Bristles tipped with blue beads have been inserted into its
external orifice and at its entry into the skull.

O. C. 1574 D.

C. Stewart, Jour. Linn. Soc, vol. xxix. 1906, p. 409.

E. 227. A similar preparation of the left labyrinth of the same
Fish, in which parts of the external walls of the sacculus,
anterior utriculus, and recessus utriculi have been removed.
A black bristle has been passed from the horizontal canal
alonw the anterior utricle into the anterior canal. The
recessus is a simple dilatation of the ventral wall of the
utricle and communicates with the sacculus by a long duct
(canalis recessu-saccularis) which is closely adherent to the
ventral wall of the utricle. This passage is marked by a
red rod, and a green rod has been passed from the sacculus
through the canalis utriculo-saccularis posterior into the
posterior utricle. A blue rod and a blue-lipped bristle have
been inserted into the ductus endolymphaticus.

0. C. 1574 c.

E. 228. The left membranous labyrinth of a Port Jackson Shark
(Cestracion 2')^iil^ppi) exposed in position within the skull
and seen from the outer aspect. Eelative to the size of the
Fish, which was 3 ft. 4 in. (100 cm.) in length, the labyrinth

ORQANS OF SPECIAL SENSE. — VERTEBRATA. 151

is very small. It is also curiously compressed antero-
posteriorly in front, the normally horizontal portion o£ the
utricle anterior to the recessus being bent up almost verti-
cally. The saccule is exceptionally small and is prolonged
below to form a blunt conical lagena. The nerves to the
ampullse are large. No otoconia were found in the labyrinth.
C. Stewart, Z. c, p. 440.

E. 229. The right membranous labyrinth of the same Fish,
dissected from the inner side and with some of its
cavities opened and a red rod passed through the canalis
utriculo-saccularis anterior. The ductus endolymphaticus,
into which a bristle has been passed, has apparently no
opening to the exterior ; after passing through the skull
in a channel 4 mm. in diameter (the fenestra vestibuli,
cf. No. E. 234), it makes the usual forward bend and then
ends abruptly.

E. 230. The right membranous labyrinth of a Greenland Shark
{Lcemargus horealis) with parts of the cranial walls and
skin of the head. The ascending portions of the two
utriculi touch above the saccule. The recessus is small
and superficially appears to be rather a dilatation of the
anterior end of the saccule than of the utricle, although it
is in close contact with the ventral wall of the latter. The
part of the anterior utricle between the recessus and the
ampulla of the anterior canal has a slight ventral dilatation.
The sacculus is extremely small. Its hinder end is pro-
longed downwards to form a blunt conical lagena, which
however is not separated from the rest of the chamber by
a constriction or other external mark. The ductus endo-
lymphaticus is broad, and its extra-cranial portion is almost
straight. The raniulus maculae neglectse is extremely
delicate. The other branches of the auditory nerve have
the usual arrangement, but those to the maculse are
relatively small. 0. C. 1574 H.

Presented hy W. Cowan, Es'.;.

Stewart, I. c, p. 408.

152

PHYSIOLOGICAL SEUIFfS,

E. 231. A similar ppecimen of tlie left membrunous labyriiitli of
u Greenland Shark {Lwmargas borealis) in which the oultr
Avails of the anterior utricle, recessus iitriculi, sacculu^, and
lagena have been in part removed. A red rod has been
inserted into the canalis recef-sii-saccularis. The cavities of
theutricnlusand recessns utricnli appear to be separated by
a membrane, the edge of which is seen in the s^^cimen. The
posterior half of this is the out edge o£ the partition wall
between the utricle and recessus, but <he anterior half is
the natural border of the ductas utriculi, leading from the
utricle into the recessus. The canalis recessu-saccularis is
large. A green rod has been passed through the short
wide canalis utriculo-saccularis posterior and a black
bristle into the ductus endolymphaticus. 0. C. 1574 g.

Presented by W. Cowan, Esq.

E. 232. Part of the left side of the cranium of a Greenland
Shark [Lcemargus borealis) with the membranous labyrinth
exposed from the outer aspect. In general form it is similar
to the two previous specimens. The course of the horizontal
canal is peculiar in being sinuous, making a dorsally convex
curve as it passes backwards from the ampulla. The mesial
and lateral walls of the ampullae are thickened by masses of
soft cartilage that project considerably from the general
surface, forming flat oval bosses ; an indication of similar
thickenings can be seen in Baja, E. 223. The Fish from
which this preparation was made measured 13 ft. (3'9 m.)
and was much larger than that from which the two previous
specimens were obtained.

The crystals of otoconia in this labyrinth were at least
fifteen times as large as any found in the other Ehismo-
branchs examined.

E. 233. The ampullae, with their nerves, from the right labyrinth
of the same Fish, mounted side by side (those of the anterior,
horizontal, and posterior canals in succession from left to
right) to show respectively their ventral, lateral, and dorsal
' surfaces and the peculiar cartilaginous ihickcnings of their
lateral walls.

ORGANS OF SPECIAL SENSE. — VEETEBRATA.

153

E. 234. Part of the cranium and integument of a Spinous
Shark {Echinorldnus spinosus) with the right membranous
Uibyrinth exposed from the mesial aspect. The fish
measured 7 ft. 6 in. (227 cm.) in length. It is similar in shape
to that of Lcemargus, and it should be noted that there is in
both a similar ventral dilatation of the utricle in front of
Ihe recessus. The posterior utricle has been opened to show
its communication with the saccule by a round aperture
( 2 mm. in diameter) . A long slit in the floor of the anterior
utricle (fissura utriculo-saccularis) forms a common means
of connection between the cayity of this chamber and those
of the recessus and saccule. The ductus endolymphaticus,
as in Lcemargus, takes an unusually straight course through
the integument ; a bristle has been passed along it from its
external opening into the saccule and its dilated external
portion has been opened. Close behind the channel in the
skull through which the ductus endolymphaticus passes is a
large oval fenestra (f. vestibuli) covered in nature by
membrane. A similar aperture, though usually not quite
so large, occurs in many Elasmobranchs (Howes, Jour.
Anat. Physiol, vol. xvii. 1883, p. 188). In this specimen
the trunks of the auditory nerve are also shown. The
branches that supply the recessus and sacculus are relatively
small. A large ramulus maculae neglectse is given off from
the apex of an upward bend taken by the nerve that supplies
the posterior ampulla.
C. Stewart, I. c, p. 439.

E. 235. A similar specimen of the left membranous labyrinth of
the same Fish seen from the outer aspect. In this pre-
paration the general form of the labyrinth, the position and
slenderness of the canals, and the nerve-branches to the
recessus and ampullae are shown; and through a hole in
the wall of the saccule can be seen a mass of otoconia (in
this species moderate in amount) embedded in mucin of
gelatinous consistency.

E. 236. The right membranous labyrinth of Noiidanns grisens,
with parts of the cranial walls and overlying muscle. This
specimen very closely resembles the membranous labyrinth

15i

PHYSIOLOGICAL SERIES.

LcBmargus horealis. The ascending portions of the utricles
are however more closely applied to each other; the sacculus
is slightly larger, and the lagena more globular and separated
from the saccule by a distinct constriction. A bristle has
been inserted into the ductus eudolymphaticus,

0. C. 1574 F.
Presented by Dr. A. Giinther.

Stewart, /. c, p. 407.

E. 237. The left membranous labyrinth of the same Shark, in
which parts of the outer wall of the anterior utricle, recessus
utriculi, sacculus, and lagena have been i-emoved. The
anterior utricle opens directly by a large ductus utriculi
(blue rod) into the recessus. Red and green rods have been
passed as in the previous specimens from the recessus and
posterior utricle respectively into the sacculus, and a black
bristle into the ductus eudolymphaticus. The extra-cranial
part of this duct is dilated to form a saccus eudolymphaticus

0. C. 1574 E.
Presented hy Dr. A. GiintJier.

E. 238. The right membranous labyrinth of a Fox Shark (Alo-
pecias vulpes) with parts of the cranial walls, and skin.
The union of the ascending portions of the two utricles is
so close that they appear to form a single vertical tube
resembling the sinus superioris utriculi of higber Verte-
brates. In reality they are completely separated by a
septum. The rest of the labyrinth closely resembles that
of Lcemargus. Associated with the union of the ascending
portions of the utricles, the ductus eudolymphaticus lies in
front of them. Its extra-cranial part is very long and con-
siderably convoluted. 0. C. 1574 b a.
Stewart, /. c, p. 408.

E. 239. A similar specimen of the left labyrinth in which the
outer walls of the recessus and sacculus haA^ebeen removed.
The canalis recessu-saccularis has thus been opened and
the long slit-like fissura utriculo-saccularis exposed. This
opening connects the cavity of the utricle with that of the

ORGANS OF SPECIAL SENSE. — VERTEBRATA.

155

recessus by its anterior parts (ductus utriculi), with that
oP the canalis recessu-saccularis by its middle region, and
with that of the sacculus by its posterior part (canalis utr.-
sacc. anterior). A piece of black paper has been thrust from
the sacculus up the ductus endolymphaticus. To the right of
it in the upper wall of the sacculus can be seen the mouth
of the short broad canalis utriculo-saccularis posterior.

O.C. 1574 B^.

E. 240. The right inembranous labyrinth of a Porbeagle {Lamna
cornuhica) with part of the cranial roof. The ascending
parts of the utricles are closely adherent and lie well behind

Fig. 30.

Right membranous labyrinth of Lamna coniubica.
L, Lagena. U. Tlie fused iiscencling portions of the utricles.

156

rilYSIOLOGlCAL SEniES.

the ductus endolympliaticus. The sacculus and lagena are
peculiar in shape, the former being cylindricid and curving
backward from the ductus endolympliaticus ; its posterior
and lower end is dilated to form the lagena. A black brittle
has been inserted into the ductus endolympliaticus. The
nerves have been removed. 0. 0. 1574 A.

Stewart, /. c, p. 408.

E. 241. Another specimen of the right membranous labyrinth
of Lamna corniihica with the nerves attached.

0. C. 1574 A a.

E. 242. Left membranous labyrinth of a Porbeagle {Lamna
cornubica) with portions of the cranial roof. The outer
walls of part of the anterior utricle, of the recessus iitriculi
and of the sacculus have been removed. The utricle opens
by means of a long slit, as in Alopecias, into the recessus
utriculi, canalis recessu-saccularis, and sacculus. Green
and red rods have been inserted as in previous specimens.
A pale blue rod has been passed from the anterior utriculus
through the ductus utriculi into the recessus. A black
bristle has been inserted into the ductus endolymphaticus.

0.0.1574 b.

E. 243. The right membranous labyrinth of Odontaspis ainericana
exposed in position within the skull. The general structure
of the labyrinth is similar to that of Lamna, especially in
the shape of the saccule and lagena and in the length of the
horizontal parts of the utricles. The ascending parts of the
utricles are however not so closely applied to each other, and
the ductus endolymphaticus in consequence lies only just
anterior to them. The recessus is also more flattened
dorso-ventrally. The ductus endolympliaticus has no com-
munication with the exterior. After passing through the
skull it bends forward and dilates to form an elongated sac
from whose upper surface a strand of fibrous tissue extends
backwards and is lost upon the cranial roof above the
fenestra. The -semicircular canals are iieculiarly thin.

ORGANS OF SPECIAL SENSE. — VERTEBRATA.

157

E. 244. Part of tlie skull-wall and overlying skin o£ a Monk
Fish (Rhina squatina) with the left membranous labyrinth
shown from the outer side. In general form the labyrinth
is remarkable for its appearance of dorso-ventral depression,
this effect being almost entirely due to the shortness of the
vertical portions of the utricles. The horizontal portions
are, on the other hand, of considerable length and pass
obUquely downwards, resting upon the dorsal and mesial
surfaces of the large globular saccule. The hinder end
of the saccule is separated by a constriction from a
small finger-like lagena. The wall of the saccule has
been removed to show a cake of sand applied to the
inner wall. This sand, which takes the place of otoconia,
is loosely cemented together by secretion and lies between
the saccular wall and the gelatinous mucin with Avhich the
saccule is filled. No otoconia were found in any specimen
examined, including embryos. The anterior utricle has also
been opened above to shovs^ the slit by which it communi-
cates with the saccule. A bristle has been inserted into
the external opening of the ductus endolymphaticus.
C. Stewart, c, p. 441.

E. 245. A similar specimen from a smaller individual, in which
the saccular mouth of the canalis utriculi posterior has
been exposed.

E. 246. A similar preparation from a larger individual, in which
the labyrinth is unopened. The skin and extra-cranial
part of the ductus endolymphaticus have been removed.

E. 21:7. The right membranous labyrinth of a Monk Fish (Rhina
squadna) exposed from the mesial side. The sacculus has
been opened and emptied to show the slit-like aperture
(fissura) by which it communicates with the anterior utricle
and the recessus. The canalis utriculo-saccularis posterior
is shown in a similar way by the removal of the wall of the
posterior utricle. A black bristle has been passed along the
ductus endolymphaticus. Close beneath the skin the ductus
is dilated to form a saccus endolymphaticus. The external

158

PHYSIOLOGICAL SERIES,

aperture is large and opens backwards at tlie anterior limit
of a shallow smooth depression. The chief branches of the
auditory nerve are shown.

E, 248. A similar specimen, but from a larger Fish, in which
the saccule has not been opened. The skin and extra-
cranial parts of the ductus endolymphaticus have been
removed.

E. 249. A piece of skin from the head of a Monk Fish {Rhina.
squatina), including the extra-cranial parts of the endo-
lymphatic ducts. Upon the right side the saccus endo-
lymphaticus has been opened and a bristle passed througli
it from the exterior and along the duct. Upon the reverse
of the specimen the smooth depressions leading to the
mouths of the ducts and no doubt facilitating the entry of
sand into them are very clearly visible.

HOLOCEPHALI.

E 250. The right and left membranous labyrinths of a Sea Cat
[Cldmcera monstrosa). Tbeutriculus approaches in certain
respects to the Teleostean type. Its ascending parts, which
in Eliismobranchs are comi)letely separate, are here fu.sed
to form a single tube (sinus superior utricnli) that opens
below into the middle of a horizontal part that corresponds
to the united horizontal portions of the two utricles of an
Elasmobranch. The common utricular cavity opens by a
sino-le utriculo-sacculine passage into the sacculus in place
of the two present in Elasmobranchs. Thus, instead of the
long slit-like fissura utriculo-saccularis and the round
canalis posterior of, for instance, Alojjecias (E. 239),
there is one long slit in the floor of the utricle the anterior
part of which opens into therecessus and the posterior part
into the sacculus. The macula neglecta, which is situated
in Elasmobranchs at the mouth of the posterior canal, here
borders the hinder end of the single large slit. In the
specimen only the external features of the labyrinths are
shown. The recessus lies between the utricle and saccule
upon the outer surface. Its opening into the sacculus is
not shown. The sacculus is of quite moderate size and is

ORGANS OF SPECIAL SENSE. — -VERTEBRATA.

159

not separable into saccule proper and la gena. In the lower
specimen a bristle tipped with blue has been inserted into
the ductus endolymphaticus. 0. C. 1574 i.

Eetzius, I. c, Bd. i, p. 102.

GANOIDEI.

E. 251. The right and left membranous labyrinths of a Sturgeon
(Acipenser sturio) . The utriculus conforms to the Teleostean
type, and consists of a horizontal part lying above the
saccule, and of a vertical sinus utriculi superior. The
anterior end of the utricle is slightly dilated to form the
recessus utriculi above which open the anterior and hori-
zontal canals. The recessus has no direct connection with
the sacculus (Eetzius). In the floor of the utricle, directly
below the sinus superioris, is a large oval canalis utriculo-
saccularis (not shown in the specimen) leading into the
saccule. The sacculus is of moderate dimensions. Pos-
teriorly it is produced, and in this part, which is not
superficially separable from the rest of the saccule, there
is a separate macula lagense. A vestigeal ductus endo-
lymphaticus runs upwards from the dorsal parts of the
saccule nearly to the apex of the sinus utriculi superior,
where it ends in a sharp-pointed extremity. Its middle
part is dilated.. The nerves that supply the labyrinth are
relatively very small, but have the usual branches with the
exception of the ramulus macula3 neglectfe.

O.C. 1568 a.

Retzius, I. c, Bd. i, p. 30.

E. 252. The otoconia from the right ear of a Sturgeon {Acipenser
sturio) placed in the natural position upon a drawing of the
labyrinth. In the sacculus the granules cohere to form an
otolith of irregular shape. A separate saccular otolith is
mounted below, showing its outer face. 0. C. 1568 b.
Eetzius, I. c, Bd. i, p. 33.

E. 253. Two pieces of the skull of a Sturgeon (Acipenser stvrio).
The upper includes the whole of the membranous labyrinth
and shows the distribution of branches of the auditory

160

niYSIOLOUlCAL SKRIKS.

nerve to the reccssus utriculi and sacculus. The lower
piece shows the distribution o£ filaments of the same nerve
to the anipullEe of the semicircuhir canals. It should be
noticed thai the semicircular canals are here inclosed in
cavities of a corresponding shape excavated in the carti-
laofinous walls of the skull, but that the saccule and utricle
are lodged in a mere depression in the side of the cranial
cavity. 0. C. 15G8. Ilunterian.

TELEOSTEA.

Retzius, Das Gehororgan der Wirbelthiere, Bd. i. p. 38.

In Bony Fishes, although there are still vestiges of the deeper
parts of the ductus endolymphaticus, the membranous labyrinth
is completely cut off from the exterior and lies within the skull-
wall in a bony encasement which is more or less imperfect
towards the cranial cavity. The transmission to this organ of
vibrations or variations in the pressure of the surrounding water
is in many cases assisted by special connections between it and
the swim-bladder, either by direct contact between the two or
by the intermediation of a chain of specially modified parls
of the skeleton.

The utricle, w hich is the least varuible port of the labyrinth, is a
sino-ular tubular sac of 1-shape. Its three arms according to their
position are known as the sinus anterior, posterior and superior,
and correspond respectively to the horizontal and ascending parts
of the two utriculi of Elasmobranchs and bear the same relations
to the semicircular canals. The sinus anterior is dilated to form
a recessus utriculi which, unlike that of Holocepliali and most
Ehismobranchs, has no communication with the sacculus. The
utricle may or may not open into the sacculus, the position of
the posterior limit of the opening being marked by the macula
neglecta, when this nerve-ending is present.

The rest of the labyrinth is less constant and shows great
variations in the size, shape and position of the saccule and
lacrena and in the length of the semicircular canals. The three
chief macula in the utricle, saccule, and lagena respectively
have otoliths of porcellaneous texture associated with them, that
show considerable constancy in shape among the members of
the minor taxonomic groups.

ORGANS OF SPECIAL SENSE. — VERTEBRATA.

161

E. 254. Riglil-, and left membranous labyrinths o£ a Hake
(Merluccius vulgaris) with the branches of the auditory-
nerve. This labyrinth shows well the general characters

Fig. 31.

S.S

S'-' GR

Tlie right membranous labryinth of Merluccius vulgaris, with the
otoliths, separate, below.

D.E. Ductus endolymphaticus. GR. Groove in saccular otolith corre-
sponding to macula sacculi. L. Lagena. L'. OtoHth from lagena.
L.D. Duct between lagena and saccule. R. Otolith from recessus.
S. Saccule. S'. Otolith from saccule. S.A. (A omitted.), S.P., S.S.
The sinus anterior, posterior and superior of the utricle.

typical of the Teleostea. Note should be made of the
following special features : — The horizontal canal opens
posteriorly into the hinder extremity of the utricle. The
sacculus is almond-shaped and of large size, extending
backwards considerably beyond the utricle. Upon its
upper and posterior part lies a well-defined lagena, whose
anterior extremity is connected with it by a narrow tubular
orifice. 0. C. 1567 h.

E. 255. The three otoliths from the sacculus, lagena, and
recessus utriculi of the right and left ears of a Hake
{Merluccius vulgaris). Those from the right ear are
mounted within an outline-drawing of the labyrinth to
VOL. III. M

1G2

PHYSIOLOGICAL SERIES.

show their relative positions. The large otolith in the
saccule is convex internally, and has along this surface a
longitudinal groove that overlies the macula. The groove
may possibly serve to prevent actual contact with the
underlying sensory cells. It is probably directly due to
the fact that this area discharges less secretion than other
parts, owing to the presence in it of large numbers o£
non-secreting sensory cells. The otolith of the lagena has
a curious notch upon its upper border. The external
surface of the otoliths' is shown in the lower specimen.

0. C. 1567 I.

E. 256. The right membranous labyrinth of a Hake {Merluccius
vulgaris) from which the otoliths and the inner wall of the
recessus utriculi and of the anterior ampullse have been
removed, to show the maculae acousticse and cristse, and
their nerve supply. The trunk of the acoustic nerve divides
into anterior and posterior divisions, the first of which
supplies the two anterior ampullae, the recessus and part of
the macula sacculi, and the second the rest of the macula
sacculi, the macula lagenfB and the posterior ampulla. In
comparison with Elasmobranchs the several branches are
more independent, particularly in the case of those going
to the saccule and lagena. The primary separation of the
main nerve trunk into anterior and posterior divisions is
thus not very clear. O. C. 1567 J.

E. 257. The right and left membranous labyrinths of a Coal-fish
{Gadus virens). The labyrinth is very similar to that of
Merluccius, but the saccule is shorter posteriorly and the
lagena forms its posterior termination. O. C. 1567 K.

E. 258. Part of the left side of the cranium of a Cod (Gadus
morrlma) including the membranous labyrinth. The
natural opening in the bony cranial wall between the
labyrinth and the cranial cavity has been enlarged to
show more fully the labyrinth and the large perilymph
spaces by which its several parts are surrounded. The
utriculus and semicircular canals have been injected with

ORGANS OF SPECIAL SENSE. — VERTEBRATA.

a red material, which however has not penetrated to
the sacculus. In the Cod there is stated (Tletzius) to be
no canalis utriculo-saccularis. 0. 0. 1560. Hunterian.
Retzius, I. c, Bd. i. p. 72.

E. 259. Two specimens of the right membranous labyrinth of
a Cod (Gadus morrhua). This closely resembles the
labyrinth of Merluccius. In the tipper specimen the
saccule is much damaged. In both, the semicircular canals
and the utricle have been injected with a red material,
which in neither case has penetrated into the saccule.

0. C. 1565. Hunterian.

E. 260. Right and left membranous labyrinths of a Fishing
Frog (Lopliius piscatorius). The utricle is greatly extended
in an antero-posterior direction and is dorso-ventrally
depressed — the sinus anterior in particular being remarkably
long, but the sinus superior very short and broad. The
semicircular canals are long. The posterior end of the
horizontal canal opens into the anterior end of the sinus
posterior utriculi. The saccule is rounded and of moderate
size. Above its hinder end lies a well-defined globular
lagena connected with it by a narrow peduncle. There is
no macula neglecta. Retzius also states that a canalis
utriculo-saccularis is absent. 0. C. 1567 c.

RetziuSj I. c, Bd. i. p. 60.

E. 261. Right and left membranous labyrinths of a Grey Mallet
{Mugil chelo). The horizontal canal opens posteriorly into
the lower extremity of the sinus superior utriculi. The
floor of the utricle directly below the sinus superior is
connected by a narrow neck (? canalis utriculo-saccularis)
to the saccule. The latter has an oval form and is con-
tinuous posteriorly, without any marked intervening
constriction, with a capacious rounded lagena.

0. C. 1567 L.

E. 262. The three otoliths from the recessus utriculi, sacculus,
and lagena of the labyrinths of a Grey Mullet {Mugil chelo).
Those of the right ear (upper specimen) are seen from the
inner side. 0. C. 1567 L a.

M 2

1C4

PHYSIOLOGICAL SERIES.

E. 263. The right membranous labyrinth and auditory nerves
of a Halibut {Hippoglossus vulgaris) seen from the median
aspect. In general form this labyrinth is just the reverse
of that of Lopldus (E. 260), being much extended dorso-
ventrally and compressed antero-posteriorly. The anterior
and posterior sinuses of the utricle are short, the sinus
superior and semicircular canals extremely long. The
recessus utriculi is larger and more prominent than in the
previous specimens of Teleostea. The sacculus is oval, of
quite moderate size, and bears upon its dorso-posterior
aspect a sharply defined lagena. There is no macula
neglecta. The ners^e to the macula lagenge is relatively
very large, that to the saccule, on the contrary, small.

0. 0. 1567 M.

E. 264. Ticf t membranous labyrmth of a Halibut [Hippoglossus
vulgaris) seen from the outer side, with the branches of the
auditory nerve removed.

The saccule is attached to the floor of the utricle by a
short and relatively slender peduncle. This probably is
not the canalis utriculo-saccularis, which is stated to be
absent in other Pleuronectids, but the saccular end of the
aborted ductus endolymphaticus. Between this peduncle
and the recessus utriculi the floor of the utricle is dilated to
form a conical pouch— the remains, possibly, of the lost
canalis utriculo-saccularis.

The hinder end of the horizontal semicircular canal opens
into the extremity of the sinus posterior utriculi.

0. C. 1567 N.

Retzius (Solea), 1. c, Bd. i. p. 74.

E. 265. The right and left membranous labyrinths of an Albicore
(ScicBna aquila). The saccules are very large and are
fused together in the mid-line by the posterior half of their
inner walls. As a result of this fusion, the hinder portion
of the macula acoustica sacculi, instead of lying horizontally
as usual, is rotated into a vertical position immediately in
front of the fused area (c/. also the otoliths E. 458). The

ORGANS OF SPECIAL SENSE. VEUTEBRATA. 16.5

Fig. 32.

E-iglit membranous labyrinth of Scicena aquila.

F. Area of fusion between the two saccules. M.S. The vertical
part of the macula sacculi.

lagena forms a pear-shaped appendage attached by its
pointed anterior end to the dorso-posterior wall of the
saccule. 0. C. 1567 u.

E. 266. Right and left membranous labyrinths of a John Dory
[Zeus fdber). The sacculus is much reduced in size. It
bears a small lagena upon its dorso-posterior surface.
There is said to be no canalis utriculo-saccularis. The
horizontal semicircular canal is relatively very short ; it
opens posteriorly into the anterior end of the sinus posterior
utriculi. The rami o£ the auditory nerve are unusually
separate. Each gives oif a large bundle to the macula
sacculi. There is no macula neglecta. 0. C. 1567 A.

Retzius, I. c, Bd. i. p. 58.

E. 267. The otoliths from the right and left ears of a John Dory
(^Zeus faher). The saccular otolith has an exceptional,
radiate, form. It consists of five radial bars : three of
larger size, two of which are horizontal and one vertical,
and two of smaller size lodged in the angles between them.
There is a definite though very delicate otolith in the
lagena (Retzius, I. c, Bd. i. p. 59). O. C. 1567 b.

166

rilYSIOLOGICAL SliUIES.

E.

E.

268. The right and left membranous labyrinths of a Lump-
fish (Cyclopteims lumpu.s). The semicircular canals,
especially the hoi-izontal canal, are very long and slightly
tortuous. The sinus superior utriculi is short and broad.
There is said to be no canalis utriculo-saccularis. The
saccule and lagena are minute. The nerve-supply is small.

0. C. 1567 D.

Eetzius, I. c, Bd. i. p. 62.

269. The right membranous labyrinth of another Lump-
fish {Cycloptervs Ivmpus). The saccule is attached by a
short and very slender pedicle (probably the saccular end
of the ductus endolympbaticus) to the utricle.

rijr. 33.

Tlight membranous labyrinth of Cyclopterus lumpus.
D.E. Ductus endolympbaticus (?). K.N. Eamulus neglectus.

A very delicate ramulus neglectus can be seen in this
specimen passing upwards from the ramus posterior of the
acoustic nerve to the macula neglecta on the ventral border
of the median wall of the utricle. 0. C. 1567 e.

E. 270. Right and left membranous labyrinths of a Wolf-fish
{Anarrhichas lupus). The nerves have been removed from
the left labyrinth (lower specimen) to show clearly the wide
separation of the saccule from the utriculus. The two
chambers are connected by a narrow tube, which probably
(Retzius, I. c, p. 66) is not a patent canalis utriculo-saccularis,
but consists in part of the aborted ductus endolympbaticus
and in part of a conical process of the utricle floor— the
vestige of the canalis utriculo-saccularis.

ORGANS OF SPECIAL SENSE. — VERTEBRATA.

167

The saccule is oval, with a pointed anterior end. Poste-
riorly it bears a well-defined lagena.

The anterior ramus of the auditory nerve (upper speci-
men) supplies a large part of the macula sacculi. The

Fig. 34.

Right membranous labyrinth of Anarrhichas lupus.
D.E. Ductus endolymphaticus. E.N. Ramus neglectus.

posterior ramus gives off a small ramulus neglectus for the
innervation of the macula neglecta, which lies on the
utricle wall at the hinder limit of the conical process that
accompanies the ductus endolymphaticus. 0. C 1567 F.
Eetzius, 1. c, Bd. i. p. 66.

E. 371. The otoliths from the right and left ears of a Wolf-fish
(^Anarrhichas lupus). Those of the right side are mounted,
with the median face exposed, within an outline of the
labyrinth. 0. C. 1567 G.

E. 272. The right and left membranous labyrinths of a Fresh-
. water Bream (Abramis hrama). The whole length of the
ventral wall of the sinus anterior utriculi is dilated to form
an exceptionally large recessus. Immediately below the
sinus superior is a wide canalis utriculo-saccularis. The
sacculus is small and tubular in form. It lies behind the
level of the anterior border of the sinus superior utriculi.

168

PHYSIOLOGICAL SERIES.

and is pointed in front. Posteriorly it opens into a large,
circular, laterally flattened lagena. A small rupture in the
median wall of the saccule in the upper specimen shows
where a delicate tube (canalis sinus imparis), by which the
two saccules are in communication with each other, has been
torn away. 0. C. 1567 o.

Retzius, Anat. Untersuch., 1872, p. 59.

E. 273. The otoliths from the ears of a Freshwater Bream
{Abramis brama). Those from the lagena (the asteriscus)
and from the recessus utriculi are of great size, that from
the saccule (sagitta) small and spine-like. 0. C. 1567 p.

E. 274. Part of the skull with the anterior end of the vertebral
column of a Freshwater Bream (Abra7nis brama), showing
the chain of ossicles by means of which movements of the
swim-bladder are transmitted to the membranous labyrinth.
The ossicles (painted red) are hinged to the lateral parts of
the three anterior vertebrae. The hindermost of them
(malleus) is a triangular plate, hinged by its apex between
the bodies of the second and third vertebrae, with its base
directed outwards and downwards, and with the posterior
angle produced into a hook-like process that curves behind
a vertical plate formed by the fusion of the fourth pair of
ribs and is there attached to the anterior surface of the
swim-bladder. The anterior angle is united by ligament to
the apex of a rod-shaped bone (incus) which is hinged by
its other, forked, end to the body of the second vertebra.
Another ligament connects the apex of the incus to a
small cup-shaped ossicle (stapes) that partly blocks the
foramen between the skull and the first vertebra with its
concave surface. This opening is also partly closed by
another ossicle (claustrum) that projects downwards and
outwards from the broadened neural spine of the first
vertebra into the cup-shaped cavity of the stapes. In
the natural state the ossicles lie in a space which is
continuous in front with the neural canal through the
foramen in which lie the stapes and claustrum and also
with the cranial cavity through the enormous lateral
occipital foramina. The space enclosed within the claustrum

OUGANS OF SPECIAL SENSK. VERTEBRATA. 169

and stapes (atrium sinus imparis) communicates in front
with a large cavity (cavum sinus imparis) in the floor of
the skull. A green bristle has been passed between the
claustrum and stapes into this cavity. It is stated that in
the Carp and other Cyprinoids the anterior part of the

Fig. 35.

Skull and part of the vertebral column of Abramis brama, showing the
connection between the membranous labyrinth and swim-bladder.
The otoliths are figured below.

CL, Claustrum. C.S.I.. Cavum sinus imparis. CN.S.I. Canalis sinus
imparis. I. Incus. L. Otolith from lagena (asteriscus). L.O.F. Lateral
occipital foramen. M. Malleus. R. Otolith from recessus. S. Otolith
from saccule (sagitta). S.BL. swim-bladder. ST. Stapes. I., II., III., IV.
The spines of the first four -vertebrae. Rods are passed through the
foramen ma^-num and from the atrium into the cavum sinus imparis.

cavus sinus imparis is occupied by an unpaired dilated part
of the membranous labyrinth (sinus impar) the front of
which is connected on either hand to each saccule by
a delicate tube (canalis sinus imparis) upon the walls of
which are special nerve-endings. These ducts and the

170

PHYSIOLOGICAL SERIES.

sinus impar are probably modifications of the ductus and
saccus endolymphaticus.

The cranial cavity, neural canal, cavum and atrium sinus
imparis, and the space in which the ossicles lie are filled with
an oily fluid, through which the movements of the stapes
and claustrum are transmitted to the membranous labyrinth.
The skull wall has been removed on the left side to the
mid-line. Black bristles have been placed in the cavities
that lodged the semicircular canals. 0. C. 1567 Q.

Nusbaum, Zool. Anz., Bd. iv. 1881, p. 552.

E. 275. The three anterior vertebrse of a Freshwater Bream
(Abramis brama) with the malleus, incus, stapes, and
claustrum isolated. The ligaments between the malleus
and incus and between the incus and stapes are painted
blue. 0. C. 1567 r.

E. 276. Otic portion of the skull of a Shad (Clupea alosa),
a great part of which has been removed to expose the
membranous labyrinth and two bony vesicles that lodge an
extension of the swim-bladder. The anterior of the two
vesicles lies below the forward extremity of the sinus
anterior utriculi, the posterior in the space enclosed between
the horizontal canal and the utricle. 0. C. 1567 s.

E. 277. A Herring (Clupea harengus) dissected from the ventral
aspect to show the relation of the swim-bladder to the ear.
The swim-bladder is a fusiform elongated sac that extends
from the skull to the vent. It opens to the exterior at the
hinder end (black bristle) and is in communication with
the stomach by means of a long ductus pneumaticus.
Anteriorly it gives off two delicate cartilaginous tubes
that pass upwards and forwards on either side of the skull
and expand below the hinder end of each sinus utriculi
posterior to form a fusiform vesicle that opens at its
apex into two pear-shaped sacs. The whole of this triple
vesicle is encased in a bony capsule. The posterior of the
two pear-shaped chambers lies within the embrace of the
horizontal canal, the anterior which is directed forwards

ORGANS OF SPECIAL SENSE. — VEUTEBUATA.

171

and downwards is situiited below and in front o£ tlie anterior
ampulla. It is stated that there is direct contact between
the membranous labyrinth and the anterior pear-shaped
dilatation of the swim-bladder, owing to the intrusion into
the bony encasement of this dilatation of a diverticulum of
the recessus utriculi.

On the right side the membranous labyrinth has been
removed. On the left, black paper has been placed beneath
the tubular forward extension of the swim-bladder and
between the horizontal canal and the posterior of the two
pear-shaped vesicles. A red rod has been inserted into the
ureter. 0. C. 1567 sa.

Ridewood, Jour. Anat. & Phys., vol. xxvi. 1892, p. 26.

E. 278. The right and left membranous labyrinths of a Pike
{Esox lucius). The inner wall of the sinus posterior
utricuh, at the base of the sinus superior, gives origin to a
pear-shaped appendix, which extends backwards within
the cranial cavity. It has no special nerve-supply. The
recessus utriculi is large. The hinder end of the horizontal
canal opens into the short and wide sinus superior utriculi.
The utricle is connected with the saccule by a wide patent
(Retzius, p. 88) canalis utriculo-saccularis. The saccule is
almond-shaped with the point in front. The greater part
of it lies anterior to the level of the sinus superior utriculi.
Its blunt hinder end forms a lagena, which is however not
externally separable from it, but has its proper otolith and
nerve supply. 0. C. 1567 t a.

Presented by Dr. Corfield.

Retzius, I. c, Bd. i. p. 84.

E. 279. Portion of the right side of the head and fore part of
the trunk of a Pike {Esox lucius). The dura mater has
been removed from the cranial wall, exposing the large
open fos?a in the skull wall in which lies the greater part of
the membranous labyrinth. The appendix utriculi can be
seen extending backward within the cranial cavity behind
the posterior margin of the general auditory fossa nearly to
the foramen magnum.

172

I'llYSIOLOGICAL SERIES.

The branches of the auditory nerve to the anterior ampulla,
recessus utriculi, sacculus, lagcna, and posterior ampulla aro
shown. 0. C. 1567 t.

Presented hi/ Dr. Corfield.

DIPNOI.

E. 280. The right and left membranous labyrinths of a Barra-
munda {Ceratodus forsteri). The recessus utriculi forms a
large flattened chamber projecting downwards upon the
outer side of the labyrinth from the line of contact between
the sinus utriculi anterior and the saccule. The sinus
superior utriculi is short and broad and receives the hinder

Fig. 36.

Left membranous labyrinth of Ceratodus forsteri.

C.R.S. Canalis recessu-saccularis. C.U.S. Canalis utriculo-sacculari.'?.
D.E. Ductus endolympbaticus. R. Recessus-utriculi. S.S. Sinus
superior utriculi. U. Horizontal part of utricle.

extremity of the horizontal canal into its lower part. The
saccule is of moderate size and shows no externally distin-
guishable lagena. A dilated vestige of the ductus endo-
lymphaticus arises from its antero-dorsal region. The
auditory nerve and its branches have been retained in the
upper specimen. The ramus recessus is very large. In
the lower specimen the recessus and saccule have been
opened. The recessus communicates with the saccule by

ORGANS OF SPECIAL SENSE. — VERTEBRATA.

173

a large oval canalis recessu-saccularis, indicated by a red
rod. A black bristle has been passed throngb a small
opening in the floor of the utricle close to the hinder part
of the canalis recessu-saccularis by which the utricle is
connected with both the sacculus and the recessus.

O.C. 1568 c.

Retzius, Z. c, Bd. i. p. 144.

E. 281. The otoliths from the recessus and sacculus of a Barra-
munda (Ceratodus forsteri). They are soft and granular in
texture and not porcellaneous as in Teleostea, and are appa-
rently formed by the cohesion of loose otoconia. Some free
otoconia were also found in the labyrinths.

The otolith from the sacculus is broken. There is no
separate otolith in the lagena. 0. C. 1568 D.

AMPHIBIA.

Eetzius, Das Gehororgan, Bd. i. 1881, pp. 151, 219.
Harrison, Internat. Monthly Jour. Anat., vol. xix. 1902,
p. 221 (perilymph).

In the Amphibia the membranous labyrinth consists of the
same parts as in Fishes, but, except in the lowest forms, with
the addition of an important sensory area in the lagena. This,
which is known as the macula acoustica basilaris, is probably the
rudiment of the cochlea (pars basilaris cochleae). At first it is
merely a separate portion of the macula lagense covering part of
the wall of the labyrinth at the base of the lagena, but in Anura
the underlying and neighbouring wall of the labyrinth undergoes
an important change and forms an extremely thin sheet (mem-
brana basilaris) stretched from the inner circumference of a
cartilaginous ring-like thickening. A similar stretched membrane
occurs in all forms of cochlea, and according to the Helmholtz
theory of audition plays an essential part in the appreciation of
differences in pitch (the Frog has lately been proved to have
distinct powers of differentiating between sounds somewhat
similar [Yerkes, Jour. Comp. Neurol., 1905]). In Mammals,
and probably also in lower Vertebrates, the fibres of which the
membrane is formed are tense in the direction of their own
length and relatively slack in their connection with one another.

174 PHYSIOLOGICAL SERIES.

They are thus able to vibrate independently. According to the
theory each fibre is tuned to vibrations of a certain rapidity and
vibrates only in sympathy with them. The whole membrane
thus forms an automatic analyser of mixed sounds and ensures

Pig. 37. Fig. 38.

Fig. 37. Lagena of Menopoma alleghanniense, Irom the inner aspect (after
Retzius).

Fig. 38. Lagena and surrounding parts of Rana esculeuta, from the inner
aspect (after Retzins).

A.L. Apertura lagente. D.E. Ductus endolymphaticas. L. Lagena
P.B. Papilla hasilaris. P.B.L. Pars basilaris lagense. R.B., R.L.,
R.N. Ramus basilaris, lagenie, neglectus. S. Sacculus.

the transmission of vibrations of one particular frequency to
certain cells only of the overlying macula.

The saccus endolymphaticus, which is developed independently
of the original communication between the ear and the exterior,
is frequently much enlarged and extends into the cranial cavity,
neural canal, and through the intervertebral foramina into the
body cavity. The Amphibia are the lowest group in which the
perilymphatic space forms a cavity lined by endothelium and
in connection on the one hand with certain areas of the labyrinth
and on the other with the cranial cavity by the ductus perilym-
phaticus. Within this group also a tympanic apparatus, due to
modification of the hyoid cleft, is met with for the first time,
and in its simplest form. When present, the cleft is usually a
combined Eustachian tube and tympanic chamber that extends

ORGANS OF SPHOIAL SENSE. — VERTEBRATA^

175

upwards from the moutli cavity and separates the otic region of
the skull from the overlying tissues. The skin over this area is
united to the mucous membrane of the tympanic chamber to
form a flat drum-membrane suspended by its edges to a thickened
cartilaginous ring (annulns membranse tympani). A rod of
cartilage and bone (columella auris) attached to the inner surface
of the drum-membrane stretches across the tympanic cavity to
an opening in the wall of the periotic capsule. By means of this
apparatus sound-vibrations are transmitted by oscillations of
the membrana tympani and columella to the perilymph and
through it to the endolympli and sensory epithelium of the
labyrinth, the necessary movements of the perilymph being
made possible by the opening in the otherwise rigid walls of
the periotic capsule, through which an enlargement of the
perilymph sac projects into the cranial cavity. In Amphibia
the membi'ana tympani lies unprotected flush with the general
surface of the head.

E. 282. The right membranous labyrinth and the membrana
tympani and columella auris of a Bull Frog (Rana cates-
hiana). In the specimen the saccule, lagena and utricle
form an oval mass, in which the several parts are
indistinguishable, surmounted by the semipircular canals
and the sinus superioris utriculi. The membrana tympani
is flush with the general surface of the head. It is
stretched from the circumference of a rino- of cartilase
(the annulus membranae tympani) which serves also to
support the walls of the tympanic chamber. To the centre
of the membrana tympani is attached the cartilaginous
outer end (extrastapedial) of the columella auris. The
inner end of the columella (interstapedial) is bound by
fibrous tissue (the cut edge of which is shown in the
specimen) to the edges of the fossa that leads to the fenestra
ovalis. The upper border of the extrastapedial is attached
to the deep margin of the tympanic ring. 0. C. 1575 a.

Ecker's, Anat. des Frosches, Gaupp, 2nd Aufl., Abt. 3,
1904, pp. 679 & 786.

E. 283. Left half of the head of a Bull-Frog (Rana catesbiana).
Tho posterior half of the membrana tympani has been

17G

PHYSIOLOGICAL SERIES.

removed leaving the annulus membranse tympani and
showing the connections and natural position of the
columella auris and the communication between the
tympanic chamber and the mouth through the Eustachian
tube. The annulus is attached by its upper border to the
squamosal and also has a slight connection in the same
region with the columella auris. A black bristle has been
passed to the anterior side of the columella and through the
tympanum into the Eustachian tube. The membranous
labyrinth has been exposed to show so far as possible the
natural position of its different parts. 0. C. 1575 B.

E. 284. The head of a Bull- Frog {Rana catesbiana) seen from
the ventral aspect with the lower jaw removed. Upon the
left side the posterior walls of the tympanum have been cut
away to show the position of the columella auris and the
inner surface of the membrana tympani. Upon the right
side is shown the wide opening of the Eustachian tube into
the mouth, and upon the reverse of the specimen the general
appearance and the position of the tympanic membranes.

0. 0. 1575. Hunterian.

E. 284 a. The head and trunk of a Frog {Rana temporaria) with
the ventral body-walls removed. On either side of the
backbone on a level with the intervertebral foramina are
paired chalky masses (chalk-sacs) of irregular shape. These
have been shown to be continuations of the endolymphatic
ducts filled with otoconia. The two sacci endolymphatici are
stated to be united around the hinder part of the brain to
form a ring-like chamber from which a continuation made
up of numerous fine tubes passes down the neural canal
above the spinal cord and gives off" laterally through each
intervertebral foramen the "chalk-sacs" shown in this
specimen. Similar extensions of the endolymphatic ducts
into different parts of the body occur in some Lizards (see
below).

Anat. Anz., Bd. v. 1890, p. 177.

E 285. Head of a Surinam Toad {Pipa americana). The
Eustachian tubes open by a small common orifice in the

ORfiAXa Ob' SrECIAL SENSE. YEUTEBRATA.

177

mid-line of the roof of the mouth. A black bristle has
been passed through this into the tympanic chamber and
beliind the extrastapedial cartilage of the columella^ A red
rod has been passed through the right nasal passage.

O.C. 1570 D.

E. 288. Skull of a Surinam Toad (Pipa americand), dried.
Upon the left -side a black bristle has been passed through
the Eustachian tube and a green bi'istle into the fenestra
ovalis. Upon the I'ight the thi'ee divisions of the columella
auris (represented by paper) have been painted different
colours — the interstapedial and extrastapedial blue, and the
mediostapedial red. 0. G. 1575 c.

KEPTILIA.

Retzius, Das Gehororgan der Wirbelthiere, Bd. ii. 1881,
pp. 3, 358.

As regards the membranous labyrinth, this is in some ways
the most important of all the Vertebrate groups, for within it
the transformation of the pars basilaris cochleae can be traced
from, a rudiment upon the basal parts of the lagena to a large,
lengthened, and slightly twisted tube to which the lagena forms
a minute terminal appendage. In its lowest state of development
(Chelonia, Ophidia) this cochlea differs little from that of a
Urodele Amphibian, and in its highest (Crocodilia) is essentially
the same as that of a Bird, but in no case is the minute structure
of the papilla basilaris comparable in its details to that charac-
teristic of the organ of Corti of Mammals, but is similar to that
of the other maculae of the labyrinth.

The rest of the membranous labyrinth consists of the same
parts as in lower Vertebrates, with the same cristse and maculge
acousticae, including a small macula neglecta upon the ventral
wall of the sinus utriculi posterior. The saccule, so far as
investigated, is always in open communication with the utricle
by a narrow canalis utriculo-saccularis, and with the cochlea by
an opening which may be wide or may be drawn out into a
relatively narrow tube (canalis reuniens). The ductus endo-
lymphaticus, which is developed independently of the original
connection between the labyrinth and the exter-ior, ends in a

VOL. m, vr

178

rilYSIOLOGlCAL SERIES.

blind dilatation that sometimes, as in certain anurous .Amphibia,
extends (filled with otoconia) beyond the ear-capsule into the
cranial cavity and other parts of the body.

Fig. 39.

Part of the riglit membranous labyrinth ot Alligator mississipiensis,
mesial aspect (after Retzius, modified) .

C. Cochlea. CSC. Canalis sacculo-cochlearis (reuniens). C.US. Canalia
utriculo-saccularis. D.E. Ductus endolymphaticus. L. Lagena. R. Re-
cessus utriculi. R.B., R.L. Ramus basilaris, and lagense. S. Sacculus.

Within this group also for the first time the perilymph space
forms a definite channel that runs from the base to the apex of
the cochlea applied to its roof-membrane forming the scala
vestibuli, and thence as the scala tympani along the outer
surface of the basilar membrane to an opening closed by
membrane in the periotic capsule (fenestra rotunda) *. The
flexible area provided by this opening in the rigid periotic wall
allows the movements of the columella to be transmitted from
the fenestra ovalis throughout the perilymph and thus to the
endolymph and the sensory cells of the maculae.

* Above Reptiles these three united passages are known as the cochlea,
and the true cochlea as the scala media, or cochlear canal.

ORGANS OF SPECIAL SENSE. — VERTEBRATA.

179

Although in some cases (Ophidica) the tympanic chamber is
absent, it frequently has considerable complexity both in its
shape and in its connections with the mouth. The tympanic
membrane is often (Lacertilia) sunk below the level of the skin
and is sometimes protected by an upstanding fold that faintly
suggests a pinna.

EHYNOHOCEPHALIA.

E. 287. The skull of a Tuatara Lizard (SpJienodon punctatus)
showing a direct connection between the extrastapedial
cartilage of the columella auris and the upper end of the
second visceral (hyoid) arch. This connection in Splienodon,
in addition to evidence derived from other animals, led
Huxley to infer that the columella auris and (in Mammals)
the incus and stapes are modifications of the upper end
of the hyoid arch. But the primary character of the
connection has been much questioned, and in consequence
this view of the origin of the columella has not found many
adherents. Latterly however it has been again brought
forward (Howes and Swinnerton), supported by embryo-
logical evidence*. 0. C. 1576 A.

Presented hy F. E. Beddard, Esq.

Huxley, Proc. Zool. Soc, 1869, p. 391.
Gadow, Phil. Trans., vol. clxxix. 1889, p. 466.
Howes and Swinnerton, Trans. Zool. Soc, vol. xvi.
1903, p. 46.

LACERTILIA.

E. 288. Right half of the head of an Australian Seine (Tiliqua
scincoides). The membrana tympani is sunk below the
general surface of the head at the bottom of a wide meatus
auditorius externus. The cavity of the tympanum and its
remarkably wide passage into the pharynx are shown upon
the reverse of the specimen. 0. C. 1605. Hunterian.

John Hunter, Essays and Observations, edit. R. Owen,
vol. ii. 186, p. 368.

• A full review of this vexed question of the origin and homologies of the
tympanic ossicles is given by Gaupp, Ergebnisse der Anat. u. Entwickl.,
JBd. viii. 1898, p. 9t)0,

N 2

180

PIIYSIOLOaiCAL SERIES.

E. 289. Head of an Iguana {Iguana iuhercidala). Tlie mem-
branous labyrinths are exposed from above, but parts of the
semicircular canals only are visible. Upon the left side
the tympanum has been opened from above to show the
position of the long slender columella. The membrana
tympani lies slightly below the general level of the skin
and is protected to some extent by an integumentary fold
along its posterior border. Upon the reverse of the
specimen the cavity of the right tympanum and the
openings of the Eustachian tubes are shown. 0. C. 1.57fi.

Tfunterian.

John Hunter, Essays nnd Observations, od'\i. K. Owen,
vol. ii. ISfil, p. 3G7.

E. 290. Cranium of a Lizard (Rhacodacti/lus leachianui)
belonging to the family Geckonidse. The saccus endo-
lymphaticus, as is usual in this family, is excessively
enlarged, and protrudes — filled wdth otoconia — between the
bones of the skull. Its chief expansions are irregularly
nodular and can be seen projecting downwards between the
two columellfG cranii towards the mouth cavity through the
unossified alisphenoidal region of the skull. A smaller
enlargement is visible between the supraoccipital and
prootic bones, and there are also traces of otoconia between
the supra- occipital and parietal bones and around the
foramen magnum, that seem to be the cranial extremities
of cervical sacs similar to those found in Phyllodactylus.

0. C. 1576 B.
Wiedersheim, Morph. Jahrb., Bd. i. 1876, p. 517.

EMYDOSATJEIA.

E. 291. A transverse section through the otic region of the head
of a Crocodile (Crocodilns aculus), showing the auditory
organs from behind. The external meatus and tympanic
chamber have been cut through on the right side, showing
theposition of the membrana tympani with the outer, convex,
surface directed upwards and outwards, its connection by
means of the columella with the internal ear, and its mode
of protection from external injury by a moveable opercular

ORGANS OF SPECIAL SENSE. — VERTEBRATA.

181.

flap of the integument that forms the dorsal wall of the
meatus. This flap is probably raised when the animal is on
land and depressed against the lower wall of the meatus
(as shown on the left side of the specimen) when in the
water. In the latter condition sound waves are conducted
to the internal ear through the bones of the skull.

The columella auris is attached by its outer end to the
membrana and extends obliquely downwards and inwards
across the tympanic cavity to ihe fenestra ovalis — an
aperture in the bony labyrinth situated opposite the base
of the cochlea.

The tympanic chamber communicates with the mouth by
a complex series of channels. In its ventral wall are t\\ o
apertures : a posterior, marked by a black bristle, and an
anterior marked by a yellow bristle. The duct jn con-
nection with the first passes inwards and downwards and
soon forks in the transverse plane. The latei'al branch of
this fork runs directly downwards between the basisphenoid
and basioccipital bones to the floor of the skull, and here
bends abruptly inwards to open into Ihe mouth in the mid-
line bc4iind the posterior nares by an aperture common to
all the Eustachian canals. The median branch of the fork
passes inwards and downwards and unites with its fellow of
the opposite side to form a median canal (posterior median
canal) tliat runs directly downwards to the common
Eustachian opening. The anterior opening into the
tympanum is in connection with a duct that runs towards
the mid-line and unites with its fellow to form an " anterior
median canal," which after a short ventral course opens
into the anterior surface of the posterior median canal.

The tympanic chambers of either side are in open com-
munication above the brain-case.

The membranous labyrinths have been exposed and show
the position of the semicircular canals and their ampullae,
ihe general form of the utricle and saccule and (upon the
left) the long cochlea stretching downwards with a slight
backward curve from the posterior end of the saccule.

0. C. 1577 B.

Hetzius, Das Gehororgan, Bd. ii. 1884, p. 121.

Van Bcneden, Arch, de Biol., t. iii. 1882^ p. 4t)7.

182

rilYSIOLOGICAL SliUlES.

E. 292. A portion of the head of a young Crocodile {Crocodilus
acutus), in which the organs of hearing are exposed from
behind. The opei'cular flap for the protection of the
niembrana tympani is shown on the right as in the previous
specimen ; on the left it has been removed. The tympanic
chambers have been opened and, upon the left side, the
relation of the base of the columella to the fenestra oralis
is particularly well shown. Quills have been passed in
front of each columella and along the communicating
passage between the two tympana. Upon the right, one of
the Eustachian canals has been opened and black bristles
have been inserted into the cavities occupied by the
horizontal and posterior semicircular canals. 0. C. 1577.

Hunterian.

John Hunter, Essays and Observations, edit. R. Owen,
vol. ii. 1861, p. 344.

E. 293. Left half of the head of a young Crocodile (Crocodilus
sp.), showing the membrana tympani sunk slightly below
the surface of the head at the bottom of a wide but shallow
external meatus. The opercular flap shown in the two
previous specimens has been removed. 0. C. 1606.

Bunteria7i.

E. 294. The posterior part of the roof of the mouth of a Crocodile,
showing the posterior nares and close behind them the
common orifice of the Eustachian tubes. Black bristles
have been inserted into the lateral and central passages of
the Eustachian tubes. 0. C. 1577 a.

CHELONIA.

E. 295. Part of the head of a Turtle {Clielone mydas), in which
the auditory organ is displayed on both sides. The
membrana tympani is covered externally by the cutis and
by one of the horny epidermic scales. On the left side the
two extremities of the long columella auris are exposed
from above and bristles are placed beneath them. The
tympanic cavity is separable into three parts : (a) An outer
chamber of large size, just internal to the membrana
tympani, into which opens the Eustachian tube— the tube
\\l)0\\ this bide (see reverse of specimen) has been slit up

ORGANS OF SPECIAL SENSli. — VEllTEBllATA. 183

and a bristle passed along it into this part of the tympanic
cavity, (b) A narrow median tubular part occupied com-
pletely by the shaft of the columella. This has not been
opened in the specimen. (c) An inner chamber (anti-
vestibulum), next the bony labyrinth, in which lies the foot
of the columella. In the specimen this chamber has been
opened and part of the wall of the labyrinth removed to
show the foot of the columella lodged in the fenestra
ovalis.

Upon the left side the membranous labyrinth has been
exposed, but its several parts are retained in their true
relations to the bony labyrinth and are still enveloped in
the perilymphatic sheath, which in the Chelonia is readily
detachable from the bony capsule. A white mass of
otoconia can be seen through the transparent walls of the
saccule.

Upon the right side the membranous labyrinth has been
more fully isolated, showing the semicircular canals and
tlieir ampuUse. Upon the reverse the mouth of the right
Eustachian tube is marked by a black bristle. 0. C. 1578.

Jlunterian.

John Hunter, Essays and Observations, edit. R. Owen.

18G1, voL ii. p. 354.
Hasse, Anat. Studien, Bd. i. 1870-73. p. 225.

E. 296. A small part of the right side of the head of a Turtle
(Chelone sp.). The cutis and epidermic scales have been
partly reflected to show the outwardly convex raembrana
tympani. The tympanic cavity has also been opened
exposing the columella auris. The extreme narrowness of
the central segment of the tympanum is well shown. The
membranous labyrinth has been isolated from its bony
coverings but is still surrounded by the perilymphatic
sheath. The extension of this into the concavity of the foot
of the columella is clearly seen. In this part there is a
considerable space between the membranous labyrinth and
the perilymphatic sheath. 0. 0. 1580 A.

E. 297. A small part of the left side of the head of a Turtle
{Chelone sp.) from which the integument has been removed

184

PHYSIOLOGICAL SKRIE«.

to show the meinbrana tympani. The tympanic cavity has
been opened displaying the whole hingth of the columella
auris, and the tympanal end of the Eustachian tube. The
membranous labyrinth is also shown, still enveloped in its
perilymphatic sheath. 0. C. 1580 A a.

E. 298. Part of the left side of the head of a Turtle {Chelone sp.),
in which the tympanic cavity and the bony labyrinth have
been opened from below. The columella and the different
parts of the membranous labyrinth are indicated by black
bristles. The upper end of the Eustachian tube is shown
opening into the outer chamber of the tympanum.

0. C. 1580. Ilunterian.

E. 299. Part of the right side of the same head, with tbe columella
auris and membrana tympani isolated. The foot of the
columella is still lodged in the fenestra ovalis. The bony
labyrinth has been opened showing fragments of the
contained membranous labyrinth. 0. C. 1579.

Hunlerian.

E. 300. The columella auris and membranous labyrinth of the
left side of a Turtle (^Chelone sp), isolated. The peri-
h'mphatic sheath has been partly removed, but the
connection between it and the foot of the columella is
still retained. 0. C. 1580 C.

E. 301. Left half of the head of a Tortoise (Testudo grcecd). A
bristle is inserted into the pharyngeal opening of the
Eustachian tube. Upon the reverse of the specimen the
membrana tympani is shown, exposed by the removal of
the overlying horny scales. 0. C. 1607. Hunterian.

AVES.

Retzius, Das Gehororgan der Wirbelthiere, Bd. ii. 1884,
pp. 139, 3t)l.

The membranous labyrinth of Birds closely resembles that of
the Crocodiles in the form and structure of the cochlea, which
is long, narrow, slightly twisted, and attached to the saccule by
a relatively narrow passage (canalis rcuniens), and terminates

ORGANS OF SPECIAL SENSE. — VERTEBRATA.

185

in a small lagena with separate macula and nerve ramus. But
the arrangement of the semicircular canals is o£ quite a peculiar
type, the anterior vertical canal being o£ great length, and it
and the posterior vertical being so placed that they cross each

Fig. 40.

A. Right membranous labyrinth of Columla domestica, mesial aspect.

B. Right utricle of the same opened from above, showing connection

between it and the saccule and between the saccule and cochlea (both
after Retzius, simplified).

A.E. Ampulla externa. C. Cochlea. C.SC. Canalis sacculo-cochlearis.
C.US. Canalis utriculo-saccularis. D.E. Ductus endo-lymphaticus.
L. Lagena. P.B. Papilla basilaris. R. Recessus utriculi. S. Sac-
culus. S.P. Sinus posterior utriculi.

other, the anterior above, and open into the apex of the sinus
superior utriculi in reversed positions, i. e., the posterior in front
o£ the anterior. The deeper parts of the periotic capsule
are made of peculiarly dense bone and form a thin encasement
to the various parts of the membranous labyrinth. This dense
" bony labyrinth "is probably in some way of assistance in
audition, as a similar though more extensive condensation of

18G

PHYSIOLOGICAL SERIES.

the perlotic cnpsulo occurs also in Mammals. The tympanic
chamber is complicated by extension into irregular cavities and
trabeculatod spaces in the skull which possibly act as resonators,
and usually the membrana tympani lies below the level of the
skin, at the bottom of a short external meatus and is further
protected by feathers or integumentary flajis.

E. 302. Skull of a Goose (Anser feru.t) , with the bony labyrinths
and tympana exposed. On both sides the columella is
shown, stretching from the tympanic membrane to tho
fenestra ovalis. On the left the relative positions of the
fenestriB ovalis and rotunda can be seen at the base of the
cochlea, and on the right the bony labyrinth has been
opened and the contained cavities painted black to show
the form and position of the cochlea and the position of
the fenestra ovalis opposite its base. The anterior and
posterior canals cross one another before entering the
sinus superior utriculi, but much less so than in some
Birds. 0. C. 1581 d.

E. 302 a. The head of a Capercaillie (Tetrao urogallus) with the
external meatus of either side opened from above. The
skin that lines the posterior wall of this passage is loose,
forming an irregular cushion, and is separated by a con-
siderable space from the deeper tissues. This space and
the deeper parts of the cushion are traversed by slender
trabeculse and are stated to be in connection with the
arterial system. During courtship and especially when the
beak is wide open at the termination of the nuptial song
these spaces become gorged with blood. The cushion
swells and completely blocks the meatus, rendering the
Bird for the time absolutely deaf.

Upon the right side of the specimen the cushion is con-
tracted, upon the left it has been artificially inflated.

V. Graff, Zeits. wiss. Zool., Bd. xli. 1885, p. 107.

E. 303. Right half of the bead of an Owl (Bubo bubo)
showing the auditory organ. In the Owls the membrana
tympani is sunli below the surface of the head at the
bottom of a deep external meatus, whose mouth is protected
by overhanging integumentary lips bordered by a circlet

OEQANS OF SPECIAL SENSE. — VERTEBRATA.

187

o£ feathers. The tympanic membrane is very delicate and
is uonnected to the internal ear by a slender columella.
Tlie foramen ovale, in which its foot is lodged, is shown in
section. The bony labyrinth has also been exposed and
opened. Bristles have been passed into the pharynx
through the anterior parts of the Eustachian tubes and
the single opening common to them.

0. C. 1581. Hunterian.

E. 304. The right half of the head of a Barn Owl {Strix
Jlammea), in which the external auditory meatus has been
opened from below by a horizontal section. The margins
of the opening into the meatus are produced as fleshy lips
which are bordered by a circlet of feathers : thus a structure
is formed analogous to the pinna of Mammalia.

0. C. 1581 A.

E. 305. Anterior part of the head of a Rook {Trypanocorax
frugilegus), with the bony labyrinths exposed and with
bristles inserted into the Eustachian tubes. The anterior
semicircular canal is very much longer than the posterior
and crosses above it before opening into the sinus superior
utriculi. The position of the openings of the canals into
this sinus is thus the reverse of that normal for other
classes — the anterior canal opening into the posterior part
of the sinus, the posterior into its anterior part.

0. C. 1581 c.

E. 306. The right halves of the skulls of two Corvine Birds.
In one the bony labyrinth has been fully exposed in situ
with a portion of its inner wall removed. An isolated left
labyrinth and columella auris are mounted separately.

0. C. 1581 B.

MAMMALIA.
Middle and Internal Ear.

In all Mammalia, except Monotremes, the cochlea is much
elongated and is twisted into a spire in which the number of
coils varies considerably (2^, in Rabbit and Man, to nearly 5 in
Coelogenys), The thickened frame upon which the basilar

188

PIIY8I0L0GICAL SERIES.

membrane is stretclied is transformed by tbis coiling from a
circular or elongated oval form as seen in Ampbibians, Reptiles
and Birds to a spiral, its anterior and posterior sides forming
respectively tbo lamina spiralis and ligamentum spirale of tlio

Fig. 41.

Part ot the right membranous labyrinth of Bos taurus (foetal), mesial aspect

(after Retzius).

0. Cochlea. O.US. Canalis utriculo-saccularis. C.SO. Canalis sacculo-
cochlearis (reuniens). D.E. Ductus endolj-mphaticus. L.S. Ligamentum
spirale. M.B. Membrana basilaris. E,, Recessus utriculi. S. Saeculus.
S.L. Lamina spiralis carrying the rami basilares.

cocblea. Tbe bony axis of the spire (Modiolus) consists mainly
of tbe base of tbe lamina spiralis and gives passage to tbe
cocblear brancb of tbe auditory nerve. In all Mammals, even
in Monotremes, the papilla basilaris, now known as tbe Organ
of Corti, has a peculiar arrangement and diflFerentiation of its
histological elements, which is quite characteristic of tbe class,
and is probably the structural expression of an increased
sensitiveness to diflferences in rapidity of vibrations transmitted
to it through the scalar and basilar membrane*. The great

* Kretschmann, Arch. f. Physiol., Bd. cviii. 1905, p. 409.

ORGANS QF SPECIAL SENSE. — VEUTEBRATA.

189

development of the cochlea is accompanied by the loss of the
lagena and macula lagense and of the macula neglecta. With
these exceptions the rest of the labyrinth resembles in essentials
that of lower forms, with however certain diflPerences in detail,
the most important of which are the length and narrowness of
the canalis utriculo-saccularis and of the canalis reuniens. The
labyrinth appears to differ relatively little in its general structure
in such Mammals as have been examined *.

The tympanic apparatus is more specialised than in lower
Vertebrates, the tympanum being enlarged by resonating air
cavitiesj which either extend as irregular spaces into the
substance of the mastoid part of the periotic bone (e. g. Man
and Anthropoids) or occupy a "bulla" formed by the inflation
of the tympanic or some other neighbouring bone of the skull,
while the relatively simple columella is replaced by a chain of
small ossicles, so hinged and attached together that each move-
ment of the drum-membrane is reproduced in a diminished
form at the fenestra ovalis. The membrana tympani, which
may be set at various angles to the sagittal plane of the head,
lies fit the bottom of a deep meatus externus which in most
cases is surrounded in its deeper parts by bone.

MONOTREMATA.

E. 307. The skull of a Dack-billed Platypus {Ornitliorhynclius
anatinus), in which the ventral wall of the right bony
labyrinth has been removed to show the cochlea and the
horizontal semicircular canal. The former is a short tube
(about 6 mm. in length), of about equal diameter through-
outj that runs forward in the petrous bone curving gently
outwards for ^ of a circle.

Examination of the membranous labyrinth (Pritchard)
shows that the cochlea is essentially of the Mammalian
type although " the acoustic apparatus of the organ of

* An excellent revie-w of the whole question of the prolDable action of the
various parts of the ear and particularly of the cochlea is given by
M'Kendrick and Gray, in Schiifer's "Text-Boob of Physiology," 1900,
vol. ii. p. 1149, and an even fuller account with a more extensive bibliography
of the subject will be found in " Die Lehren v. d. Funktionen der einzelnen
Theile des Ohrlabyrinths," von Stein, trans. (German) C. v, Krzywicki, 1894.

190

PHYSIOLOGICAL SERIES.

Corti is not nearly so extensive as in typical Mammals
nor do the various minute structures forming it appear to
be so well developed." It however diflfers from the
Mammalian cochlea in being coiled only at its tip, in being
of nearly equal diameter throughout and in having at its
apex a small lagena cochleai.

Transferred from Osteol. Series, 3970.
Pritchard, Phil. Trans, vol. clxxii. 1882, p. 267.

E. 308. Skull of a Spiny Ant-eater {Tachyglossus [Echidna]
aculeatvs). Upon the right side the membrana tympani has
been retained attached to the tympanic ring and malleus.
It faces almost directly downwards. Upon the left the
membrane has been removed to show the large tensor
tympani muscle (painted red) passing directly outwards
from the floor of the tympanum to the process by which
the malleus is attached to the membrana tympani.

Transferred from Osteol. Series, 3957 A.
Peters, Monatsber. Ak. Wiss. Berlin, 1868, p. 779.

OETACEA.

John Hunter, Phil. Trans., vol. Ixxvii. 1787, p. 430.
Beauregard, Jour, de I'Anat., T. xxx. 1894, p. 379, and
T. xxix. 1893, p. 196.

E. 309. The organ of hearing of the left side of a Bottle-nose
Whale [Hyperoodon rostrata) seen from the inner and lower
aspect. The meatus auditorius externus is laid open
throughout its whole lengih ; it is very narrow at its
commencement where its lining membrane continues
smooth for about an inch and a half (4 cm.) ; then the
passage dilates a little and the orifices of many follicles
analogous to the ceruminous glands, may be observed in it.
Beyond this part the inner surface is slightly plicated
longitudinally and afterwards is surrounded by a fibro-
cartilaginous sheath and gradually expands to within an
inch of the membrana tympani, where the cartilage termi-
nates. Further on the passage again contracts to its

ORGANS OF SPECIAL SENSE. — VERTEBRATA.

191

termination, just before which it winds round a smooth
mammilloid projection of the tympanic bone. The cavity
of the tympanum is laid open showing its delicate lining
membrane, the largo tympanic plexus of vessels, and the
strone triangular ligament which connects the membrana
tympani with the malleus. The cut edge of the externally
concave membrana tympani can be seen just below the
mammilloid process of the tympanic bone. The cord of
soft tissue issuing from the lower Tanterior) part of the
tympanic cavity is the end of the Eustachian tube. The
petrous bone is preserved entire upon the right of the
specimen. 0. C. 1584. Hunterian.

E. 310. Part of the nasal passage of the same Whale, including
the opening of the Eustachian tube. The Eustachian tube
is laid open to show its reticulated structure.

0. C. 1585. Hunterian.

E. 311. A similar specimen, showing the " termination of the
Eustachian tube in a Whale." Label 1817.

0. C. 1586. Hunterian.

E. 312. Part of the head of a Porpoise {Phocoina pJioccend),
showing the auditory organ of the left side. The narrow
winding external meatus is laid open from its small external
orifice situated at a point about 4 cm. posterior to the
eye to the tympanic membrane. The tympanum has been
opened, showing the thick membrana tympani, the triangular
ligament that connects it to the malleus, and the tympanic
plexus of blood vessels. Bristles are passed from the
tympanic cavity into the Eustachian tube and also into
some of the sinuses described by Hunter (Phil. Trans., 1787,
p. 431). These sinuses are filled with an Entozoon
{Strongylus minor, Kuhn). The Eustachian tube, into which
the stoutest bristle has been passed, is laid open through
the greater part of its extent, showing the glandular
structure of its pharyngeal end. Part of the skull wall

102

niYSIOLOOrCAL SKUIKS.

has been removed to show the denss bony tympanic bulla
and the petrous bone that contains the internal ear. The
auditory nerve has been exposed.

0. C. l.')82. Tluiderian.

Fig. 42.

T. M

■ Riglit auditory organ of Thocmia jyhocana, in position, latoral aspect.

E. Eustachian tube. E.M. Extei-nal meatus. L, Ligament unitiug tympanic
membrane to malleus. P. Petrous bone. K, liete. T. Tympanic
bone. T.M. Tympanic membrane.

E, 313. Part of the floor of the cranium of a Porpoise (Fhoeceim
phoccena), showing the right half of the nasal cavity. In
the lateral wall of this, about 2 cm. in front of the hinder
limit of the septum nasi, is a small orifice — the opening
of the Eustachian tube. A bristle passed into this indicates
upon the reverse of the specimen the continuity of the
Eustachian tubes with certain sinuses described b}'- Hunter
(Phil. Trans. 1787, p. 431) in connection with the tym-
panum and Eustachian tube and compared by him with
the guttural pouches of the Horse. The sinuses are infested
by a number of thread worms {Strongylus minor).

0. C. 1587. Hunie nan,

ORGANS OF SPECIAL SBKSE. — VERTEBRATA.

193

E, 314. The hinder part of the left side of the head of a Porpoise
{Plioccena phocaina), showing the auditory organ in situ
from in front and below. The specimen has been minutely-
injected and steeped in acid : the dense nature of the
tympanic and especially of the petrous bone and the great
amount of inorganic matter contained in them in com-
parison with the other bones of the cranium, is shown by
their whiter and more chalky appearance. The cut edge
of the tympanic plexus (c/. E. 309) can be seen in the
groove between the tympanic and petrous bones, A black
bristle has been placed in the wide Eustachian tube
and into the internal meatus which is still filled by
fibres of the auditory nerve. Upon the reverse of the
specimen the narrow external meatus is shown^ opened
throughout its length ; a bristle has been inserted into its
orifice. 0. C. 1588. Hunterian.

E. 315. Petrous and parts of the tympanic bones of the right
side of a Porpoise {Plioccena phoccena), showing, from the

Fig. 43.

■vn

A.

Right petrous bone and a fragment of the tympanic hone of Phoccena

phoccena, lateral aspect.
Surface of articulation between petrous and tympanic bones. A 0
Aqueductus cochlcso. C. Cochlea. F.R. Foramen rotundum. H.'
Hollow lodging the swollen head of malleus. I. Incus. L. Ligament
uniting tympanic membrane to malleus. M. Processus grac'ilis of
malleus articulating with tympanic. S. Stapes. S.M. Stapedius
muscle. T. Tympanic bone. T.M. Tympanic membrane. T.T. Tensor
tympani. VII. The facial nerve. ' .

VOL. III. Q

niYSIOLOGICAL SERIKS,

ventral and innor aspect, the cavity of the tympanum and
the ossicles with their ligaments and muscles, A small
part of the membraua tympani is retained to show the
strong triangular ligament (conspicuous for its glistening
fibres) that connects its deep (convex) surface with the
vestigeal manubrium of the malleus. From the apex of
the blunt processus muscularis of tlie malleus a stout conical
tensor tympani runs forward to the petrous bone. The
articular surfaces of the malleus and incus have been
slightly separated. The stapes can be seen extending from
the incus to the fenestra ovalis, which lies at the bottom of
a depression in the petrous bone. From the head of the
stapes the stapedius muscle passes backwards and inwards
to the petrous bone between the fenestra ovalis and fenestra
rotunda.

The fenestra rotunda is divided transversely by a bony
septum (c/. E. 324). 0. C. 1590. Hunterian.

E. 316. A similar preparation of the right ear of a Porpoise, in
which the form of the cochlea is displayed in addition
to the parts shown in the preceding specimen. The scala
tympani has been opened throughout its whole length from
the fenestra rotunda showing the mode of coiling of the
cochlear canal and scala vestibuli. These upon leaving the
vestibule bend at first outwards in a left-handed direction
and then suddenly inwards to form a right-handed spire of
two and a half turns. 0, C. 1591. Hunterian.

E. 317. The tympanum and labyrinth of the left ear of the
same Porpoise, similarly prepared.

0. C, 1592. Hunterian.

E. 318. The right ear of a Dolphin {DelpUnus tursio), dissected
in a similar way to show the tympanum with the membrana
tympani and the ossicles and their muscles, and parts of
the internal ear. The general arrangement is similar to
that seen in the Porpoise. The root of the auditory nerve
has been exposed in the modiolus as far as the first turn
of the lamina spiralis. 0. 0. 1593. Hunterian.

ORGANS OF SPECIAL SENSE. — VERTEBnATA.

195

E. 319. The left internal ear of a Dolphin (Delphinus tursio),
showing the cavities occupied by the semicircular canals
and the cochlea. The canals have the same disposition as
in other Mammals, but their size in proportion to the
cochlea is much less. 0. C. 1594. Hunterian.

E. 320. The right tympanic bone, with part o£ the fatty substance

in which it is imbedded, of a Piked Whale {Balcenoptera
acuto-rostrata) . The fatty tissue has been removed from
the outer surface of the bone : the opposite involuted part
is covered by a dense membrane continuous with the lining
of the tympanum.

At the upper (anterior) end of the elongated fissure that
leads into the cavity of the tympanum, the deep end of the
external meatus and the membrana tympani are preserved.
The latter, which has been slit along one side, is " projecting,
and returns back into the meatus for above an inch in
length, is firm in texture with thick coats, is hollow on its
inside and its mouth communicating with the tympanum "
(Hunter, Phil. Trans. 1787, p. 434).

0. C. 1596. Hunterian.

F. 321. The mass of fatty tissue that surrounds the tympanic

bone, from the same Whale. 0. C. 1597. Hunterian.

E. 322. The pouch-like membrana tympani of a Rorqual
(Balcenoptera horealis). From an animal taken in the
River Crouch, Essex (Flower, Proc. Zool. Soc, 1883),
28 ft. 5 in. (8-66 m.) in length. 0. C. 1598 c.

E. 323. A small portion of the tympanum of a young Whalebone
Whale {Ba Icena sp.) including the membrana tympani and
a part of the external meatus. The membrana tympani is
attached in an elliptical form to the tympanic bone and
bulges outwards in the form of a pouch into the external
meatus.

The outer layer of the membrana tympani which is

0 2

19G

TIIVSIOLOOTCAL SERIES.

continuous with the lining of tlic meatus is in part removed,
and in the same way a portion of the inner layer, which is
continued from the lining of the tympanum, has been
reflected, leaving the intermediate or proper layer of the
membrana isolated and showing very clearly its fibrous
structure. 0. C. 1598 a.

E. 324. Left petrous bone and ossicula auditus of the same
animal seen from the ventral surface, Avith the posterior
extremity to the right. The ossicles lie in their natural
position, but the malleus has been detached from the
tympanic bone. The tensor tympani and stapedius
muscles can be seen passing respectively from the blunt
processus muscularis of the malleus forwards and from the
head of the stapes backwards and inwards to the petrous
bone. Dorsal to the articulation between the incus and
stapes lies the facial nerve. The triangular piece of
cartilage in connection with the posterior part of the
petrous bone (Home, Lectures, PI. n.) is probably the
upper end of the anterior cornu of the hyoid. The foot of
the stapes and the fenestra ovalis are hidden behind the
prominence of the petrous bone that contains the cochlea.
The fenestra rotunda can be seen at the base of the scala
tympani. It is closed by a membrane and is not divided
by a transverse septum as in the Dolphins (E. 315). Both
the scalse of the cochlea and the intervening lamina spiralis
are exposed in part of their gyrations, and the acoustic nerve
is preserved where it enters the meatus auditorius internus.
This specimen is figured by Home, Lectures on Com-
parative Anatomy, 1823, PI. ci. 0. C. 1598 b.

UNGULATA.

E. 325. Cranium of a Hyrax (Procavia capensis), showing on
either side of the basioccipital below the otic region of the
skull, a thin-walled membranous dilatation of the Eustachian
tube. That on the right side has been cut open.

0. C. 1170 AO.

Peter, Arch. f. mikr. Anat., Bd. xliii. 1894, p. 359.

ORGANS OF SPECIAL SENSE.— VERTEBllATA.

107

E. 326. Hinder part of the cranium of a Tapir {Tapirus
americanus) , showing from the ventral aspect a pair of
membranous dilatations of the Eustachian tubes similar to
those seen in the previous specimen. They are large and
of irregular form, and occupy the space between the skull,
the greater cornu of the hyoid, and the pharynx wall,
meeting one another in the ventral mid-line. The
dilatation on the left side has been opened and blue
rods have been inserted into the pharyngeal openings of
the Eustachian tubes. 0. C. 1170 A n.

Peter, L c, p. 354.

E. 327. Posterior part of the left side of the head of an Ass
{Equus asinus), showing from the mesial aspect, the dilated
Eustachian tube and its opening into the hinder part of
the nasal passage. This opening (indicated by a blue rod;
has the form of a long oblique slit in the outer wall of the
nasal passage. Its upper lip protrudes somewhat and
forms a valve by which the orifice can be closed. Some
2 or 3 cm. from the pharyngeal opening the Eustachian
tube dilates to form a large membranous sac (air-sac,
guttural pouch) similar to those seen in the two previous
specimens, and like them occupying a position between the
floor of the skull, the pharynx wall, and the great cornu
of the hyoid.

Above the anterior part of this dilatation, and in close
contact with it, is a backwardly directed diverticulum of
the nasal cavity. 0. C. 1170 A I.

John Hunter, Essays and Observations, edit. R. Owen,
vol. ii. 1861, p. 159.

Peter, 1. c, p. 328.

E. 328. The right Eustachian tube and neighbouring parts
from the same animal, with the inner wall of the guttural
pouch removed. A blue rod has been inserted into the
tube and through the tympanum into the external meatus.
The partial separation of the guttural pouch into an external
and an internal chamber by the cornu of the hyoid is shown.

198

I'll VSIOLOGICAL SERIES,

The function of the dilatations found upon the Eustachian
tubes of some few Mammals has been the subject of many-
speculations, but at present without much result. They
have been thought, amongst other things, to be resonating
chambers to enforce or give some special tone to the voice,
or to be a mechanism for ensuring a constant supply of
warmed air to the tympanum, or to be a resonating
chamber or microphone in which sounds too delicate to
directly affect the drum are magnified and thus made
audible. The latter suggestion harmonizes with the great
keenness of hearing observed in the animals in which
these dilatations occur. 0. C. 1170 A m.

Peter, I. c, p. 364.

EODENTIA.

E. 329. The cranium of a Jerboa [Dipus sagitta), showing the
great bullate expansions of the tympanic cavities. These
have the same form and position as in the Chinchilla
shown and described in A. 198. Upon the right side the
membraua tympani is preserved with the attachment of
the malleus. On the left the tympanic chamber is laid
open and the ossicula and cochlea exposed. The latter
makes three entire turns and a half.

0. C. 1599. Hunterian.

CARNIVOBA.

E. 330. A portion of the cranium of a young Lion (Felis leo)
including the organ of hearing of the left side. The
anterior wall of the external meatus and tympanum have
been removed to show the niembrana tympani (convex
internally as in most Mammalia), with the handle of the
malleus attached to it. A slit-like opening in the posterior
wall of the tympanum leads into the enlarged tympanic
bulla. The entry of the Eustachian tube into the anterior
and inner part of the tympanum is also shown in section
(c/. A. 201). 0. C. 1600. Hunterian.

ORGANS OF SI'ECIAr. SHNSE. — VEllTEBHATA.

190

PEIMATBS.

E. 331. The bony parts of the ear of a Foetus, from both sides.
The upper specimen shows the right squamosal and
tympanic bones from within, with the membrana tympani
and ossicula retained in their natural positions. Below is
a similar specimen o£ the left ear without the membrana
tympani and with the addition oi: the periotic bone. The
cavities in the latter occupied by the cochlea and the semi-
circular canals have been partially opened. 0. C. 1602 B.

From the Museum of Sir Astley Cooper.

£. 332. Skull of a Foetus at the ninth month, showing upon the
right side the membrana tympani and upon the left the
cavity of the tympanum and the ossicula auditus in situ.
The tympanic membrane is almost horizontal in position.
It is bordered by the horseshoe-shaped tympanic annulus,
which is not yet of sufficient size to form a bony meatus.

0. C. 1602 B a.

E. 333. A horizontal section of part of a Human head, including
the organ of hearing of the right side. The external meatus
is laid open from above throughout its whole length,
showing its direction and structure, and the oblique position
of the membrana tympani facing outwards, downwards
and slightly forwards. The cavity of the tympanum is
also exposed with the ossicula retained in their natural
positions. A large bristle is passed between the malleus
and the processus longus of the incus, and a smaller one
through the foramen of the stapes. The section also
exposes part of the vestibular cavity, leaving entire the
periosteal membrane covering the fenestra ovalis against
which the foot of the stapes is applied. Portions of the
cavities that enclose the semicircular canals are laid open
too-ether with the mastoid cells. 0. C. 1601.

o

Hunterian.

E. 334. A vertical section of the left ear of the same head seen
from behind. The section passes through the external

200

rilYSlOLOGICAL SERIES.

meatus, the tympanum, the vestibule and the internal
meatus. The membrana tympani is shown more clearly
than in the previous specimen. The cavity occupied by
the posterior semicircular canal and its connection with the
vestibule are indicated by a black bristle. The auditory
nerve is shown in the internal meatus. 0. C. 1602.

Ilunterian.

E. 335. The right tympanic bono with the cavity of the cochlea
opened and with the ossicles exposed in their natural
position. 0. C. 1602 a.

E. 336. Part of the hinder end of the nasal passage showing
from below the lower extremities of the Eustachian tubes
and their openings into the nasal cavity. 0. C. 1604.

Ilunterian.

External Ear.

Schmidt, Vergl.-anat. Untersuch. ii. d. Ohrmuschel, Berlin,
1902.

Baum u. Kirsten, Anat. Anzeig,, Bd. xxiv. 1903, p. 33

{muscles).

The hinder and mesial margins of the opening into the external
meatus are usually produced to form an external ear or pinna,
which when highly developed is trumpet-shaped and capable of
voluntary movements in different directions. Its cavity can
thus be turned towards the point from which a sound proceeds
and it acts both as a collector of sound vibrations and an instru-
ment for locating their source. In many Mammals, particularly
in burrowing and aquatic species, the pinna is almost or quite
absent, and in all groups its form and degree of development
varies considerably.

In the following descriptions the different parts of the
external ear and its supporting cartilages are named so far as
possible in accordance with the usage of Human Anatomists,
but as the external ear of Man is degenerate, a named diagram
of the cartilages of the ear of a Fallow Deer (E. 358) is given
..here to assist in comparison : —

ORGANS OF SPECIAL SENSE. — VBRTBBRATA. 201

Diagram of ear cai-tilages of Ca-ms dama.

A. Proximal part of cartilage of pinna and concha.

B. Annular cartilage.
0. Scutellum.

A. Antihelix. A.T. Antitragus. C.H. Crus helicis. C.I.A. Crusinferius
antihelicis. C.S. Clefts of Santorini. C.S.A. Crus superius antilielicis.
F.A.H. Fissura antitrago-helicina. F.T. Fossa triangularis. H. Helix.
I.I. Incisura intertragica. P.A. Processus aboralis. P.O. Processus
caiidatus. S. Styloid process. SC. Scapha. T. Tragus.

The part of the external ear distal to the meatus is termed
the pinna. Its edge whether inturned or not is the helix. From
this edge to the transverse ridge which represents the antihelix
is the scapha. The base of the pinna between the antihelix and
the meatus is the concha, forming a sort of vestibule to the
meatus. Its hollow is the cavitas conchse and the corresponding
convexity on the mesial surface, the eminentia conchas. The
lower mesial part of the couch cartilage continues along the
inner and posterior wall of the meatus and gives off a series
of flat processes for the support of its outer wall. These are
followed by a completely separate annular cartilage and repre-
sent rings which may be completely independent but here are

202

PHYSIOLOGICAL SERIES.

partly fused together. The spaces between them form the clefts
of Santorini.

The muscles proper to the pinna can be divided into two
sets — extrinsic and intrinsic. The extrinsic consist of adductors
inserted upon the anterior border of the pinna (attrahentes
lioni.), levators inserted upon its median surface (attollens
bom.), abductors inserted upon its hinder and deep mesial parts
(retrahentes hom.), a depressor inserted upon the antitragus,
rotators passing backwards around the median surface to its
hinder part, and a curious and variable muscle, the tragicus
major, which passes upwards from the zygoma or some
neighbouring part of the skull to the conch near the anterior
edge of the tragus. In addition to these truly auricular muscles,
there are several thin sheets (scutularis) that converge from
the frontal and parietal parts of the skull to a loose plate
of cartilage (scutellum) that lies in front of the pinna and
serves as a point of origin for the adductors and certain other
of the true extrinsic muscles. The intrinsic muscles are not so
important as the extrinsic and are in lower Mammals essentially
Bimilar to those of Man. Among the following preparations
of the auricular muscles, the specimen of the Dog has been
described in detail to act as a standard of comparison for
the rest.

MONOTEEMATA.

E. 337. Right half of the head of a Duck-billed Platypus
(^Ornitliorhynchus anatinus), showing the external auditory
meatus. The meatus is of great length, and passes down-
wards and backwards from the external aperture, which is
flush with the general level of the skin, to the point of the
jaw, round which it curves inwards and forwards to reach
the tympanic membrane. The whole length of the meatus
is enclosed in a scroll-shaped sheet of cartilage which
expands slightly near the external opening to form a small
vestibule.

Ruge, Morph. Jahrb., Bd. xxv 1898, p. 214.

E. 338. Right side of the head of a Spiny Ant-eater {Tachy-
glossus \_Ec1xidna\ aculeatus), with the skin partly raised to

ORGANS OF SPECIAL SENSE. —VBRTEBEATA.

203

show the external meatus and the muscles in connection
with it. The meatus, which is in no part bony, is very
lonff and assumes a twisted course between the external
opening and the tympanic membrane, passing successively
forwards, transversely inwards, backwards, and again
forwards. Close within the external orifice it is spaceous
forming a funnel-shaped vestibule comparable to the
concha of other Mammals. Beyond the concha the tube
gradually decreases in calibre towards the tympanum and
is supported and kept open by a longitudinal strand of
cartilage from which on either hand lateral processes are
given off having the appearance of tracheal rings. The
longitudinal cartilage is continuous distally with an ex-
panded trumpet-shaped plate that supports the concha.
The tympanic end of the meatus has been opened from
below to show the tympanic membrane through which
a bristle has been thrust along the Eustachian tube.

The concha is surrounded by powerful cutaneous muscles.
One of these — a conspicuous bundle that passes backwards
from the maxilla over the external surface of the conch —
is attached in passing to its outer and anterior part, forming
what resembles in many ways a combination of adductor
externus and depressor conchte. Inserted upon the mesial
surface of the conch is a large and very definite levator
auris that arises from the deeper parts of the skin in the
mid-line behind the head. 0. C. 1609 A a.

Ruge, Morph. Jahrb., Bd. xxv. 1898, p. 220 (meatus);

also, Semon's Zoolog. Forschungsreise in Australien,

Bd. ii, 1894-97, p. 144 (muscles).

E. 339. The left meatus of a smaller individual with the
cartilages exposed, showing the transverse processes given
off from the longitudinal cartilage of the meatus and the
continuity of the latter with the anterior wing of the
expanded cartilage of the conch. The large external
orifice of the meatus is vertically lengthened and is
bordered by a thickened fold of skin which is especially
prominent along the posterior and upper margin, though
not distinct enough to form a pinna.

204

niYSIOLOOICAL SERIES.

^0. Parts of the skull of a Spiny Ant-eater {Tachyglossus
aculeahts), showing a connection between the anterior
hyoid cornu and the cartilage of the external meatus.

Fig. 45.

ANT

TR. PR

HY. C

Connection between the hyoid cornu and meatal cartilage
of Tachyglossus aculeatus.

AN.T. Annulus ti/mpanicus. HY.C, Hyoid cornu, M.C, Longitudinal
part of meatal cartilage. TE.PR. Its transverse processes. T.P. Tym-
panic plate.

The cornu, as it passes the tympanic annulus, gives o£E a
process from its anterior border that expands to form
a small plate (tympanic plate) situated directly ventral
to the membrana tympani and continuous by its outer
parts with one of the transverse processes of the longi-
tudinal cartilage of the meatus. In this specimen the
tympanic plate does not form a single piece with the cornu
of the hyoid, but is jointed to it by the intervention of a
thin layer of connective tissue.

Upon the left a bristle has been passed between the
tympanic plate and the membrana tympani. On the right
the tympanic plate is separated from the hyoid cornu.

This connection between the hyoid arch and the cartilage
of the meatus has been thought to indicate that the latter
is a derivative of the hyoid arch.

Kuge, Morph, Jahrb., Bd. xxv. 1897, p, 201,

ORGANS OF SPECIAL SENSE. — VERTBBRATA.

205

MAESUPIALIA.

E. 341. Part o£ the skull with the cartiLages of the left pinna o -
a Bandicoot (Peragale lagotis). The cartilage of the conch
and scapha is trumpet-shaped and is quite separate from
the ring-like cartilages that support the meatus. The
border of the helix is comparatively plain and is not
inturned. It has apparently (c/. Kangaroo, E. 343) two
crura — the outer of which forms a flat plate overlying the
tragus and the inner is represented by a thin lamina that
passes almost directly inwards into the cavity of the conch
from the base of the outer crus. It is perforated by an
aperture which in the natural state is filled by muscle
tissue. Above and nearly parallel to the inner crus helicis
is another thin lamina which is possibly the antihelix.
By comparison with the Kangaroo it seems that the
posterior border of the aperture of the conch is not formed
by the antitragus but by an upward extension of the tragus
to the processus caudatus. The true antitragus may,
however, be represented by a vertical lamina projecting
from the posterior wall of the pinna into the cavity of the
conch. The posterior end of the lower border of the
tragus gives off a long slender process, which probably
corresponds to a much larger though similar bar in the
Kangaroo, which supports the hinder part of the meatus.
The cartilage of the scapha, as in the case of most large
pinnse, is irregularly perforated by holes.

The most distal of the three half rings that support the
meatus is partly double, forming a single plate in front,
but bifid behind. The two proximal half rings are single.
There is no bony meatus. 0. C. 1609 b a.

E. 342. The right ear of an Opossum (Didelphi/s marsupialis).
The pinna is large, thin and leaf-like with bluntly rounded
apex. The lower anterior border of the helix is inturned
and divides below to form inner and outer crura. The
inner crus continues the helix into the cavity of the conch.
The outer crus projects from the convexity of the inturned

20G

rnYSIOLOGICAL SERIES.

border of the helix and joins the tragus to form the lower
edge of the aperture of the conch. The antitragus is forked
to form outer and inner crura. 0. C. 1G09 b.

E. 343. Part of the skull, with the cars, of a Black-faced
Kangaroo {Macropus melanops). Upon the left side the
cartilages of the pinna and meatus have been exposed.
In spite of minor differences these compare well with
those of Peragale. The anterior border of the helix is
inturned at its lower end and has two clearly defined
crura — an inner continuing the edge of the helix into
the cavity of the conch, and an outer projecting outwards
and downwards from the convexity of the helix-scroll
to the anterior end of the tragus. Two low transverse
ridges between the scapha and concha probably represent
the antihelix. The antitragus is slight and is overhung
by a very prominent processus caudatus of the posterior
expansion of the scapha. A well defined thickened
ridge continues the antitragus upwards and separates
the main part of the scapha from its posterior expansion.
The tragus bears upon its lower border a broad process
which is united at its extremity with the first half-
ring of the meatus (processus aboralis intermedius). The
proximal half-ring of the meatus is free. There is no bony
meatus.

Upon the right side the skin has been retained upon the
pinna and several of the ear-muscles have been exposed.
The most remarkable of these is a large sheet of muscle
(A) that covers the mesial and posterior surface of the
conch, it seems to represent a combination of the levator
and abductor longus of the more typical arrangement.
The other letters on the specimen signify the following
muscles : — B. levator medius, C. levator brevis, E. adductor
superior, F. adductor inferior, G. helicis, H. depressor
conchse, I. antitragicus. Between the levator medius and
the adductor inferior lies a strong adductor medius passing
downward and inwards from the fascia that represents the
scutellum to the conch, and below the inferior adductor,
between the meatus and the skull can be seen part of
a peculiarly large tragicus major. This when entire

OHGANS OF SPECIAL SENSE. — VERTEBRATA.

207

consists of two parts — one inserted upon the skull above
the temporo-maxillary joint, the other inserted by a long
slender tendon to the mandible.

E. 344. The ears of a Native Bear [Phascolarctus cinereus).
The right pinna is mounted below, hidden by the thick
bushy fur that covers its outer surface and margins, above
• is the left ear with the hair clipped short to show its
general form. It is short, erect, rather wider above than
below and truncated at its apex. The prominences around
the opening into the concha can be compared with those in
the Opossum's ear, though their form and relative pro-
portions are different. The inner crus of the antitragus is
more conspicuous and encloses a deep upwardly directed
pocket between itself and the wall of the conch. The
outer crura of the helix and antitragus are very slight.

O.C. 1609
Presented hy J. Abrahams, Esq.

EDENTATA.

E. 345. The ear of a Great Anteater {Myrmecophaga jubata)
with the hair clipped close to show its small size, stoutness,
and short rounded shape. 0. C. 1609 D.

E. 346. The sldn of the left side of the head of a Manis [Manis
longicauda). There is no pinna. The opening to the
external meatus is a long vertical slit, overlapped
postei-iorly by a thickened fold of skin. Compare with
Mydaus and Echidna. 0. C. 1609 E.

CETACEA.

E. 347. Part of the skin of the head of a Dolphin (Delphinus
tursio) showing the external aperture and commencement
of the external auditory meatus. The minute opening is
situated behind the posterior angle of the eye and leads
into a narrow tube enveloped in subcutaneous fat and with
its walls stiffened by cartilage. The passage is largo
enough to admit an ordinary bristle only. There is no

208

PHYSIOLOGICAL SERIES.

vestige of a pinna. The auditory aperture of Platanisla
gangetica is shown in E. 1147, in Phoccena in E. 312, and
in Uyperoodon in E. 309. 0. 0. 1609 c.

Presented by F. T. Buckland, Esq.

. 348. Part of the meatus auditorius externus of a Dolphin
{Delpliinus tursio). Q. C. 1583. Huntenan.

UNGULATA.
HYRACOIDEA.

E. 349. The right ear of a Hyrax {Procavia capensis). The
pinna is small and bluntly rounded at the apex. The
anterior border of the helix is slightly inturned and is
continuous below with the tragus. The cavity of the
conch is separated from the scapha by a pair of promin-
enceSj one of which commences under the anterior inturned
border of the helix, and runs backwards to meet the other
which passes in the opposite direction from the antitragus.

0. C. 1618 b.

PROBOSCIDEA.

E. 350. The cartilage of the pinna of an Elephant {Elephas
indicus). It forms a plate of irregular form continuous
and fairly thick in its proximal parts, but thinning out
towards the margin and perforated here by holes of different
sizes which at the extreme edge run together, leaving an
irregular fringe of cartilage bars. 0. 0. 1618 A.

E. 351. The right pinna of a foetal Indian Elephant (ElepJias
indicus) with the cartilage laid bare and some of the
muscles shown. Upon the outer face may be seen : a
large adductor superior, arising from the surface of the
fibrous scutellum and inserted upon a ridge that forms
the anterior lip of the apertura conchae ; the helicis and
tragicus minor, which together form a thin sheet covering
the outer surface of the meatus up to the border of the
apertura conchas ; the depressor conchas lying posterior to
the meatus and inserted into the lower edge of the posterior
expansion of the scapha. BetweGTr-tb« adductor superior

OEGANS OF SPECIAL SENSE. — VERTEBRATA.

209

and the meatus lies a cylindrical muscle that runs from the
deep end of the meatus to the base of the anterior surface
of the conch. This is apparently the tragicus major.

Upon the reverse of the specimen the insertions of
several muscles are shown. These are the levators and
abductors, but in the condition of the specimen it is not
wise to attempt any detailed comparison with those of
other Mammals. In this view also can be seen a muscle
(rotator auris or adductor medius) that passes backwards
from the deep surface of the scutellum to the convexity of
the conch ; and between two of the insertions in the
mid-line of the pinna ai-e traces of a considerably developed
transversus auris. 0. C. 1618 A a.

Miall & Grreenwood, Jour. Anat. & Physiol., vol. xii,
1878, p. 388.

PERISSODACTYLA.

E. 352. The cartilages of the right ear of a Horse [Equus
cahallus). The pinna is trumpet-shaped with long narrow
pointed scapha. The anterior border is inturned below
and continued into the cavity uf the conch as the inner
crus helicis. There is also a well marked outer crus helicis
projecting from the convexity of the inturned helical
border and covering the greater part of the tragus. This
crus probably represents the spina helicis of man. It gives
attachment to the superior adductor. The tragus is formed
by the broadened end of the most distal of the half-rings
that support the meatus. It is separated by a gentle
depression from the antitragus. This latter prominence is
formed by an inturuing of the border of the apertura
conchse between the processus helicis caudutus and the
incisura intertragica. In this case, however, it does not as
usual support part of the actual edge of the apertura
conchse but projects into the cavity of the conch, the
margin of whose aperture is formed by a band of cartilage
that bridges over the incisura antitragico-helicina from the
processus caudatus to the hinder limit of the incisura
intertragica in a manner somewhat similar to that seen in
Perarjale. Below the tragus the cartilage of the meatus

VOL. III. P

210

PHYSIOLOGICAL SEIUES.

gives ofF anteriorly another broad process (processus
aboralis intermedius), and is prolonged proximaliy in the
form of a style (processus aboralis proximalis). The deep
end o£ the meatus is supported by an annular cartilage
which is quite independent and encircles the outer three-
fourths of the tube. Deep down within the cavity of the
conch is a transverse ridge that probably represents
the antihelix.

In front of the ear, attached to it by the adductor
superior, is a triangular plate of cartilage — the scutellum.
This serves as a point of insertion and origin for certain
skin muscles of the head (scutulares) and extrinsic muscles
of the ear.

Schmidt, Vergl. anat. Untersuch. iiber d. Ohrmuschel
versch. SaugethierOj 1902, p. 28.

E. 353. The cartilages of the right ear of a Horse {Equus
cahallus). 0. C. 1617. Hunterian.

E. 354. The left ear of a Horse (Equus cahallus), showing upon
the convex surface of the concha, a mass of fat. This is
always present even in individuals that have died of
starvation and probably acts as a lubricant in the move-
ments of the ear. 0. C. 1617 b,

Presented hy Prof. McFadyean.

E. 365. The cartilages of the left ear of an Ass {Equus asinwt).

0. C. 1618. Hunterian.

ARTIODACTYLA.

E 356. The right ear of a Peccary {Tayassu tajaqu). The
pinna has a simple form, with broad base and pointed apes,
and shows but slight indications of tragus and antitragus
upon the borders of the apertura conchse. The anterior
border of the helix is strongly inturned, and within the
cavity of the conch deep down towards the meatus can be
seen a sharp crescentic fold enclosing an upwardly directed
pocket. This is probably the inner crus helicis. In the
hollow of the scapha are three longitudinal folds of the
skin (plicae auriculares longitudinales). 0. 0. 1618 c.

ORGAXS OF SPECIAL SENSE. — VBRTEBUATA.

2L1

E. 357. The right ear of a Water Chevrotaia {Dorcatherium
aqxiatimm). The pinna has a simple bluntly rounded form,
with very slight prominences upon its inner surface or
around the margins of the conch aperture. Between the
scapha and concha are two transversa folds. The lower of
these, which is the most ^^I'ominent, lies above the inner
crus heHcis and is probably the antihelix. The upper one
is probably an integumentary fold merely^ similar to the
plicsB longitudinales seen, in the previous specimen.

O.C. ]616a.
Presented hy Staff- Surgeon Thomas.

E. 358. The cartilages of the left ear of a Fallow Deer (Cervus
dama). The pinna and external end of the meatus are
supported by a long trumpet- shaped scroll of cartilage (the
scapha and concha), similar in general form to that of the
Horse. The anterior border of the helix is internal at its
lower end forming a crus, but is not bifid as in the Horse.
The antitragus resembles that of the Horse, but is not
obscured hy the filling in of the incisura intertragica. The
tragus is formed us usual by the process representing the
upper half-ring of the meatus. It is followed by two
similar processes, the last of which corresponds to the base
of the styloid process that projects down from the main
cartilage in the Horse. In the cavity of the conch is a
prominent transverse ridge representing the antihelix.
The annular cartilage and scutellum are attached to the
lower parts of the preparation. 0. C. 1615. Himterian.
Schmidtj I. c, p. 32.

E. 359. A similar specimen of the proximal end of the cartilages
of the right ear of the same animal. 0. C*. 1616.

Hunterian.

E. 360. The hinder part of the head of a Sheep (Ovisaries) with
the muscles of the ears shown. On the right most of those
belonging to the superficial layer have been cut and turned
aside. The extrinsic muscles of the ear are very powerful
and provide for the most varied movements. The most
important are marked by letters as follows : — A. fronto-

r 2

212

PHYSIOLOGICAL SERIES.

scutularis, B. levator medius^ C. adductor superior, D. ad-
ductor externus, F. depressor concha?, G. abductor longus,
H. abductor brevis, I. levator longus, K. rotator auris,
0. tragicus major. In addition to these there is a well
marked levator brevis passing from the scutellum beneath
the adductor superior to the median surface of the conch
distal to the insertion of the levator longus. There is also
a well defined though small adductor medius (best seen on
the right side) which passes from the posterior edge of the
scutellum across the deep surface of the levator brevis to
the anterior edge of the helix under cover of the adductor
superior. Broadly speaking, the adductors and the levator
brevis correspond to the attrahens hom., the levators to the
attollens hom., and the abductors to the retrahentes bom.
In comparison with the Dog the size of the muscles is
remarkable, and there are also many minor differences.
A levator brevis is not present in the Dog, but is well
developed in the Sheep. The adductor inferior of the
Dog is represented in the Sheep by an adductor externus
arising from the zygoma, not from the scutellum. The
abductor is very much larger in the Sheep tlian in the
Dog and arises to a great extent from the deep surface of
the abductor longus. Its insertion extends around the
anterior mesial and posterior surfaces of the base of the
conch. The tragicus major of the Sheep is stouter and
shorter than that of the Dog and takes origin from the
base of the zygomatic process above the temporo-maxillary
joint.

Baum u. Kirsten, Anat. Anzeig., Bd. xxiv. 1903, p. 33.

EODENTIA.
HYSTRICOMORPHA.

E. 361. The right ear of a Coypu Rat {Myocastor coijpus). This
is a small rounded ear with a greatly extended posterior
and lower border. The anterior border of the helix is
strongly inturned. The tragus and antitragus are not
prominent. The entry to the meatus is protected by tufts
of hair. 0. C. 1614 b.

ORGANS OF SPECIAL SENSE. — VERTEBRATA.

213

E. 362. Tlie left ear of Ca2:)romys piloriJes. The pinna is some-
what more pointed than in the Coypu. The anterior
margin of the helix is strongly inturned, and there is a
well developed crus helicis passing inwards towards the
meatus. The tragus and antitragus are strongly marked,
and between the latter and the expanded posterior border
of the scapha is a distinct indication o£ a sulcus auris
posterior (c/'. Lemurs and Apes). 0. C. 1G14d.

E. 363. The left ear of a Porcupine {Hystrix javanica). The
pinna is small, erect, with a thickened, but not inturned,
anterior border. The crus helicis passes deeply into the
concavily of the conch ; just above it, is a rounded promi-
nence that probably represents the crus antihelicis. The
tragus and antitragus are well defined and are separated
by a peculiarly deep and narrow incisura. The sulcus auris
posterior is large and deep. 0. C. 1614 c.

E. 364. Skin of the head of Cuvier's Chinchilla {Lagidium
cuvieri) showing the external ears. They are larger and
more membranous than in the foregoing Rodents. The
general form is elongated, widening slightly towards the
rounded tip. The anterior border of the helix is slightly
inturned and is continuous ventrally with a very promi-
nent and narrow crus that dips into the concavity of the
concha. The tragus is scarcely perceptible, but the anti-
tragus is very large and has the appearance of a flap of
skin forming the anterior lip of a deep pocket — the sulcus
auris posterior (?). A slight transverse ridge above the
crus helicis is probably to be regarded as an antihelix.

0. C. 1614 Da.
Presented hy Mr. S. Epprett.

E. 365. The right ear of a Viscacha (Viscaccia maxima). In its
general form the pinna is very like that of a Pig, with
straight anterior border inturned for nearly its whole
length, pointed apex and broadly expanded posterior
border. The outer crus helicis passes external to the
tragus, separated from it by a deep sulcus auris anterior.

214

niYSlOLOGICAL SKIUES.

The inner crus is hidden by a tuft of hair. The tragus and
antitragus are prominent and are separated by a deep and
naiTow incisura. The sulcus aiiris posterior is very exten-
sive but otherwise resembles that of Lagidium.

O.C. 1C14A.

E. 366. The right ear of a Patagonian Cavy {Dolicliolis magel-
lanica). The pinna is large and closely resembles that of
Lagostomus in general form ; its anterior border is strongly
inturned and originates below in a double inner and an
outer crus. The latter is separated from the tragus by a
well marked sulcus auris anterior. The chief limb of the
inner crus continues the inturned edge of the helix into the
conch ; below it, above and behind the tragus, is another
very sharply- marked crescentic fold, which appears to be a
second limb to the inner crus helicis. The incisura inter-
tragica is deep and narrow. The helix posterior to the
antitragus is broad, but shows no indentation that can be
considered a sulcus posterior comparable to those of Lago-
stomus and Lagidium. Above the inner crus helicis is a
prominent transverse fold, probably the antihelix.

O.C. 1614 E.

LAGOMORPHA.

E. 367. The left pinna of a Kabbit {Lepits cuniculus), injected
and with the hair removed. 0. C. 1614. Hunterian.

E. 368. The cartilages of the right ear of a Babbit (Lepus cuni-
culus). The concha is peculiarly long. The anterior border
of the helix is strongly inturned, and in its lower part
unites with the tragus to support the tragal prominence
upon the margin of the entry to the concha. The tragus
is remarkable for its length. Distally it is forked, one
fork being applied to the anterior inturned helix, the other
in a similar w^ay to the posterior inturned helix or anti-
tragus. Above the antitragus is a deep incisura antitragica
helicina overhung by a pronounced processus caudatus.
. ...The meatus is supported by half-ring.^ partially con-

ORGANS 01- SPECIAL SENSE. — VERTEBRATA.

215

tinuous with the lower border of the tragus and by a free
annular cartilage. There are no prominences between the
scapha and the concha.

E. 369. The right side of the head of a Hare (Lepus europcBus)
with the muscles of the pinna shown. The several muscles
have been lettered as in the preparation of those of the
Dog (E. 379). The adductor inferior (D) (Krause's
scutulo-auricularis superior posterior) is of very great size;
beneath its upper end can be seen the extremity of the
helicis major (tragicus major, Krause). The tragicus
major (0) takes origin from the posterior process of tho
zygoma. There is apparently no adductor medius or
adductor externus. The other muscles marked are A.
fronto-scutularis, A.' scutularis intermedins, C, adductor
superior (scutulo-aur. sup. ant., Krause), F. depressor
conchse (parotideo-auric. ant. & post., Krause) .
Krause, Anat. des Kaniuchen, 1868, p. 133.

E. 370. Part of the head of a Hare [Lepus europceus) seen from
the dorsal aspect to show the levator and abductor muscles
of the ear and the several divisions of the scutularis. The
transverse part of the scutularis is divided into two layers
marked A' and A". The cervico-scutularis is small and
forms a thin fan-shaped muscle converging from the liga-
mentum nuchse to the hinder edge of the scutellum. The
levators are represented by a levator longus (cervico-auric,
Krause) (1) and a small levator brevis lying between it
and the adductor superior (C). The abductors (G, B)
(occip. auric. & helico-occip., Krause), and the rotator
auris (K), are not in any way remarkable.

E. 371. Part of the skull and left ear of a Rabbit (Lepus cuniculvs),
\\i(h the superficial auricular muscles removed to show the
helicis major (N) and the tragicus major. The latter consists
of two parts : the first (0) (Krause's max. auric.) corre-
sponds very closely to the tragicus major of the Sheep
(E. 360) and runs from the posterior process of the zygoma
to the hinder mesial edge of the pars antei'ior helicis ;

210

rHYSIOLOGICAL SRllIES.

the otlior (0') (temporo-auric, Krauso) lies upon the
convexity of the inturned anterior part of the helix and
passes thence to the upper border of the bony meatus.

371 a. The head of a young Rabbit {Lepus cuniculus), one day
old, showing the pinnas. The lumen of the external meatus
at this age is completely closed by the apposition and con-
tinuity of the lining epithelium. The position of the future

Fig. 46.

Transverse section through the upper part of the external meatus of a

Kabbit, one day old.
0, Cartilage of the conch. E.M. Fused epidermal lining of the meatus.
T. Cartilage of the tragus.

entry to the conch can, however, be traced by a narrow
V-shaped line upon the lateral surface of the ear, bordered
externally by thickened lips, that represent the inturned
borders of the helix.

PINNIPEDIA.

E. 373. Part of the integument from the left side of the head of
a Sea Lion {Otaria sp.) showing the small pointed external
ear. Its size, shape and position are such as to present no
impediment in swimming. The external meatus is shown
upon the reverse of the specimen. It is long and tortuous,
and its walls are supported by a series of oblong cartilages,
moveably connected together. 0. G. 1611. Ilunterlan.

ORGAN'S OF SPECIAL SENSE. — VERTEBRATA.

217

E. 373. Bight lialE of the head of a Seal [Plioca vitulina) . There
is no pinna. The external auditory meatus opens directly
upon the surface surrounded by a slightly raised border of
soft crinkled skin. It is very long (55 mm.) and runs
backwards to the skull parallel to the dorsal border of the
jugal process of the squamosal. The walls of the meatus
are supported by two rings of cartilage — one, answering to
the tinnular cartilage of other Mammals, lies close to the
skull ; the other which is three times as large extends from
the external border of the annular cartilage nearly to the
skin upon the surface of the tube turned towards the skull ;
it is continuous mesially, but upon the outer side is inter-
rupted in its middle and again near the external opening
by extensive membrane-covered lacunae. In this specimen
part of the Eustachian tube is also shown (indicated by a
black bristle) as well as the eyelids and the globe of the
eye with its muscles. 0. C. 1611 A.

OAENIVOEA.
AROTOIDEA.

E. 374. The right ear of a Kinkajou {Potos caudivolvulus).
The pinna is oblong, widening slightly towards its bluntly
rounded apex. The inner crus helicis, the tragus and the
an ti tragus are clearly marked. Within the cavity of the
conch is a small but very prominent transverse projection
which corresponds to a similar lamina in many other
Carnivores ; it is probably the crus inferior of the anti-
helix. The posterior border of the helix is not cleft to form
an integumentary pocket as in many Carnivora.

0. C. 1610 E.

E. 375. Left ear of a Grison {Galidis vittata). The ear is small,
flat and rounded, lying close against the head. Upon
the lower posterior border is a small integumentary cleft
or pocket. The antitragus is prominent, and above it is a
plica longitudinalis that closely resembles the body of the
antihelix in Man. Close to the upper end of this plica are
a pair of folds at right angles to the axis of the ear— the
cura antihelicis. The upper of these is slight, but the lower
is plate-like and remarkably prominent. 0. C. 1610 A.

218

PHYSIOLOGICAL SERIES.

E. 376. The right ear of a Ferret {Putorius faro). Tlie pinna
has much the same shape as that of Galictis, but is shghtly
more pointed. The cleft or pocket upon the posterior
border is larger, and more definite and regular in shape.
The incisura intertragica is peculiarly deep and narrow
and the tragus in consequence api)ears prominent. Between
the cavity of the conch and the scapha are three parallel
transverse ridges. The lowest of these is the inner crus of
the helix, the middle one is the very pronounced lower crus
of the antihelix and the upper its less prominent upper
crus. 0. C. 1610 B.

Presented hy J. B. Perrin, Esq.

E. 377. akin of the left side of the head of a Teledu {Mydaus
meliceps). The external ear is quite vestigeal. It has the
appearance of a lengthened vertical slit opening forwards
and overhung slightly above behind and below by a
thickened fold of skin fringed with hair. The pig-like
form of the snout of this small burrowing Badger is also
shown. 0. G. 1610 g.

Presented hy J. W. Clark, Esq.

E. 378. Part of the skin of the left side of the head of a Ratel
(Mellivora indica) including the external ear. This is
represented by a wide concavity sunk below the general
level of the face, and bordered, except in front, by a thick
slightly protuberant fold of skin. Within the concavity
can be seen two folds — an upper that probably represents
the crus antihelicis, and a lower and less prominent
swelling — the internal crus helicis ; while upon the margin
are slight indications of tragus and antitragus. In this
animal, which burrows for temporary purposes, the pro-
jecting external ear is only so far developed as is compatible
with subterranean progression. 0. C. 1610. Hunterian.

CYNOIDEA.

E. 379. The head of a Dog (Canis familiaris), with the muscles
of the pinna shown on both sides. The muscles can be
separated into those that move the ear as a whole, and
those that are proper to the pinna itself.

ORGANS OK SPECIAL SENSE. — VERTEBUATA.

219

The former consist ol: : — the scutularis (A), a large
sheet of muscle that covers the temporalis and is attached
posteriorly to the scutelliim ; its hinder pax-t (A') forms a
separate muscle — the cervico-scutulaiis, which is more or
less blended with the levator longus (I). The scutularis
holds the scutellum in position, to act as a fixed point for
the muscles that pass from it to the ear.

The adductors, comprising an adductor superior (C)
from the scutularis and scutellum to the anterior border of
the helix, an adductor inferior (D) from the scutularis to
the antitragus, and an adductor medius from the scutellum
to the antero-mesial border of the concha, above the tragus.
These adductors draw the ear forward. The depressor
conchse (F), a long narrow slip taking origin in the skin
muscles on the ventral surface of the neck and inserted
upon the antitragus beneath the adductor inferior. This
muscle depresses the ear and rotates it outwards. The
abductors, comprising an abductor longus (Gr) and an ab-
ductor brevis (H), arising in the mid-line of the occiput
and inserted respectively upon the posterior and median
surfaces of the conch. They lift the ear and rotate it
outwards. The levator?, including the levator medius
(attollens) (B), a muscle arising from the mid-line in front
of the abductors and inserted partly into the deep surface
of the scutellum and partly into the median surface of the
conch ; and the levator longus (I) arising from the mid-
line of the neck with the cervico-scutularis and inserted by
two slips into the median surface of the conch. These
muscles draw the pinnse up towards the mid-line. The
rotator auris (K), a small muscle that runs from the deep
surface of the scutellum backwards upon the median
surface of the conch. It twists the ear outwards and
backwards. The tragicus major (0), a long slender muscle
that takes origin from the angle of the jaw and is inserted
upon the outer crus of the helix.

The intrinsic muscles include the trausversus auris (L),
a muscle-sheet applied longitudinally to the mesial surface
of the conch, between the two insertions of the levator
longus; the helicis minor (M) filling in the groove between
the two crura of the helix ; the helicis major (N) passing

'2-20

PHYSIOLOGICAL SRRIRi?,

from the point o£ the outer crus helicis to the surface of the
tragus. In action the trans versus would stiffen the scapha
and thus prick the ears, the helicis minor would increase
the curvature of the anterior part of the helix, and the
liolicis major would assist this movement hy approximating
the horJcr of the helix to the trajias.

E. 380. The cartilages of the right ear of a Dog {Cams
familiaris). The helix terminates anteriorly in two well
marked crura — an inner and an outer. The latter is
expanded and overlaps the tragus in front. Posteriorly
the tragus is continuous with a large triangular cartilage —
the processus uncinatus or outer crus of the antitragns.
The autilielix is represented by a transverse fold running
backwards from the inner crus of the helix.

The meatus is supported hy four half-rings. The upper
three are almost completely united and are continuous with
the cont'h. The free portion of the first half-ring forms
the tragus. The fourth half-ring is independent, forming
the annular cartilage.

AILUROIDEA.

E. 381. The right ear of a Ferret {Genetta tigrlna). The pinna
is elongated, erect, and with a rounded apex. Its posterior
and lower margin is deeply incised with an irregular
integumentary pocket, as in many other Carnivora. The
helix, which is nowhere inturned, has outer and inner
crura. The former is very slightly marked, but the inner
crus is sharply prominent and extends backwards diagonally
towards the meatus. The ti'agus is squarish in outline and
is separated by a sulcus auris anterior from the outer crus
of the helix and by a very slight incisura from the anti-
tragus. The antitragus has inner and outer crura, the
former of which overlies a longitudinal plica. The cavity
of the conch is occupied by an abrupt rounded projection
set transversely to the long axis of the ear. This corre-
sponds to the lower of the two laminae seen in Crossai'chus,
and probably is the crus inferius antihelicis. 0. C. 1610 F.

Presented hy St. George Mivart, Esq.

OUGANS OF SPECIAL SENSE. — VERTEBRATA.

221

E. 382. The right ear of a Kusiinanse {Crossarchus olscurus).
This is a small ear of almost quadrangular outline, showing
a considerable flat extension in front of the external crus
helicis. Tlie latter is weak, but the inner crus is strongly
marked and runs deeply into the caAity of the conch,
within which, above the crus, lie also two extremely promi-
nent laminte disposed parallel to one another and approxi-
mately at right angles to the long axis of the ear. They
are strikingly similar to a pair of laminie found in the ears
of certain Lemurs, and probably represent the two crura of
the antihelix in an exaggerated form. There is no cleft in
the integument upon the posterior border of the helix.

0.0. 1610 D.

E. 383. The right ear of Galidea elegans. The pinna is bluntly
pointed and is considerably broadened in front of the outer
crus of the helix. There is a very large and regularly shaped
integumentary cleft upon the posterior border of the helix,
closely similar to that seen in the Ferret (E. 376). The
prominences in and around the aperture of the conch are
few and simple, the internal crus helicis and the crus anti-
helicis being the only two of any considerable size.

0. 0. 1610 c.

INSECTIVOEA.

E. 384. The anterior part of a Mole (Talpa ewopcea), showing
the entrance to the external meatus unprovided with a
projecting pinna, which would be an impediment in the
act of burrowing and an unnecessary appendage.

0. 0. 1609. Ilunterian.

E. 385. The anterior part of a Mole (Talpa europcea), with the
fur removed to show the external orifices of the ears and
eyesj into ^^■hich bristles have been placed.

0. 0. 1608. Ilunterian.

CHIROPTEEA.

E. 386. The head of a Bat {Megaderma lyra). The external
ears are of very great size, thin, elongated, and pointed.
The anterior borders of their helices unite across the fore-
head, being supported in the mid-plane by a vertical

PHYSIOLOGICAL SKUIKS.

triangular thickening. The tragus is also greatly deve-
lopod, and stands up in front of Ihe opening into the meatus
in the form of a large leaf-like flap, torminaling above in a
pair of pointed processes. Behind the tragus upon the
inner surface of the conch can be seen a well-marked
plica longitudinalis.

The pinna in Bats not only serves to direct sound-
waves into the meatus, but is also most probably extremely
sensitive to tactile impressions, and in conjunction with the
wing-membranes and the nasal appendage (when such
is present) forms a touch-organ, by means oE which the
creature can direct its course in the dark. 0. C. 1423 a.

PEIMATES.
LEMUROIDEA.

E. 387. Right ear of a Totto {Perodiciicus 2:)otlo). The helix is
not inturned, but its anterior lower end is bent into the
cavity of the conch and divides to form scarcely dis-
tinguishable inner and outer crura. The antihelix is
weak, with the exception of its crus inferius, which is
thin and remarkably prominent, and agrees in position
and general appearance with the lower of the two trans-
verse laminas which occur in the ears of certain other
Lemurs and Curnivora. 0. C. 1612 A.

Presented by F. M. Skues, Esq.

E. 388. Right ear of a Slender Loris (Loris gracilis). The
pinna is thin, erect, and delicately curved, but the helix is
in no part inturned. The tragus is slight, but the anti-
tragus more prominent. Both lie almost vertically, and
form the anterior and posterior borders of a remarkably
deep incisura intertragica. Behind the antitragus the
scapha is hollowed out to form a deep concaA-ity (sulcus
auris posterior), which is also strongly developed in certain
Monkeys and Rodents. From the antitragus a longi-
tudinal ridge runs upwards between the scapha and the
conch. This is the stem of the antihelix. Its crura are
probably represented by two laminaj that stand out abruptly
between the scapha and the cavitas conchas transverse to
the long axis of the ear. 0. C. 1612. Hunterian.

ORGANS OF SPECIAL SENSE. — VERTEBRATA.

223

E. 389. Right ear of a Calabui' Potto {Aixiocehus calabar en sis').
This difters in no important feature from the ear of
Loris gracilis. 0. C. 1612 b.

Presented hy Andrew Murray, Esq.

ANTHROPOIDBA.

E. 390. The right ear of a Marmoset (Midas osdipvs). The
helix is inturned along its anterior and upper border.
The apex is pointed and directed posteriorly. The anti-
helix has the same form as that of Man and other
Anthropoidea and is fairly prominent. The tragus and
antitragus are slight. ■ 0. C. 1619 A.

E. 391. Right ear of a Woolly Monkey {Lagothrix liumholdti).
The helix is inturned only in its ascending and horizontal
parts. The descending part, although not inturned, is
much reduced in comparison -with that of Lemurs and most
lower Mammals. The antihelix is prominent, with well-
marked superior and inferior crm-a. The incisura inter-
tragica is broade-r and shallower than in Cehus.

O.C. 1619 c.

E. 392. Right ear of a Sooty Mangabey (Cercocehus fiiU-
gin'osiis). The helix resembles that of Cehus, but the stem
of the antihelix is less definite and is sejiarated by the
apex of the fossa triangularis from its crus inferius. The
scapha terminates below in a rounded hollow (sulcus auris
posterior) behind the antitragus, but this is less marked
than in Cebus. 0. C. 1619 E.

E. 393. Right ear of a Capuchin (Celus capucinus). The helix
originates in the cavity of the conch by a well-marked
lamelliform crus, and although inturned along its whole
circumference, borders a broad and well developed scapha.
The tragus and antitragus are particularly prominent and
are separated by a deep and narrow incisura. The lower
end of the scapha forms a pit-like sulcus posterior. The
antihelix is well developed and closely resembles that of
Man. O.C. 1619 b.

224:

PHYSIOLOGICAL SEltlES.

E. 394. Ears of a Bi.boon (Fapio mormon). These are of a
lower and more animal type than those of the Monkeys
previously described. The helix is inturned only along its
anterior border and the pinna is ])ointed dorsally. The
posterior part of the scapha is broad and slightly holloived
out, the hollow passing ventrally into a deep pit beliind
the antitragus. The antihelix (which apparently in Apes
increases in importance as the scapha is reduced) is scarcely
indicated except at either end. The tragus, antitragus, and
incisura iutertragica are strongly marked.

0.0. 1G19. Ilunterian.

E. 395. The cartilages of the right ear of a Baboon {Papio
habuhi). In comparison with those of the Human ear,
the processes that support the tragus and antitragus are
large and prominent, and it is specially worthy of note
that the cartilages of ihe meatus are more separate and
have retained more clearly signs of their annular origin.
The antihelix is less marked, with the exception of its
crus inferior, which is separate from the stem and of
some size. The processus helicis caudatus is lai'ge and
flat.

E. 396. Eight ear of a Gibbon {Hylolotes Jar). The ascending,
horizontal, and upper half of the descending parts of the
helix are strongly inturned, and the lower posterior part
though not inturned is greatly reduced. The antihelix is
well developed. The crus inferius is separated from it by
a depression. 0. C. 1G20. Hunterian.

E. 397. Eight ear of an Orang-utan {Simia satyrus). The ear
is of very small size and in general form very Human, but
is without a lobule. The helix is inturned throuo-hout.
The antihelix is very prominent, but lacks the crus
inferius. The incisura iutertragica is remarkably broad
and shallow. 0. C. 10,20 a.

E. 398. Part of the skull with the cartilage of the left ear of an
Orang-utan (Simia satyrus). The meafcal part of the
cartilage is clearly separable into three half- rings, which

ORGANS OK' SPECIAL SENSE. — VERTEBRATA.

225

are united into a single plate along their inner anterior
border, bnt posteriorly and externally are separated by
deep clefts of Santorini. The upper ring bears the tragus
and antitragus and is continuous with the hinder part of
the conch. The cartilage of the conch is very similar to
that of Man, except for its smnll size, for the slight deve-
lopment of the crus inferius antihelicis, and for the greater
acuteness of the stem of the antihelix.

E. 399. Left ear of a Chimpanzee {Anth'opopithecus troglodijtes).
The pinna is large with strongly developed scapha, intunied
along its entire helical border, although but slightly in its
posterior and lower part. Towards the antitragus the scapha
deepens into a slight hollow (sulcus auris posterior) that
suggests the deep pit in the Baboon and other Apes. The
antihelix is slight. The incisura intertragica resembles
that of the Orang in being wide and shallovr,

O.C. 1620 b.

E. 400. Part of the skull with the cartilages of the left ear of a
Chimpanzee (Antliropopithecus troglodytes). The cartilages
resemble those of the Human ear more nearly than do those
of the Orang. In comparison with that of the Orang the
crus helicis is large and bears upon its convexity a small spine
(spina helicis) which represents the outer crus found in lower
Mammals. The antihelix is very Human, with a broad
shallow stem and well-defined crus inferius. The tracus is
joined more completely to the second half -ring of the
meatus than in the Oi-ang, being continuous with it both
in front and behind, but separated in the middle by a cleft
of Santorini. The lowest half-ring is joined to the one
above by only a very slender bar of cartilage.

E. 401. The right ear of a Negro. It is of large size and has
no lobule. 0. C. 1621. Flunterian.

Keith, Nature, vol. Ixv. no. 1671, p. 16.

E. 402, The right ear of a Bushwoman.

VOL. III.

O.C. 1621 A.
Q

220

PHYSIOLOGICAL 8ERIE.S.

E. 403. The loft ear of a New Zealander. The lobule has been
perforated to carry soine heavy pendent ornament.

0. C. 1G22. Ilunterian.

E. 404. The ears of a Taliittm. Tlioi-c is no lobule.

O.C. 1G22A.

E. 406. The left ear of a European female. This shows well
the " Orang type " of ear, in which the ear is small, with
i-educed and inturned helix. There is a small lobulus.

0. C. 1623. Eunterian.

E. 406. Right ear of a European male. The lobulus is large.
This ear is of the " Chimpanzee " type, with flat expanded
scapha. 0. C. 1624. Hunterian.

E. 406 a. An ear, showing " Darwin's point," a small process
upon the inturned edge of the helix "at its upper and
posterior part, which probably represents the pointed apex
of the ear of lower Mammals.

E. 407. The supporting cartilage of the right ear. The car-
tilage conforms roughly to the external shape of the ear,
but has no process corresponding to the lobule. The
cartilage of the meatus is plate-like and shows its original
formation from rings by two transverse fissures — the clefts
of Santorini. The crus inferiiis antihelicis is strong and
sharply prominent. On the anterior edge of the ascending
helix is a small process (spina helicis). This answers to
the external crus helicis of lower Mammals.

0. C. 1623 A.

OTOLITHS, OSSICULA AUDITUS, AND BONY LABYRINTHS*.

PISCES.
GANOIDEI.

E. 408. Otoliths from the right saccule of a Sturgeon (Acipe7iser
sturio).

* Preserved in the Rail-case of Room V. (Lower Gallery).

ORGANS OF SPECIAL SENSE. — VERTEBRATA. 227

TELEOSTEA *.
CLUPEIDuE.

E. 409. Otolith of a Shad (Clupea alosa) : from two indi-
viduals.

E. 410. Otoliths of a Herring (Clupea harengus) : two from the
left side and one from the right, from different indi-
viduals.

E. 411. Otoliths of a Pilchard (C^itpmp27c/ia?'(iMs).

SALMONIDjE.

E. 412. Otoliths of a Salmon (Sahno salar).

E. 413. Otoliths of a Sea-Trout (Salmo trutta).

E. 414. Otoliths of a Grey Trout (Salmo trutta, var. cambricus).

E. 415. Otoliths of a Brook-Trout (Salmo fario).

E. 416. Otoliths of a Smelt (Osmerus eperlanus).

E. 417. Otolith of a Grayling ( Thymallus vulgaris) : from the
right side.

E. 418. Otoliths of a Carp (Cyprinus carpio) : from the lagena.

E. 419. Otoliths of a Roach {Leuciscus rutilus) : apparently
from two individuals. The upper specimen on the left
and the lower on the right are from the lagena, the other
two from the recessus utriculi.

E. 420. Otoliths of a Sheat-fish (Silurus glanis).

E. 421. Otoliths of Spix's Sheat-fish (Hypophthalmus edentatus).
E. 422. Otoliths of Platystoma orbignianum.
E. 423. Otolith of an Electric Silurus (Malapterurus electricus).
E. 434. Otoliths of a Hassar (Callichthys asper).

* These otoliths; except where otherwise stated, are from the sacculus.

Q2

228

PHYSIOLOGICAL SERIES.

AKGVJLLlDAi.

E. 425. Otoliths of an Eel (Anguilla vulgaris).

E. 426. Otoliths o£ a Conger Eel (^Conger vulgaris).

E. 427. Otoliths of Murcenesox talahon.

Presented hy W. Clarke, Esq.

ESOCID^.

E. 428. Otolith of a Pike {Esox lucius) : from the left side.

CYPniNODOlfTJDu^.

E. 429. Otoliths of a Star-gazer (Anableps tetropJithalmus).

SCOMBRESOCIDJE.

E. 430. Otolith of Scomhresox saurus : from the left side.

E. 431. Otoliths of a Gar-fish {Belone vulgaris).

E. 432. Otoliths of Hemirhamphus intermedius.

E. 433. Otoliths of a Flying-fish (Exoccetics volitans).

AMMODYTID^.

E. 434. Otoliths of a Greater Sand-Launce (^Ammodytes lanceo-
latus) : from two individuals.

E. 435. Otoliths of a Lesser Sand-Launce (Ammodytes tobianus) .

MUGILID^.

E. 436. Otoliths of a Grey Mullet {Mugil capito).

SPHYB^NJD^.

E. 436 a. Otoliths of a Barracuda (Sphyra^na cameroonii).

E. 437. The otoliths (including those from the recessus utriculi
and lagena) from the left ear of a Cod (Gadus morrlma),
mounted in position upon an outline drawing of the
membranous labyrinth.

ORGANS OF SPECIAL SENSE. — VBUTBBRATA. 229

E. 438. Otoliths of a Cod (Gadus morrhua).

E. 439. Otoliths of a Coal-fish (Gadus virens) : from a young
specimen .

E. 440. Otoliths of a Coal-fish (Gadus virens) : from an adult.

E. 441. Otoliths of a Pollack (Gadus poUachius) : two of the
same size and shape, and one very much larger and
smoother.

E. 442. Otoliths of a Bib (Gadus luscus) : from two individuals
of different ages.

E. 443. Two otoliths of Gadus anglicus, Koken, from the
Coralline Crag, near Orford Castle.

E. 444. Otoliths of a Haddock (Gadus cBglefinus) : from
difi'erent individuals, one from the right side and two
from the left.

E. 445. Otoliths of Gadus pseudwglefinus, from the Coralline
Crag, near Orford Castle.

E. 446. Three otoliths of Gadus pseudoiglefinus = ? G. luscus,
from the Coralline Crag, near Orford Castle : much worn.

E. 447. Otoliths of a Whiting (Gadus merlangus).

E. 448. Otoliths of Gadus elegans, from the Coralline Crag,
near Orford Castle.

E. 449. Otoliths of a Hake (Merlucdus vulgaris).

E. 450. Otoliths of a Common Fork-beard (Pliycis blennoides).

E. 451. Otoliths of a Ling (Molva vulgaris).

E. 452. Otoliths of a Three-bearded Rockling (Motella tri-
cirrata).

PEUCIDJE.

E. 453. Otoliths of a Bass (Lahrax lupus).
E. 454. Otoliths of a Pope {Acerina cernua).

230

rilYSIOLOGICAL SERIES.

SEnnANlDM.

E. 455. Otoliths of a Gaper {Serranus cahrilla).

E. 456. Otoliths of a Sea-Perch {Serranus hrunneus).

E. 457. Otoliths of Lvtjanus annularis.

E. 458. Otoliths o£ an Albicore (Scicena aquila).

Presented by E. T. Newton, Esq.

E. 459. Otoliths of Scicena helangerii : from two individual;^.
E. 460. Otoliths of Otolithus argenteus.
E. 461. Otoliths of a Scisenoid.

E. 462. Otoliths of a Sea-Bream (Pagellus centrodontus) : from
two individuals.

MULLID^.

E. 463. Otoliths of a Red Mullet (Mullus harhatus).

E. 464. Otoliths of a Ballan "VVrass (Lahrus maculatus).
E. 465. Otoliths of a Striped Wrass {Lahms mixtus).
E. 466. Otolith of a Coral-fish {Platyglossus dussumieri).

CARANGID^.

E. 467. Otoliths of a Horse-Mackerel {Caranx trachurus).

GEIiltrDyE.

E. 468. Otoliths of Eqmda nucJialis.

ZEIDjE.

E. 469. OtoHths of a John Dory {Zeus faber).

OKGANS OF Bl'KClAL SENSE. — VERTEBKATA. 231
PLEVnONECTW^.

E. 470. Otoliths of a Turbot (Rhombus maximus).

E. 471. Otoliths of a Brill {lihomhus Icevis) : from different
individuals, one from the left side and two from the
right.

E. 472. Otoliths of a Plaice (Pleuronectes platessa) : from
ditferent individuals, one from the right side and two
from the left.

E. 473. Otoliths of a Flounder (^Pleuronectes flesus).

E. 474. Otoliths of a Dab (^Pleuronectes limanda).

E. 475. Otoliths of a Sole (^Solea vulgaris).

E. 476. Otoliths of Plagusia bilineata.

CALLIOJSnrMTD^.

E. 477. Otoliths of a Dragonet (^Callionymus lyra).

COTTIDJE.

E. 478. Otoliths of a Father-lasher (Cottus bubalis).
E. 479. Otoliths of a Sea-Scorpion (^Cottus scorpius).

PLATYCEPHALIDjE.

E. 480. Otoliths of Platyceplialus scaber.

TRIGLIDJE.

E. 481. Otoliths of a Streaked Gurnard {Trigla lineata).

E. 482. Otoliths of a Grey Gurnard {Trigla gurnardus) : from
two individuals.

E, 483. Otoliths of a Piper (Trigla lyra).

E. 484. Otoliths of a Red Gurnard {Trigla cucidics).

TliACHimP/K.

E. 485. Otoliths of a "W'eever {Trachinus draco), including one
from the lagena (mounted above).

232

rilYblOLOaiCAL SERIES.

AMPHIBIA.
URODELA,

E. 486. Mcnobranch (JVeclunis maculatus) : columella, of both
sides.

E. 487. Spotted Salamander {Salamandra maculosa) : columella,
of the left side.

ANURA,

E. 488. Surinam Toad {Pipa americana) : columella, of both
sides.

E. 489. Tree-Frog {Hyla arhorea) : columella, of both sides.

E. 490. Common Frog {Rana temporaria) : columella, of both
sides.

E. 491. Noisy Frog (Rana clamata) : columella, of both sides.
E. 492. Bull-Frog {Rana cateshiana) : columella, of both sides.

EEPTILIA.

RHYNOHOCEPHALIA.

E. 493. Tuatara Lizard {Sphenodon punctatus) : columella, of one
side.

LACERTILIA.

E. 494. Indian Gecko {Gecko verticillatus) : columella, of both
sides.

E. 495. Egyptian Mastigure {Uromastix spinipes) : columella, of
both sides.

E. 496. Iguana {Iguana tuherculata) : columella, of both sides,
from a specimen one foot long.

E. 497. Naked-necked Iguana {Iguana delicatissima) : columella,
of both sides, from a specimen measuring a few inches.

E. 498. Monitor Lizard ( Varanus griseus) : columella, of one side.

E. 499. Lacerta sp., columellae in situ in the skull. The position
of the semicircular canals is also shown by bristles.

ORGANS OF SPECIAL SENSE. — VERTEBUATA. 233

E. 500. Great Cycled us (Itliqua gigas) : columella, of both
sides.

E. 501. Common Chameleon (^Chamoileon vulgaris): columella,
of both sides.

OPHIDIA.

E. 502. Python sp. : columella, of both sides.

E. 503. Indian Cobra {Naja tripudians) : columella, of both
sides.

EMYDOSAUEIA.

E. 504. Nilotic Crocodile {Crocodilus niloticus) : columella, of
one side, from No. 717 D, Osteol. Series.

E. 505. Crocodilus niloticus : columella, of both sides.
E. 506. Crocodilus sp. : columella, of both sides.

E. 507. False Gravial {Tomistoma schlegelii) : columella, of the
right side.

OHELONIA.

E. 508. Snapping Turtle {Macroclemmys temmincUi) : columella,
of one side.

E. 509. European Tortoise (Testudo grceca), both columellffi,
with parts of the skull showing the cavities in the quadrate
bones occupied by the outer chambers of the tympanum.

Max Huhricli Collection.

E. 510. Chelone mydas : columella, of both sides.

E. 511. Chelone mydas : columella, of both sides.

AVES.
EATITiE.
RHEIFORMES.

E. 512. Rhea {Rhea americana) : columella, of both sides.

* M.C., 2094.

APTERYGIFORMES.

E. 513. Kiwi {Apteryx australis) ; columella, of both sides.
* Original Manuscript Catalogue of the OoUection of Auditory ossicula.

2U

PHYSIOLOGICAL SEIUES.

CARINAT^.
TINAMIFOKMES.

E, 514. Tinamou {Tinanms soUtarius) : columella, of the riglit
side. M.C., 2079.

Presented Inj Professor W. K. Parker.

GALLIFORMES.

E. 515. Brush-Turkey (Catheturus lathami): columella.

M.O., 2071.

E. 516. Black Grouse (Lyrurus tetrix) : bony labyrinth and
columella, o£ both sides. M.C., 2007.

Max Hiibneh Collection.

E. 517. Capercaillie (Tetrao urogallus) : bony labyrinth of both
sides, and one columella. Part of the bony wall of the
tympanic chamber is attached to the left labyrinth.

M.C., 2003.
Max Hubrich Collection.

E. 518. Greek Partridge (Caccabis saxatilis) : bony labyrinth,
of the right side and one columella. M.C., 2023 B.

Max Hubrich Collection.

E. 519. Partridge (Perdix perdix) : bony labyrinth, of the right
side. M.G., 2021.

Max Hubrich Collection.

E. 520. Fowl (Gallus gallus, var. domesticus) : bony labyrinth
and columella auris, of the right side. M.C., 1983.

Max Hubrich Collection.

E. 521. Golden Pheasant [Chrysolophus pictus) : bony labyrinth
of both sides, and one columella. M.C., 1966 a.

Max Hubrich Collection.

E. 522. Turkey {Meleagris gallopavo) : bony labyrinth of both
sides, and one columella. M.C., 2046.

Max Hiibrich Collection.

ORGANS OF SPECIAL SENSE. — VERTEBRATA.

235

COLUMRIFORMES.

£. 523. Stock- Dove (Columha conas) : bony labyrinth o£ the
rioht side, and one columella. M.C., 628 A.

Max Huhricli Collection.

E. 524. Turtle-Dove (lurtur titrtiir) : bony labyrinth and
columella, of both sides. M.C., 662 A.

Max Huhrich Collection.

E. 525. Solitaire (Pezophaps solitarius) : columella auris. From
the series of bones collected by the Rev. H. H. Slater, 1874.

M.C., 706.

RALLIFORMES.

E. 526. Corn Crake {Crex crex) : bony labyrinth of both sides,
and one columella. M.O., 1917.

Max Hubrich Collection.

PROCELLARIIFORMES.

E. 527. Wandering Albatross (Diomedea exulans) : columella
auris. M.C., 1524.

Presented hy Alhan Doran, Esq,

LARIFORMES.

E. 528. Tern {Sterna fluviatilis) : bony labyrinth of the right
side, and one columella. M.C., 1677.

Max Hubrich Collection.

CHARADRIIFORMES.

E. 529. Lapwing ( Vanellus vanellus) : bony labyrinth of the
right, and columella of both sides. M.C., 1719.

Max Hubrich Collection.

E. 530. Curlew {Numenius arquata) : bony labyrinth and
columella auris, of both sides. M.C., 1813.

Max Hubrich Collection.

E. 531. Dunlin (Felidna alpina) : bony labyrinth, of the right
side. M.C., 1769.

Max Hiibrich Collection.

23G

PHYSIOLOGICAL SERIKS.

E. 532. Woodcock (Scolopax rusticula) : bony labyrintli and
columella auris, o£ both sides. M.C., 1751.

Max Hubrich Collection.

ARDEIFORMES.

E. 533. Heron (Ardea cinerea) : bony labyrinth and columella
auris, of both sides. M.O., 1295 a.

Max Huhricli Collection,

E. 534. Bittern (Botaurus stellaris) : bony labyrinth and colu-
mella auris, of both sides. M.C., 1321.

Max Hubrich Collection.

ANSERIFORMES.

E. 535. "Wild Goose (Anser ferus) : bony labyrinth of the right
side, and one columella. M.C., a 1388.

Max Hubrich Collection.

E. 536. Bean-Goose {Anser fabalis) : bony labyrinth of the left
side, and one columella. M.C., 1380 a.

Max Hubrich Collection,

PELECANIFORMES.

E. 537. Cormorant (Fhalacrocorax carbo) : bony labyrinth and
columella auris, of both sides. M.G.. 1253.

Max Hiibricli Collection.

C ATHARTIDIFOEMES .

E. 638. Black Vulture ( Catharistes urubu) : columella, of both
sides. M.C., a 885.

ACCIPITEIFORMES.

E. 539. Griffon Vulture {Gyps fulvus) : columella, of the right
side. M.C., 914.

Presented by Professor W. K. Parker,

E. 540. Hen-Harrier (Circus cyaneus): bony labyrinth and
columella, of both sides. M.C, 933.

Max Hubrich Collection.

ORGANS OF SPECIAL SENSE. — VEUTEBRATA, 237

E. 541. Sparrow-Ha-wk (Accipiter nisus): bony labyrinth, of
both sides, and one columella. M.G., 959.

Max Huhrich Collection.

E. 542. Buzzard (Buteo huteo) : bony labyrinth and columella,
of the right side. M.C., 966.

Max Huhrich Collection.

E. 543. Harpy Eagle (Thxisaetus Jia^yyia): columella, of both
sides. M.C., A 983.

E. 544. Golden Eagle {Aquila clirysaetus) : right bony labyrinth
and surrounding parts of the skull. The semicircular
canals and vestibule have been opened and their cavities
marked by black bristles. M.C., 975.

E. 545. Golden Eagle (Aquila clirysaetus) : part of the left side
of the skull, showing the air-spaces in connection with the
tympanum. M.C., 975 A.

E. 546. Golden Eagle (Aquila clirysaetus) : columella, of both
sides. M.C., 975 b.

E. 547. Rough-legged Buzzard (Archibuteo lagopus) : bony
labyrinth and columella, of both sides. M.O., 970 A.

E. 548. Bateleur Eagle (Helotarsus ecaudatus) : columella, of both
sides. M.C., 985 a.

E. 549. Peregrine Falcon (Falco p)eregrinus) : bony labyrinth
and columella, of both sides. M.O., 1023 A.

Max Huhrich Collection.

E. 550. Merlin (Falco merillus) : bony labyrinth of the left
side, and one columella. M.C., 1032 A.

Max Huhrich Collection.

STRIGIEORMBS.

E. 551. Long-eared Owl (Asio otus) : bony labyrinth and
columella, of both sides. M.C., 1072.

Max Huhrich Collection.

238

PHYSIOLOGICAL SERIES.

E. 552. Groat Eagle-Owl {Bubo bubo) : bony labyrinth and
columella, of both sides. M.C., 1052.

Afax Hubrich Collection.

E. 553. Barn-Owl (Striv flammea) : bony labyrinth, oP the left
side. M.C., 1100.

• PSITTACIFORMES.

E. 554. Rose-crested Cockatoo (^Cacatua moluccensis) : colu-
mella, of both sides. M.O., a 1140.

E. 555. Blue-and- Yellow ^lacavv (Ara ararauna) : columella, of
both sides. M.O., 1148.

CORACIIFORMES.

E. 556. Kingfisher (Alcedo ispida) : bony labyrinth and colu-
mella, of both sides. M.O., 752.

Max Hiihrich Collection.

E. 557. White-beaked Hornbill (Anthracoceros convexus) : one
columella auris. M.C., 856.

Presented by Prof. W. K. Parker.

E. 558. Red-necked Hornbill (Ehytidoceros jjUcatus) : one colu-
mella auris. M.C., 867 a.

E. 559. Hoopoe (Upupa epops) : bony labyrinth of both sides,
with one columella. M.C., 616.

Max iJiibrich Collection.

E. 560. Swift (Cijpselus apus): bony labyrinth and columella,
of the left side. M.C., 788.

Max Hubrich Collection.

TROGONES.

E. 561. Cuckoo {Cuculus canorus) : bony labyrinth and colu-
mella, of the right side. M.C., 720 a.

Max Hubrich Collection.

ORGANS OF SPECIAL SENSE. — VERTEBRATA. 239

PICIFORMES.

E. 562. Green Woodpecker ( Gecinus viridis) : bony labyrinth
and columella, of the left side. M.C., 556.

Ma:x! Hubrich Collection.

PASSERIFORMES.

E. 563. Swallow {Hirundo rustica) : bony labyrinth and colu-
mella, of both sides. M.C., 514.

Max Huhrich Collection.

E. 564. Wren (AnortJmra troglodytes) : bony labyrinth and
columella, of both sides. M.C., 444.

Max Hubrich Collection.

E. 565. Blackbird (Menda memla) : bony labyrinth and colu-
mella, of the left side. M.C., 425.

Max Hubrich Collection.

E. 566. Nightingale {Aedon luscinia) : bony labyrinth and colu-
mella, of both sides. M.C., 427.

Max Hubrich Collection.

E. 567. Eobin {Erythaciis rnhecida) : bony labyrinth and colu-
mella, of both sides. M.C., 430.

Max Hubrich Collection.

E. 568. Redstart (PJweniciirus phcenicura) ; bony labyrinth and
columella, of both sides. M.C., 434.

Max Hubrich Collection.

E. 569. Blackcap (Si/lvia atricapilla) : bony labyrinth and
columella, of both sides. M.G., 394.

Max Hubrich Collection.

E. 570. Ked-backed Shrike (Hnneoctonus collyrio) : bony laby-
rinth and columella, of the left side. M.C., 3G7.

Max Hubrich Collection.

E. 571. Blue Titmouse {Cyanistes cceruleus) : bony labyrinth and
columella, of both sides. M.C., 344.

Max Hubrich Collection.

21:0 PHYSIOLOGICAL SKIIIES'.

E. 572. White Wagtail [Molacilla alhu) : bony labyrinth and
columella, of the right side. M.C., a 288.

Max Huhrich Collection.

E. 673. Skylark {Alauda arvensis) : the bony labyrinths partly
separated from the cranium. M.C., 277.

E. 574. Crossbill (Loxia curvirostra) : bony labyrinth and
columella, of both sides. M.C., 253.

Max IliiJirich Collection.

E. 575. Canary (Serinus canarid) : bony labyrinth and columella,
of both sides. M.C., 241.

Max Huhrich Collection.

E. 576. Canary {Serimis canaria) : bony labyrinths partly
separated from the cranium. M.C., 242.

E. 577. House-Sparrow {Passer domesticus') : bony labyrinth
and columella, of the right side. M.C., 232.

Max Huhrich Collection.

E. 578. Siskin {Chrysomitris spinus) : bony labyrinth and
columella, of the right side. M.C., 217.

Max Huhrich Collection.

E. 579. Goldfinch {Carduelis carduelis) : bony labyrinth and
columella, of both sides. M.C., 212.

Max Huhrich Collection.

E. 580. Starling (Stnomus vulgaris) : bony labyrinth and colu-
mella, of both sides. M.C., 87.

Max Huhrich Collection.

E. 581. Magpie (Pica pica) : bony labyrinth and columella, of
the left side. M.C., 51.

Max Huhrich Collection.

E. 582. Nutcracker {Nucifraga caryocatactes) : bony labyrmth
and columella, of the right side. M.C., 49.

Max Huhrich Collection.

OBGANS OF SPECIAL SENSE. — VERTEBKATA.

241

E. 683. Hooded Crow (Corone comix) : bony labyrinth of both
sides, with one columella. M.C., 33.

Max Hiibrich Collection.

E. 584. Jackdaw {Colceus monedula): bony labyrinth and colu-
mella, of the left side. M.G., 27.

Max Hiibrich Collection.

E. 585. Raven (Corvus corax) : bony labyrinth and columella,
of both sides. M.C, 20.

Max Hubricli Collection.

MAMMALIA.

* Doran, Morphology of the Mammalian ossicula auditus.
Trans. Linn. Soc, ser. 2, vol. i. 1879, p. 371.

MONOTEEMATA.
Doran, I. c, p. 492.

OJiNJTHORHYNCHID^.

E. 586. Duck-billed Platypus (OrnithorhpicJms anathms) : ossi-
cula of both sides. The mallei are joined to the tympanic
bones. M.C., 3972 A.

Doran, I. c, p. 491.

ECHWNID^.

E. 587. Spiny Anteater (Tachyglossus [^EcUdnd] aculeatus) :
ossicula of both sides, with the mallei attached to the
tympanic bones. M.C., 3960 A.

Doran, I. c, p. 488.

E. 588. Spiny Anteater {Tachyglossus aculeatus). The right
ossiculaj with the stapes still attached to the processus
longus of the incus. The shrivelled remains of the tensor
tympani muscle and tendon are painted red. The tympanic
bone is placed below the ossicula. M.C., 3960 B.

• A separate copy of the paper (-whicli is a descriptive account of this
collection) is kept in the Museum.

VOL. III. K

242

PHYSIOLOGICAL SEUIES.

MAESUPIALIA.
Doran, I. c, p. 486.

POLYPROTODONTIA.
DASYimiDjE.

E. 589. Common Dasyure [Dasywnis viverrinus) : left malleus
and incus, and the riglit stapes.

Osteol. Series, 3899 ; M.C., 3899.

Presented hy Ronald Gunn, Esq.

E. 590. Dasyurus sp. : malleus of both sides. M.C., 3899 A.

E. 591. Tasmanian Devil (^Sarcophilus \_Dasyi(rus'] ursinus) :
ossicles of the right side, with the malleus of the left.

M.C., 3910.

Doran, I. c, p. 483.

E. 592. Tasmanian Wolf ( Thylacinus cynoceplialus) : left malleus
and incus (Osteol. Series, 3930) with the left stapes from
another individual (Osteol. Series, 3928). M.C., 3928.
Doran, I. c, p. 482.

E. 593. PJiascologale sp. : ossicula of both sides. The left
malleus is attached to the tympanic bone. M.C., A 3881.
Doran, I. c, p. 483.

E. 594. Marsupial Anteater (Myrmecobius fasciatiis) : ossicula
of both sides. M.C., 3879.

Doran, I. c, p. 483.

PERAMJELIDJE.

E. 595. Long-eared Bandicoot {Peragale lagotis) ; ossicula of
both sides. The malleus is of a peculiarly low type. From
an adult, 18 inches (460 mm.) long. M.C., 3862 a.

Doran, I. c, p. 486.

E. 596. Long-eared Bandicoot {Peragale lagotis) : right tympanic
bone with the malleus attached, and left tympanic bone,
with the incus and stapes, isolated. M.C, 3862 b.

ORGANS OF SPECIAL SENSE. — VERTBBRATA. 243

E. 597. Peragale sp. : left malleus and incus. M.O., 3862 c.

E. 598. Pig-footed Bandicoot {Chceropus castanotis) \ ossicula
of the right side. M.C., 3877.

Doran, I. c, p. 486.

DIDELPHYIDJE.

E. 599. Virginian Opossum {Didelphys marsupialis) : ossicula
of both sides. M.C., 3947 A.

Doran, I. c, p. 480.

E. 600. Virginian Opossum {Didelpliys marsupialis) : ossicula
of both sides. The malleus and incus of the left side are
articulated. M.C., 3947 b.

E. 601. Four-spotted Opossum {Didelphys opossum) : the ossicula
of both sides. The tympanic bone is still connected to
the right malleus. M.C., A 3947.

Doran, I. c, p. 482.

DIPROTODONTIA.
UTACBOPODW^,

E. 602. Grreat Kangaroo (Macropus giganteus) : right tympanic
bone, with membrana tj^mpani and ossicles in position.
The left malleus and incus and right stapes mounted
separately below. Osteol. Series, 3708 ; M.C., 3708.

E. 603. Great Kangaroo (Macropus giganteus) : mallei.

M.C., 3713.

Doran, I. c, p. 478.

E. 604. Bennett's Wallaby (Macropus rujicollis) : right ossicles.
From a young specimen two inches (50 mm.) in length
without the tail. M.G., 3731 b.

Doran, I. c, p. 479.

E. 605. Bennett's Wallaby (Macropus rujicollis) : ossicles of
both sides and right tympanic bone. The malleus and
tympanic bone are united. M.O., 3731 a.

R 2

244 PHYSIOLOGICAL SERIES.

E. 606. Rod Kangaroo {Macropns rufus) : ossicles of the right
side. " M.C., 3722 a.

E. 607. A Hare-Kangaroo {Maeropus sp.) : malleus and incus
of both sides and two right mallei. M.C., 3739.

E. 608. Gaimard's Rat-Kangaroo {Beltongia gaimardi) : ossicula
of both sides. M.C., 3812 a.

E. 609. Gaimard's Rat-Kangaroo (-Beiion^ia ^amari?) : malleus
and incus of the left side. M.C., 3812 b.

E. 610. Kangaroo-Rat (Potoroiis tridactylus) : ossicula of both
sides. M.O., 3808 a.

Doran, Z. c, p. 480.

PHASCOLOMYW^.

E. 611. Hairy-nosed Wombat (Phascolomys latifrons) : left
malleus, with right incus and stapes. M.C., 3649.

Doran, /. c, p. 485.

E. 612. Common Wombat (Phascolomys ursinus) : right malleus,
left incus and stapes, and a slightly imperfect left malleus.

M.C., 3632 A.

Doran, /. c, p. 485.

PHA LANGERlDAi.

E. 613. Vulpine Phalanger (Trichosurus vulpecida, var. fuUgi-
nosa) : ossicula of both sides. M.C., 3665.

Doran, I. c, p. 483.

E. 614. Cook's Phalanger (Pseudochirus peregrinus) : ossicula of
the left side. M.C., 3688.

Doran, I. c, p. 484.

E. 615. Great Flying Phalanger {Petaurus australis) : ossicula
of the right side. Osteol. Series, 3693 ; M.C, 3693.

E 616. Taguan Flying Phalanger (Petauroides volans) : right
malleus. Osteol. Series, 3692 ; M.C, 3692.

Doran, I. c, p. 484.

ORGANS OF SPECIAL SENSE. — VERTBBRATA.

245

E. 617. Koala (Phascolarctus cinereus) : ossicula of the right
side, and the malleus (attached to the tympanic ring) and
incus of the left. M.C., 3652 a.

E. 618. Koala [Phascolarctus cinereus) : ossicula of the right
side (the malleus and incus articulated), and the left malleus
and incus. M.C., 3652 b.

E. 619. Koala (^Phascolarctus cinereus) : left malleus and incus.

M.G., 3652 c.

Doran, I. c, p. 484.

EDENTATA.

Doran, I, c, p. 476.

XENARTHKA.
BHADYPODW^'.

E. 620. Three-toed 'Sloth (Bradypus tridactylus) : ossicula of
both sides. M.O., 3423 b.

E. 621. Three-toed Sloth {Bradypus tridactylus') : ossicula of
both sides, lacking the right malleus. From a young
specimen. The aperture between the crura of the stapes is
wider than in the adult. M.O., 3433.

E. 622. Three-toed Sloth {Bradypus tridactylus) : right malleus
and incus. M.C., 3423 A.

Doran, I. c, p. 470.

E. 623. Two-toed Sloth {Choloepus didactylus) : the ossicula of
the right side (in the middle), the right and left malleus
and incus (above), and the left incus (below).

M.C., 3438 b.

E. 624. Two-toed Sloth ( Cholospus didactylus) : ossicula of the
left side. From a new-born specimen. M.C., 3438 c.

Doran, I. c, p. 471.

246

I'llYSlOLOOICAL SUKIES.

MliGATllEUIDJK.

E. 625. Grypolherium Ustai : ossicula of the right side. The
ossicles of Gvtjpotheriam closely resemble those of existing
Sloths, especially of CUolcepus didactylus.

Presented hy Dr. F. P. Moreno.
Smith Woodward, Proc. Zool. Soc. 1900, p. 69, pi. vi.
fig. 4.

E. 626. Grypotherium Ustai : ossicula of the left side, from the
same individual as the preceding. The malleus and incus
are still united. In this individual (Smith Woodward's
skull No. 1) the malleus articulates with the incus not only
by the head, but also by a small facette situated below the
head. Presented by Dr. F. P. Moreno.

E. 627. Grypotherium Ustai : right malleus and incus.

Presented by Dr. F. P. Moreno.

E. 628. Grypotherium Ustai : ossicula of the left side.

Presented by Dr. F. P. Moreno.

MYRMECOPHAGW^.

E. 629. Great Anteater (Myrmecophaga jubata) : the malleus
and incus of both sides, with the left stapes of another
individual. M.C., 3543.

Doran, I. c, p. 475.

E. 630. Tamandua Anteater (Tamandua tetradactyla) : right
malleus and incus, and a left malleus.

Osteol. Series, 3547 ; M.C., 3547.

Doran, I. c, p. 475.

E. 631. Tamandua Anteater (Tamandua tetradactyla) : right
malleus and incus, and left malleus.

Osteol. Series, 3548 ; M.C., 3548.

E. 632. Prehensile-tailed Anteater (Cycloturus didactylus) :
ossicula of the right side. M.C, 3552.

Doran, I. c, p. 475.

ORGANS OF SPECIAL SENSE. — VERTEBUATA, 247

E. 633. rroheiisile -tailed Anteater {Cydoturus d'ulactylus)
left malleus and incus. M.O., 3552 A.

LORIOATA.
DASYPODJDA<:,

E 634 Six-banded Ai-madillo (Dasypus semcfus) : ossicula of
the riglit side. Osteol. Series, 3567 ; M.C., 3567.

Presented by the Zoological Society.

Doran, I. c, p. 472.

E 635. Hairy Armadillo (Basypus villosus) : ossicula o£ the
■ right side. M.C.,3573.

E. 636. Hairy Armadillo {Dasypus villosus) : ossicula oE the
left side, from a fully developed foetus. M.C., 3573 A.

E 637. Little Armadillo {Zaedijus minutus) : ossicula of the
right side. Osteol. Series, 3576 ; M.O, 3576.

E. 638. Great Armadillo {Priodontes giganteus) : the ossicula of
the left side, and the malleus of the right. M.O., 3580.
"Doran, I. c, p. 473.

E. 639. Three-banded Armadillo {Tolypeutes conurus) : ossicula
of the right side. Osteol. Series, 3581; M.C., S581.

Presented by Charles Darwin, Esq.

Doran, I. c, p. 473.

E. 640. Nine-banded Armadillo (Tatusia novemcincta) : malleus
and incus of both sides, one stapes, and an imperfect cast
of the bony labyrinth. _ M.C, 3553

Max Hubrich Collection.

Doran, I. c, p. 473.

E. 641. Seven-banded Armadillo (Tatusia hybrida) : ossicula of
the right side, from a foetus at full term. M.C., 3565 A.

NOMARTHRA.

E. 642. Chinese Pangolin {Manis aurita) : ossicula of the left
side. The stapes is peculiarly sauropsidan. M.O., 3615.
Doran, I. c, p. 474.

248 PHYSIOLOGICAL SERIES.

E, 643. Chinese Pangolin (Alanis aurila) : right malleus and
incus. M.C., 3615 a.

E. 644. Javan Pangolin (^Manis javanica) : ossicula of" the left
side. Osteol. Series, 3618 ; M.O., 3618.

Ilowship Collection.

E. 645. Long-tailed Pangolin (Alanis tetradactyla) : ossicula of
both sides, from a young specimen.

Osteol. Series, 3621 ; M.C., 3621.

Brookes Collection.

E. 646. Long-tailed Pangolin {Manis tetradactyla) : malleus and
incus of the left side.

E. 647. White-bellied Pangolin (Manis tricuspis) : ossicula of
the right side. M.C., A 3621.

ORYCTEROPID^.

E. 648. Aard-Vaark (Orycteropus afer) : right tympanic bone
and ossicula, from a new-born example. M.C., 3625 A.
Doran, I. c, p. 476.

E. 649. Aard-Vaark (Orycteropus afer): left malleus (the
processus gracilis was firmly anchylosed to the tympanic
bone as in the Kangaroos), with the right stapes and incus
from another specimen. M.C., 3623.

CETACEA.

Doran, I. c, p. 463.

ODONTOCETI.

E. 650. DelpJunus sp. : ossicula of the left side. Note the
enlarged stapedial crus of the incus, characteristic of
Delphinidse. M.O., 3031.

DoraUj I. c, p. 459.

E. 651. Delphinus sp. : ossicula of the left side, from a foetus.

ORGANS OF SPECIAL SENSE. — VERTEBRATA, 249

E. 652. Clymenia ohscurus : right malleus and stapes, and left
malleus. The latter is attached to the tympanic bone.

M.C., 3030.
Presented by Captain Almond.

E. 653. Sharp-nosed Dolphin {LagenorhjncJius acutus) : malleus
and incus of the right side and stapes of the left.

M.C., 3025.

Doran, I. c, p. 460.

E 654. Tasmanian Dolphin (Glohicephalus sp.) : ossicula of the
eft side. M.C., 2994.

Doran, I. c, p. 460.

E. 655. Tasmanian Dolphin (Glohicephalus sp.) : ossicula of both
sides, lacking the left incus. The right incus and malleus
are articulated together. M.O., 2995.

E. 656. Tasmanian Dolphin (Glohicephalus sp.) : three right
mallei, a right incus, and three stapedes. M.O., 2996.

E. 657. Pseudorca crassidens : ossicula from both sides. The
malleus and incus ai-e from Osteol. Series, 2983.

M.C., 2983.
Presented hy W. L. Crowther, Esq.

Doran, I. c, p. 461.

E. 658. Pseudorca crassidens : right malleus and incus.

Osteol. Series, 2986 ; M.C., 2986.
Presented by W. L. Crowther, Esq.

E. 669. Grampus (Orca sp.) : ossicula of the right side, and the
malleus and stapes of the left. M.C., 2979 A.

Doran, I. c, p. 461.

E. 660. Killer (Orca orca) : both stapedes and the left malleus.

M.C., 2979.

E. 661. Porpoise (Phoccena phocama) : ossicula of the left side
and the right stapes, from a young individual.

M.C., 2972 a.

Doran, 1. c, p. 460.

250

PHYSIOLOGICAL SERIES.

E. 662. Porpoise {Phocccna phoccena) : ossicula of the left side.

M.C., 2972.

E. 663. Beluga (DelpMnajjterus leucas) : ossicula of both sides
The left malleus and incus are articulated.

Osteol Series, 2958 ; M.C., 2958.

Doran, I. c, p. 460.

E. 664. Beluga {Delphinapterus leucas) : ossicula of both sides.
The membrana tympani and tensor tympani are preserved
in connection with the left malleus. From a foetal skull.

Osteol. Series, 2964 j M.C., 29G4.

E. 665. Narwhal (Monodon monoceros) : ossicula of the right
side. The membrana tympani and the tendon of the
tensor tympani are preserved in connection with the
malleus. M.C., 2944 a.

Doran, I. c, p. 461.

E. 666. Narwhal (Monodon monoceros) : left stapes from an
adult female. It was not ankylosed to the fenestra ovalis.

M.C., 2944.

E. 667. Narwhal {Monodon) (?) : malleus of the right side,
attached to the tympanic bone. M.C., 2944 b.

PLATANISTID^.

E. 668. Soosoo {Platanista gangetica) : ossicula of the right
side, and the malleus and incus (articulated) of the left.

M.C., 2936 A.

Doran, I. c, p. 462.

E. 669. Soosoo [Platanista gangetica) : ossicula of the left side.
The membrana tympani is still adherent to the malleus.

M.C., 2936 B.

E. 670. Soosoo {Platanista gangetica) : the right malleus and
incus. M.C, 2936 c.

ORGANS OF SPECIAL SENSE. — VERTEBRATA.

251

PHYSETEEIDJE.

E. 671. Arnoux's Xiphoid Whale (Berardius arnouxi) : ossicula
o£ the left side, and the right stapes. Note the extreme
modification o£ the malleus in the Physeteridse.

M.C., 2909.

Doran, I. c, p. 457.

E. 672. Mesoplodon grayi : ossicula of the left side, and the
right stapes. Osteol. Series, 2903 ; M.C., 2903.

Presented hy Dr. Jidius von Haast,

Doran, I. c, p. 458.

E. 673. Bottle-nosed Whale (Hyperoodon rostratus) : ossicula of
the right side. Osteol. Series, 2899; M.C., 2899,

Doran, I. c, p. 457.

E. 674. Bottle-nosed Whale {Hyperoodon rostratus) : ossicnla of
the left side. Osteol. Series, 2899 ; M.C., 2899 a.

E. 675. Sperm- Whale (Physeter macrocephalus) : ossicula of
both sides, from an adult. M.C., 2860.

Doran, I. c, p. 456.

E. 676. Sperm- Whale {Physeter macroceplialus) : right malleus
of an adult (Osteol. Series, 2361), and the right incus from
another individual. M.C., 2861.

MYSTACOCETI.

E. 677. Rudolphi's Rorqual (Balcenoptera horealis) : ossicula of
the right side. M.C., 2762 c.

E. 678. Rudolphi's Rorqual (Balcenoptera horealis) : ossicula of
the left side. M.C., 2762 d.

E. 679. Rudolphi's Rorqual {Balcenoptera horealis) : stapes.

M.C., 2762 b.
Presented by Professor Turner.

252

niYSIOLOGICAL SERIES.

E. 680. Piked Whale (Balcimojytera acuto-ro strata) : ossicula of
the right side, from a nearly adult male.

Osteol. Series, 2757 ; M.C., 2757.
Presented by J. II. Gumey, Esq.

Doran, /. f., p. 453.

E. 681. Greenland Whale {Balcena myslicetus) : ossicula of the
left side, articulated. From a young specimen.

M.C., 2742 a.

Doran, I. c, p. 450.

E. 682. Greenland Whale (Bakena mysticetus) : right incus,
top of the right stapes, and base of the left stapes. From
an adult female. Osteol. Series, 2742 ; M.C., 2742.

SIEENIA.

Doran, I. c, p. 469.

E. 683. African Manatee (Trichechus [Manatus'] senegalensis) :
malleus of the left side.

Osteol. Series, 2735 ; M.C., 2736 a.
Presented by Captain Harris.

Doran, I. c, p. 468.

E. 684. African Manatee (^TricJiechus l_Manatus^ senegalensis) :
left incus and stapes. Osteol. Series, 2735 ; M.C., 2736 b.

Presented by Captain Harris.

E. 685. African Manatee (Triclieclius [^Manatus] senegalensis) :
ossicula of the right side.

Osteol. Series, 2735 , M.C., 2736 c.
Presented by Captain Hams.

E. 686. African Manatee (Trichechus [Afanatus] senegalensis) :
left malleus and stapes. M.C., 2736 D.

E. 687. American Manatee ( Trichechus manatus) : malleus and
incus of the left side. Osteol. Series, 2729 ; M.C., 2729.

Presented by Henry Christy, Esq.

Doran, I. c, p. 467.

OKGANS OF SPECIAL SENSE. — VERTEBRATA.

253

HALICOnWJE.

E 688. Duo-ong (Ilalicore dugong) : ossicula of the right side.

Osteol. Series, 2697 ; M.C., 2697.
Presented hy Lieut. Ilelpman, R.N.

Doran, I. c, p. 465.

E. 689. Dugong (Ilalicore dugong) : ossicula of the right side.

Osteol. Series, 2698 ; M.C., 2698.

E. 690. Steller's Sea-Cow {Rhytina gigas) : left malleus.

M.C., 2728 a.

Presented hy Professor d'Arcy Thompson, C.B.
Doran, I. c, p. 469, and Jour. Linn. Soc, vol. xvii.
1883, p. 366.

E. 691. Steller's Sea-Cow (Rhytina gigas) : left incus and
stapes. M.C., 2728 b.

Presented hy Prof. B'Arcy Thompson, C.B.

UNGULATA.
Doran, I. c, p. 431.

HYRACOIDEA.
PBOCAVJTDJE.

E. 692. Cape Hyrax (Procavia capensis) : ossicula of the right
side. M.C., 2236 a.

Doran, I. c, p. 432.

E. 693. Tree-Hyrax (Dendrohyrax dorsalis) : malleus and incus
of both sides, with the stapes of the left side. The right
malleus and incus are firmly articulated (Osteol. Series,
2240). The left malleus and incus are from Osteol. Series,
2239. M.G., 2240.

E. 694. Tree-Hyrax (Dendrohyrax dorsalis) : ossicula of the left
side. M.C., 2240 a.

25i

PHYSIOLOGICAL SERIES.

PllOBOSCIDEA.
ELEPHANTIDjE.

E. 695. Indian Elephant {Eleplias indicus) : ossicula of the
right side. Taken from a female Elephant which lived in
the Zoological Gardens from 1851 to 1875. M.C., 2264 b.
Doran, /. c, p. 430.

E. 696. The left ossicula from the same individual.

M.C., 2264 c.

E. 697. Indian Elephant {Eleplias indicus) : right malleus and
incus, with the left stapes from another individual.

M.C., 2264 a.

E. 698. Indian Elephant (Elephas indicus) : ossicula of the
right side, from a young individual. M.C.^ 2264 D.

E. 699. The left ossicula of the same specimen. M.C., 2264 e.

E. 700. African Elephant (Elephas africanus) : left malleus and
stapes, from a young specimen. M.C, 2496.

Doran, I. c, p. 431.

PERISSODACTYLA.

E. 701. Baird's Tapir (Tapirus hairdi) : the left malleus and
incus, and right malleus. M.C, 1973 A.

Doran, I. c, p. 420.

E. 702. Baird's Tapir {Tapirus hairdi) : mutilated malleus and
incus of both sides, from a young individual.

Osteol. Series, 1973 ; M.C, 1973.

nmNOCEROTID^.

E. 703. Two-horned Rhinoceros (Rhinoceros hicornis) : left ossi-
cula, from a very large skull. The malleus is of a peculiarly
low type. Osteol. Series, 2149 ; M.C, 2149.

Doran, I. c, p. 419. Hunterian.

ORGANS OF SPECIAL SENSE. — VERTEBRATA. 255

E. 704. Sumatvan Rhinoceros (R. sumatrensis) : right malleus
and stapes, with the left malleus.

Osteol. Series, 2141 ; M.C., 2141.
Presented hy Sir T. Stamford Raffles.
Doran, I. c, p. 420.

E. 705. Sondaic Rhinoceros (R. sondaicus) : malleus and incus
of the right side. Osteol. Series, 2134 ; M.O., 2134.

Doran, 1. c, p. 420.

E. 706. Horse (Equus cdballus) : ossicula of both sides, from a
foal six days old. M.C., 2071.

Doran, I. c, p. 420.

£. 707. Horse (Equus cahallus) : ossicula of the right side, from
a large cart-horse. M.C., 2029 A.

E. 708. Horse {Equus cdballus) : malleus and stapes of the
right side. M.C., 2071a.

E. 709. Zebra {Equus zebra) : ossicula of the left side, with the
malleus and stapes of the right.

Osteol. Series, 2115 ; M.C., 2115.

Doran, I. c, p. 421.

E. 710. Ass {Equus asinus) : ossicula of the left side.

M.C., 2102 A.
From the Collection of the late Mr. Swan.
Doran, I. c, p. 421.

E. 711. Ass {Equus asinus) : a rough preparation of the internal
bony ear and the tympanum of the right side.

M.C., 2102 B.

ARTIODACTYLA.

E. 712, Pig {Sus scrofa) : ossicula of both sides, from a foetus.

Osteol. Series, 1794 ; M.C., 1794.

Doran, I. c, p. 422.

256 PHYSIOLOGICAL SEItlES.

E. 713. Pig (Sus scrcfa) : ossicula of the right side and a cast
of the cavity oi: the bony hibyrintli. M.C., 1765.

Max Iluhrich Collection.

E, 714. Babirussa (Babirussa bahirussa) : ossicula of the right
side, and the malleus and stapes of the left. M.C., 1831 a,
Doran, /. c, p. 423.

E. 715. Babirussa (B. babirussa) : left malleus.

Osteol. Series, 1831 ; M.C., 1831.
Presented by T. II. Stewart, Esq.

E. 716. Wart-Hog (PhacocJiosrus a'thiopicus) : ossicula of the
right side, and malleus and incus of the left. M.C., 1852.
Doran, I. c, p. 422.

E. 717. Collared Peccary {Tayassu tajagu) : ossicula of the right
side. . Osteol. Series, 1741 ; M.C., 1741.

Doran, I. c, p. 423.

HIPPOPOTAMW^.

E. 718. Hippopotamus (H. amphibius) : ossicula of both sides.

M.C., 1858.

Doran, I. c, p. 421.

E. 719. Hippopotamus {H. amphibius') : ossicula of the right
side, from a specimen two days old born in the Zoological
Gardens, Feb. 21, 1871. Osteol. Series, 1872 ; M.C., 1 872.

CAMELTD^.

E. 720. Camel (Camelus dromedarius) : the ossicula of both
sides. The stapedes are damaged. The stapedius tendons
are extensively ossified. M.C., 1696.

Doran, I. c, p. 424.

E. 721. Camel (Camelus dromedarius) : right and left malleus.

M.O., 1696 J..

E. 722. Llama (Lama glama) : ossicula of the left side, and the
malleus and incus of the right. M.C., 1698.

Doran, I. c, p. 424.

E. 723. Alpaca (Lama pacos) : right malleus. M.C, 1704.

ORGANS OF SPECIAL SENSE. — VERTEBRATA.

257

TRAGULWuE.

E. 724. Ja van Chevrotain ( TVci^mZms ^ctm^MCMs) : ossicula o£ both
sides. The stapedes are from an adult, the rest from a
yomig animal. M.C., 1673.

Doran, I. c, p. 423.

E. 725. Javan Ohevrotain (Tragulus javanicus) : ossicula of the
right side. M.C., A 1682.

Doran, I. c, p. 424.

E. 726. Napu Ohevrotain (Tragulus napu) : ossicula of both
sides. M.C., 1682 a.

E. 727. Napu Ohevrotain (Tragulus napu) : malleus and incus
of the left side. M.O., 1682 b.

CERVW^.

E, 728. Musk-Deer (Moschus moschiferus) : ossicula of the right
side. M.O., 1445.

Doran, I. c, p. 430. ■*

E. 729. Musk-Deer (Moschus moschiferus) : ossicula of the left
side. M.O., 1445 a.

Presented hy the Zoological Society.

E. 730. Chinese Water-Deer (Hydropotes inermis) : ossicula of
the left side and a second left incus. M.O., 1651.

Doran, I. c, p. 430.

E. 731. Indian Muntjac (Cervulus inuntjac) : ossicula of the left
side, and the stapes of the right.

Osteol. Series, 1455 ; M.C., 1455.

Doran, I. c, p. 430.

E. 732. Axis Deer (Cervus axis) : malleus and incus of both
sides. Osteol. Series, 1490 ; M.O., 1490.

Doran, I. c, p. 429.

E. 733. Red Deer (Cervus elaphus) : ossicula of the right side,
from an adult male. M.C., 1492.

VOL. m. s

258 rHYSIOLOGICAL fSEEIKf?.

E. 734. Red Deer (Cervus elapJius) : ossicula of the left side,

Osteol. Series, 1494 ; M.C., 1494.
Presented hy N. E. Vau[/han, Esq.

E. 735. Fallow-Deer (Cervus dama) : malleus of both sides and
the right stapes, from a fawn.

Osteol. Series, 1571 ; M.C., 1527.

E. 736. Hoe (Capj^eolus caprea) : tympanic bone, bony labyrinth,
and ossicula of the left side. M.C, 1636.

Max Iliibnch Collection.

E. 737. Mexican Deer (Cariacus mexicanus) : malleus of both
sides and the right stapes.

Osteol. Series, 1662 ; M.C, 1662.

E. 738. Pudu Deer (Pudu pudu) : malleus of both sides.

Osteol. Series, 1668 ; M.C, 1668.

GIRAFFID^.

E. 739. (ji\vQ.^Q {Giraffa camelopardalis) : ossicula of both sides,
from a young male. M.C, 1437.

Doran, I. c, p. 429.

E. 740. Giraffe (Giraffa camelopardalis) : left ossicula, from a
young individual. M.C, 1440.

ANTILOCAPRW^.

E. 741. Prong-horn Antelope (Antilocapra americana) : ossicula
of the right side. M.C, 1424.

Doran, I. c, p. 424.

E. 742. Prong-horn Antelope (Antilocapra americana) : malleus
and stapes of the left side. M.C, 1419.

BOVWuE.

E. 743. Bubal (Bubalis boselaphus) : ossicula of the right side,
with the malleus and incus of the left. M.C, C 1406.

Doran, I. c, p. 429.

E. 744. Tora (Bubalis tora) : left malleus. M.C, A 1406.

ORGANS OF SPECIAL SENSE. — VERTEBRATA. 259

E. 745. Sassaby (Damaliscus lunatus) : left malleas.

M.C., 1408.

Presented hy Sir Victor Brooke, Bt.

Doran, I. c, p. 429.

E. 746. Bontebok (Damaliscus pygargus) : both mallei.

M.C., 1407 a.
Presented hy Sir Victor Brooke, Bt.

Doran, I. c, p. 429.

E. 747. White-tailed Gnu {ConnocJicetes gnu) : both mallei and
the right stapes. Osteol. Series, 1412 ; M.C., 1412.

Doran, I. c, p. 429.

E, 748. Brindled Gnu (ConnocJicetes taurinus) : right malleus
and left stapes. Osteol. Series, 1414 ; M.C., 1414.

E. 749. Maxwell's Duiker (Cephalophus maxwelli) : ossicula of
both sides. Those of the left side from another and larger
specimen. M.C., 1391 c.

Presented hy Sir Victor Brooke, Bt.

DoraUj I. c, p. 428.

E. 750. Common Duiker (Cephalophus grimmi) : both mallei.

Osteol. Series, 1394 ; M.C., 1394.
Presented hy B. Travers, Esq.

E. 751. Four-horned Antelope ( Tetraceros quadricornis) : ossicula
of the left side. Osteol. Series, 1399 ; M.C., 1399.

Presented by R, C. Beavan. Esq.

Doran, I. c, p. 428.

E. 752. Klipspringer (Oreotragus saltator) : right malleus.

M.C., H 1387.

Doran, I. c, p. 428.

E. 753. Zanzibar Antelope {Nesotragus moscTiatm) : two left
mallei, and a right malleus. M. C, B 1390.

Doran, I. c, p. 428.

s 2

2G0 PHYSIOLOGICAL SERIES.

E. 754. Royal Antelope {Neotragus pygmceus) : ossicula o£ the
right side. M.C., F 1387.

Presented hy Sir Victor Brooke, Bt.

Doran, I. c, p. 428.

E. 765. Abyssinian Ourebi {Ourehia montana) : ossicula of the
right side. M.C., E 1387.

Doran, I. c, p. 428.

E. 756. Common Water-buck {Kohus ellipsiprymnus) : left
malleus and incus. M.C., 1387.

Presented hy Sir Victor Brooke, Bt.

Doran, I. c, p. 428.

E. 757. Black Buck (Antilope cervicapra) : right malleus and
stapes. M.C., 1376.

Doran, c, p. 428.

E. 758. Saiga (Saiga tatarica) : ossicula of the right side, and
the malleus of the left. M.C., 1369.

Presented by Sir Victor Brooke, Bt.

Doran, I. c, p. 428.

E. 759. Dorcas Gazelle (Gazella dorcas) : ossicula of both sides.

M.O., 1361.

Doran, I. c, p. 428.

E. 760. Gazella sp. (probably dorcas) : ossicula of both sides.

M.C., 1361a.

E. 761. Indian Gazelle (Gazella hennetti) : ossicula of the left
side. M.C., 1364.

E. 762. Tibetan Gazelle (Gazella picticauda) : mallei and left
incus. M.C., A1735.

E. 763. Gazella Icevipes : right malleus and incus.

M.C., A 1364.

E. 764. Harnessed Antelope ( Tragelaphus scriptus) : left malleus
and incus. M.C., 1345 b.

Presented hy Sir Victor Brooke, Bt.

Doran, I. c, p. 429.

OKGANS OF SPECIAL SENSE. — VBRTEBRATA. 261

E 765. Chamois (Rupicapra tragus) : ossicula of both sides.

M.C., 1327.

Poran, I. c, p. 427.

E. 766. Himalayan Goral (JVemorrJiccdus goral) : right malleus
and the incus of both sides. M.C., 1317.

E. 767. Camhmg-Viiim{Nemorrh(£dus sumatrensls) : right malleus
and stapes. M.C., 1323.

Doran, I. c, p. 428.

E. 768. Goat (Capra hircus) : tympanic bone, bony labyrinth,
and ossicula of the left side ; and a cast of the cavity of a
cochlea. The malleus is preserved in position. M.C., 1300.

Max Hilhricli Collection.

Dovan, I. c, p. 427.

E. 769. Markhoor {Capra megaceros) : ossicula of the left side,
with the malleus and incus of the right. M.C., 1310 A.

Presented hy Sir Victor Brooke, Bart.

E. 770. Grrecian Ibex ( Capra hircus) : ossicula of the left side.

Osteol. Series, 1304 ; M.C., 1304.
Presented by W. H. Colvill, Esq.

E. 771. Alpine Ibex (Capra ibex) : the mallei. M.C., 1286.

E. 772. Sheep (Ovis aries) : ossicula and bony labyrinth of both
sides, from a lamb. M.C., 1244.

Max Uiibrich Collection.

Doran, I. c, p. 425.

E. 773. Sheep {Ovis aries) : the tympanic bone of the right
side. M.C., 1244 a.

Max Uiibrich Collection.

E. 774. Sheep (Ovis aries): ossicula of both sides, from an
adult. M.G., 1223 a.

Doran, I. c, p. 425.

E. 775. Sheep {Ovis aries) : right malleus. M.O., 1223.

^62 THYHIOLOGICAL SEUIKS.

E. 776. Nahoor (Oris nalioor) : ossicula of the right side.

Osteol. Series, 1278 ; M.C., 1278.
Presented hy General R. Slrachey.

Doran, I. c, p. 427.

E. 777. Musk- Ox {Ovibos moscJiatus) : ossicula of both sides.

M.C., 1213.

Doran, I. c, p. 429.

E. 778. Anoa {Anoa depressicomis) : ossicula of the left side.

Osteol. Series, 1173; M.C., 1173.
Presented hy Dr. B. C. Henderson.

Doran, I. c, p. 429.

E. 779. Ox (Bos taurus) : ossicula of both sides, from a
specimen six weeks old. M.C., 1310.

Doran, I. c, p. 425.

E. 780. Ox [Bos taurus) : the left tympanic bone and bony
labyrinth, with the ossicula of both sides, lacking one stapes,
from a calf. M.C., 1127 a.

Max Hiibrich Collection.

Doran, I. c, p. 426.

E. 781. Ox {Bos taurus) : ossicula of the left side, from a full-
term foetus. Osteol. Series, 1133 ; M.C., 1131.

E 782. Ox {Bos taurus) : ossicula of the left side, from a large
adult skull. M.C., 1131 A.

E. 783. Zebu {Bos taurus) : ossicula of the right side.

Osteol. Series, 1149 ; M.C., 1149.

Doran, I. c, p. 427.

EODENTIA.
Doran, I. c, p. 418.

SCIUROMORPHA.
ANOMAL URID^.

E. 784. Fraser's Scaly-tailed Squirrel {Anomalurus fraseri) :
ossicula of the right side, with the left malleus and incus.

Osteol. Series, 3065 ; M.C., 3065.
Presented by Capt. R. Burton.

Dorun, I. c, p. 408.

OEGANS OF SPECIAL SENSE. — ^VERTEBRATA.

263

PEDETID^.

E. 785. Cape Jiimping-Harc {Pedetes cafer) : a mutilated
malleus and a stapes. M.C., 3199.

Doran, 1. c, p. 414.

E. 786. Common Squirrel (Sciurus vulgaris) : tympanic bone,
bony labyrinth, and ossicula of the right side (the malleus
and incus articulated), with the left malleus, from a young
skull. M.C., 3072.

Max Hubrich Collection.

Doran, I. c, p. 408.

E. 787. Malabar Squirrel {Ratufa indica) : ossicula of both
sides. Osteol. Series, 3075 ; M.C., 3075.

Presented by Capt. Gideon.

Doran, I. c, p. 407.

E. 788. Jelerang Squirrel {Sciurus Ucolor) : ossicula of the right
side. Osteol. Series, 3073 ; M.C., 3073.

Doran, I. c, p. 408. Hunterian.

E. 789. Bristly Ground-Squirrel (Xerus capensis) : ossicula of
both sides. • M.C., 3086.

E. 790. Chipping-Squirrel (Tamias asiaticus) : ossicula of the
right side. M.C., 3088 b,

Doran, I. c, p. 408.

E. 791. Flying Squirrel {Pteromys nitidus) : ossicula of the right
side. Osteol. Series, 3066 ; M.C., 3066.

Doran, I. c, p. 409.

E. 792. Prairie Marmot ( Cynomys ludovicianus) : ossicula of the
left side. M.C., 3093 a.

Doran, I. c, p. 409.

E. 793. Alpine Marmot (Arctomys marmotta) : ossicula of the
right side. M.C., 3096 A.

264

rHYSIOLOOICAL SERIES.

E. 794. European Souslik (SpermopMhts citillus) : ossicula of
both sides. Osteol. Series, 3090 ; M.C., 3090.

Presented by the Zoological Society.

Doran, /. c, p. 408.

CASTOBID^.

E. 796. European Beaver {Castor fiber) : ossicula of the left
side. M.C., 3104.

Doran, I. c, p. 410.

E. 796. European Beaver (Castor fiber): part of skull, showing
tympanic chamber and bony labyrinth of the right side.

M.C., 3105.

E. 797. Canadian Beaver (Castor canadensis) : ossicula of the
right side. Osteol. Series, 3122 ; M.C., 3122.

Hunterian.

MYOMORPHA.

E. 798. Fat Dormouse (Myoxus glis) : ossicula of both sides.

Osteol. Series, 3130 ; M.C., 3130.

Doran, I. c, p. 409.

E. 799. Common Dormouse (Muscardinus avellanarius) : ossicula
of the right side. Osteol. Series, 3131 ; M.C., 3131.

Presented by Miss V. J. Flower.

E. 800. Golden-bellied Beaver-Rat (Hydromys chrysogaster) :
ossicula of the left side. Osteol. Series, 3132 ; M.C., 3132.
Doran, I. c, p. 411.

E. 801. Hamster (Cricetus cricetus) : right malleus and incus.

Osteol. Series, 3138 ; M.C., 3138 a.
Presented by the Zoological Society.

Doran, I. c, p. 412.

E. 802. Field-Mouse (Microtus agrestis) : bony labyrinth and
ossicula of both sides. M.C., 3178 A.

Max Hiibrich Collection.

Doran, I. c, p. 411.

ORGANS OF SPECIAL SENSK. — VBRTEBRATA. 265

E. 803. Field-Mouse (Microtus agrestis) : tympanic bone, bony-
labyrinth, and ossicula of the right side. The malleus is
attached to the tympanic bone. M.C., 3178.

Max Uubrich Collection.

E. 804. Field-Mouse {Microtus agrestis) : skull, showing the
tympanic bullae. M.C., 3178 B.

Max Hiihricli Collection.

E. 805. Water-Vole (Arvicola terrestris) : ossicula o£ the left
side. M.C., 3176.

Doran, I. c, p. 411.

E. 806. Musquash {Fiber zibetMcus) : ossicula of the right side.

M.C., 3171.

Doran, I. c, p. 411.

E. 807. Ellobius talpinus : ossicula of the right side (the malleus
and incus are united), and the left malleus and incus.

Osteol. Series, 3180 ; M.C., 3180.
Presented by Professor Peters.

Doran, I. c, p. 412.

E. 808. Black Eat (Mus rattus) : bony labyrinth of both sides,
with two tympanic bones and two sets of ossicles from the
right side. One malleus is in its natural position. There
is a well marked orbicular apophysis on the malleus.

M.C., 3142.
Max Hubrich Collection.

E. 809. Norway Eat (Mus decumanus) : right malleus and incus.

Osteol. Series, 3147 ; M.C., 3147.

Presented by Professor Owen.

Doran, I. c, p. 410.

E. 810. House-Mouse (Mus musculus) : tympanic bone, bony
labyrinth, and ossicula of the left side. The malleus is in
its natural position. M.C., 3160.

Max Hiibrich Collection.

E. 811. House-Mouse (Mus musculus) : tympanic bone and
malleus and incus of the left side. The malleus is in
position. M.C., 3160 a.

266 riiYsioLoaicAL series.

E. 812. MitchelPs Hapalote (Conilwus milc/ielli) : ossicula of
both sides, lacking the right stapes. M.C., A 3166.

Doran, I. c, p. 411.

SPALACfD^.

E. 813. Mole-Rat {Spalax typldus) : ossicula of the right side.

Osteol. Series, 3181 ; M.O., 3181.

Doran, I. c, p. 412.

E. 814. Bay Bamboo-Rat (Rhizomys badius) : ossicula of the
right side. M.C., 3184.

Doran, I. c, p. 412.

BA THYERGID^.

E. 815. Coast Rat {Bathyergus maritimus) : ossicula of the right
side. The malleus and incus are united.

Osteol. Series, 3186 ; M.C., 3186
Presented by Thomas Keate, Esq.

Doran, I. c, p. 413.

GEOMYID^.

E. 816. Pouched Gopher {Geomys bursanus) : ossicula of the
right side. M.C., 3192.

Doran, I. c, p. 413.

E. 817. Egyptian Jerboa (Dipus sagitta) : ossicula of both sides,
lacking the left stapes. M.C., 3194.

Doran, I. c, p. 414.

E, 818. Egyptian Jerboa (Dipus sagitta) : ossicula of both sides.
The malleus and incus are united. M.C, 3195.

HYSTRICOMORPHA.
OCTODONTJD^:

E. 819. Cuming's Octodon (Octodon degus): ossicula of both
sides, from a very young skull. The left incus is malformed.

Osteol. Series, 3205 ; M.C., 3205.
Presented by Professor Flower.

Doran, I. c, p. 415.

ORQANS OF SPECIAL SENSE. — VERTEBRATA.

267

E. 820. Fournier's Capromys (Capromi/s pilorides) : ossicula of
the left side, with the right malleus and incus from another
individual. The malleus and incus are articulated.

M.C., 3210.

Doran, I. c, p. 415.

E. 821. Ground-Rat (^Tliryonomys swindernianus) : ossicula of
the left side. Osteol. Series, 3214; M.C., 3214.

Presented hy R. J. Garden, Esq.

Doran, I. c, p. 415.

COENDTD^:

E. 822. Guianan Tree-Porcupine (Coendu insidiosus) : ossicula
of the right side. The malleus and incus are articulated.

M.C., 3216.

Doran, L c, p. 415.

E. 823. Crested Porcupine {Hystrix cristata) : ossicula of tho
right side. The malleus and incus are articulated.

Osteol. Series, 3224 ; M.C., 3224,

Doran, I. c, p. 414.

E. 824. Javan Porcupine (ITystrix javanica): ossicula of tho
right side. The malleus and incus are articulated.

Osteol. Series, 3231 ; M.C., 3232 a.
Presented by the Zoological Society,

Doran, I. c, p. 415.

LAGOSTOMID^.

E. 825. Chinchilla (Chinchilla lanigerd) : ossicula of the right
side. The malleus and incus are articulated. The head of
the malleus is extremely developed.
Doran, I. c, p. 416.

DASVPROCTW^.

E. 826. Golden Agouti (Dasyprocta aguti) : right periotic and
tympanic bones, with the floor of the auditory bulla re-
moved, showing the prominence of the periotic that encloses
the cochlea. ]y[ 3249

2()8 PHYSIOLOGICAL SEltlKS.

E. 827. Golden Agouti (Dasyprocta agiiti) : left tympanic and
periotic bones, prepared in a similar way, but with the
cochlea laid open. Tlie stapes is retained in position.

M.C., 3249 A,

E. 828. Golden Agouti (Dasyprocta aguti) : ossicula of the right
side, with the malleus and incus articulated. M.C., 3249 c.
Doran, /. c, p. 416.

E. 829. West-Indian Agouti (Dasyjjrocta cristata) : malleus
and incus of the left side (articulated) and stapes of the
right. M.G., a 3250.

Doran, I. c, p. 416.

E. 830. Spotted Cavy (Agouti paca) : left malleus and incus,
articulated. Osteol. Series, 3255 ; M.C., 3255.

Doran, I. c, p. 416.

CAVIJD^.

E. 831. Guinea-Pig {Cavia porcellus) : tympanic bone, bony
labyrinth, and ossicula of both sides. The left stapes is in
position. The mallei and incudes are articulated.

M.O., 3267 A.
Max Huhricli Collection.

Doran, I. c, p. 417.

E. 832. Guinea-Pig {Cavia porcellus) : portions of the skull,
prepared to show the cochlea of both sides. The left has
been opened. M.C., 3267 b.

E. 833. Patagonian Cavy {DoUchotis magellanica) : ossicula of
the right side, with the malleus and incus articulated.

Osteol. Series, 3268 ; M.C., 3268.

Doran, I. c, p. 416.

E. 834. Capybara {Hydroclioerus capyhara) : the ossicula of both
sides, from an individual eight days old.

Osteol. Series, 3276 j M.C., 3276.

Doran, I. c, p. 417.

ORGANS OF SPECIAL SENSE. — VERTEBRATA.

269

LAGOMORPHA.
LEPORID^.

E. 835. Hare {Lepus europceus) : three specimens o£ the tympanic
bone, with the bony labyrinth o£ the right side, the left
cochlea in section, and the ossicula. M.C., 3281 c.

Max Huhrich Collection.

Doran, Z. c, p. 417.

E. 836. Hare {Lepus europceus) : bony labyrinth and ossicula of
the right side. M.C., 3281 b.

Max Huhrich Collection.

E. 837. Hare {Lepus europceus) : bony labyrinth and ossicula of
the left side. M.C., 3281a.

Max Hubricli Collection.

E. 838. Hare {Lepus europceus) : part of the right side of the
skull, showing the tympanic membrane and cavity, and
the various parts of the internal ear in section. A bristle
is passed behind the tensor tympani muscle and the
stapes. M.C., 3281 d.

Max Huhrich Collection.

E. 839. 'R&hhii (Lepus cuniculus): tympanic bone, bony labyrinth,
and ossicula of both sides. The left ossicles are in their
natural position. The processus muscularis mallei is
situated on the inner edge of the manubrium at some
distance from its root. M.C., 3316 A.

Alax Huhrich Collection.

Doran, I. c, p. 418.

E. 840. Eabbit (Lepus cuniculus) : ossicula of the left side.
The processus muscularis mallei is situated on the root of
the manubrium. M.C., 3316 b.

PINNIPEDIA.
Doran, I. c, p. 407.

OTABIID^.

E. 841. Falkland-Island Sea-Lion {Otaria australis) : ossicula
of both sides. Note the small size of the ossicles compared
with those of Phocidse. M.O., 983.

Doran, I, c, p. 401.

♦

270 PHYSIOLOaiCAL SERIES.

E. 842. ^teller's Sea-Lion (Otaria stelleri) ; ossicula of the left
side, with the right malleus.

Osteol. Series, 979 ; M.C., 979.

Doran, I. c, p. 400.

E. 843. Californian Sea-Lion (^Otaria calif orniana) : ossicula o£
both sides. From a young specimen once living in the
Southport Aquarium. M.C., 981.

E. 844. Southern Sea- Lion {Otaria jubata) : left incus, from a
young specimen. M.C., 978,

Doran, I. c, p. 400.

E. 845. Walrus (Odohcenus rosmarus) : ossicula o£ both sides.

M.C., 1008 A.

Doran, I. c, p. 401.

E. 846. Walrus (Odobcenus rosmarus): incus and stapes of the
left side. M.C., 1008 b.

PHOCID^:

E. 847. Grrey Seal {Halichoerus ffrypus) : ossicula of the left
side. The ossicles closely resemble those of PJioca barbata.

M.O., 1061.

Doran, I. c, p. 406.

E. 848. Grey Seal {Halichoerus grypus) : right incus.

Osteol. Series, 1060 ; M.C., 1060.

E. 849. Common Seal {Plioca vitulina) : ossicula of both sides.

M.C., 1066.

Doran, I. c, p. 404.

E. 850. Common Seal (Phoca vitulina) : ossicula of both sides.
The left malleus and incus are united, to show their double
articulation. M.C., 1068.

E. 851. Harp Seal (Phoca groenlandica) : ossicula of the left
side. Osteol. Series, 1079 ; M.C., 1079.

Doran, I. c, p. 405.

ORGANS OF SPECIAL SENSE. — VERTEBRATA. 271

E. 862. Ringed Seal (Plioca fcetida) : ossicula of both sides.

Osteol. Series, 1074 ; M.C., 1074.

Doran, I. c, p. 406.

E. 853. Bearded Seal {Phoca harhata) : ossicula of both sides.
The right malleus and incus are from Osteol. Series, 1086 ;
the remainder from Osteol. Series, 1087. M.C, 1086.

E. 854. Bearded Seal [Phoca harhata) : malleus and incus of
both sides. The left malleus and incus are united. There
is no second articulation, as in Phoca vitulina.

M.C, 1087 a.

Doran, I. c, p. 406.

E. 855. Monk-Seal (Monachus albiventer) : left malleus and
incus. The malleus resembles that of Phoca, for the neck
is not elongated as in Cystophora, nor so very short with
a conspicuously short manubrium as in Stenorhynchus,
Lohodon, or Macrorhinus. There is no extra articular
process as in P. vitulina, a trace of a processus muscularis
exists. The manubrium forms an angle with the body as
wide as in Phoca; that is, midway between the wider
angle of Cystopliora and the sharper angle in Macrorhinus
and the Stenorhynchina. The incus has decided tendencies
to the Stenorhynchus type. It is larger and bulkier than
that of Phoca or Halichosrus, and the development of the
posterior part of the body and the deep grooved pit internal
to the facets strongly remind one of the Stenorhynchina;
in Phoca the groove internal to the facets is far shallower.

Osteol. Series, 1088 ; M.C, 1088.

Hunterian.

E. 856. Leopard-Seal {Stenorhynchus leptonyx) : ossicula of both
sides. The left malleus and incus are articulated.

M.C, 1096.

Presented hy Thomas Chevalier, Esq.

Doran, I. c, p. 403.

E. 857. Leopard-Seal (Stenorhynchus leptonyx) : malleus and
incus of both sides from Osteol. Series, 1095, with the
right stapes from Osteol. Series, 1092. M.C, 1095.

272 PHYSIOLOGICAL SERIES.

E. 858. Hooded Seal {Cystopliora cnstata) : ossicula of both
sides. M.C, 1105.

Doran, I. c, p. 403.

E. 859. Elephant-Seal (Macrorhinus leoninus) : right ossicula of
a young specimen. Osteol. Series, 1107 ; M.O., 1107.
Doran, I. c, p. 402.

E. 860. Elephant-Seal (Macrorhinus leoninus) : ossicula of the
left side. From the same individual as the preceding.

Osteol. Series, 1107 ; M.C, 1107 A.

E. 861. Elephant-Seal (Macrorhinus leoninus) : right incus of an
adult. M.C, HOG.

OAENIVOEA.
Doran, I. c, p. 406.

ARCTOIDEA.

E 862. Polar Bear {Ursus maritimus) : ossicula of both sides.

M.C, 945.

Doran, I. c, p. 399.

E. 863. American Black Bear (C/rsus americanus) : ossicula of
the right side. M.C, 818.

E. 864. Spectacled Bear {Tremarctos ornatus) : ossicula of the
left side. Osteol. Series, 815 ; M.C, 815.

Doran, I. c, p. 399

E. 865. Himalayan Black Bear {Ursus thibetanus) : right and
left malleus, and right stapes. M.C, 831.

Doran, I. c, p. 399.

E. 866. Himalayan Black Bear (Z/rsMsf/wiefamts) : right malleus
and incus. M.C, 831 a.

E 867 Sloth-Bear (Melursus ursinus) : right and left malleus.

M.C, 954.

Doran, /. c, p. 399.

ORGANS OF SPECIAL SENSE. — VERTEBRATA. 273

E. 868. Panda {Ailurus fulgens) : right malleus and incus.

Osteol. Series, 806 ; M.C., 806.

Doran, I. c, p. 398.

pnocyomD^.

E. 869. Racoon (Procyon lotor) : ossicula of the left side.

Osteol. Series, 782 ; M.C., 782.

Doran, I. c, p. 397.

E. 870, Bassariscus astutus : malleus and incus of both sides.

M.C., 799.

Presented hy Sir Victor Brooke, Bt.

Doran, I. c, p. 398.

E. 871. Coati Mundi (JSfasua nasua) : ossicula of the right side.

M.C., 791 A.
Presented hy Mr. James Flower.

Doran, I. c, p. 397.

E. 872. Coati Mundi {Nasua nasua) : ossicula of the left side.

Osteol. Series, 791.

E. 873. Kinkajou (Potos caudivolvulus) : ossicula of both sides.

M.C., 800.

Doran, I. c, p. 398.

MUSTELW^.

E. 874. American Badger {Taxidea americana) right malleus
and incus. M.C., 746.

Doran, I. c, p. 397.

E. 875. Badger (Meles meles) : ossicula of the right side.

Osteol. Series, 754 ; M.O., 754.

Doran, I. c, p. 397.

E. 876. Badger (Meles meles) : malleus and incus of both sides.

Osteol. Series, 752 ; M.C., 752.

E. 877. Helictis orientalis : malleus of both sides and the left
iocus. Osteol. Series, 741 ; M.C., 741.

Presented by E. C. Beavan, Esq,

Doran, I. c, p. 397.

VOL. III. m

274

PHYSIOLOUIUAL SKRIES.

E. 878. African Skunk {Ictomjx zorilla) : ossicula o£ the right
side. Osteol. Series, 740 ; M.C., 740.

Doran, I. c, p. 396.

E. 879. Tayra (Galera barbara) : ossicula of both sides.

M.C., 737.

E. 880. Weasel (Ptitorius vulgaris) : the tympanic bone, bony
labyrinth, and ossicula of both sides. M.C., 713.

Max Hubrich Collection.

Doran, I. c, p. 396.

E. 881. Stoat {Putorius ermineus) : three tympanic bones (two
left and one right), of which two have the membrana
tympani and malleus still attached ; the bony labyrinth of
both sides ; the right ossicula ; and the left stapes.

Max Hubrich Collection.

E. 882. Pole - Cat (Putorius putorius) : tympanic bone and
ossicula of both sides, with the right bony labyrinth.

M.C., 696.
Max Hubrich Collection.

E 883 American Mink (Putorius vison) : ossicula of the left
side. M.C., 727.

Doran, I. c, p. 396.

E. 884. Pine-Marten (Mustela martes) : the tympanic bone and
ossicula of both sides, with part of the right bony labyrinth.

M.C., 677.
Max Hubrich Collection.

E. 885. American Sable (Mustela americana) : malleus and
incus of both sides. Osteol. Series, 687 ; M.C., 687.

Presented by the Smithsonian Institution.

E. 886. Glutton (Gulo luscus) : ossicula of the right side.

Osteol. Series, 730 ; M.C., 730.

Hunto'ian.

Doran, I. c, p. 396.

ORGANS OF SPECIAL SENSE. — VERTEURATA.

275

E. 887. Common Otter {Lutra lutra) : part of the right side of
the skull with tlie tympanum and internal ear exposed.
The floor of the bulla has been removed to show the partial
separation of the tympanum into median and outer
chambers. The membrana tympani and ossicles have been
i-etained in their natural position. M.C., 761 A.

E. 888. Common Otter (Lutra lutra), young : the left tympanic
bone, bony labyrinth, and ossicula. The right malleus and
stapes from another individual have been mounted below.

M.C., 761.
Max Hiihrich Collection.

Doran, I. p. 397.

E. 889. Common Otter {Lutra lutra) : bony labyrinth of the
left side with its cavities partly exposed. M.C., 761 b.

E.. 890. Common Otter (Lutra lutra) : ossicula of the left side.

Osteol. Series, 771 ; M.C., 771.

E. 891. Javan Otter (Lutra cinerea) : right malleus and incus.

M.C., A777.

E. 892. Sea-Otter (Enliydra lutris) : ossicula of both sides.

M.C., 779.

Doran, I. c, p. 397.

CYNOIDBA.

E. 893. Indian Wild Dog (Canis indianensis) : left malleus and
incus, and right malleus. Osteol. Series, 537 ; M.C., 537.

Presented hy Mrs. J. P. H. Walker.

. 894. Dog (Canis familiaris) : tympanic bone and ossicula of
both sides, with the right bony labyrinth and an imperfect
cast of the cavity of the left. The malleus is retained in
position upon the right tympanic bone. M.C., 564.

Max Hubrich Collection.

Doran, I. c, p. 394.

T 2

27G PHYSIOLOGICAL SERIES.

E. 895. Dog (Canis familiaris): tympanic chamber and bony
labyrinth of the left side. The membrana tympani has
been preserved and the tympanic bulla laid open.

M.C., 564 a.

E. 896. Dog (Canis familiaris) : portion of the right internal
ear, with the malleus in position. A left malleus is mounted
separately. M.C., 564 B.

E. 897. Dog (Canis familiaris) : ossicula from the skull of a
very large young individual. M.C., 564 C.

E. 898. Common Wolf (Canis lupus): left tympanic bone and
bony lab3a-inth, with the right ossicula. M.C., 623.

Max HUbrich Collection.

E. 899. Wolf (Canis lupus) : right bony labyrinth, with the left
malleus and stapes. M.C., 623 a.

Max Hubrich Collection.

E. 900. Fox (Vulpes vulpes) : bony labyrinth and ossicula of the
right side. M.C., 654 a.

Max HUbrich Collection.

Doran, I. c, p. 395.

E. 901. Red Fox (Vulpes fulva) : ossicula of the right side.

M.C., 656.

Doran, I. c, p. 395.

E. 902. Arctic Fox ( Vulpes lagopus) : right malleus and incus,
and left stapes. Osteol. Series, 660 ; M.C., 660.

Doran, I. c, p. 395.

E 903. Arctic Fox ( Vulpes lagopus) : malleus and incus of
both sides. M.C.,660A.

E. 904. Cape Hunting-Dog (Lycaon pictus) : malleus and incus
of both sides.

Doran, I. c, p. 395.

E 905 Bush-Dog (Speothos venaticus) : ossicula of both sides.

Osteol. Series, 533 ; M.C., 533.

ORGANS OF SPECIAL SENSE. — VERTEBRATA. 277

E. 908. Long-eared Fox (Otoc?/on meffalotis) : right malleus and
incus. Osteol. Series, 673 ; M.C., 673.

Doran, I. c, p. 395.

AILUROIDBA.

E. 907. Aard Wolf (Proteles cristatus) : malleus and incus of
both sides. M.C., 509.

Doran, I. c, p. 392.

E. 908. Spotted Hysena {Hycena crocuta) : ossicles of the right
side, and the left malleus. M.C., 524.

Doran, I. c, p. 391.

E. 909. Striped Hysena {Hycena hycena) : malleus of the right
side. M.C., 516.

E. 910. African Civet Cat ( Viverra civetta) : ossicula of the
right side, from a young individual.

Osteol. Series, 454 ; M.C., 454.

Doran, I. c, p. 393.

E. 911. Rasse ( Viverra malaccensis) : ossicula of both sides.
The malleus and incus from Osteol. Series, 458 ; the stapes
from another individual. M.C., 458.

Doran, I. c, p. 393.

E. 912. Common Genet (Genetta vulgaris) : left malleus, right
incus, and stapes. M.O., 468.

Doran, I. c, p. 393.

E. 913. Two-spotted Paradoxure {Nandinia hinotata) : malleus
and incus of the right side.

Osteol. Series, 473 ; M.C., 472.

Doran, I. c, p. 393.

E. 914. Gray's Paguma {Paradoxurus grayi) : right malleus
and incus. ^ M.C., a478.

Doran, /. c, p. 393.

278 PHYSIOLOGICAL SERIES.

E. 915. Musanga Paradoxure (Paradoxurus Jiermaphrodi/ta) :
right malleus and incus (Osteol. Series, 479), with the
right malleus from another specimen. M.C., 479.

Doran, c, p. 393.

E. 916. Parodoxurus sp. : ossicula of the left side. The stapes
is imperfect. Osteol. Series, 482 ; M.O., 481.

Presented hy Bryan H. Hodgson^ Esq,

E. 917. Binturong (Arctictis hinturong) : right incus and stapes
(Osteol. Series, 486), with the right malleus of another
individual. M.C., 486.

Doran, I. c, p. 393.

E. 918. Cynogale hennetti : right ossicula. M.C., 489.

Doran, I. c, p. 393.

E. 919. Eupleres (joudoti : ossicula of the right side and the left
malleus. M.O., 490.

Doran, I. c, p. 393.

E. 920. Grey Ichneumon {Herpestes griseus) : ossicula of the
right side. Osteol. Series, 494 ; M.C., 493.

Presented hy W. Crozier, Esq.

Doran, I. c, p. 394.

E. 921. Grey Ichneumon (Herpestes griseus) : right malleus and
incus. Osteol. Series, 495 ; M.C., 494.

Presented by W. Crozier, Esq.

E. 922. Nepalese Ichneumon {Herpestes auropunctatus) : ossicula
of the right side. M.C., 499.

Doran, I. c, p. 394.

E. 923. Marsh-Ichneumon (Herpestes galera) : left malleus and
right incus and stapes. Osteol. Series, 503 ; M.C., 503.

E. 924. Dustj Ichnenmon (Herpestes pulve7'ulentus) : ossicula of
the right side and the left malleus and incus.

M.C., A 492.

Doran, 1. c, p. 394.

ORGANS OF SPECIAL SENSE. — VERTEBRATA. 279

E. 925. Banded Ichneumon (CrossarcJius fasciatus) : ossicula of
both sides. M.C., A 501.

E. 926. Suricate (Suricata tetradactyla) : ossicula of the left
side, and the right malleus. Osteol. Series, 508 ; M.O., 508.
Doran, I. c, p. 394.

E. 927. Foussa {Cryptoprocta ferox) : ossicula of the right side.

Osteol. Series, 450 ; M.O., 450.

Doran, I. c, p. 394.
E. 928. Cheetah (Cyncelurus jubatus) : right malleus.

iM.C, 439.

Doran, 1. c, p. 391.

E. 929. Northern Lynx (Felis lynx) : malleus and incus of both
sides. Osteol. Series, 436 ; M.C., 436.

Doran, /. c, p. 391.

E. 930. Persian Lynx (Felis caracal) : right malleus and stapes.

Osteol. Series, 433 ; M.C., 433.

E. 931. Persian Lynx (Felis caracal): malleus and stapes of the
right side, with a left incus. Osteol. Series, 434; M.C., 434.
Doran, I. c. p. 391.

E. 932. Persian Lynx (Felis caracal) : left malleus and incus.

Osteol. Series, 432 ; M.C., 432.

ITunterian.

E. 933. Cat (Felis domestica) : ossicula and tympanic bones of
both sides, from a new-born kitten. M.C., 419 d.

E. 934. Cat (Felis domestica) : bony internal ear and tympanic
bulla of the left side. Parts of the outer and of the inner
walls of the bulla have been removed to show the ossicles
and the separation of the tympanum into inner and outer
chambers (cf. Physiol. Series, A 200), M.C., 419 a.

E. 935. Cat (Felis domestica) : bony labyrinth, ossicula, and
tympanic bone of the right side, from a kitten. The tym-

280

PHYSIOLOGICAL SERIES.

panic bone shows the separate ossification that forms the
■wall of the inner chamber of the auditory bulla.

M.C., 419 b.
Max Hilhrich Collection.

Doran, I. c, p. 391.

E. 936. Cat (Felis domestica) : left bony labyrinth, ossicula, and
tympanic bone, from a kitten. The membrana tympani
has been preserved, with the malleus in position. The
inner wall of the bulla has been mounted separately.

M.O., 419 c.
Max Huhrich Collection.

E. 937. African Golden Cat (Felis chrysotlirix) : right malleus
and incus. Osteol. Series, 393 ; M.C., 393.

Presented by Staff-Surgeon J. R. Thomas.
Doran, /. c, p. 391.

E. 938. Leopard {Felis pardus) : the malleus and incus of the
left side, from a young specimen (Osteol. Series, 368),
with the left stapes of an adult. M.C., 368.

Doran, I. c, p. 391.

E. 939. Leopard (Felis pardus) : left malleus and incus.

Osteol. Series, 364 ; M.C., 364.
Presented by Dr. B. C. Henderson.

E. 940. Lion (Felis lea) : ossicula of both sides, from an infant
lion with a cleft palate. M.C., 312 B.

Doran, I. c, p. 391.

E. 941. Lion (Felis leo) : right malleus and left incus.

M.C., 312 A.

INSEOTIVOEA.
Doran, I. c, p. 443.

INSECTIVORA VERA.
TUPAIWJE.

E. 942. Tupaia (Tupaia tana) : left malleus and incus, and right
stapes. M.O., 3373.

Doran, I. c, p. 441.

ORGAKS OF SPECIAL SENSE. — VERTEBKATA.

281

MACROSCELIDJE.

E. 943. Elephant-Shrew (Macroscelides intuft) : ossicula of the
left side. Osteol. Series, 3367 ; M.C., 3367.

Presented by the Zoological Society.

Dorarij I. c, p. 440.

E. 944. Rhynchocyon cirnei : ossicula of the left side.

Osteol. Series, 3370; M.C., 3370.

Doran, I. c, p. 441.

EBINACEID^.

E. 945. Gymnura gymnura : ossicula of the right side, with the
malleus and stapes of the left.

Osteol. Series, 3364 ; M.C., 3364.

Doran, I. c, p. 439.

E. 946. Hedgehog {Erinaceus europceus) : the bony labyrinth,
ossicula, and tympanic bone of the right side.

M.C., 3359 A.
Max Hubricli Collection.

Doran, I. c, p. 438.

E. 947. Hedgehog (Erinaceus europams, var. dealhatus) : malleus
and stapes of both sides. M.C., A 3359.

SORICID^.

E. 948. Common Shrew (Sorex araneus) : bony labyrinth,
ossicula, and tympanic bone, of both sides. M.C., 3346.

Max Huhrich Collection.

Doran, I. c, p. 434.

E. 949. Common Shrew (Sorex araneus) : bony labyrinth, ossi-
cula, and tympanic bone of the right side. M.C., 3346 A.

Max Huhrich Collection.

E. 950. Sorex sp. : malleus and incus of both sides, from a laroe
American species. The left malleus is attached to the
tympanic bone. M.C., 3346 b.

Doran, I. c, p. 433.

282

PHYSIOLOGICAL SERIES,

TALPIDAi.

E. 951. Desman {Myogale moschata) : ossicula of both sides.

M.C., 3338 A.
Presented by A. 11. Garrod, Esq.

Doran, I. c, p. 434.

E. 962. Desman (Myogale moschata) : ossicula of tlio left side.

Osteol. Series, 3338 ; M.C., 3338.

E. 953. Star-nosed Mole {Condylura cristata) : malleus and
tympanic bone of both sides, and the right incus.

M.C., A 3337.

Doran, I. c, p. 437.

E. 954. Mole ( Talpa europcea) : the bony labyrinth and ossicula
of the right side. The stapes is in position. M.C., 3337 b.

Max Hubrich Collection.

Doran, I. c, p. 436.

E. 955. Mole (Talpa europcea): malleus and incus o£ both sides.

M.C., 3337 c.

S0LEN0D02rriD^.

E. 956. Almiqui (Solenodon cubanus) : left malleus.

Osteol. Series, 3326 ; M.C., 3326.

Doran, I. c, p. 440.

CENTETID^.

E. 957. Tenrec (Centetes ecaudatus) : left malleus, with right

incus and stapes. M.C., 3320.
Doran, I. c, p. 440.

E. 958. Ericulus setosus : ossicula of the right side. M.C., 3324.
Doran, I. c, p. 440.

E. 959. Ericulus setosus : malleus, tympanic bone, and stapes of
the left side. M.C., 3324 a.

COBYSOCHLOniDuE.

E. 960. Cape Golden Mole {ChrysocJdoris aurea) : ossicula of
the right side (Osteol. Series, 3318, Hunterian), and right

ORGANS OF SPECIAL SENSE.- — VERTEBRATA.

283

malleus and incus from another specimen (Physiol, Series,
2069). The head of the malleus is of relatively enormous
size. M.C., 3318.

Doran, I. c, p. 437.

DERMOPTERA.
GAT.EOPITHECIDjE.

E. 961. Colugo {Galeopithecus volans) : ossicula of both sides.

Osteol. Series, 3378 ; M.C., 3378.
Presented by the Zoological Society.

Doran, I. c, p. 442.

E. 962. Colugo (Galeopithecus volans) : ossicula of the left side.

M.O., 3378 A.

CHIROPTEEA.
Doran, I. c, p. 449.

MEGACHIROPTBRA.

E. 963. Fruit-Bat (Pteropus medius) : ossicula of both sides.
The right malleus is attached to the tympanic bone.

Osteol. Series, 3384 ; M.C., 3384.

Doran, I. c, p. 445.

E. 964. Javanese Fruit-Bat (PieropMs/t^/pomeWs): the ossicula
of the left side, with the right malleus and incus. Both
mallei are damaged. M.C., A 3382.

MIOROCHIROPTERA.
nmNOLOPHID^.

E. 965. Phyllorhina tridens : malleus and tympanic bone of the

1^^'* M.C., 3398.

Doran, I. c, p. 446.

E. 966. Phyllorhina speoris : ossicula of both sides. The rio-ht
malleus is attached to the tympanic bone. The right stapes
is damaged. M.C., A .3400.

Presented by G. E. Dobson, Esq.

28i

PHYSIOLOGICAL SERIES.

VESPERTILIONJDM.

E. 967. Loug-eared Bat (Plecotus auritus) : bony labyrinths,
and right tympanic bone with the malleus attached.

M.O., 3402.

Doran, /. c, p. 448.

E. 968. Vesperugo serotinus : ossicula, bony labyrinth, and tym-
panic bone of right side. M.C., 3403 a.

Max Huhrich Collection.

Doran, I. c, p. 448.

E. 969. Vesperugo serotinus : ossicula, bony labyrinth, and tym-
panic bone of the left side. The malleus is attached to the
tympanic bone. M.C., 3043 b.

Max Huhrich Collection.

E. 970. batterer's Bat ( Vespertilio natteren) : left bony labyrinth
and incus, and tympanic bone and malleus of both sides.

M.C., 3410.

Doran, I. c, p. 448.

EMBALLONURID^.

E. 971. Rhynclionycteris naso : bony labyrinth, tympanic bone,
malleus, and incus of the right side. M.C., B 3414.

E. 972. Taphozous melanopogon : tympanic bone and malleus of
both sides. M.C., a 3414.

E. 973. Molossus rufus : left malleus and tympanic bone.

M.C., 3414.

Doran, I. c, p. 449.

PHrLLOSTOMID^.

E. 974. Cliilonycteris parnellii : malleus and incus of both sides.

Osteol. Series, 3415 ; M.C., 3415.
Presented hy Lucas Barrett, Esq.

Doran, I. c, p. 449.

E. 975. Mormops blainvillei : malleus, incus, and tympanic bone
of the right side. Osteol. Series, 3416 ; M.C, 3416.

Presented hy Lucas Barrett, Esq.

Doran, I. c, p. 449.

ORGANS OF SPECIAL SENSE. — VERTEBRATA.

285

PEIMATES.
Doran, I. c, pp. 379, 382, 389.

LEMTIROIDBA.
CmROMYIDJE.

E. 976. Aye-Aye {JDaubentonia [^Chiromys] madagascariensis) :
ossicula of left side, with another left malleus and right
incus and stapes. The upper set are from Osteol. Series,
302 ; the lower from Osteol. Series, 301. M.C., 302.

Doran, I. c, p. 388.

E. 977. Aye-Aye {JDaubentonia madagascariensis) : ossicula of
the left side.

TABSIID^.

E. 978. Tarsier (Tarsius tarsius) : ossicula and tympanic bones of
both sides, from a young specimen. M.C., 300.

Doran, I. c, p. 388.

E. 979. Tarsier (Tarsius tarsius) : malleus and incus of both
sides. M.C., 300 a.

E. 980. Bosman's Potto (Perodicticus potto) : ossicula of the
right side, from an adult. M.C., 295.

Doran, 1. c, p. 388.

E. 981. Tailless Potto (Arctocebus calabarensis) : malleus of
both sides. Osteol. Series, 297 ; M.C., 297.

Presented by Andrew Murray, Esq.

Doran, I. c, p. 388.

E. 982. Slender Loris {Loris gracilis) : ossicula of the left side.

Osteol. Series, 290 ; M.C., 290.

Doran, I. c, p. 388.

E. 983. Slow Loris (Loris tardigradus) : ossicula of the right
side, and another right malleus.

Osteol. Series, 291 ; M.C., 291.

Presented by Sir Stamford Raffles.

Doran, I. c, p. 387.

286

rilYSTOLOGICAL RERIRS.

E. 984. Javan Loris {Nycticehus javanicus) : left malleus,

Osteol. Series, 293 ; M.C., 293.

E. 985. Grand Galago {Galago crassicaudatus) : ossicula of the
right side. ' M.C., 283.

Doran, I. c, p. 387.

E. 986. Allen's Galago {Galago alleni) : ossicula of the left side,
and malleus and incus of the right. M.C., 287.

LEMURIDJE.

E. 987. Chirogaleus pitsillus : malleus and incus of both sides.

Osteol. Series, 281; M.C., 281.

Doran, I. c, p. 387.

E. 988. Chirogaleus pusillus : right malleus.

Osteol. Series, 282 : M.C., 282.

E. 989. Lepidolemur mustelinus : ossicula of the right side.

Osteol. Series, 278 ; M.C., 277.

E. 990. Ruffed Lemur (Lemur varius) : tympanic bone and
malleus and incus of both sides, with a damaged right
stapes. Osteol. Series, 262 ; M.C., 262.

Doran, I. c, p. 386.

E. 991. White-fronted Lemur (Lemur mongos) : ossicula of the
left side. Osteol. Series, 274 ; M.C., 274.

Doran, I. c, p. 386.

E. 992. Black-fronted Lemur (Lemur mongos) : ossicula of the
leftside. M.C., C276.

Doran, I. c, p. 386.

E. 993. Ring-tailed Lemur (Lemur catta) : ossicula of the left
side. Osteol. Series, 269 ; M.C., 269.

Doran, I. c, p. 386.

E. 994. Yellow-whiskered Lemur (LmMr.ra?ii/to??J?/s^a.r): ossicula
of the left side. M.C., b 276.

Doran, I. c, p. 386.

ORGANS OF SPECIAL SENSE. — VERTEBRATA. 287

E. 995. Lemur sp. : the left bulla, prepared to show the tympanic
ring. M.d., A 269.

E. 996. Woolly Lemur {Avahis laniger) : ossicula of the right
side. A bony canal was found between the crura of the
stapes. M.C., 258.

E. 997. Diadem Lemur (Propithecus diadema) : ossicula of the
right side, and malleus and incus of the left. M.O., A 256.
Doran, I. c, p. 386.

E. 998. Diadem Lemur (Propithecus diadema) : ossicula of both
sides. Osteol. Series, 256 ; M.C., 256.

ANTHROPOIDBA.

E. 999. Midas geoffroyi: ossicula of the right side, with the

malleus and incus of the left. M.C., B 244.
Doran, I. c, p. 385.

E. 1000. Pinche Monkey {Midas wdipus) : ossicula of the right
side. M.C., 244 a.

Doran, I. c, p. 385.

E. 1001. Pinche Monkey (Midas osdipus) : malleus and incus of
both sides. Osteol. Series, 244 ; M.C., 244.

E. 1002. Red-handed Tamarin (Midas midas) : left malleus and
incus. M.C., A 244.

E. 1003. Marmoset (Hapale jacchus) : ossicula of the left side.

M.C., 249.

Doran, I. c, p. 385.

E. 1004. Marmoset (Hapale jacchus) : left malleus and incus.

Osteol. Series, 250 ; M.C., 250.

Presented hy the Zoological Society.

E. 1005. Hapale melanura: left ossicula. M.C., A 251.

Doran, I. c, p. 385.

288

PHYSIOLOGICAL .SEItlES.

E. 1006. Silky Howler (Alonata senicula) : ossicula of the left
side. Osteol. Series, 239 ; M.C., 239.

Doran, I. c, p. 384.

E. 1007. Mycetes ursinus : ossicula o£ the right side, with the left
malleus and incus. M.C., A 242.

Doran, I. c, p. 384.

E. 1008. Red Howler {Alonata senicula) : right malleus and
incus. M.C., 23(5.

Doran, I. c, p. 384.

E. 1009. Black Saki (Pithecia satanas) : left malleus and incus.

Osteol. Series, 233 ; M.C., 233.

Doran, I. c, p. 385.

E. 1010. Feline Douroucouli (Aotus vociferans) : ossicula of the
right side. The malleus and incus from Osteol. Series, 228;
the stapes from another individual. M.C., 227.

Doran, I. c, p. 384.

E. 1011. Feline Douroucouli (Aotus vociferans) : ossicula of
the right side. Osteol. Series, 227 ; M.O., 228.

E. 1012. Feline Douroucouli (Aotus vociferans) : ossicula of the
right side. M.C., 228 a.

E. 1013. Black-handed Spider-Monkey {Ateles geqffroyi) : ossi-
cula of both sides. M.C., 218.
Doran, I. c, p. 383.

E. 1014. Brown Spider-Monkey {Ateles hyiridus) : incus and
stapes of both sides. Osteol. Series, 220 ; M.C., 220.

Doran, I. c, p. 383.

E. 1015. Black-faced Spider-Monkey (Ateles ater) : ossicula of
both sides. M.C., 219.

Doran, I. c, p. 383.

OUGANS OF SPECIAL SENSE. — VBRTEBRATA. 289

E. 1016. Capuchin {Cebus capudnm) : ossieula of the right side.

Osteol. Series, 209 ; M.C., 209.

Hunterian.

Doran, L c, p. 384.

E. 1017. White-cheeked Capuchin {Ceh\u^ lunatus) : ossieula of
the left side. M.C., A 215.

E. 1018. Cebm sp. : ossieula of both sides. M.C., 214.

E. 1019. Squirrel- Monkey {Chrysothrix scnirea) ; ossieula of the
right side, and malleus and incus of the left.

Osteol. Series, 204 ; M.C., 204.

South Collection.

Doran, I. c, p. 385.

CERCOPTTHECfD^.

E. 1020. Anubis Baboon {Pa2no anuhis) : ossieula of both sides.

M.C, 188.

Doran, I. c, p. 382.

E. 1021. Chacma Baboon (Papio porcariuS) : ossieula of the right
side. M.C, 191.

E. 1022. Black Ape {Cynopithecus niger) : ossieula of both sides.

M.C, 177.

Doran, I. c, p. 382.

E. 1023. Rhesus Monkey (Macacus o^hesus): ossieula of both
sides. From a new-born male.

Osteol. Series, 159 ; M.C, 159.

Presented hy the Zoological Society.
Doran, I. c, p. 381. J y

E. 1024. Pig-tailed Monkey {Macacus nemestrinus) : ossieula of
both sides. M.C, 165.

E. 1025. Macaque (Macacus cynomolgus) : ossieula of both sides.

M.C, 134.

E. 1026. White-collared Mangabey {Cercocehus collaris): left
malleus and incus. M.C 129.

VOL. UL u

290 PHYSIOLOGICAL SERIES.

E. 1027. Moustache Monkey (Cercopithecus cephis) : ossicula o£
both sides. M.C., 123.

E. 1028. Malbronck Monkey (Cercopithecus cynosurus) : ossicula
of both sides. M.C., A 128.

Doran, I. c, p. 381.

E. 1029. Diana Monkey (Cercopithecus cliana) : ossicula of the
right side. M.C., 121.

Doi-an, I. c, p. 381.

E. 1030. Cercopithecus sp. : the ossicula of both sides, lacking
the right stapes, and casts of the cavities of the bony
labyrinths. M.C., B 128.

Max Huhrich Collection.

E. 1031. Entellus Monkey (Semnojnthecus entellus): .ossicula of
both sides. M.C., 91.

Doran, I. c, p. 380.

E. 1032. Semnopithecus sp. : the ossicula of both sides, with the
left bony labyrinth and a cast of the interior of the right
bony labyrinth. M.C, 91 A.

Max Huhrich Collection.

E. 1033. Semnopithecus sp. : three left mallei and a right incus
and stapes. M.O., 95.

E. 1034. Black Colobus (Colobus satanas) : ossicula of the right
side. M.C, 81.

Doran, I. c, p. 381.

E. 1035. King Colobus (Colobus polijcomus) \ left malleus and
incus. M.C, A 81.

SIMIID^.

E. 1036. Silvery Gibbon (Hylohates leuciscus) : ossicula of the
right side. Osteol. Scries, 65 ; M.C, 65.

Presented hij Dr. B. C. Henderson.

Doran, I. c, p. 379.

ORGANS OF SPECIAL SENSE. — VERTEBRATA. 291

E. 1037. Siamang [Ilylohates syndactylus) : ossicula of the left
side, and malleus and incus of the rieht.

Osteol. Series, 61 ; M.C, 61.

P- , „„„ Brookes Collection.

Doran, I. c, p. 379.

E. 1038. Ilylohates sp. : ossicula of the right side.

Osteol. Series, 70 ; M.C, 70.

E. 1039. Orang-utan (Simia satyrus) : ossicula of both sides.

r> 7 o^o M.C, 38.

Doran, I. c, p. 378.

E. 1040. Gorilla (Anthropopithecus gorilla) : ossicula and tym-
- panic bone of the right side, from a fcetus of full term.

n ; M.C, 30 a.

Doran, I. c, p. 377.

E. 1041. Gorilla (Anthropopithecus gorilla) : ossicula and tym-
panic bone of the left side, from the same individual.

M.C, 30 b.

E. 1042. Gorilla (Anthropopithecus gorilla) : malleus and incus
of both sides, from a young specimen. M.C, 30.

E. 1043. Gorilla (Anthropopithecus gorilla) : left malleus.

M.C, 30 c.

E. 1044. Chimpanzee (Anthropopithecus troglodytes) : ossicula of
the left side, and the malleus and incus of the right.

rv 7 o^o ^-^^v 12 A.

Doran, I. c, p. 378.

E. 1045. Bushman : right malleus, and the left incus and stapes,
-brom the female Bushman described in Journ. Anat. and
Physiol. 1867. Osteol. Series, 1302 ; M.C, 1302.

E. 1046. Two right and two left tympanic bones from new-born
infants ; in one (left) the malleus and membrana tympani
are retained in position. Max Eubrich Collection.

V 2

292

rilYSIOLOGICAL SERIES.

E. 1047. Right squamosal and tympanic bones from a foetus of
the ninth month, with the ossicles in position, seen from
the inner aspect. Max Ilubrich Collection.

E. 1048. Right bony labyrinth and left ossicula of a new-born
child. Max Hiihrich Collection.

E. 1049. Left bony labyrinth of a new-born child, roughly dis-
sected. Max IluhricJi Collection.

E. 1050. Right and left malleus and incus of the Irish Giant,
O'Brian. Osteol. Series, 223 ; M.C., 223.

E. 1051. A collection of 25 right stapedes.

E. 1052. A collection of 17 left stapedes.

E. 1063. Two sets of ossicula of the right side.

Max Hiihrich Collection.

Doran, I. c, p. 372.

E. 1054. Two sets of ossicula of the left side.

E. 1055. Ossicula of the right side. 0. C. (Physiol), 1602 f.

E. 1056. Right bony labyrinth, opened from the tympanic aspect.
The left ossicula articulated. Max Hiihrich Collection.

E. 1057. Left bony labyrinth, with the cochlea laid open.

Max HUhrich Collection.

E. 1058. Right bony labyrinth, right malleus, and left incus and
stapes. Max HUhrich Collection.

E. 1059. Left bony labyrinth, with the cochlea laid open to show
the lamina spiralis. Max HUhrich Collection.

E. 1060. A similar specimen. Max HUhrich Collection.

ORGANS OF SPECIAL SENSE. — VERTEBRATA. 293

E. 1061. Right bony labyrinth, with fine bristles passed into the
aqueducts of the vestibule and cochlea.

Maw Huhrich Collection.

E. 1062. Left bony labyrinth. Max Huhrich Collection.

E. 1063. Left bony labyrinth, with the cochlea, canals, and
vestibule laid open. Max Huhrich Collection.

E. 1064. A similar specimen^ opened upon the reverse side.

Max Huhrich Collection.

E. 1065. Left bony labyrinth and ossicula. The stapes is
attached to the foramen ovale, and the malleus and incus
are articulated. Max Huhrich Collection.

VISUAL ORGANS.

Carriere, Die Sehorgane der Thiere, 1885 {anat.).

Living matter is capable of response to light stimulation
without any apparent special modification of sti-ucture, such
response being manifested by movements to or from the source
of light (Heliotropism). But in the majority of animals parti-
cular cells of or derived from the epidermis are specially
modified, either singly or in groups, to act as light receptive or
visual organs. In these organs the sensory cells are, so far as
observed, always senso-neural, like those of the olfactory epithe-
lium, i. e. sensory cell and nerve-fibre combined, the body of the
cell being drawn out proximally to form the nerve-fibre and
surmounted distally by a refractive rod-like end organ by which
ihe stimulation is actually received. The simplest forms of
light receptive organs are patches of pigmented epithelium,
which, owing to their greater absorptive power, are more open to
light- and also probably heat-stimulation than the neighbouring
integument ; but in most cases rod-bearing sensory cells are
present, which may be themselves pigmented or may be partly
surrounded by pigment, the object of the pigment being appa-
rently to ensure that the hght shall strike one special part of

294

rFFYSIOLOGICAL SERIES.

the end organ only, and, in llio more perfect foms of eye, to
absorb diffuse reflected light and thus prevent halation. Very
generally between the sensitive membrane (retina) and the
source of light some form of lens is interposed, by which the
light can be concentrated and brought to a focus upon the end
organs of the retina. Around these more essential parts of the
visual organ vascular and protective capsules are developed in
the case of the larger and more perfect forms of eye.

From a physiological point of view, light receptive organs
can, in idea though not so readily in practice, be separated into
those without powders of vision in the ordinary sense of the term,
but which enable the brain to distinguish light from darkness,
and in their more developed forms are sensitive to alterations of
light and shade, and thus in a vague way to movement; and
into true visual organs, in which by accurate focussing of light
reflected from external objects upon the retina, pictures of the
outside world are formed and transmitted to the brain. In eyes
of this kind the focussing-apparatus is usually not fixed, but is
capable of adjustment, so that the focus may be accommodated
for light proceeding from objects at different distances from the
eye. In the more perfect forms of eye the individual cells of
the retina are not only sensitive to variations in the quantity of
light which give rise in the brain to the perception of form,
but also to differences in the rate of vibration upon which
depends the sense of colour.

INVERTEBRATA.

Hesse, Zeitschr. f. wiss. Zool. Bd. Ixxii. 1902, p. 589.
Beer, Wiener klin. Wochenschr. 1901, Nos. 11, 12, 13.

The eyes and light perceptive organs of most Invertebrata
are too small to be included in this collection, so that very little
idea can be given of their variations in structure and extent of
occurrence in this Sub-kingdom. As a matter of fact, eyes
varying from single cells (Earthworm) and mere pigment spots
to highly complex visual organs are found fairly generally dis-
tributed in all the main Phyla, the most perfect occurring, as
might be supposed, in the more active and predaceous forms
{e.g.. Errant Annelids, Dibranch Cephalopods, Heteropods, &c.),

ORGANS OF SPECIAL SENSE. — INVERTEBIIATA.

295

setlontary and buried forms being usually eyeless {e. g., Sponges,
Internal Parasites, most Pelecypods, Tube Worms).

In Invertebrates the eyes are formed by direct modification
of the epidermis and can be grouped into two main divisions : —
(1) Simple eyes, including pigment-spots, in which a certain
area of the integument is pigmented and otherwise modified to
form a continuous retina, upon which light either falls direct or
is concentrated by a single dioptric apparatus. Such eyes are
generally sunk below the skin in the form oi pits or vesicles,
the deep wall of which constitutes the retina, the outer wall
in the case of the complete vesicular form being transparent,
and with the overlying transparent skin and a mass of gela-
tinous secretion within the cavity of the vesicle forming the
dioptric apparatus. (2) Compound eyes (almost entirely con-
fined to Arthropods), in which each eye consists of a large
number of simple eyes packed together and isolated from each
other optically by pigment.

MOLLUSCA.

Hesse, Zeitschr. f. wiss. Zool. Bd. Ixviii. 1900, p. 379.

For the better understanding of the various forms of simple
eye that occur among the Mollusca a figure is given of the
vesicular eye of a Helix pomatia (PI. II. figs. 1, 2), which in con-
struction occupies a fairly central position among eyes of this
kind, and thus makes a good standard of comparison for inter-
preting the structure of both the simpler and the more complex
eyes formed on the same plan.

E; 1066. A Chiton (Acantliopleura spiniger). Scattered irregu-
larly over the marginal parts of the lateral areas of the
shells are a number of minute black specks. These are the
transparent chitinous cornese of eyes of a simple kind.
Each cornea is externally convex and covers over a pear-
shaped chamber in the tegmentum, or superficial layer of
the shell, in which the soft parts of the eye are lodged.
This ocular cavity in the shell is lined by a pigmented
capsule, the distal parts of which are slightly inturned to
form an iris. Within the capsule are a hom,ogeneous

2UG PHYSIOLOGICAL BEIUES.

biconvex lens and a cup-shaped retina of simple structure.
The retina is innervated by a large nerve which forms part
of the system of nerves that enters the shell in the groove

Fig. 47.

Diagram of eye of Acanthoplmra spiniger. (After Moseley.)

JEi. Esthetes. C. Pigmented capsule of the eye. CN. Cornea. I. Iris.
L. Lens. N. Optic nerve. R. Eetina.

between its superficial and deep layers, and supplies a series
of integumentary sense-organs of obscure function, known
as esthetes. There is little doubt that the eyes are aesthetes
that have undergone special adaptation. 0. C. 1627 a a.

Moseley, Quart.* Jour. Micr. Sci. vol. xxv. 1885, p. 45.

Plate, Zool. Jahrb. Suppl. Band. v. 1892, p. 5U2.

E. 1067. An enlarged model of a portion of the lateral area of a
shell and neighbouring parts of the mantle of a Chiton
(AcantJwpleura spiniger), showing a cluster of eyes. In
the centre of each eye is a black spot representing the
pupil seen through the transparent cornea. 0. C. 1G27 A.

PI . II

J.Green liLh.

PLATE II.

1. Longitudinal section through the eye of Helix aapersa,

X 100.

2. Longitucliniil. section through the retina of llelir

poDiufiu (after Backer *).

i\. Longitudinal section through the eye of Ferfea
jacohanis (after Patten).

•4, Part of the retina of Fecten jacobwiis, x 300 (after
Hawitz).

5. Median section through an onimatideuni of Pcviplamda
orientalis, x 700 (after Hesse).

0. Median section through the central ocellus of Jlelo-
phUuH sp., X 315 (after Hesse).

m., basemeiat membrane; c, cuticular cornea; c\ c', c\ the outer
epidermal, middle llbrous, and inner epidermal layers of the cornea ;
cc, crystal cones; ch., "choroid"; epidermis ;/., selvage of
terminal receptive fibrils (stiftchensaum) ; y., ganglion cells ;
(f, (J-, outer and inner layers of gangHon cells; /.,leus; optic
nerve ; p., pigment cells ; r., retinal cells ; r.c, rod-cells ; r.d., rods ;
/•.A.,rhabdome; t., tapetum lucidum; y., cavity of optic vesicle.

* Arbeit. Zool. Inst. Wien, T. xiv., 1903.

■.ffifintl'ufK,,

OllGANS OF SPECIAL SKNSE. — INVEllTEBUATA.

297

E. 1068. A Scallop (Feden sp.) with the left valve and mantle-
lobe removed. Along the margin of the mantle amongst
the fringe of tentacles are about thirty eyes, which in the
specimen appear as minute black rings surrounding a central
white area, but in life are brilliantly coloured. These eyes
(PI. II. figs. 3, 4), unlike those of most Molluscs, have
a striking similarity to the eyes of Vertebrates in that the
rods or terminal receptive organs of the retina face away
from the light instead of towards it. The eye is, never-
theless, an integumentary vesicle strictly comparable to
that of other Molluscs, but in which the cavity of the
vesicle has been lost owing to the invagination of its
anterior wall by a lens developed between it and the over-
lying epitheHum. The eye consists of an outer cornea
continuous with the epidermis of the ocular tentacle, of a
cellular lens attached to the deep surface of the cornea,
of a retina formed from the external half of the primary
optic vesicle, and in consequence with its rods turned away
from the light, and of a brilliantly coloured tapetum lucidum
and deeply pigmented " choroid " formed from the posterior
wall of the vesicle. 0. C. 1628 B.

Hesse, Zeits. f. wiss. Zool. Bd. Ixviii. 1900, p. 390.

E. 1069. Anterior part of an Apple Snail (AmpuUaria sp.),
showing the eyes. These are situated, as in most Proso-
branchs, on the outer side of the tentacles near the base.
Each is lodged in a short rounded process and consists of
a spherical vesicle lined by a deeply pigmented retina.
The cavity of the vesicle is filled by a firm transparent
body— the lens— which is probably secreted by the non-
sensory cells of the retina. The distal wall of the vesicle
and the skin overlying it are transparent and together
form the cornea. On the right, the eye has been longitu-
dinally divided, the lens has been removed and mounted
separately at the side, and the optic nerve has been exposed.

0. C. 1628 A a.

E. 1070. The proboscis, tentacles, and eyes of a Prosobranch
Gastropod. The eyes are situated at the free ends of a pair

298

PHYSIOLOGICAL iiliUlES.

of stout processes that form the hiteral and largest branches
of the bifurcated extremities of the tentacles. The speci-
men is much bleached, but the left eye can be recognised
by its transparent strongly convex cornea. The right eye
has been bisected to show the cavity of the optic vesicle.
The brain and proximal parts of the tentacular nerves have
been exposed. 0. C. 1G28 a.

E. 1070 a. The anterior parts of a Heteropod (Pterotrachea
eoronata), with the body-wall removed from the dorsal part
of the head to show the eyes and the dorsal ganglia. The
eyes are relatively larger than in most MoUusca, particu-
larly in comparison with the size of the cerebral ganglia.
In their high organisation as well as in size they form a
striking parallel to the eyes of Decapod Cephalopods,
which, like the Heteropods, are active free-swimming forms.
The detailed structure of the eyes has been described by
Grenacher. Each is composed of cornea and sclerotic,
choroid, lens, and retina, and is attached to a special optic
ganglion whose presence helps to explain the disproportion
in size between the eye and the cerebral ganglia. The lens
does not occupy the whole of the optic vesicle, but is sepa-
rated by fluid-filled spaces from the cornea and the retina.
Special muscles (one of which can be seen on the left side)
give considerable powers of independent movement to the
eyes. Upon the right side part of the cornea has been
removed to show the anterior chamber of the eye and the
lens.

Grenacher, Abhandl. naturf. Ges. Halle, Bd. xvii. 1892,
p.l.

E. 1071. Two specimens showing the eye and other cephalic
sense-organs of a Pearly Nautilus (Nautilus macro7nphalus).

The eye is a very simple structure compared with that
of the dibranchiate Cephalopods. It consists of a hemi-
spherical chamber of dense connective tissue lined by a
retinal membrane, and with its cavity in open communi-
cation with the surrounding water through a minute hole
in the centre of its flattened external wall. A slight super-
ficial groove leads from the hole to the lower border of the

ORGANS OF SPECIAL SENSE. — INVERTEBRATA.

299

eye. The nerve-supply to the retina is derived from a
relatively small optic ganglion attached to the outer end of
the cerebral ganglion (c/. D. 59).

The auditory organ is represented by a small spherical
vesicle lying on either side upon the posterior surface of
the pedal ganglion. Within the vesicle is a round otolith.

An olfactory function is supposed to be performed by a
deep integumentary pit situated immediately beneath the
eye, and also possibly by a pair of supraocular tentacles.

The lower specimen shows the left eye in its natural
relations to the other parts of the head. In the upper
specimen a dissection has been made of the right side of
the head from behind, showing the eye in section, the right
half of the brain with the optic lobe, the auditory vesicle
(indicated by black paper), the olfactory pit with a red
bristle placed behind its nerve, and the posterior of the two
supraocular tentacles. .0. C. 1646 D.

Merton, Zeits. f. wiss. Zool., Bd. Ixxix. 1905, p. 328
(p'etina),

E. 1072. The brain and eyes of an Octopus {Octopus vulgaris).
On either side of the cerebral ganglion is a large oval optic
ganglion, from whose distal surface a brush of nerve-fibres
are given off for the innervation of the retina. These
nerve-fibres enter the eye through perforations spread over
a large area of the deep surface of the cartilaginous capsule
in which the greater part of the globe of the eye is enclosed.
In front of the lens is an iris of silvery lustre, with a
tongue-like process projecting from its upper border.
Bateson states (Jour. Mar. Biol. Ass., vol. i. 1889, p. 216)
that in Cephalopoda the iris is contractile. 0. C. 1696 A.

E. 1073. Anterior portion of the head of a Cuttle-fish {Sepia
filliouxi) seen in section from behind. The posterior half
of each eye has been removed to show the relations of its
several parts to one another, and of the whole organ to the
central nervous system.

The eye is protected externally by a lower eyelid.
Individuals of the related genus Sepiola have been observed
to " sit on the ground with their eyes closed by the lower

I'll Y«R)L0U1CAL SKKIES.

lids throughout the day " (Buteson, Jour. Mar. Biol. Ass.,
vol. i. 1889, p. 216). Upon the section surface o£ the lid
can be seen the band of muscle by which this closure is
effected. The surface of the eye is covered by an extremely
delicate cornea, beneath which is a contractile iris. In the
specimen both these membranes are closely applied to the
surface of the lens. The hinder part of the globe of the
eye consists of a cai'tilaginous sclerotic capsule, lined by a
pigmented retina in which the pigment is situated in the
actual sensory cells.

The lens is a spherical body composed of transparent
concentric lamellae of homogeneous structure. It is sepa-
rated into a large inner and small outer portion by a mem-
brane (septum lentis), which })asses at its periphery into a
thick ring of epithelial cells (corpus epitheliale), which
serves for the suspension of the lens to the walls of the
globe, and also secretes the laminae of which the lens is
composed. The circum-cesophageal nerve-ring is shown
in the centre of the specimen. Between it and the deep
surface of either eye are the large optic ganglia. The
angles between the upper and lower surfaces of these
ganglia and the globe of the eye are filled by a white sub-
stance (white bodies), which probably are the degenerate
remains of brain-substance.

There is little difficulty in tracing the relationship of this
complex organ to the typical Molluscan vesicular eye. The
primitive vesicle is represented by the posterior chamber,
including the corpus epitheliale and its derivative — the
lens. External to this, subsequent insinkings of the in-
tegument have produced the iris, cornea, and lid.

The Dibranch Cephalopods are amongst the few Inver-
tebrates, if not the only ones, that have the power of
accommodation. In the resting condition the eye is
focussed for near vision, but by means of a circular muscle
passing forwards from the eye-capsule to the corpus
epitheliale the lens can be drawn towards the retina, thus
bringing more distant objects into focus. 0. 0. 1(346 B.

Hesse, Arch. f. Physiol., Bd. cix. 1905, p. 393.

Beer, Arch. ges. Physiol., Bd. Ixvii. 1897, p. 581
(^accommod.).

ORGANS OF SPECIAL SENSE. — INVERTBBRATA.

301

E. 1074. The head of a Cuttle-fish {Sepia officinalis) in which the
brain, optic ganglia, and ejcs have been exposed from
in front. The coverings of the right eye have been partly
removed to lay bare the sclerotic capsule, the iris, and the
front part of the lens. The left eye has been divided to
show its internal structure. 0. C. 1629.

Hunterian.

E. 1075. The eyes of a Cuttle-fish {Sepia officinalis) with the
outer integuments and the cornea removed. The lower
specimen shows from in front the peculiar shape of the
pupil, which is due to a bilobed process of the upper border
of the iris that extends downwards in front of the upper
half of the lens {cf. E. 1093, E. 1104). The upper specimen
is in vertical section and shows the relation of the iris to the
lens, and the division of the latter into two parts by the
corpus epitheliale and the septum lentis. 0. C. 1646 c.

E. 1076. The outer half of the eye of a Cuttle-fish {Sepia offici-
nalis) seen from within with the lens in situ. The lens is
attached to the anterior part of the sclerotic capsule by a
ring of tissue, radially pleated like the ciliary body of
the Vertebrate eye. This is the corpus epitheliale, which,
with its secretion (the lens), is the modified anterior wall
of the primary optic vesicle. 0. C. 1633.

Hunterian.

E. 1077. The lens and corpus epitheliale from the eye of a
Cuttle-fish {Sepia officinalis). Q. C. 1633 A.

Presented hy Sir AntJiony Carlisle.

E. 1078. The lens of the eye of a Cuttle-fish {Sepia officinalis)
in section. The concentric structure of the lens is apparent
owing to differences in the action of alcohol on its various
parts. In the centre is a hard transparent nucleus. This
is surrounded by a white opaque zone, and this again by a
translucent and an opaque layer. Q. C. 1636.

Hunterian.

Home, Phil. Trans., vol. 84, 1794, tab. v. fig. 1.

302

PHYSIOLOGICAL KERIES.

E. 1079. Two preparations showing the laminated structure of
the lens of a Cuttle-fish {Sepia of nnalis). 0. 0. 1639.

Huntenan.

E. 1080. A vertical section of the cje and optic ganglion of a
Cuttle-fish (Sepia ofidnalis). The separate nerve-bundles
given ofE from the ganglion are well shown passing
through the sclerotic to the retina. 0. C. 16.30.

Ilunterian.

ARTHEOPODA.

Hesse, Zeitschr. f. wiss. Zool., Bd. Ixx. 1901, p. 434.
Viallanes, Ann. Sci. Nat., ser. 7, t. xiii. 1892, p. 369
{Physiol.).

In Arthropods there occur compound eyes, in which what super-
ficially appears to be a single eye is in reality an aggregate of
many eyes, €ach with its own retina (retiuula) and dioptric
apparatus and separated from its neighbours by pigment-cells.
Grood examples of such eyes are found in Crustacea and in the
lateral eyes of Insects. When highly developed {e.g., some
Clrustacea, Lepidoptera), each single eye or ommatideum con-
sists of the parts shown in PI. II. fig. 5. The cornea (a
specialised part of the general cuticle of the head) and the
crystal cones form the dioptric apparatus ; the retinula consists
of several cells (7 usually) surrounding a central refriugent rod
(the rhabdom) composed of the rod-like receptive end organs
(rhabdomeres) of the retinula-cells, fused together. The entire
ommatideum is surrounded by pigment-cells. The whole
number of the ommalidea rest with their deep ends upon an
outwardly convex basement-membrane and radiate outwards
thence to the corneal surface of the eye, the curve of which
corresponds to that of the basement-membrane. Between the
rotinulge and the bi-ain is a complex optic ganglion. Simpler
forms of ommatidea are common in which, although the same
plan is kept, the details are less perfect. The crystal cones may
be absent (Coleoptera, Heteroptera) (acone eyes) or may be
represented by a space filled with a transparent fluid (Diptera)
(pscudocone eyes), or the cells of the retinulse may be more
independent, each containing a separate refringcnt rod (rhab-
domere) not united together centrally to form a rhabdom.

OKGANS OF SPECIAL SENSE. — INVERTEBRATA.

303

The mode of action of such eyes is still a debated point. The
most generally accepted hypothesis is that due to Johannes
Mullev, according to which each retinula is stimulated only by
light rays which are parallel to the long axis of the ommatideum.
Thus each retinula receives light only from one restricted spot
of the general field of vision, but the sum of these impressions
gives a complete erect picture formed like a mosaic of as many
pieces as there are retinulse. A critical discussion of thi.^ and
other hypotheses, including those of Grenacher, Exner, and
Lowne, will be found in Lowne's 'Anatomy of the Blowfly,^
vol. ii. 1893-95, pp. 554-582, but to those there mentioned
should be added that of Viallanes, which, like those of Exner
and Lowne, depends on the fact that each united cornea and
crystal cone when isolated can be seen to form a minute reversed
image of a considerable field. These images on Viallanes's
hypothesis are combined by the brain, as in ordinary binocular
vision, to form a single picture. If this is so, the vision, although
not very acute, would be highly stereoscopic and sensitive to
movement. Simple eyes are also found in many Arthropods
(Arachnoidea and the ocelli of Insects), which although ex-
tremely variable in the details of their structure are characterised,
broadly speaking, by a single cuticular lens overlying a cup-
shaped continuous retina (PI. II. fig. 6). Occasionally the
sensory cells are grouped to form retinulae, although still
covered by a single lens, giving a condition somewhat transi-
tional between a simple and a compound eye.

CEUSTAOEA.

E. 1081. A Crab (PodopJithalmus vigil). The compound eyes
are borne upon the ends of remarkably long pedicels. The
elongation is due to the length of their basal segments.
Between these segments and the small terminal ones that
carry the eyes are movable articulations, and as the whole
pedicel is also movably jointed to the carapace, the eyes
have a very extensive range of movement. When not in
use the eyes and pedicels can be placed for protection in a
deep groove situated along the anterior border of the
carapace. 0. C. 1626 b.

Presented hy the late F. C. Pascoe, Esq.

PHYSIOLOGICAL SEUIES.
ARACHNOIDEA.

E. 1082. Part of the carapace of a Scorpion (^Scorpio africanus)
showing the position of the eyes. These are eight in
number, two of large size situated near the mid-line one
on either side of a central prominence, and six smaller ones
lying at either anterior and lower angle of the carapace.
In the specimen both of the larger eyes are preserved (that
of the left side being in section), but of the smaller ones
only the three on the right side.

The central eyes of Scorpions differ in structure from the
lateral, and are intermediate between the simple and the
compound type. The retina is covered by a single lens,
but is divided into retinulae — the sensory cells being
grouped into separate bundles surrounded by a sheath of
pigment-cells. The lateral eyes are simple.

0. C. 1625. Ilunterian.

Lankester & Bourne, Quart. Jour. Micr. Sci., vol. xxiii.
1883, p. 177.

INSECTA.

E. 1083. The head of a Cicada {Tacua speciosa) showing upon
its dorsal surface between the large compound eyes three
simple eyes or ocelli arranged in a triangle with the apex
directed forwards.

E. 1084. Head of a Longicorn Beetle {Ceramhjx Jieros) showing
the large compound eyes. Their numerous corneal facets
are of sufficient size to give the organs a punctate appearauce
to the naked eye. The facets, as shown in the drawing
below the specimen, are hexagonal.

E. 1085. A Water-Beetle {Dineides mellyi). Each compound
eye is divided by a horizontal band of plain chitin into two
parts, one of which faces directly upwards, the other down-
wards. The insect, which swims on the surface, is thus
enabled to see at the same time in both air and water.
This adaptation finds a parallel in the small Teleostean fish
{Anahleps), Nos. E. 1111 and E. 1112.

ORGANS OF SPECIAL SENSE. — VERTEBRATA. 305

E. 1086. A male Dipterous Fly (Achias longividens). The
compound eyes are borne upon stiff and immoveable
pedicels, produced by the lateral elongation of the sides of
the head. The antennae are situated on the front of the
head below the bases of the eye-stalks.

E. 1087. A Dipterous Fly (Biopsis tenuipes) from South Africa.
A slender process of the head on either side bears at its
extremity the antenna and the compound eye.

0. C. 1626 a.

VERTEBRATA.
The Eyeball.

John Hunter, Essays and Observations, edit. R. Owen, vol. i.
p. 166 ; and this Catalogue, 1st ed. vol. iii. pt. 1, p. 129.
On the Colour of the Pigmentum o£ the Eye in different
Animals, Animal Economy, "Works of Hunter, Palmer,
vol. iv. p. 277.
Letter to Sir Joseph Banks on the Structure of the
Crystalline, Phil. Trans, vol. Ixxxiv. 1794, p. 91 ; also
Works of Hunter, Palmer, vol. iv. p. 287.
Beer, Wiener Klin. Wochenschr., Bd. xi. 1898, no. 42, p. 942
(accom.').

Slonaker, Jour. Morph., vol. xiii. 1897, p. 445 {acute vision),
Leuckart, Graefe u. Saemisch Handb. Augenheilkunde, Bd. ii.

Th. 2, 1876, p. 145 {anat.).
Greef, Grraefe u. Saemisch Handb. Augenheilk.,. Zweite

Auflage, Bd. i. 1900, p. 74 (retina and hibliog.).

In Vertebrates the actual sensitive membrane or retina is not
a single layer of senso-neural cells, as it is in most Invertebrates,
but is built up of many layers. One of these consists of senso-
neural and pigment cells and is analogous to the typical Inverte-
brate retina ; the rest form part of the central nervous system
and are in fact an optic ganglion comparable to that found
beneath the compound eyes of Arthropods.

Owing to the development of the retina from an outpushing
of the brain and not by direct invagination of the epidermis, the
receptive end organs face away from the light and not towards

VOL. III. T

30G

rHYSIOLOGlCAL SEUIES.

it, as in most Invertebrates. In every retina tbe retinal end
organs have the form of refringent rods or cones, but the
relative numbers of these in different retinae and in different
parts of the same retina varies greatly. Thus it is stated
(Slonakcr) that in Mammals and Amphibians the rods far out-
number the cones, but in Birds the cones are more numerous
than the rods, while in Reptiles the rods are scarce or even
absent and cones may alone be present ; in Fishes the rods and
cones are about equal in number, or the cones may outnumber
the rods. In many animals cones ouly are present over one or
two (Bii'ds) areas of the retinal surface situated usually in the
direct line of vision. In Man, this area (macula lutea) and
particularly a depression in its centre (fovea centralis) is the
point of acutest vision and of the most delicate colour dis-
crimination. Towards the margins of the retina, where the
proportion of cones is diminished, there is a notable loss of
sharpness of vision and of sensitiveness to colour, but the sensi-
tiveness to weak stimulation is much increased. These facts in
Man suggest that the cones differ in function from the rods,
being the agents in acute vision and chiefly concerned in the
discrimination of colours, while the rods are more sensitive to
subdued stimulation. This idea is to some extent borne out by
comparative anatomy. In the eyes of many nocturnal animals
cones are scarce or possibly quite absent, whereas the fovea
centralis, which in Man is the area of acutest vision, is present
chiefly in those animals whose vision is undoubtedly acute —
e. g., Primates, Birds, and, to a less extent, in Lizards.

Although the rods and cones in all cases have a fundamental
similarity of structure, they differ considerably in form and
other details not only from each other but amongst themselves.
Thus rods of very different sizes and proportions occur in
the several Vertebrate classes or even in the same retina
(e. g., Rana) ; and there is still greater variation among the
cones. The cones, for instance, in the fovea centralis of the
Human retina are more than three times as long and as narrow
as those at the periphery, and in the different groups of Verte-
brates the variations in size and proportions are equally striking.
The largest cones are found in Fishes, the longest and narrowest
in Birds, and the smallest in Amphibia. In all classes, except
Mammals, the cones often are united by their inner segments in

PI . III.

(J.Green lith.

PLATE III.

Fig. 1. Large twin cone from a Perch, x 330 (from Graefe-
Saemisch).

Fig. 2. Double cone from a Roach, x 500 (from Grraefe-
Saemisch).

Fig. 3. Crystals from the tapetum lacidiim of Sci/llium catuhis
X 300.

Fig. 4. Surface view of a portion of the tapetum lucidum of
Carcharias glaucus, x 75.

Fig. 5. A. Double and single cone and a rod from the retina
of a Frog exposed to light (from Grfefe-Sa?misch) ;
the cones are retracted. B. Double cone from a
Frog kept in the dark — the chief cone is extended
(from Graefe-Saemisch). x 500.

Fig. 6. Section through the eyelids of a Snake (Tropidonnfu.<
natriiv), x 280.

Fig. 7. Distribution of coloured oil-globules in the macula of
a Fowl, x 500 (frojn Graefe-Saemisch).

Fig. 8. Cones from the retina of a Pigeon, showing coloured
oil-globules, X 870 (from Graefe-Saemisch).

Fig. 9. Section of the lachrymal gland of Chelone mydas
(after Stewart),

Fig. 10. Section of the nictitating gland of a Pig, x 150.

Fig. 11. Section of the Harderian gland of a Pig, x 150.

Fig. 12. Section of the Harderian gland of a Eabbit, x 150
A. White part ; B. Pink part.

c, cone-cells ; <;/., conjunctiva ; ci!., ci!'., old and new cuticle ; rf, dermis ;
/., filamentous root of cone-cell; i., inner segment of cone;
i.e., intercellular substance; lumen; m., Malpighian layer of
epidermis ; o., outer segment of cone or rod ; o.g., oil-globule ;
i., cells in transverse section.

m M T .

aiit'vi oili Inn ii ixuj 'nur ^ Mfdrn^f

no-) ofdiJO' •)BtJ'}1 'HJ:

•)iioo "ioiil'j ')ril — il'ijilj orft

.00c. X .uIy>.iiU9iif^<-')'lyjn ■

fro ho'inolo!) 1<> n'-

Iniiividoul 'nil "io r

V> [if

AntiH

'InnH "(ft 'io fioh-
iinq 'ili

ORGANS OF SPECIAL SENSE,— VERTEBRATA.

307

pairs, forming, when they are of unequal size, " double cones," or
if they are similar in every way, " twin cones (PI. III. fig-g. 2),"
In the cones of Birds, and of some Reptiles and Amphibia,
brilliantly coloured or colourless oil-globuIes occur in the outer
end of the inner segment (PI. III. figs. 7, 8). The physiological
meaning of these variations in structure is unknown.

Little is known of the actual mode of stimulation of the
visual end organs. In the rods of many Vertebrates it is
apparently due to the decomposition of a peculiar pigment
(visual purple) located in their outer segments, which is
gradually deposited there when the eye is kept in the dark, but
is bleached and decomposed on exposure to light. In the cones
there is no such pigment, but they have been observed (in
the Frog) to extend or retract according to their degree of
illumination (PI. III. fig. 5).

The whole external surface of the retina is covered by a
vascular and deeply pigmented tunic (choroid) ; this is in part
nutritive owing to its great vascularity, but also serves to absorb
surplus light that has passed through the retina and which unless
absorbed would tend to blurr the retinal image. In some few
groups (Elasmobranchs, Ungulata, Cetacea, Carnivora) the
retinal surface of the choroid has a silvery or iridescent lustre,
due either to the presence of a layer of cells packed with crystals
of guanin(?) or (Cetacea, Ungulata) to a special arrangement of
fibrous tissue. This reflector (the tapetum lucidum) is at present
of unknown function, though its occurrence most frequently in
nocturnal or aquatic animals suggests that it may be of some
service in assisting vision in weak light. Among several
suggestions as to its action the most plausible seems to be that
put forward by Piitfer (Zool. Jahrb., Bd. xvii. 1903, p. 324), in
which he supposes that the diffuse or decomposed light reflected
from the tapetum serves as a subminimal stimulus by which the
retina is sensitised and rendered more capable of response to
feeble direct stimulation. This hypothesis would also explain
the otherwise inexplicable fact of the illumination of the
posterior chamber of the eye of certain Deep-sea Fishes by
special luminous organs.

The contents of the globe and the cornea constitute a com-
pound lens, which by means of accommodating mechanisms
of different kinds can accurately focus upon the retina light

X 2

308 rilYSlOLOGICAL SERIES.

proceeding from different objects at different distances. The
refractive indices of some of the components of this lens (the
cornea, aqueous humour, and \itreous) are all practically the
same as water and higher than that of air, while that of the
crystalline lens is again somewhat higher. Thus, in air, light
is refracted at the surface of the cornea and upon entering and
leaving the lens ; but in water, the cornea is optically obliterated,
its refractive index being the same as that of water, and its place
is then taken by a sharper curvature of the lens. The dioptric
apparatus is completed by a diaphragm, the iris, interposed
between the lens and the cornea. This is chiefly composed of
the inturned anterior border of the choroid, and, except in most
Teleostea, is contractile to regulate the amount of light admitted
to the retina.

The outermost tunic of the globe (sclerotic) is protective, and
although mainly fibrous may be strengthened by cartilage or
plates of bone. Posteriorly it is continuous with the sheath of
the optic nerve and so with the dura mater. In front it passes
into the cornea.

PISCES.

Berger, Morph. Jahrb., Bd. viii. 1882, p. 97 (anat.).
Beer, Arch. ges. Physiol., Bd. Iviii. 1894, p. 523
(accominod.y

Hirschberg, Arch. f. Anat. u. Physiol. (Physiol.), 1883,

p. 493 (diopt.).
Eabl, Zeits. wiss. Zool., Bd. Ixiii. 1898, p. 502 (lens).

In Fishes the globe of the eye is generally large and more or
less hemispherical with a flat cornea. The curvature of the
cornea is optically of little importance, as it has roughly the
refractive index of water, so that its flatness is probably part of
the general adaptation of the body-contours to the needs of
aquatic locomotion by the avoidance of unnecessary prominences.
The sclerotic is usually strengthened by cartilage or thin plates
of bone. The lens, to compensate for the want of a refractive
corneal surface, has a far sharper curvature than in most Land
animals, and is normally in focus for near objects. Accommo-

ORGANS OF SPECIAL SENSE. — VEllTBBKATA.

309

datiou for distant vision is effected by the retraction o£ the lens
towards the retina, and not by an alteration in its curvature.
The mechanism for this purpose is best developed in Teleostea,
and consists of a muscle (campanula Halleri) attached to the
lower part of the lens and retracting it in opposition to a
suspensory ligament (lig. quadratum).

An iris is always present, but, except in Ellasmobranchs and a
few Teleosts, is not appreciably contractile. The choroid has
the usual Vertebrate characters, including in some cases a
zone of feeble ciliary pleats for the efficient anchorage of the
suspensorium of the lens, converging from the ora serrata towards
the iris. Between the capillary and vascular layers there is in
Elasmobranchs a silvery tapetum lucidum (PI. Ill, figs. 3, 4),
which consists of cells filled with crystals of different form, but
probably composed of guanin. Crystals of guanin also occur in
some few Teleosts in the pigment-cells of the retina, forming
a retinal tapetum lucidum, and in very many Fishes of this group
there is a strong layer of argentea between the choroid and
sclerotic — a position in which it can have little or nothing to do
with vision. Most probably the guanin in this case is merely a
waste product, like similar layers of argentea that fre(iuently
occur in skeletogenous tissue in other parts of the body, e. g.
beneath the scales and in the muscle septa.

In Bony Fishes also, but apparently only in those possessed of
a pseudobranch, there is a large rete of blood-vessels (choroid
gland) situated around the optic n(>rve between the vascular
layer of the choroid and the sclerotic. In structure it closely
resembles the pseudobranch, but its function is unknown. The
retina in Teleostea is interrupted ventrally along a diagonal line
from the optic disc to the base of the campanula, by the intrusion
of a narrow fold of the vascular layer of the choroid (falciform
process) into the cavity of the globe for the conveyance of
nerves and blood-vessels to the campanula.

Although many Fishes, especially Teleosts, hunt their prey
by sight, their power of vision is probably not very acute,
except in the case of some few which, like the Wrasses and Pipe-
fishes, minutely examine seaweed for any creatures suitable for
food (Bateson, Jour. Mar. Biol. Ass., vol. i. 1889, p. 215). A
fovea centralis is rarely present.

310

rilYSIOLOGICAL SEnilSH.

ELASMOBRANCllII.
Franz, Jena. Zeitschr., Bd. xxxiii. 1905, p. 697.

E. 1088. Parhs of the two eyes of a " Grey Shark " (Galeus sp.)
showing a silvery layer of argentea (tapetum lucidum) that
lies between the retina and the vascular layer erf the choroid.
In the lower specimen the argentea has been scraped off to
show the underlying pigmented choraid. 0. C. 16G9.

Hunterian.

E. 1089. A similar specimen of the posterior half of the eye of a
Dog-fish (Sct/llium catulus), showing the tapetum lucidum,
which in this species covers only the upper half of the
globe. The tapetum consists of a layer of flattened cells,
which contain elongated plate-like hexagonal crystals,
probably consisting of guanin.

E. 1090. A longitudinal section of the eye of a Basking Shark
(Selache maxima). The sclerotic cartilage is of great
thickness as far forward as the line of insertion of the
ocular muscles. Here it turns inwards and becomes for a
short space relatively quite thin, thickening again at its
corneal border. The outer surface of the globe is flattened.
The cornea has apparently been dried and so is probably
thinner than it should be ; it is perfectly flat and passes
peripherally into the thick conjunctiva external to the
sclei-otic cartilage. The cartilaginous eye-stalk is attached
to the sclerotic by a thick fibrous pad about 2 to 3 cm. in
length. The spherical lens is also shown separately.

0.0. 1670 c.

Franz, I. c, p. 730.

E. 1091. The inner and outer portions of the eye of a Basking
Shark (Selache maxima), showing in the outer half the
weakly developed ciliary plicae and the elongated form of
the pupil, and in the inner half the choroid membrane with
some of the ciliary nerves. 0. 0. 1670 a & B.

E. 1092. A ])iece of skin from the right side of the head of a
Monk- fish (Rhina squatina) including the eye. The cornea
has been removed to show the shape of the contracted pupil.
It forms a narrow slit directed diagonally froin behind
downwards and forwards. The expanded pupil is circular.

ORGANS OF SPECIAL SENSE. — VERTEBRATA.

311

A slit-like contracted pujail is common to nocturnal Sharks.
The iris is speckled like the surface of the body, forming
part of the general pi'otective scheme of coloration.
Preserved in 50 per cent, glycerine.
Bateson, I. c, p. 215.

E. 1092 a. The posterior half of the eye of a Monk-fish (E/dna
squatina) showing the tapetum lucidum.

E. 1093. Two preparations of the eye of a Skate {Raja bads).
The cornea has been removed from the lower specimen to
show a fringed process of the upper border of the iris that
projects downwards across the pupil. This process shields
the retina from the direct action of light coming from
above, and in the daytime covers the whole pupil. During
twilight it is gradually drawn up and at night is entirely
so, leaving the pupil clear (Bateson). In the upper speci-
men the iris with the fringed process expanded, has been
isolated by the removal of the anterior and posterior parts
of the eyeball. O.C. 1658 b.

Bateson, 1. c, p. 215.

E. 1094. Eye of a Thornback {Eaja clavata) with the outer
parts and the retina removed. Upon the surface of the
choroid, above the optic nerve, is a horizontal glistening
band of argentea (tapetum lucidum) about 4 mm. broad.
Bateson (I. c, p. 216) states that " the eyes of the Elasmo-
branchs glow in the light of the lantern like a Cat's eye,
but the eyes of the other fishes in the tanks do not."

E. 1095. A longitudinal section of the eye of a Devil-fish {Cepha-
loptera giornce), including the eye-stalk. The cartilaginous
layer of the sclerotic is of great thickness proximally, and
is in places further thickened for the attachment of the
ocular muscles and for the articulation of the expanded end
of the eye-stalk. The joint between the eye-stalk and the
globe is truly diarthrodial ; its cavity has been opened by
the removal of part of the capsule. The vitreous humour
has been removed, but the small spherical lens is preserved
in situ, as are also the retina and the choroid. The termi-
nation of the retina at the margin of the ciliary zone is
clearly marked. Q. C. 1673. Hanterian,

312

PHYSIOLOGICAL SKIUES.

GANOIDEI.

E. 1096. Vertical section through the riglit eye of a Sturgeon
{Acipenser sturio). The globe of the eye is protected
externally by an immoveable fold of skin, which is separated
from it by a remarkably deep conjunctival space. The
eye has thus, for a Fish, great freedom of movement. The
sclerotic consists of two layers — cartilage within and a
fibrous layer without. The latter is extremely thick, and
is without a definite boundary towards the orbit. It is
continuous with the sheath of the optic nerve. The pos-
terior chamber of the eye is relatively small, and somewhat
longer than broad. The lens is spherical, and the cornea
very nearly flat.

Mounted in 50 per cent, glycerine.

E. 1097. A similar specimen in which the cartilaginous layer of
the sclerotic is relatively very much thicker. The lens and
optic nerve have been removed. The continuation of the
sheath of the optic nerve into the fibrous layer of the
sclerotic is clearly shown. 0. C. 1666. Hunterian.

TELEOSTEA.

E. 1098. The right eye of a Sea-Bream (Pagellus centrodontus)
with the posterior half of the sclerotic removed to show
upon the deep surface of the choroid a band of yellow
tissue arching over the optic nerve like a horse-shoe.
This tissue (the choroid " gland is composed of blood-
vessels and capillaries and is of unknown function. It is
said to occur only in those fishes in which there is a pseudo-
branch.

In this specimen also the optic nerve has been divested
of its sheath to show its fiattened ribbon-like form and
deep longitudinal pleating. 0. C. 1661 A.

E. a 1098. Two specimens of the eye of a Pike {Esox lucius).
The upper specimen, which is one-half of a vertical section,
shows the general form and structure of the eye. The
cornea is slightly convex and is thinner in the centre than
at the circumference^ a form similar to that found also in

ORGANS OF SPECIAL SENSE. — VERTEBRATA.

313

aquatic Mammals. The lens is globular and projects some
way through the large circular pupil into the anterior
chamber. The sclerotic, which is easily separable from the
choroid owing to the presence o£ loose areolar tissue be-
tween the two, is hemispherical, but the posterior chamber
of the eye is considerably shortened antero-posteriorly by
the presence of a thick choroid gland in the outer parts o-f
the choroid. This can be seen in section above the optic
nerve. Along the lower border of the posterior chamber
lies the falciform process, projecting as a thin pigmented
lamina through the retina. At its anterior end it is con-
fluent with the campanula Halleri, a rounded mass of
pigmented tissue attached by its free end to. the lower
surface of the lens capsule. In the lower specimen, which
is the ventral half of -an eye with the lens removed, the
falciform ligament and campanula are shown from above.
Preserved in 5 per cent, formol.

E. 1099. A longitudinal section through the eye of a Bonito
(T/iynnus pelamys). The falciform ligament is remarkably
prominent and projects as a thin pigmented lamina into
the posterior chamber of the eye. In this preparation are
also shown the cornea and iris, the coagulated vitreous, the
retina, which has partly separated into layers at its edges,
the choroid, and the sclerotic. Between the two latter
tunics at the posterior end of the globe the dense tissue of
the choroid gland is visible upon the section surface.

0. C. 1651. Huntenan.

E. 1100. The sclerotic of a Bonito {Tliynnus pelamys). The
periphery of the sclerotic is stiffened by a pair of thin
bony plates that meet in a straight line above and below,
and bound the corneal aperture by their inturned and slightly
thickened anterior edges. Posteriorly they are separated
by a large diamond- shaped membranous area, perforated
in the centre for the passage of the optic nerve.

0. C. 1663. Hunlei nan.

E. 1101, A similar specimen of the sclerotic, together with Ihe
flattened cornea of Short-finned Tunny [Thunnus tliynnus).

0. C. 1664. Hunterian.

3U

rilYSIOLOGICAL SERIES.

E. 1102. Two specimens of the riglit eye of a Cod [Gadus
moTvlma), in which the blood-vessels of the choroid
" gland " have been injected. The arteries are shown in
the upper specimen, the veins in the lower. Arterial
blood is brought to the " gland " by the arteria ophthalmica
after having in the first place passed through tlie pseudo-
branch. In the "gland'' the artery divides, and finally
breaks up into a mass of radially-arranged capillaries,
which reunite to form vessels spread over the deep surface
of the choroid. The venous blood is returned from the
gland by a large vein situated upon the postero-dorsal
surface of the optic nerve. 0. C. 1661 b.

Berger, Morph. Jahrb., Bd. viii. 1882, p. 142.

E. 1103. The posterior half of the globe of the eye of a
Haddock {Gadus ceglefinus), with the retina and most o£
the choroid removed to show a glistening silvery mem-
brane that coats the inner surface of the sclerotic. This
membrane (Membrana argentea) consists of elongated
irregular cells packed with needle-iike crystals of guanin.
Similar tissue occurs beneath the scales and sometimes
upon the swim-bladder and between the muscles of Teleost
Fishes. The choroid gland has been left around the point
of entry of the optic nerve. 0. C. 1652 B.

Mus. Sir Astley Cooper.

E. 1104. The eye of a Turbot [Rhombus ma.nmus), with the
cornea removed to show the iris. The pupil, unlike that
of most Bony Fishes, is contractile. The movement is
confined to a part of the upper border of the iris. When
the pupil is contracted, as in daylight, this part extends
downwards in the form of a rounded curtain, shutting olF,
very much as in the Skate, light coming from above.
When ddated during the night the curtain shriidcs to an
insignificant knob. In the specimen the pupil is contracted,
as usually is the case in death. A similar curtain is said
to be present in the Brill (Rhombus Icevis).

Preserved in 50 per cent, glycerine.

Bateson, Jour. Mar. Biol. Ass., vol. i. 1889, p. 228.

ORGANS OF SPECIAL SENSE. — VEUTEBRATA.

315

E. 1105. The greater part of the cartilaginous sclerotic of a
Sun-fish (Orthacforiscus sp.), with the cornea and conjunc-
tiva. 0. C. 1665 A.

E. 1106. An antero-posterior section o£ the distal parts of the
eyeball of a Sun-fish {Ortliagoriscus sp.). The cornea is
separable into two layers, a superficial conjunctival layer
of considei'able thickness continuous with the skin, and a
deeper true corneal layer attached to the edge of the
sclerotic. In the specii«en these layers have been arti-
ficially separated ; in life they are more or less firmly
united by fibrous tissue. 0. C. 1665. Ilunterian.

E. 1107. A segment of the eye of a Sun-fish {Orthagoriscus
mola), including parts of the cornea, iris, and ventral wall
of the globe. The retina terminates anteriorly at the
distance of nearly an inch from the margin of the pupil.
Part of the coagulated vitreous is shown attached to the
wall of the globe by the falciform process.

0. 0. 1649. Ilunterian.

E. 1108. The posterior part of the eye of a Sun-fish {Orthago-
riscus mola), showing the small size of the optic disc and
the fine radiation of the retina around it. From the lower
border of the disc (left in the specimen) the deep end of
the falciform process can be seen passing to the cut edge
of the specimen. From it a part of the coagulated vitreous
is suspended by the hyaline membrane. Between the
retina and sclerotic is a thick layer of cellular tissue which
is composed of the vascular layer of the choroid and also,
in its outer parts, of the lymph-containing supra-choroidal
t^'ssue. 0. C. 1648. Ilunterian.

E. 1109. Eyeball of a Light-horseman Fish {EpUppus gigas\
^"ed. Hunterian.
(la rail-case, Room V.)

E. 1110. Bony sclerotic of the eyes of a Light-horseman Fish
{EpUppus gigas), dried. Ilunterian.
(In rail-case, lioom V.)

E. nil. A male " Four Eyes " {AnaMeps t€trop>htlialmus) .
The cornea is divided into an upper and a lower portion

810

PHYSIOLOGICAL SKltlES.

hy a narrow transverse band of pigment .sitiiated in its
deeper layers. Besides this, the pupil is divided into an
upi)er and a lower division by a pair of lobes which pro-
ject from the sides of the iris, and overlap without fusion.
The cornea has been removed from the left eye to show
the iris and double pupil.

The following is a brief account of the habits of the fish
as observed by Klinckowstrom. The fish inhabit estuaries
and delta channels, and usually lie partly above water in
small shoals near the bank waiting for flies and similar
prey. When lying thus, the water-line coincides with the
pigmented band across the cornea. Occasionally the
whole shoal darts forward for a few hundred paces, but
the fish always swims half out of the water and has never
been seen to dive beneath the surface. 0. C. 1658 a.

Presented hy Walter Watkins, Esq .

Klinckowstrom, Skandinavisches Arch. f. Physiol., Bd. v.
1895, p. 67.

E. 1112. Posterior view of a transverse section through the
cranium of Anableps dovii, including the eyes. In addition

Fig. 48.

Trausverse section of the left eye of Anableps dovii, enlarged.
Ch. Choroid. F. Fat. I. Iris. 1'. Lobe of iris separating the two pupils.
L. Lens. P. Band of pigment in the cornea. R. Retina. Scl. Sclerotic.

ORGANS OF SPECIAL SENSE. — VERTEBRATA. 317

to the features described in the previous specimen, it can
be seen that the curvature of the lower cornea is much
sharper than that of the upper, and also that the lens is
oval, its two axes being to one another in the ratio of 4 : 5
and so placed that the light passing through the lower
pupil traverses the long axis, that through the upper pupil
the shorter axis. The retina is bent (not enough in fig. 48)
opposite the pigmented band of the cornea in such a way
that its upper half is at right angles to the long axis of the
lens, its lower half at right angles to the short axis. Each
eye is thus physiologically divided into two eyes, one
directed downwards with a lens of sharp curvature for
vision in water (the curvatui'e of the cornea being in this
case ineffective), and one directed upwards with slightly
convex cornea and lens of relatively low curvature for
vision in air. 0. C. 1658 A a.

AMPHIBIA.

Hirschberg, Arch, f . Anat. 1882 (Suppl.), Physiol. Abt.,

p. 509 (diopt.).
Rabl, Zeits. wiss. Zool., Bd. Ixiii. 1898, p. 527 Qens).
Beer, Arch. ges. Phjsiol., Bd. Ixxiii. 1898, p. 501

(acGommod?).

Amphibia in general are probably short-sighted, as may be
inferred from the convex cornea and almost spherical lens
usually found in members of tliis group. In water, however,
they are apparently in many cases hypermetropic owing to the
optical loss of the corneal refractive surface. At rest the eye
is in focus for the distant limit of clear vision, and frequently
has no power of accommodation, especially in nocturnal forms,
in which the iris is strongly contractile ; but in some cases
slight accommodation for nearer sight can be effected by the
bodily shifting of the lens away from the retina. This move-
ment is brought about by the contraction of a ciliary muscle
which compresses the vitreous and causes it to push forward the
lens, which is the least fixed part of the wall of the posterior
chamber of the eye.

E. 1113. A vertical longitudinal section of the eye and eyelids
of a female Guppy's Fi-og (Rana gyppyi). The cornea^

318

niYSIOLOGICAL SERIES.

which is very thin, is too much deformed to show its true
curvature. The lens is ahnost spherical, and is remarkable
for its great size. The inner parts of the sclerotic are
composed of hyaline cartilage as far forward as the meridian
of the posterior chamber. Q. C. 1694 a.

Ecker's Anat. des Frosches, 2te Aufl. Gaupp, Abt. 3,
1904, p. 7G2.

REPTILIA.

Beer, Arch. ges. Physiol., Bd. Ixix. 1898, p. 507
(accom.)

Studnicka, Lehrb. vergl. mikr. Anat., Oppel, Th. v.

1905, p. 124 (pariet. eye).
Rabl, Zeits. f. wiss. Zool., Bd. Ixv. ]899, p. 257 {lens).

In Reptiles (with the exception of the Ophidia) accommo-
dation for near distance is effected, as in the higher Vertebrates,
by alteration of the curvature of the lens, particularly of its an-
terior surface. This is due to the action of the ciliary muscle,
which by dragging forward the choroid slackens the suspensory
ligament and allows the lens to assume by its natural elasticity
a more rounded form. In most Snakes the mechanism is in
principle the same as in Amphibians. The lens undergoas no
alteration in curvature (except in special cases), but is pushed
bodily forward owing to the compression of the vitreous by a
circular muscle-band situated at the base of the iris. In many
Lizards the contents of the globe receive their nourishment
from a process of the vascular layer of the choroid comparab'e
to the pecten of Birds, that projects into the vitreous from
beside the optic disc. The sclerotic, as in almost all Vertebrates
other than Mammals, is partly cartilaginous and in Lizards and
Chelonians is stiffened in its anterior parts by a ring of bony
plates radiating in a circlet round the cornea.

In many Lizards besides the two lateral eyes of the normal
Vertebrate type there are vestiges of what seems to be a median
unpaired eye lodged in a foramen in the roof of the skull and
connected by nerve-tissue with the brain in front of the pineal
body. This " parietal " eye varies much in its degree of degeneracy
in different species, and shows a type of structure comparable
to the simple vesicular eye of an Invertebrate, consisting when

ORGANS OF SPECIAL SENSE. — VERTEBUATA.

310

least degraded (e. g., Sphenodon) of a vesicle whose proximal
wall has some resemblance to a retina with the sensory elements
iiicing the light, and whose distal wall forms a cellular lens.

LACEETILIA.

E. 1114. The sclerotic and cornea of a Monitor Lizard (Varanus
salvator), dried. The anterior, inturned, border of the
sclerotic is strengthened by a ring of 15 overlapping bony
plates. 0. C. 1754 E.

E, 1115. The right eye of a Monitor Lizard ( Varanus salvator)
in vertical longitudinal section. The lens and vitreous
have been removed, leaving the lens-capsule and parts of
the hyaloid membrane visible. The hinder part of the
globe has kept its natural hemispherical form owing to the
stiffness of the cartilaginous layer of the sclerotic, but the
softer cornea has collapsed. The greater part of the optic
disc is included in the lower specimen and from it a long
pointed process of vascular and pigmented tissue projects
forward across the posterior chamber to the hinder surface
of the lens-capsule, to which it is attached by a fold of the
hyaloid membrane. This process is similar to the pecten
in the eye of Birds and carries nutriment from the choroid
to the contents of the globe. In these specimens the con-
junctival sac and the eyelids are a^so shown, and in particular
the position and thickness of the tarsal cartilage in the
lower lid. 0. C. 1765 b.

E. 1116. Longitudinal vertical section of the head of a Monitor
Lizard ( Varanus salvator). A hollow process of the brain
(pineal body) extends upwards from the roof of the third
ventricle just anterior to the optic lobes towards a foramen
(parietal foramen) in the mid-line of the roof of the skull.
Before reaching the foramen it narrows to form a nerve
that terminates in a small eye-like structure (visible as a
black speck in the specimen) embedded in the outer parts
of a plug of connective tissue by which the foramen is filled.
Above this "parietal" eye the integument is transparent
and forms a cornea-like area known as the brow-spot. The
microscopic structure of this vestigeal eye has been recorded

320

PHYSIOLOGICAL SERIES.

for Varanns by Spencer (Quart. Jour. Micr. Soc, vol. xxvii.
p. 165). The nerve of the parietal eye is probably not
continuous with the pineal body, but passes along its
anterior surface independently to the roof of the brain iti
the region of the corpora habenulaj. 0. C. 1C99 i).

Fig. 49.

Diagrammatic longitudinal vertical section through the parietal foramen of
Varanus giganteus, showing the eye -within the parietal foramen and
the pineal stalk. (After Spenser.)

B.V. Blood-vessels. EP. Epiphysis (Pineal body). L. Lens. O.S. Pineal
stalk. P. Pigment. PA. Parietal bone. R. Retina.

E. 1117. Part of the skin from the top of the head of a Monitor
Lizard {Varanus salvator), showing the large white scale
(brow-spot) resembling a cornea beneath which lies the
parietal eye. 0. C. 1699 c.

E. 1118. Head of a Monitor Lizard ( Varanus sp.), showing the
brow-spot. In this specimen it is peculiarly well marked.
The centre is transparent and shows the dark pigment of
the eye beneath, 0. C. 1699 a.

ORGANS OF SPECIAL SENSE. — VEfiTEBRATA. 321 •

E. 1119, Head of an Iguana (Lophura aniboinensis). The brow-
spot forms a rounded eminence. 0. C. 1699 b.

E. 1120. The anterior parts o£ the eye of a Chameleon {Cluima;-
leon sp.), showing from within the ciliary region of the
choroid, upon which the pleats are very inconspicuous,
the glistening inner surface of the iris, and the circular
form of the pupil. At the side o£ the specimen parts of the
lids have been removed to show the extent of the conjunc-
tival sac. O.G.I 69.9. Hunterian.
John Hunter, 'Essays and Observations,' edit. E. Owen,
. vol. ii. 1861, p. 373.

OPHIDIA.

E. 1121. The right eye of a Python {Python reticulatus), in
longitudinal vertical section, with the surrounding parts.

Fig. 50.

Eye of Python reticrdaUis, in vertical longitudinal section.
(From E. 1121, slightly modified.)

C. Cornea. C.S. Conjunctival sac. E. Cut edge of the eyelids. I. Iris.
L. Lens. E. Retina. R.I., R.S. Inferior and superior recti.

The conjunctival sac, which is closed in front by the perma-
nently united eyelids, extends back three parts of the way to
the optic nerve. The transparent lids (PI. III. fig. 6), which
form the first refracting surface, are strongly convex ; the
cornea is flatter, but is of great thickness, and the lens, which

VOL. III. Y

322

I'HYSIOLOOICAL SKltlKS.

is remarkably large and nearly fills the whole posterior
chamber of the eye, is approximately spherical. Strong
curvature of the refracting surfaces would be expected from
the observed shortsightedness of Snakes. The sclerotic has
no ring of bony plates around the margin of the cornea.
The Harderian gland, which is of very great size and pours
its secretion directly into the mouth (c/. E. 1232), has been
left in its natural position enveloping the optic nerve and
recti muscles. 0. C. 1G99 e.

E. 1122. A similar section through the eye of a Sea-Snake
(Distira omata). The eye shows characters resembling
those seen in the previous specimen, but the lens is relatively
much smaller and the cornea thinner. In this specimen it
has collapsed. 0. C. 1G99 f.

CHELONIA.

E. 1123. The sclerotic of a Turtle (Chelone mydas) dried to show
the ring of bony sclerotic plates that surrounds the cornea.
The plates are ten in number, of irregular form, and over-
lap one another by their edges. 0. C. 1754 d.

E. 1124. The eye of a Turtle (^Chelone mydas), transversely
divided. The ciliary arteries are injected and form a fine
plexus around the optic nerve. The nerve forms a blunt
conical projection at its entry into the cavity of the eve.
The choroid is thick and of a brown colour ; it has no fold
projecting through the retina comparable to the processus
falciformis of Fishes or the pecten of Birds. The ciliary
plicse are sharply defined though small, and, as in Fishes,
do not project forward as distinct " processes." The pupil
is circular. The sclerotic consists of two layers — a thin
outer one of fibrous tissue and an inner layer of hyaline
cartilage. The latter is thicker over the posterior part of
the globe than in front and on the temporal surface than
on the nasal. The cornea is circular and flat.

0. C. 1674. Hunterian.
John Hunter, ' Essays and Observations,' edit. R. Owen,
vol. ii. 18G1, p. 354.

ORGANS OF SPECIAL SENSE. — VERTEBRATA.

323

E. 1125, The sclerotic and cornea of a Leathery Turtle (Bermo-
clielys coriacm). The plates, as in Chelone mydas, are ten in
number and overlap by their edges, but they are somewhat
more regular in shape and stouter in build.

E. 1126. The globe of the left eye o£ a Leathery Turtle ( Dermo-
clielys coriacea) in longitudinal vertical section. From the
one half (upper specimen) the contents of the globe have
been removed, leaving only the cornea and sclerotic. The
cornea is surrounded, as inChelone, by a ring of bony plates
which sligbtly overlap the anterior edge of the cartilaginous
part of the sclerotic. The sclerotic is thin from the edge
of the bony plates to slightly in front of the meridian, but
then suddenly increases in thickness, its whole posterior
part being about 6 mm. thick. The cartilage is soft and
towards its inner surface contains an increasing quantity
of fibrous tissue. It is perforated by numerous pigmented
blood-vessels, and upon its inner surface is deeply pitted
and scored where the vessels emerge. In the lower speci-
men the contents of the globe are retained. The lens is
nearly circular and, as in Chelone, of peculiarly small size,
measuring 7 mm. x 7*5 mm.

AYES.

Beer, Arch. ges. Physiol., Bd. liii. 1893, p. 175 {ac-
commod.}.

Eabl, Zeits. f. wiss. ZooL, Bd. Ixv. 1899, p. 304 (lens).

Direct observation shows that in Birds the visual apparatus
reaches a very high degree of efficiency, and this conclusion is
fully borne out by its structure. The eye, relative to the size of
the Bird, is peculiarly large ; the retinal area directly exposed
to stimulation is generally very extensive, owing to the wide
curve of the posterior wall of the globe, and there are frequently
two areas of acute vision in each retina. There is also provision
for great range of accommodation. The globe of the eye, espe-
cially in Kocturnal and Eaptorial Birds, has a somewhat tubular
shape, due to the horizontal lengthening of the ciliary area to
form a more or less cylindrical segment between the broadly
curved fundus of the globe and the much more sharply convex

y 2

PHYSIOLOGICAL SERIES.

cornea. This region is strengthened, as in many Reptiles, by a
ring o£ scleral plates, which serve as a basis of attachment
for the powerful ciliary mi;scles by which accommodation is
effected.

Active accommodation is for near vision as in Mammals, and
is directly due to the relaxation of the capsule and suspensorium
of the lens and its consequent resumption of its natural and
more rounded form. The relaxation is brought about partly by
the backward dragging of the margin of the cornea by the action
of Crampton's muscle and partly as in Mammals by the forward
dragging of the choroid.

In all Birds, except Apteryx, the contents of the globe are
nourished by means of a pleated process of the vascular layer of
the choroid that projects through the retina into the vitreous.
This, which is known as the pecten, extends for a variable
distance from the optic disc along the wall of the posterior
chamber. Nutriment is also probably furnished by the ciliary
processes, which in Birds are peculiarly large ; their chief
function, however, seems to be to afford an efficient anchorage
for the suspensorium of the lens.

E. 1127. The cornea and sclerotic of an Ostrich {Strutldo
camelus), dried. The form of the globe is characteristically
Avian. The posterior wall is extensive and of shallow
convexity, and is separated from the much more sharply
convex cornea by a short tubular segment stiffened by a
ring of sixteen bony sclerotic plates. 0. C. 1754 c.

E. 1128. A transverse section of the cornea, sclerotic bony
plates, and a small part of the sclerotic of an Ostrich
(^Struthio camelus). The internal lamina of the cornea has
been reflected, and the fibrous tissue which is continued
from it to the bony plates is left attached to its outer
margin. 0. C. 1755 A.

E. 1129. The eye of an Ostrich (Sttnithio camelus) transversely
divided, showing (in the posterior segment) the pecten,
surrounded by the remains of the retina and attached by a
portion of the hyaloid membrane to one side of the posterior
part of the capsule of the lens. On the anterior segment

ORGANS OF SPECIAL SENSE. — VERTEBRATA.

325

may be observed the broad ciliary zone, with its deep
sharply defined ciliary folds, which terminate abruptly
towards the iris to form ciliary processes/' The pupil is
circular. 0. C. 1744. Hunterian,

E. 1130. A segment o£ the posterior part of the eye of an Emeu
(Dromceus novce-hollandiai), showing the pecten. This
consists of a vascular pigmented membrane (an extension
of the vascular layer of the choroid) that projects freely
into the posterior chamber of the eye from a line extending
downwards from the optic disc and is folded fan-wise upon
itself five times. The folds converge towards its free end,
so that it terminates in a bluntly pointed extremity.

0. C. 1744 A.

E. 1131. A similar preparation from the opposite eye of the
same Emeu. Two folds of the pecten have been cut off"
near their bases, showing their breadth and mode of
plication. A part of the hyaloid membrane and the
capsule of the lens remains attached to the apex of the
pecten in this and the preceding preparation.

O.C. 1744 b.

E. 1132. Cornea and ring of sclerotic bones of a Groose (Anser
ferus), dried. In this condition the cornea is practically
flat. The intermediate area of the globe, which is pro-
tected by the sclerotic bony ring in this specimen, is not
tubular as in most Birds. 0. C. 1755 d.

Mus. Sir Astley Cooper.

E. 1132 a. The eye of a Groose {Anser ferus) in vertical longi-
tudinal section. Although the cornea has a far sharper
curvature than the posterior part of the sclerotic and is
separated from it by a ciliary zone concave externally and
slightly prolonged forward in a tubular form, the general
shape of the globe is not so markedly avian as in many
Birds. The lens is relatively small and strongly curved,
especially upon its posterior face. Its antero-posterior and
transverse diameters are equal. The position of the pecten,
passing diagonally forward and outwards upon the floor of

320

PHYSIOLOGICAL SERIES.

the globe from the optic disc is clearly shown. The pecten
consists of ten folds that slightly converge towards their
apices.

Preserved in 5 per cent, formol.

E. 1133. Eye of a Crane {Grus cinerea), with part of the wall
removed to show the pecten. This is relatively shorter
and wider than in Struthio or Dromceus and consists of
many more pleats. Part of the hyaloid membrane remains
attached to its apex. The ring of sclerotic bones lies more
nearly in the vertical plane than in Sti-uthio, but less so
than in the Goose. 0. C. 1748 a.

E. 1134. The head of an Eagle (Aquila sp.). The anterior parts
of the left eye, including the lens and the vitreous humour,
have been removed to show the origin of the pecten from a
line that extends obliquely downwards and forwards from
the optic disc. The pecten is of an unequal quadrilateral
form, broadest at its base and projecting upwards and
inclined a little backwards with a slight convexity towards
the nasal side of the eyeball. The right eye has been
divided horizontally, and the lens, vitreous, and the greater
part of the retina removed to show in the lower half the
pigmented choroid and the pecten. In this section the form
of the eyeball is well shown — the hinder part of the globe
llattish and encased in the thin but very dense sclerotic ;
the sudden transition to a cylindrical tubular form in the
region of the sclerotic bony ring ; and the sharply convex
cornea. The relatively large size of the eyes is worthy of
notice. The eyes of an Erne (Haliaetus albicilla) are
shown in No. E. 120. 0. C. 1741. Hunterian.

John Hunter, Essays and Observations, edit. R. Owen,
vol. ii. 1861, p. 270.

E. 1135. The eye of an Eagle {Aquila sp.) with a portiou of the
coats removed from one side, showing the pleated pecten,
from which the colouring-matter has been removed.

0. 0. 1743. Hunterian.

E. 1136. The cornea and sclerotic of a Virginian Hooded Owl
{Bubo virginianus), showing the shape of the eyeball, which

OEGANS OF SPECIAL SENSE. — VEKTEBUATA.

327

is flattened posteriorly, greatly extended in the form of a
tube in the region of the sclerotic bony ring, and with
a strongly convex cornea. 0. C. 1754 B.

Mus. Sir Astley Cooper.

E. 1137. The sclerotic bony ring of a Virginian Horned Owl
{Bubo virffinianus), consisting of fourteen narrow quadri-
lateral plates. 0. C. 1754 A.

E. 1138. The crystalline lens and vitreous humour of a Great
Horned Owl (Bubo bubo), prepared to show that the
vitreous humour has a distinct capsule (hyaloid membrane),
part of which is in the specimen reflected from its outer
surface. 0. C. 1749. Hunterian.

Jofm Hunter, Essays and Observations, ed. R. Owen,
vol. ii. 1861, p. 279.

E. 1139. The eye of a Great Horned Owl {Bubo bubo), from which
the cornea, the walls of one side, and the lens and vitreous
have been removed, showing the remarkable elongation of
the intermediate segment of the eye, which assumes in con-
sequence a tubular form. The posterior part of the sclerotic
is very thin. The pecten is relatively small, consisting of
seven slightly converging plicae. 0. C. 1755. Hunterian.

E. 1140. A longitudinal section of the tunics of the eye of a
White or Albino Thrush {Turdus sp.), showing the absence
of pigment. 0. C. 1753. Hunterian.

E. 1141. The anterior part of the other eye of the same Bird,
showing the absence of the colouring-matter of the iris.

0. 0. 1754. Hunterian.

E. 1142. The eyes of a Crow (Corvus sp.). In the upper specimen
(reverse side) the cornea has been cut away to show the
dark-coloured iris ; parts of the sclerotic, choroid, and
retina have also been removed from the posterior surface of
the globe to show the apex of the pecten sunk in the vitreous
humour. In the lower specimen the eye is laid open from
above. 0. C. 1746. Hunterian.

E. 1142 a. The eye of a Raven (Corvus corax). A bony sclerotic
plate surrounds the entry of the optic nerve.

328

rilVSIOLOGICAL SERIES.

MAMMALIA.

Lindsay Johnson, Phil. Trans., vol. cxciv. 1901, p. 1.
A'irchow, Morph. Jahrb., Bd. xi. 1886, p. 437 («7. proc).
Eabl, Zeits. f. wiss. Zoo)., Bd. Ixvii. 1900, p. 1 (lens).
Lang & Barrett, Ophth. Hosp. Kep., vol. xi. 1886*, p. 103
(refrac).

In Mammals the eyeball varies very considerably in size, and
in some species of underground habits is quite vestigeal. It is
generally more or less globular, with the cornea of somewhat
sharper curvature than the sclerotic. The sclerotic is thin,
except in aquatic and some few other species, and is not
strengthened by cartilage (except in Monotremes) or by plates
of bone. There is great variation in the curvature of the cornea
and lens ; usually the lens has the anterior surface flatter than
the posterior, but in aquatic and nocturnal animals it is almost
spherical. This is also the case where the axes of the eyes are
very divergent, and then also the cornea is peculiarly extensive,
giving a wide field of vision. The majority of wild Mammals
are long-sighted. With the possible exception of some aquatic
forms, near objects are brought into focus by alteration in the
shape of the lens, as in Birds. This is due to the contraction
of the ciliary muscle, by which the choroid is dragged forward
and the suspensorium and capsule of the lens are relaxed,
allowing the lens to assume its natural and more rounded form.
The iris is always contractile, but the form of the contracted
pupil varies greatly. In many Ungulates special processes of
the uvea (corpora nigra) project from the upper and lower
margins of the iris. These, although similar in many ways to
the umbracula of Rays and Flat-fishes, are not contractile
except in Hy rax, but from their position may perhaps to some
extent act as a shield from light coming from above. Similar
uveal prominences occur in Man as congenital malformations
(Stephenson, Med. Press, 1893, p. 419).

A fovea centralis is confined to Man and the Apes, but in
most Mammals there is an area comparable to the macula lutea,
though it is often very indefinite. Probably vision is not acute
in most members of the class and is not used for the close
examination of near objects.

In most Mammals and some few Snakes the retina is
nourished in part by a special system of vessels that enter

ORGANS OF SPECIAL SENSE. — VERTEBRATA,

329

the globe in the centre of the optic disc. This special blood-
supply is correlated with the absence o£ a pecten or superficial
and deep hyaloid vessels, through which the retina indirectly
gets part of its nourisliment in lower Vertebrates. Remains of
the hyaline vessels occur, however, in foetal life, and may persist
in some cases in the adult.

MARSUPIALIA.

E. a 1143. The eye of a Kangaroo (Macropus melanops) in
vertical longitudinal section. The globe, excei^t for the
slightly sharper curve of the cornea, would be spherical.
The cornea is very extensive, reaching to within a few
mm. of the limits of the conjunctival sac. It passes
abruptly into the sclerotic at the base of the iris, the line
of junction being marked externally by a pigmented band
upon the conjunctiva. The sclerotic is of nearly equal
thickness throughout, but shows an appreciable thinning
in the equatorial region. The lens is biconvex, with its
antero-posterior diameter to its transverse as 11-15. The
posterior surface is more sharply curved than the anterior.
The relation of the ciliary processes to the iris and lens
can be well seen on the section surface ; they are very
strongly developed.

Preserved in 5 per cent, forinol.

OETACEA.

John Hunter, Phil. Trans., vol. Ixxvii. 1787, p. 437.

ODONTOCETI.

E. 1143. The sclerotic and cornea in longitudinal section and
the optic nerve of a Bottle-nose Whale {Hype^'oodon sp.).
The globe of the eye is much flattened antero-posteriorly.
The sclerotic is enormously thick over the hinder part of
the globe, but thins out, as in the Pinnipedia, in the equa-
torial region, and is again thicker where it joins the cornea.
The optic nerve, owing to the great width of the head in
comparison with that of the brain, is remarkably long.
It passes through the sclerotic in a funnel-shaped passage.

0. C. 1692. Hunterian.
Putter, Zool. Jahrb., Bd. xvii. 1903, p. 272.

PHYSIOLOGICAL SERIES.

E. 1144. A portion of the eye of a Bottle-nose Whale {Hypero-
odon dalei), in which the canal in the sclerotic that lodges
one of the long ciliary arteries is laid open. A canal
occupied by a vein that receives blood at the circumference
of the iris is also opened, and a bristle is inserted into the
trunk of another similar vein upon the section surface.
The dense fibrous structure of the sclerotic and the spongy
appearance of the vascular layer of the choroid are well
shown in this specimen. The tapetum lucidum covers the
whole of the fundus of the globe, and has the appearance
of a dense white layer internal to the lamina vasculosa of
the choroid. In the Cetacea the tapetum is fibrous, as in
Ungulates. The ciliary processes ai-e small, pointed, and
crinkled. In this specimen the colour of the choroid and
tapetum is lost. 0. C. 1690. Hunteriaii.

E. 1145. Eye of a Bottle-nose Whale {Hyperoodon dalei) with
the cornea and a segment of the anterior part of the
sclerotic removed. The long ciliary arteries can be clearly
seen passing on either side on to the iris, and branching to
form the circulus major, from which numerous serpentine
folds (doubtless enclosing arteries) radiate to the periphery
of the iris. The pupil, as in other Cetacea, is bean-shaped,
convex below and concave above. The concavity is due to
a downward process of the upper border of the iris, said
to be almost entirely composed of muscle.

0. C. 1689. Hunter 'lan.

E. 1146. The eye of a Porpoise {Plwccena phoccBna) injected and

with the cornea removed to show the iris and the form of

the pupil. The anterior surface of the iris is characterised

by wavy vessels that radiate outwards, as in Hyperoodon,

from the circulus major. The circulus itself is very

indistinct in the specimen.

The pupil is bean-shaped, encroached upon from above

by a process of the superior margin of the iris. Compare

with the Skate E. 1093, Turbot E. 1104, and Hyrax

^- 115^- 0. C. 1688. Jlunterian.

Piitter, L c, p. 239.

OHGANS OF SPECIAL SENSE

, — VBRTEBRATA.

331

E. 1147. A longitudinal section through the right eye of a
Porpoise {Phoccma phoccena). The globe is much flattened
antero-posteriorly. The cornea is flat and is much thinner
in the centre than at the periphery. The sclerotic is very
thick posteriorly, though not so much so as in other Whales.
It thins considerably where it turns in to form the anterior
face of the globe, and thickens again at its margin. The
marginal thickening of the cornea and sclerotic results in
a structural form well calculated to withstand pressure on
the surface of the cornea. The lens is spherical. Between
the sclerotic and the outer edge of the ciliary zone a
coagulum can be seen in the strongly developed peri-
choroidal lymph space. The optic nerve, which has been
mesially divided, is surrounded by a thick sheath of fibrous
tissue different in texture from the sclerotic.

O.C. 1677 a.

E. 1148. Skin from the right side of the head of a young
Gangetic Dolphin (Platanista gangetica), showing the ex-
ceedingly small size of the degenerate eye. In this specimen
the small auditory aperture is also shown ; it lies at a con-
siderable distance behind the eye, and is not provided with
a pinna of any kind. 0. C. 1776 A.

Presented hy Sir Joseph Fayrer, Bt.

E. 1149. A lono-itudinal section of the sclerotic and choroid of
a Grampus {Orca orca), showing the great thickness of the
posterior parts of the sclerotic and their penetration by
the conical anterior termination of the sheath of the optic
nerve. The nerve itself narrows very much in its passage
through the sclerotic. 0. C. 1693. Hunterian.

E. 1150. The eye of an adult Sperm- Whale {Physeter macro-
cephalus) longitudinally bisected, showing the enormous
thickness of the hinder parts of the sclerotic, the small
spherical lens, and the relatively small size of the cavity
of the eye. This specimen was taken from the animal
whose skeleton (2846, Osteol. Ser.) is suspended in the
centre of Koom V. The whole eye is minute compared
to the size of the animal. 0. C. 1692 a.

Presented by W. L. Crowther, Esq.

332

PHYSIOLOGICAL SERIES.

MYSTACOCETI.

E. 1151. Part of the cornea of a Piked Whale (Balwnoplera
acuto-rostrata). It is much thinner in the centre than at
the margin. This feature is common to the cornea of most
aquatic Mammals. Hunter (CEcon. of Whales, p. 733)
states that it is soft and very flaccid.

0. C. 1681. Hunterian.

John Hunter, Essays and Observations, edit. R. Owen,

vol. ii. 1861, p. 117.
Putter, I. c, p. 188.

E. 1152. The other half of the cornea of the same Whale, in which
its laminated structure is shown.

0. C. 1682. Hunterian.

E. 1153. The anterior part of the choroid with the iris and
ciliary processes of a Piked Whale (Balcenoptera acuto-
rostrata). Bristles are placed in the long ciliary arteries,
which, advancing on either side in the direction of the
long axis of the pupil, may be seen to terminate in a canal
(circulus major) surrounding at a little distance the pupil-
lary margin. Wavy branches radiate from this canal to
the circumference of the iris. The pupil is slightly bean-
shaped, owing to a feeble downgrowth of the superior
margin of the iris. The veins of the choroid surrounding
the iris have been injected. 0. C. 1683. Hunterian.

E. 1154. The anterior part of the eye of a Piked Whale {Balce-
noptera acuto-rostrata), from which the cornea and lens
have been removed to show the iris and ciliary processes.
The form of the ciliary processes is very clearly shown ; of
the numerous minute folds which constitute the ciliary
zone every third, fourth, or fifth is enlarged to form an
inwardly directed wrinkled process about 5 mm. in length,
said to be composed almost entirely of blood-vessels ; the
intermediate processes are shorter, but vary in length: the
larger processes are about seventy in number.

0. C. 1680. Hunterian.

ORGANS OF SPECIAL SENSE. — VERTEBRATA.

333

E. 1155. The hinder part of the same eye, showing externally
the cut ends of the vessels that form a close plexus around
the optic nerve, and internally the collapsed retina with
part of the coagulated vitreous suspended from the optic
disc ; the choroid divisible into an inner white layer
(tapetum lucidnm) and an outer spongy vascular layer ;
and the cut surface of the thick fibrous sclerotic, in the
outer parts of which can be seen the four canals that lodge
the long ciliary arteries and the vorticose veins.

0. C. 1679. Hunterian.
Beauregard et Boulart, C. R. Soc. Biol. Paris, (10)
vol. i. pp. {plexus).

E. 1156. The eye of a Whalebone Whale {Balcena mysticetus ?)
divided transversely into two equal hemispheres. By this
section, in consequence of the great thickness of the
posterior parts of the sclerotic, the cavity of the globe is
left almost entirely within the anterior hemisphere, being-
laid open just beyond the entrance of the optic nerve.
On the outside of the posterior hemisphere can be seen
the elastic vascular mass of tissue that surrounds the optic
nerve in its passage through the sclerotic. Upon the section
surface is the small optic disc with part of the retina
plicated in a radiated manner adhering to it. The tapetum
lucidum and vascular layer of the choroid are clearly dis-
tinguished by their colour and texture.

In the sclerotic, at a little distance from the choroid, are
several orifices for the short ciliary vessels, and near its
outer margin are four nearly equidistant apertures, which
are the canals for the passage of the long ciliary arteries
and vorticose veins in section. 0. C. 1678 A.

Piitter, I. c, p. 221.

UNGULATA.
HYRACOIDEA.

E. 1157. Two specimens of the eye of a Gape Hyrax {Procavia
capensis) with the cornea removed in each case to show a
lobe of the upper border of the iris depending in front of
the pupil. In the upper specimen this " umbra culum'^

PnYSlOLOGICAL SERIE.^,

almost reaches to the lower border of the iris, constrictinnr
the pupil to an hour-glass shape. In the lower specimen
it extends still further downwards, forming a curtain over
the whole pupil. A tlircud has been stretched across the
pupil beneath the umbraculum to distinguish it from the
rest of the iris.

The umbraculum is analogous to the contractile lobe of
the iris seen in the Turbot, and no doubt shades the retina
from a strong top light. It differs from the cor|)ora
nigra of other Ungulates in being composed of all layers of
the iris, and not only of the uvea, and in being thus capable
of movement.

Preserved in 50 per cent, glycerine.
Johnson, /. c, p. 27.

PROBOSCIDEA.

E. 1158. The tunics of the eye of an Elephant (ElepJias indicus)
longitudinally bisected. The sclerotic is thick, especially
towards its hinder part. The retina has been removed to
show the tapetum lucidum, which covers a large part of
the fundus of the globe. The cornea is thick and strongly
convex, and the optic nerve of great length.

0. C. 1739. Jluntei 'lan.
John Hunter, Essays and Observations, edit. R. Owen,
vol. ii. 1861, p. 173.

E. 1159. The eye of an Indian Elephant (ElepJias indicus) trans-
versely bisected. In the anterior half (upper specimen)
the lens and ciliary processes are shown. In the posterior
segment one half of the retina has been removed to show
the position and extent of the tapetum lucidum, which
covers the upper part of the fundus^ extending also for
several mm. below the optic disc.

Presented hy the London County Council
(Horniman Museum) .

PBRISSODACTYLA.

E. 1160. The tunics of the eye of a Horse (Equus cahallus)
minutely injected, cut open transversely and everted to
show the central artery of the retina and the vascularity

ORGANS OF SPECIAL SENSE. — VERTEBRATA. 333

of tlie choroid and the ciliary processes. The form and
arrangement of tlie latter are particularly well displayed.
Upon the nasal side the ciliary zone is narrower than else-
where, owing to the relative shortness of the outer parts of
the ciliary plicae in this region. 0. C. 1711 b.

Museum Heaviside.

E. 1161. The eye of a " Horse, foaled of a white cream colour,"
bisected transversely to show that pigment is absent except
upon the ciliary bodies and upon the corpora nigra. The
latter show in strong relief against the white iris; they
form a fringe of nodular masses of uvea along the inner
surface of the upper edge of the iris. Their function is
not clear. Upon the reverse of the upper specimen the
white iris is exposed by removal of the cornea. The pupil
is transversely oval. 0. C. 1726. Hunterian.

ARTIODACTTLA.

E. 1162. The two eyes of a Boar {Sus scrofa), minutely injected
by the ciliary arteries and the vorticose veins. In the
upper specimen the eyeball is transversely bisected and
the humours with part of ihe retina removed to show the
vascularity of the choroid. In the lower specimen the
sclerotic has been transversely divided and reflected to
display the peculiar convergent course of the vorticose
^eins. 0. C. 1711. IJunterian.

E. 1163. The posterior half of the eye of a Hog {Sus scrofa),
showing the cup-like form of the optic disc and the radiate
character of the surrounding retinal surface. One half of
the retina has been removed to expose the choroid.

0. C. 1703. Hunterian.

E. 1164. Two specimens of the . anterior segment of the eye of a
Camel {Camelus dromedarius), showing the iris and pupil
from the inner and outer aspect. Corpora nigra very
similar to those of the Sheep occur upon both the upper
and lower margins of the iris, but those upon the latter
are very minute. The pupil is transversely oval.
Preserved in 50 per cent, glycerine.

Presented hy Prof. G. Elliot Smith.

PHYSIOLOGICAL SERIES.

E. 1165. The posterior hal£ of the eye of an Antelope {Antilope
sp.) in "which the retina has been removed to show a broad
band-like tapetum lucid inn lying transversely above the
optic nerve. Its lower border is clearly defined, but it
gradually fades away above. 0. C. 1729. liunterian.

E. 1166. Part of the globe of the eye of a foetal Calf {Bos taurus)
injected, to show the central artery of the vitreous and
lens. 0. C. 1705 a.

Mus. Sir Astley Cooper.

E. 1167. The eye of an Ox (^Bos taurus) transversely divided.
The retina has collapsed, thus uncovering the choroid and
a large band-like tapetum lucidum of the normal Ungulate
' type that occupies the whole upper half of the globe. In
the anterior segment of the eye the ciliary processes, iris,
corpora nigra, and pupil are well shown. The corpora
nigra are not nodulated, but form a pair of smooth folds of
the uvea, of which that on the upper part of the iris is the
larger. 0. C. 1728. Hunterian.

E. 1168. The crystalline lens and parts of the lens-capsule of an
Ox (^Bos taurus). The anterior face of the lens, as in most
other Mammals, is less sharply convex than the posterior.

0. C. 1705. Hunterian.

E. 1169. The choroid tunic of the eye of a Sheep (Ovis aries)
with the short ciliary arteiies injected with mercury.

0. C. 1711a.
Presented by William Laiorence, Esq.

E. 1170. The eye of a Sheep {Ovis aries) transversely bisected,
showing, in the upper specimen, the iris, corpora nigra,
and pupil. The corpora nigra form an irregular deeply
pigmented fringe upon both the upper and lower margins
of the iris. In the lower specimen the retina has been
removed to show the tapetum lucidum, which has the
normal Ungulate position and form.

Preserved in 50 per cent, glycerine.

ORGANS OF SPECIAL SENSE. — VERTEBRATA.

337

E. 1171. The anterior segment o£ the eyes of a Sheep (Ovis
aries) showing the ciliary zone. This pleated area of the
choroid is narrower upon the nasal side than elsewhere,
measuring (in the upper specimen) 4 mm. upon this side,
as compared with 5 mm. above and below, and 5-5 mm.
upon the temporal side. In the upper specimen the lens
and retina have been removed, but have been retained in
the lower to show the position of the ora serrata. A similar
disproportion in the breadth of the ciliary zone occurs in
the Horse.

Preserved in 50 per cent, glycerine.

E. 1172. The eye of a large Quadruped, with the cornea removed
and the long ciliary arteries injected with mercury. The
trunk of each artery divides at the ciliary margin of i he
iris into two branches, that diverge and run parallel to
the border of the pupil until they meet the corresponding
branches of the other long ciliary artery, forming thus a
vascular ring (circulus major). So far as can be seen, tlie
circle is not completed by anastomosis of the finer branches
of each ciliary artery. Numerous vessels are given off
from the ciliary side of the circle, but none can be seen
upon its pupillary side. The pupil is small and oval, but
it is doubtful whether it should be vertical or horizontal.
Judging by analogy with the Human subject, the long
ciliary arteries should lie in the horizontal plane, in which
case the long axis of the pupil should be vertical.

0. C. 1737 b.

E. 1173. A transverse section of the tunics of the eye of a large
Quadruped with the capillary layer of the choroid minutely
injected. The ciliary zone and processes are very clear.
The latter are much nodulated. 0. C. 1738. Hunterian.

EODENTIA.

E. 1174. The globe of the eye of a Flying Squirrel {Pteromys
petaurista) showing the large size and pronounced convexity
of the cornea in this nocturnal species.

0. C. 1708. Hunterian.
VOL. III. z

338

PHYSIOLOGICAL SERIRS,

E. 1175. The oyo of tlio same animal, transversely divided,
showing the large almost spherical lens, the ciliary processes,
iris, and cornea. 0. C. 1707. Ilunterian.

E. 1176. Skin from the left side of the head of a Strand Mole-
Rat (Spalaw iyplihis) seen from the deep aspect. The
eyeball is reduced to a minute pigmented speck buried
beneath the skin in connective tissue. This is the most
extreme example of reduction of the eye among Rodents.
The animal lives in its winding underground galleries and
practically never comes to the surface. 0. C. 1787 B a.

Presented hy Dr. J. Anderson.
Hanke, Arch. f. Ophth., Bd. li. 1900, p. 321.

E. 1177. The skin of the right side of the head of a Coast Rat
[Batliyergus maritimus), with the eyeball exposed upon its
inner surface. Although the eye is of very small size, it
is apparently complete, with an optic nerve and with well-
developed lacrymal glands. The palpebral orifice is also of
considei^able size.

E. 1178. The eyes of a Black and a White Rabbit (^Lejms
cuniculus), showing the strongly pigmented choroid and
iris in the former, in contrast to the entire absence of
pigment in the latter.

Preserved in 50 per cent, glycerine.

PINNIPEDIA.

E. 1179. A longitudinal section of the eye of a Seal (Phoca
vituUna). The cornea is flattened (in this specimen) and
is considerably thinner in the centre than at the periphery,
as in Fishes and Cetaceans. The sclerotic is thick
posteriorly and along its corneal margin, but is extremely
thin in its middle third. The marginal thickening of the
sclerotic and cornea are fitted to withstand pressure on
the surface of the cornea, but the physiological meaning
of the meridional thinning of the sclerotic is not clear. It
has been suggested by Blumenbach (Manual Comp. Anat.,
Engl, trans. 2nd ed. p. 289) that it may adapt the eye for
vision in air by allowing the posterior chamber to be

OEGANS OF SPECIAL SENSE. VERTEBRATA.

339

shortened by the contraction of the muscles around the globe.
The choroid is peculiarly thick and is covered internally by a
tapetum lucid um, which is said to resemble that of the Cat
and other Carnivora in its minute structure. Interposed
between the base of the ciliary zone and the sclerotic is a
liighly vascular ligamentum pectinatum. This structure
and the longitudinal part of the ciliary muscle (tensor
chorioidag) are remarkably developed in Pinnipedia, and it
has been suggested (Putter, p. 334) that in these animals
accommodation takes place, as in Amphibians, by the
forward movement of the lens as a whole and not by
alteration of its shape, which in the resting condition is
nearly spherical. In this action the tensor chorioid£e is
supposed to compress the vitreous and drive forward the
lens, the extra pressure in the anterior chamber being
relieved by the expansion of the ligamentum pectinatum.
The retina has shrunk away from the choroid, keeping its
attachment only at the ora serrata and around the optic
disc. The optic nerve is accurately bisected. It is
surrounded by a thick sheath of connective tissue, which is,
however, relatively soft and, as in the Cetacea, forms a
conical plug let into the thickened hinder part of the denser
sclerotic. 0. C. A 1694.

Piitter, Zool. Jahrb., Bd. xvii. 1903, pp. 130, 308.

E. 1180. Anterior part of the eye of a Bladder-nosed Seal
{Cystophora cristata), showing the cihary zone, iris, and
pupil. The cihary processes are long and show a sharply
indented line of division about halfway between their free
extremities and the ora serrata. The pupil is ovalj but in
the condition of the specimen it is impossible to say whether
its long axis should be horizontal or vertical. In Phoca
it is vertical. 0. C. 1738 A.

E. 1181. The eye of a Sea-Lion (Otaria sp.). The cornea and
half the sclerotic have been removed with the lens, humours,
and retina. The whole inner surface of the choroid is
exposed, showing that it is covered to the margin of the
ciliary zone by a tapetum lucidum. The ciliary processes
are well developed but thin. The ligamentum pectinatum

z 2

340

PHYSrOLOGICAL SERIES.

is very large, as in Plwca, and is houncjed on both sides by
a dense membrane. The sclerotic is greatly thickened in
its anterior and posterior parts, but very thin upon a level
with the base of the ciliary zone, as in Plwca. The sheath
has been removed from the optic nerve to show its
diminution in size as it nears the optic disc.

0. C. 1C94. Ilunterian.

CARNIVOEA,
AILUKOIDEA.

E. 1182. Three preparations of the eye of a Cat [Felis doniestica) .
The upper specimen is the hinder part of the globe with
the vitreous and retina removed to show the glistening
metallic-coloured tapetum lucidum which occupies a con-
siderable area o£ the fundus above and just including the
optic disc. The tapetum consists o£ a layer of cells filled
with crystals of guanin and lying external to the capillary
layer of the choroid. The light that falls upon it is
decomposed and reflected by the crystals and possibly,
acting as a sub-minimal stimulus, increases the sensitiveness
of the retina to direct stimulation and thus assists vision in
the dark. In the middle and lower specimens the iris and
pupil are shown in a state of slight contraction and complete
expansion. When fully contracted the pupil forms a
vertical slit, in the dark it expands to a circular form.
The slit-like form of the contracted pupil apparently acts
as a corrective to the astigmatism of the cornea, which has
been shown to be A^ery marked in the Cat (Wolfskehl).
In the lower specimen the lens has been retained and
shows upon its anterior and posterior faces a faint
Y-shaped mark, which is upright upon the anterior face,
reversed upon the posterior. These lines indicate the point
of end-to-end junction of the fibres of which the lens is
composed. 0. C. 1733 a.

Preserved in 50 per cent, glycerine.

Wolfskehl, Zeits. f. vergl. Augenheilkunde, Bd. i. 1882,
p. 7 (pupil).

Schultze, Centrbl. med. Wiss., Bd. x. 1872, p. 582
(tapetuin).

ORGANS OF SPECIAL SENSE. — VERTEBRA'l'A.

341

E. 1182 a. The eye of a Cat {Felis domestica) in vertical longi-
tudinal section. The cornea is strongly convex and very
extensive, forming almost the whole of the conjunctival
area of the globe. The sclerotic is peculiarly thin, in
contrast to the decidedly thick coi'nea. The lens is situated
ahnost midway between the cornea and fundus, dividing
the eye into anterior and posterior chambers of nearly
equal size, of which the posterior is slightly the larger.
The ciliary zone is of great breadth, the ora serrata
reaching very slightly in front of the middle of the posterior
chamber. The lens is more strongly curved upon its
anterior than its posterior surfaces. The antero-posterior
and transverse diameters are to each other as 2-3. Upon
the section surface above the optic nerve part of the
tapetum lucidum is visible beneath the retina.

Preserved in 5 per cent, formol.

E. 1183. The hinder part of the eyeball of a Lion {Felis leo)
with the vitreous and retina removed to show the tapetum
lucidum. This has the same form and position as in the
Cat. 0. C. 1730. Hunterian.

John Hunter, Essays and Observations, edit. R. Owen,
vol. ii. 1861, p. 43.

E. 1184. The eye of a Lion {Felis leo) divided horizontally,
showing that almost the whole of the tapetum lucidum is
confined to the upper half as in the Cat. The humours,
lens, and retina have been removed, and the long pointed
ciliary processes are well displayed.

0. 0. 1731. Hunterian,

E. 1185. The eye of a Leopard (Felis pardalis) transversely
bisected and with the lens, vitreous, and most of the retina
removed to show the tapetum lucidum, which exactly
resembles that of the Cat. 0. C. 1733. Hunterian.

John Hunter, Essays and Observations, edit. R. Owen,
vol. ii. 1861, p. 46.

342

PHYSIOLOGICAL SERIES.

INSEOTIVOEA.

E. 1186. The skin of the head of a Golden Mole (Chri/socJiloris
treveh/ani), bisected to show upon the inner side of the
right half the minute A^estigeal eyeball (surrounded by-
black paper), and upon the outer surface of the left half
the small hairless patch of skin that overlies the eyeball,
and may be regarded as a cornea that has resumed tlie
characters of ordinary integument. To show this patch it
was necessary to cut off some of the surrounding hair.

0. C. 1787 E&.

E. 1187. The anterior jxirt of a young Mole (Talpa europcea),
showing the minute circular palpebral orifices, through
which can be seen the pigment of the vestigeal eyes.
The colour has been much lost through age.

0. C. 1772. Hunterian.
Kohl, Bibliotheca Zoolog., Bd. v. 1892-95, p. 1.

PEIMATES.
LEMUROIDEA.

E. 1188. Portions of the two eyes of a Slender Loris {Lor'is
gracilis). The upper specimen shows the large and
prominent cornea, — large to allow of the admission of as
much light as possible, and convex to adapt the vision of
this nocturnal species to the small distances at which the
gloom of night renders its prey visible to it. A portion of
the sclerotic has been removed to show its thinness and the
uniform dark brown colour of the choroid. (The Loris are
stated to show with the ophthalmoscope indications of a
tapetum lucidum. Johnson, I. c, p. 13.)

The middle specimen shows the iris. The lens, which
is very convex, as in other nocturnal animals, is mounted
separately below. 0. C. 1706. Hunterian.

ANTHROPOIDEA.

E. 1189. The anterior parts of the eye of a Monkey, with the
lens removed to show the circular form of the pupil. The

ORGANS OF SPECIAL SENSE. — VEUTEBBATA.

343

cliaracteristic difference between this and the Human eye
is the dark colour of the conjunctiva that surrounds the
cornea. The coiour has completely faded.

0. 0. 1736. Ilunte nan.

E. 1190. The iris and membrana pupil laris, injected, of a fcetus.
The membrana pupillaris is the anterior part of a vascular
membrane (tunica vasculosa lentis) that surrounds and
nourishes the lens during its development. It is a
mesenchymal structure supplied by the central artery and
from the circulus iridis. The membrana pupillaris lies
beneath the iris and is later absorbed. When occasionally
it persists the condition known as atresia pupillge congenita
results. 0. C. 1735 f.

Mus. Sir Astley Cooper.
Schultze, Festschr. A. von Kolliker, 1892, p. 4.

E. 1191. A similar specimen of the ii*is and membrana pupillaris
of a foetus. The membrana is partially absorbed.

0. C. 1735 G.
Mus. Sir Astley Cooper.

E. 1192. The eye of a foetus injected and with one half removed
to show an extremely delicate central vitreous artery.
A piece of black paper has been placed behind it. This
vessel is present only in the foetus, although in some of the
lower V^ertebrates it persists throughout life. 0. C. 1709 A.

Mtis. Sir Astley Cooper.
Schultze, Festschrift A. von Kolliker, 1892, p. 8.

E. 1193. The eye of a " fair Person," from which a lateral
segment of the tunics and the whole of the humours have
been removed to show the light-coloured choroid. The
specimen is much faded. 0. C. 1721. IJunterian.

E. 1194. A longitudinal section of the sclerotic of a Human
eye, with the optic nerve attached. This layer is slightly
thicker in its posterior region than elsewhere.

0. 0. 1740. Ihmterian.

PHYSIOLOGICAL SEKIES.

E. 1195. Preparations of the two eyes of a "dark Person."
From the Oj^por specimen one half has been removed
longitudinally, showing the collapsed retina in relief
against the dark colour of the choroid. The ciliary
l)rocesses and iris can also be seen. In the lower specimen
the cornea and anterior part of the sclerotic have been
removed and the posterior part of the sclerotic reflected to
expose the iris and choroid, which are both pigmented, but
are separated by a paler ciliary zone, upon the surface of
Avhich fibres of the ciliary muscle can be seen. The ciliary
nerves are well defined, running forward over the dark-
coloured choroid. 0. C. 1714. Hunlerian.

E 1195 a. The anterior segment of the coats of the eye of a
Fair Person," with the cornea cut away to show the iris
and pupil. The uvea has been removed from the posterior
surface of the iris. 0. C. 1722. Hunterian.

E. 1196. The anterior segment of a Human eye, with the lens
removed, showing the ciliary body with its processes and

the iris. This is divisible into two sepai'ate regions a

smooth area around the pupil and an outer zone radially
marked by pleats that form inward prolongations of the
ciliary processes. The pupil is circular. Upon the
reverse of the specimen the small convex cornea is shown.

0. 0. 1735. Hunterian.

E. 1197. The sclerotic and choroid tunics of a Human eye
transversely divided to show the ciliary body, ciliary
processes, and iris. 0. C. 1713. Huntenan.

E. 1198. The tunics of the eye of a Negro, transversely bisected.
The dark colour of the uvea is especially remarkable,
although the pigment of the choroid is much faded.

0. C. 1716. Huntevtan.

E. 1199. A segment of the hinder part of a Human eye, including
half the optic nerve. The latter is encased in a thick
fibrous sheath continuous with the sclerotic and becomes
much contracted as it enters the globe.

O.C.I 702. Hunterian.

ORGANS OF SPECIAL SENSE. — VEUTEBIIATA. 345

E. 1200. The clioroid, iris, and ciliary ligament, injected and
exposed from without. 0. C. 1713 o.

Mus. Sir Astley Cooper.

E. 1201. The eye of a Human Albino, from which a portion of
the sclerotic has been reflected to show the thin colourless
and almost transparent choroid ; the vascularity of which
being unobscured by the usual pigment occasions the
pink colour observable in the eye of these persons during
life. 0. C. 1724 a.

Presented hy Jos. Henry Green, Esq.

Parts accessory to the Organ of Vision.

John Hunter, Use of the Oblique Muscles, Animal
CEconomy, Works, Palmer, vol. iv. p. 274.
■'^Power, Med. Times and Gazette, 1883, vol. ii. pp. 335,
363, 419, 508, 540.

Corning, Morph. Jahrb., Bd. xxix. 1902, p. 94 (muscles).

Peters, Arch. £. mikr. Anat., Bd. xxxvi. 1890, p. 192
[Hard. gl.).

Sardemann, Berichte naturf. Gesell. Freiburg, Bd. i.
1886, p. 95 Qac.gl.).

The eyes of Vertebrates, except sometimes when vestigeal,
are lodged in cavities in the skull-wall (orbits) and are usually
so placed that their optic axes have, broadly speaking, a lateral
and horizontal direction. The position of the axes varies,
however, considerably in the horizontal plane, examples being
easy to find (especially among Mammals) of almost any
direction between the purely frontal and the transverse.
Deviation from the horizontal plane is less frequent, but in
many bottom Pishes the eyes are turned more or less directly
upwards. The orbit is not entirely filled by the eyeball and
its appendages, the rest of the space, which is often (Fishes)
very great, being occupied partly by a lymphatic or venous

* Many of the following preparations were made to illustrate Mr. Power's
lectures on the Protective and Lachrymal Apparatus of the Eye.

rilYSlOLOGlCAL SERIES.

cavity (Tenon's capsule, orbital sac), which envelops the hinder
part o£ the globe and the ocular muscles and nerves, and partly
by fat, which, when present in any quantity, forms a supporting
cushion or jiivot, upon which the eye can rotate when acted
upon by the individual ocular muscles. In the Elasmobranchs
this support is usually given by a rod o£ cartilage that stretches
across the orbital sac from the skull-wall to the sclerotic.

The eyeball is moved within the orbit by a series of ocular
muscles. In all cases (except where the eye is degenerate) there
are at least six of these — four recti, which, with few exceptions
(Chimcera, some Teleosts), arise close together in the depth of
the oi'bit behind or around the optic nerve and are respectively
inserted upon the upper, lower, anterior, and posterior surfaces
of the sclerotic ; and two obliqui which normally arise from the
anterior walls of the orbit and are inserted upon the upper and
lower surfaces of the sclerotic near the insertions of the superior
and inferior recti. In Mammals the superior oblique gains an
increased length of pull by the transference of its origin to the
fundus of the orbit near to that of the recti, the direction of
the pull being preserved by its passage at the anterior and
upper part of the orbit through a ligamentous ring (trochlea) .
The ocular muscles are always innervated by the iiird, ivth,
and Vith cranial nerves : the superior oblique by the ivth, the
posterior rectus (and in Petromyzon the inferior rectus) by the
vrth, and the rest by the iiird. Among the Amphibia, Reptiles,
and Birds, and in many Mammals a sheath of muscle, often of
great size, surrounds the optic nerve within the recti and acts
as a retractor of the eyeball. It is probably derived from the
posterior rectus.

The orbit is closed in externally by the skin. This may pass
smoothly from its edge to the surface of the eyeball (some
l^'ishes), but is usually loose in this part to allow the movement
of the eye within the orbit, and in most cases the area of loose
skin is tucked in between the orbit and the globe to form a
conjunctival space the orbital margin of which projects more or
less as a palpebral fold around the eye. A circular and
immoveable fold of this kind is commonly found in Fishes and
has been secondarily acquired in the case of many aquatic
Mammals, but in most Land Vertebrates the u]>per and lower

ORGANS OF SPECIAL SENSE. — VERTEBRATA,

347

borders o£ the fold are enlarged to form horizontal eyelids, one
or both of which can generally be moved by special muscles.
These lids are most perfect in Mammals and take an important
share in cleaning the surface of the eye by sweeping the
lachrymal secretion across it. In lower Land Vertebrates, where
they frequently have no power of independent movement, their
place as regards this function is taken by a fold of the conjunctiva
(nictitating membrane) situated either under cover of the lower
lid (some Amphibia) or at the anterior comer of the eye, and
capable of being rapidly drawn in front of the eye by means of
ligamentous connections with the muscles of the globe or by
muscles specially developed from the retractor bulbi for the
purpose. In Mammals, although this membrane is present,
it is usually in a degenerate condition and is incapable of
independent movement. In Fishes a similar third lid occurs
only in some few Sharks.

Except in Fishes, where the exposed surface of the eye is
washed and moistened , by contact with the surrounding water,
a special fluid is secreted for this purpose by glands developed
at the reflection of the conjunctiva. These usually lie at the
anterior and posterior corners of the eye and are known
respectively as the Harderian and lachrymal glands. The first
is best developed in those Animals in which the nictitating
membrane is highly functional and may be completely absent
when the membrane is very degenerate (Man). In some
Mammals it is separable by a difference of structure into two
parts known as the nictitating and true Harderian glands
(PL III. figs. 10, 11).

The lachrymal gland, on the other hand, is absent (Anurous
Amphibia, Ophidia) or of small proportions in lower Vertebrates,
and increases in importance with the functional activity of the
horizontal lids. The mechanism for cleansing the eye is com-
pleted by a duct (lachrymal duct) through which the lachrymal
fluid and dirt swept from the surface of the eye by the
nictitating membrane or eyelids are discharged into the nose-
cavity, or in rare cases (Snakes, Geckos) into the mouth. The
entry to this duct lies at the anterior corner of the eye and
consists of from one to about eight minute pores upon or near
the margins of the lids.

348

PHYSIOLOGICAL SEKIES.

PISCES.

Bishop Ilarman, Jour. Anat. & Pliyslol., vol. xxxlv.

lyoo, p. 1.

ELASMOBRANCHII.

Tiesing, Jena Zeits., Bd. xxx. 1896, p. 76 {muscles).

E. 1202. Two dissections of the eyelid-muscles of a Dog-fish
{Scyllium catulus). The muscles of the right eye are shown
in the upper specimen from within, those of the left eye
in the lower specimen from without. As in the Carchariidsc
(see Nos. E. 1205, E. 1207), levator palpebrae nictitantis
and depressor palpobrse superioris (marked A and B) are
present, but in this case both muscles, and not only the
levator of the third eyelid, are apparently derived from
the superficial constrictor group of muscles {cf. No. E. 1212).
They arise together from the skull between the levator
maxillse superioris and the constrictor superficialis dorsalis
II., the levator nictitantis above and to the median side of
the depressor palpebrse superioris. Both muscles run
forward and cross each other to reach their respective
insertions upon the posterior corners of the upper lid and
of the fold of skin in the lower lid that represents a
nictitating membrane.

Ridewood, Jour. Anat. & Physiol., vol. xxxiii. 1899,
p. 238.

E. 1203. The left eye of a Spotted Dog-fish {Scyllium catulus)
dissected to show the contents of the orbit. The orbital
sac is a spacious cavity, enveloping the hinder part of the
globe and traversed by the ocular muscles and nerves and
by branches of the trigeminus and facial. Its outer limit
is shown by the cut edge of its enclosing membrane. The
globe of the eye is not supported by a cartilaginous rod.
The eye-muscles have the number and arrangement usual
among Fishes — four recti arising from the binder wall of
the orbit and passing respectively to the anterior, posterior,
dorsal, and ventral surfaces of the globe, and two obliqui
that arise close together from the anterior wall of the orbit

ORGANS OF srECIAL SENSE. — VERTEBUATA.

U9

and are inserted into the dorsal and ventral parts o£ the
anterior surface of the globe. The superior oblique is
innervated by the ivth cranial nerve, the posterior

Fig. 51.

Diagram of the contents of the orbit of Scyllium catulus.

A. Dorsal aspect. B. Ventral aspect.
C. Ciliary nerve. O.A. CiUary artery. V.PE. Ophthalmicus profundus V.
II., III., IV., VI. Cranial nerves. The branches of the third and fourth
nerves are black.

(external) rectus by the vith, and the rest by branches of
the iiird. The chief trunk of the liird nerve, as it passes
between the superior and posterior recti, gives off a small
ciliary branch for the supply of the eyeball. A branch of
the trigeminus (ophthalmicus profundus) which arises
from the root of the superficial ophthalmic traverses the
orbit longitudinally, passing round the posterior margin of
the superior rectus across the main trunk of ui, and con-
tinuing above the optic nerve to a foramen in the anterior
wall of the orbit between the obliqui. The optic nerve
enters the orbit almost as far forward as the anterior
margin of the globe, not, as in higher Vertebrates, far back
amongst the recti. Branches of the liird and vith nerves
and the ophthalmicus profundus have been marked by
black paper, and a red rod has been inserted into the
ophthalmic artery where it gives origin to the ciliary
artery.

E. 1204. The right eye of a Tope (Galeus communis), showing
the circular palpebral fold and the nictitating membrane.

PHYSIOLOGICAL SERIES.

A secreting conjunctiva is deeply reflected between the
eyelids and the globe of ihe eye and also forms a smooth
lubricated covering to both sides of the third eyelid. The
third eyelid lies at the anterior and ventral margin of the
orbit and is moved over the eye in a postero-dorsal direction
by a special muscle, the cut end of which can be seen at the
posterior edge of the specimen (see also following specimen).
The upper part of the circular eyelid is also capable of
feeble movements, the range of which is indicated by a
slight fold in the skin just above the lid.

0. C. 1763. ITunterian.
John Hunter, Essays and Observations, edit. R. Owen,
vol. ii. 1861, p. 400.

E, 1205. The left eyelids and neighbouring parts of the skin of
a Tope (Galeus communis'), showing the muscles of the lids
from the inner side. These are two in number — a large
levator palpebrse nictitantis and a levator palpebras
superioris. The origin of the first is not shown. It in
fact arises from the skull in conjunction with the dilator
spiraculi, of which it is probably a part, between the
levator maxillse superioris and the superficial constrictor
of the hyoid arch (cf. E. 1207). Thence it passes down-
wards and forwards external to the muscle of the upper
lid to its insertion into the posterior corner of the nicti-
tating membrane. The depressor palpebra3 superioris
arises from the skin above the spiracle in close connection
with the sphincter spii-aculi, and passes forwards between
the levator palpebrsft nictitantis and the descending portion
of the infraorbital lateral-line canal to be inserted into
the posterior corner of the upper lid. A blue rod has
been placed in the spiracle. 0. C. 1763 b.

Ridewood, Jour. Anat. & Physiol., vol. xxx. 1899,
p. 233.

E. 1206. The left eye of a Tope (^Galeus communis) isolated, to
show the optic nerve, the cartilaginous eye-stalk, and the
mode of insertion of the ocular muscles. The obliqui are
attached to the same protuberances of the sclerotica as
the superior and inferior recti, which is the position most

ORGANS OF SPECIAL SENSE. — VERTEBRATA. 35 i

favourable for effecting the rotatory movements o£ tlae eye
upon its axis due to the action of these muscles.

0. C. 1761. Hunterian.

E. 1207. Right eye of a Tope (Galeus communis) dissected in
situ from below to show the muscles of the eyelids and of
the globus oculi. Green and red rods have been placed
respectively beneath the levator palpebrae nictitantis and
the depressor palpebrae superioris. The muscles of the
globe are well developed and quite normal in their
disposition. The delicate rod of cartilage by which the
globe is connected with the skull and supported is
attached to the wall of the orbit close in front of the
origin of the recti muscles. The optic nerve leaves the
skull more than 1 cm. in front of this eye-stalk.

0. C. 1763 a.

E. 1208. The head of a small Hammer-headed Shark {Zygcma
sp.) sagittally bisected and with the two halves mounted to
show the ocular muscles in dorsal and ventral view.
The recti muscles are remarkably long in consequence
of the position of the eyes at the ends of lateral expansions
of the head. The muscular tissue, however, extends from
the insertion of the muscles little beyond the limits of the
globe, the whole of the proximal part of the muscles
between this point and the skull being degenerate and
represented by tendinous strands that ensheath the car-
tilaginous eye-stalk, and are only with difficulty to be
separated from one another. The obliqui are nurmal in
form and position. 0. C. 1760. Hunterian,

Bishop Harman, I. c, p. 29.

E, 1209. Right eye and surrounding parts of a Porbeagle
(Lamna cornuhica), showing the ocular muscles, the
eyelids, and the conjunctival sac. The depth of the latter,
which is sufficient to allow of very considerable movement
of the eyeball, has been displayed by the removal of the
ventral parts of the circular immoveable eyelid. The
muscles of the globe are six in number — four recti arisino-

PHYSIOLOGICAL SERlRS.

I'rom the skull posterior to the optic nerve, and two obliques
rising respectively from the roof and floor of the orbit at
its anterior end. They are all strongly developed.

0. a 1667 A.

E. 1210. The eyeball, part of the optic nerve, and the car-
tilaginous eye-stalk of a Basking Shark (Scdache maxima),
showing the relatively enormous development of the ocular
muscles. The eye-stalk is united to the cartilaginous
sclerotic by a ligamentous substance and not by a diar-
throdial joint as in many Elasmobranchs. 0. C. 1761 a.

E. 1211. Eyelids and part of the right side of the head of a
Spiny Dog-fish (Acanthias vulgaris) dissected from within
to show the muscles from wLich in other species the
palpebral muscles are probably derived. The eyelids are
immoveable and have no musculature. The spiracle is
large and capable of considerable dilatation by the
action of a muscle (dilator spiraculi) (derived probably
from the levator maxillae superioris) that arises from the
skull between the latter muscle and the second part of the
constrictor dorsalis superficialis, and is inserted partly
into the upper jaw, but mainly into the spiracular
cartilage.

E. 1212. Specimens of the eye and neighbouring parts of the
head of a Spiny Dog-fish {Acanthias vulgaris) showing
the relation of the globe of the eye to the orbit. In the
lowest specimen the left orbit has been dissected from
above to show the extent of the orbital sac. This is a
cavity lined by a smooth membrane very similar to Tenon's
capsule and filled by lymph or in some cases by blood
(Parker, Phil. Trans, vol. 177, 1886, p. 711). The sac
occupies a large part of the ocular cavity and is traversed
freely by the ocular muscles and nerves. The capsule of
the sac has been opened and part of the superior rectus
removed to show by means of black paper the reflected
(visceral) layer of the capsule upon the stump of the
muscle. The orbital cavity in the parts not occupied by
the orbital sac or the eyeball is filled with gelatinous con-
nective tissue, two especially large masses of which occur

ORGANS OF SPECIAL SENSE. — VERTEBRATA. 353

anteriorly and posteriorly at the point of reflection of the
capsule. Black paper has been inserted beneath the
upper eyelid to mark the depth of the conjunctival sac.

In the middle specimen are shown the position and form
of the cartilaginous rod by means of which the globe of
the eye is held away from the mesial wall of the orbit,
and (in the upper specimen) the diarthrodial mode of
articulation that occurs between the ex]3anded plate-like
head of this rod and the sclerotic. The capsule of the
joint is furnished by the "visceral" layer of the orbital
sac, which is closelj'^ adherent to the head of the rod,
but is free from the sclerotic for some distance around it.
This specimen also shows the line of reflection of the
capsule.

Bishop Harman, I. c, p. 23.

E. 1213. The eyes of a Ray (Raja clavata) dissected to show
the cartilaginous process of the skull that extends from a
point on the median wall of the orbit posterior to the exit
of the optic nerve to the deep surface of the eyeball. The
eyeball is pivoted upon this " eye-sta1k," being jointed to
its end by a diarthrodial joint. The joint has, however, no
definite capsule, but the connective tissue that envelops
the globe passes direct from the sclerotic cartilage to the
outer surface of the eye-stalk, leaving the actual surfaces
of contact bare. The rod is steadied in its position by a
ligament that runs from its distal end to the anterior wall
of the orbit. Below ..the chief specimen, in which the
general relations of the globe to the eye-stalk are shown,
separate pieces of the mechanism are mounted, showing
the flattened almost ribbon-like form of the stalk and the
presence of a prominent articular boss on the sclerotic
cartilage.

GANOIDEI.

E. 1214. The left eye of a Sturgeon (Acipenser sturio) in its
natural position, showing the circular immoveable eyelid,
the great extent of the conjunctival space, and the muscles
of the globe. The optic nerve leaves the skull at least 1 cm.
in front of the origin of the recti muscles.

VOL. III. 2 A

354

PIIYKIQLOGICAL SKIUEK.

TELEOSTEA.

E. 1215. The head of a Shad {Clnpea alosd), sliowing the
eyelids of transparent muco-areoLar tissue that extend
partly over the eyes from their anterior and posterior
horders. The posterior fold is a simple enlarf^ement of
the posterior border of the circular palpebral fold, but the
anterior has more the characters of an immoveable third
eyelid, being a process extending backwards from beneath
the anterior part of the true palpebral fold. These lids
are more pronounced during the breeding-season. Black
paper has been placed between the eyeball and the eyelids.

1759 a.

Bishop Harman, I. c, p. 7.

E. 1216. Two sp3cimens showing the arrangement of the eye-
muscles of a Shad {Clupea alosd). In the lower specimen
the head and shoulders are seen in median sagittal section
from the left, with the inner wall of the right orbit
removed. The oblique and inferior rectus muscles are of
normal length and disposition, but the other recti extend
to different degrees backwards beyond the orbital cavity.
The superior rectus is the shortest and arises mainly from
the back of the orbit, but its lower fibres are prolonged for
about 1 cm. beyond this point. The internal and external
recti pass backwards below the floor of the skull and
anterior part of the vertebral column, and take their origin
from the vertebral column and aorta as far back as the
third vertebra. The extra-orbital part of these muscles is
enclosed in a canal formed by two delicate wings that
project backwards from the lower surface of the sphenoid.
This canal and its connections with the orbit are shown in
the sagittal section of a skull mounted above. Below is a
diagram.

E. 1217. Head of a Herring {Clupea harengus), showing the
anterior and posterior protective palpebral folds. A black
bristle is placed beneath them. 0. C. 1759. Tlunterian.

E. 1218. The head of a Conger {Conger vulgans). In this fish
there are no definite eyelids. The skin of the head passes

ORQAKS OF SPECIAL SENSE. — VERTEBRATA.

355

directly over the cornea, without forming a conjunctival
recess. The cornea is slightly convex and of very great
extent, covering the whole outer surface o£ the globe. Its
conjunctival layer is thick, and is separated by loose con-
nective tissue from the deeper true corneal layer. The
loose intervening tissue allows of a limited amount of
movement to the eyeball, notwithstanding the want of a
conjunctival reflection. The ocular muscles are, however,
very feeble. Upon the right side, the skin, conjunctiva,
and cornea are shown in section, and the orbital sac has
been opened, exposing two of the ocular muscles. The
capsule of the orbital sac is peculiarly thick.
Bishop Harman, I. c, pp. 5, 21.

E. 1219. The head of a Mackerel (Scomber scombrus), showing a
development of the eyelids similar to that described in the
Shad and Herring (Nos. E. 1215, E. 1217). The special
adipose lids are slightly raised by a black bristle.

0. C. 1758. Hunterian,

E. 1220. Part of the head of a John Dory {Zeus faber), with
the right eye dissected from the median aspect. In fishes
with the head much laterally compressed, the position of
the eye and the relative length of the internal and external
recti are such that the contraction of the internal rectus
causes an outward projection of the posterior part of the
globe, thus allowing an increased frontal range of vision.
The insertions of the obliqui overlap those of the superior
and inferior recti.

Bishop Harman, I. c, p. 31.

E. 1221. Left eye of a Halibut (Bippoglossus vulgaris), with the
muscles of the globe displayed. The superior oblique is
double. One part of the muscle has the usual insertion
upon the centre of the dorsal margin of the sclerotic in
apposition to that of the superior rectus. The other part
arises close beneath the first, then runs backwards around
the posterior surface of the eyeball, crosses superficial to
the superior rectus 1 cm. from its insertion, and is finally
attached to the margin of the sclerotic at the postero-

2a 2

35C

PHYSIOLOGICAL SERTKf*.

dorsal part of tlie globe. This extra oblique muscle is
peculiar to the flat fishes, either as a separate muscle or
as an offshoot of the superior oblique, and materially
assists in the strong rotation of the eye about its axis that
has been observed in fishes of this family. All the eye-
muscles except the external rectus are remarkably largo,
and by reason of the great length of their muscular
portion are capable of producing extensive movements of
the eyeballs, especially those of convergence. Great
freedom of movement is allow^ed to the eyes of these fishes
by the area of loose skin betv^^een the conjunctiva and the
margin of the orbit.

Bishop Harman, I. c, p. 33.

E. 1222. Head of a Halibut (liippoglossus vulgaris), showing
the mechanism for the protrusion of the eyes. The left
eye has been removed and a blue rod inserted into a passage
that leads from the outer part of the floor of the orbit into
a large muscular outpushing of the orbital wall (recessus
orbitalis) situated upon the blind side of the head. This
sac can be seen upon the reverse of the specimen. A
similar though less marked recessus is present upon the
outer and posterior wall of the right orbit. In the specimen
this part of the orbital wall has been exposed and in part
removed to show the connections of this rudimentary sac
with the orbital cavity. The recessus orbitalis serves as a
reservoir into which a great part of the orbital fluid
passes when the eye is retracted. Upon relaxation of the
muscles of the globe, the fluid is again driven into the
orbit by the contraction of the walls of the recessus, and
in consequence the eye is protruded.
Holt, Proc. Zool. Soc, 1894, p. 422.

E. 1223. Specimens of the recessus orbitalis in the Plaice
{Pleuronectes platessa). The recessus orbitalis of the left
eye has similar relations to the orbit as that of the Halibut,
but is of rounder form and is not embedded in fat. The
recessus of the right eye is quite as large as the left ; it
opens into the posterior part of the orbital cavity. Both
recessus have thin walls strengthened on the inner side bv

■

ORGANS OF. Sl'KCIAL SENSE,— VEUTHDUATA. 357

numerous delicate muscular trabeculse. The general form
and position of the recessus are shown in the two lower
specimens. Above are isolated specimens of the recessus
opened to show the internal structure. A blue rod has
been inserted into the passage from the recessus of the
blind side into the left orbit.

Holt, Proc- Zool. Soc, 1894, p. 422.

AMPHIBIA.

E. 1224. The eyes of a female Guppy's Frog {Rana guppyi),
showing the palpebral and muscular apparatus. In the
upper specimen (left eye) the lower part of the conjunc-
tival reflection has been cut through and the bulb turned
upwards. The muscles of the globe are left in their
normal position, and the tendon of the lower eyelid is
shown passing round the ventral surface of the globe
between the recti and the retractor bulbi muscles from one
corner of the lid to the other. Black paper is placed
beneath the tendon. In the lower specimen (right eye)
the oblique and recti muscles have been separated to show
their small size in comparison with the enormous retractor
bulbi that surrounds the optic nerve. The course of the
tendon of the lower lid is also shown, with its fibrous
attachment to the inferior rectus and retractor bulbi. The
small Harderian gland can be seen at the inner corner of
the eye between the obliqui. The lower eyelid is far
larger than the upper ; it is transparent towards its
margin, and although it has no muscles of its own, is
capable of movement by the traction of the retractor bulbi
on its tendon. The upper lid has no intrinsic muscles, but
only moves slightly through its attachment to the eyeball.
Ecker^s Anat. des Frosches, 2nd Aufl., Gaupp, Abt. 3,
1904, p. 872. . O.C. 1763 d.

E. 1225. A male Megalophrys nasuta, showing a prominent
integumentary fold above each eye. This is a triangular
expansion of the external surface of the eyelid. It is said
to be lowered at will. 0. C. 1763 js.

rJlYSIOLOCilCAL SEllIES.

IIEPTILIA.
LACERTILIA.

Weber, Arch. f. Naturges., Bd. xliii. 1877, p. 201.

E. 1226. The left eyeball and eyelids with their muscles of a
Chameleon. The conjunctival reflection has been, cut
except along its dorsal part and the ejelids turned upward
to show the extent of the conjunctival sac and the small
size of the palpebral opening. The recti and obliqui
muscles are also shown. 0. C. 1764. Ilunterian.

E. 1227. Left half of the head of a Chameleon, showing the
circular and prominent eyelids, the loose flexible character
of the skin where they join the border of the orbit, and the
small fusiform palpebral orifice. The eyelids in the
Chameleon move chiefly with the eyeball.

0. C. 1765. Huntenan.

E. 1228. The right eye and eyelids of a Chameleon (Chamceleon
vulgaris). The globe of the eye has been removed by
cutting the conjunctiva along its line of reflection. The
skin of the head is mounted below to show the extent of
the conjunctival space, the small palpebral orifice, and the
circular tarsal cartilage in the lower lid into which is
inserted a well-developed depressor palpebrae inferioris.
Above is shown the eyeball from its ventro-median aspect.
It is moved by the usual recti and obliqui muscles, and in
addition by a retractor bulbi formed of three indistinctly
separate bundles. The superior rectus is particularly
strong. A rudimentary nictitating membrane can be seen
at the inner corner of the eye, extending some little way
across its surface. In connection with it is a well-marked
JIarderian gland, partially concealed in the specimen by
the inferior oblique.

E. 1229. The head and an isolated specimen of the eye of a
Monitor Lizard ( Varanm griseus), dissected to show the
muscles of the eye and eyelids and the Harderian gland. In
the lower specimen the left eye has been removed from its

ORGANS OF SPECIAL SENSE. — YERTEBRATA.

359

socket to expose the nictitating membrane and its tendon and
the Harderian sland. The tendon arises from about the middle
of the median border of the roof of the orbit and passes thence
behind the optic nerve around the posterior and ventral
parts of the globe to be inserted into the lower corner of

Fig. 62.

I.R

E,iglit eye of Varanus griseus.

A.R. Anterior rectus. B. Bursalis. I.O. Inferior oblique. I.R. Inferior
rectus. P.R. Posteiior rectus. 11. B. Retractor bulbi. S.O. Superior
oblique. S.R. Superior rectus. The tendon of the nictitating membrane
dotted. 11., 111., IV., v., VI. The cranial nerves.

the third eyelid. At the back of the orbit, immediately
behind the optic nerve, the tendon passes through a sling
formed by the bursalis muscle, which by means of this
connection is enabled to draw the nictitating membrane
over the surface of the eye. The bursalis muscle is inner-
vated by the sixth nerve and belongs to the same group as
the retractor bulbi. The chief part of it is inserted upon
the globe of the eye.

In the upper specimen the innervation of the muscles of
the globe and nictitating membrane and their insertions
are shown. The depressor palpebrse inferioris has been cut
short and the chief part of the Harderian gland removed.

E. 1230. The lids and glands of the left eye of a Monitor Lizard
{Varanus salvator), seen from within. The lower lid is
larger and capable of more movement than the upper. It

3(50

PHYSIOLOGICAL SERIICS.

can l>e opened by a slieel-Iike fJo])ressor muscle (not sl)o\vn
in this specimen) inserted mainly into a large round tarsal
cartilage embedded in the substance of the lid. The
nictitating membrane is well developed ; it has a vertical
position at the anterior corner of the eye, and can be
drawn across the surface of the eyeball by a special muscle
and tendon : in the specimen part of this tendon, from its
insertion in the lower corner of the nictitating membrane
to its passage through the bursalis muscle, is retained. The
nictitating membrane is lubricated by the secretion of a
large compact Hardorian gland situated at the anterior
part of the orbit. The lachrymal gland is attached to the
outer surface of the reflection of the conjunctiva at the
posterior corner of the lower eyelid. 0. C. 17G5 A.

OPHIDIA.

E. 1231. Tlie left eye of a Python {Python reticulatus) showing,
from the inner aspect, the muscles and glands of the eye-
ball. The muscles (four recti and two obliqui) are feebly
developed, but normal in their arrangement. There is no
retractor bulbi. In the specimen the muscles have been
spread out ; their insertions upon the eyeball are obscured
by the reflected edge of the peculiarly deep conjunctival
sac. The lachrymal gland is represented by a slight
glandular thickening upon the postero-dorsal part of the
conjunctival reflection, just behind the external rectus.
The Harderian gland, on the contrary, is an enormous
structure, that in its natural position wraps around the
mass formed by the globe, the optic nerve, and eye-muscles.
In the specimen it has been turned forwards (the hollow in
* which lay the eye-complex being occupied by a pink rod).
The gland communicates with the lachrymal sac by a wide
duct (green rod), and is said by Cloqnet (Mem. du
Museum, t. vii. 1821) to assist deglutition by pouring its
secretion through the lacrymal duct, direct to the mouth.
The opening of the passage from the palpebral cavity
into the lachrymal sac (purjile rod) is so valved that the
secretion of the Harderian gland cannot pass into the
palpebral cavity. O.C. 1770 c.

ORGANS OF SPECIAL SENSE. — YEKTEBRATA.

E. 1232. Left half o£ the fore part of the head of an Anaconda
[Eunedes murimts), in which the lachrymal duct has been
exposed throughout its course from the conjunctival sac
to the mouth. An explanatory diagram has been mounted
below the specimen. The lachrymal duct leaves the con-
junctival sac at its anterior and ventral reflection. Very
soon it receives the duct of the Harderian gland, and
then runs forward within the outer wall and floor of
the nasal cavity and opens together with the organ
of Jacobson into the mouth-cavity. In this specimen the
strongly convex outer covering of the eye is also clearly
shown. This at first sight appears to be the cornea, but is
in reality the eyelids fused together and transparent.
Around them the integument is again invaginated, giving
rise to a false conjunctival space and circular lid.

EMYDOSAUETA.

E. 1233. Eight half of the head of a young Crocodile, showing
the three eyelids. The horizontal ones have each been
divided and reflected from the front of the eyeball : the
vertical or nictitating eyelid is drawn over the coi'nea and
a bristle placed under it, showing its extent and semi-
transparency. 0. C. 1769. Hunterian.

E. 1234. The left eyelids of a Crocodile. The upper and under
lids have been separated at their posterior union and spread
apai't to show the nictitating membrane and, at its base,
at the point of reflection of the conjunctiva, the wide
open mouth of the duct of the Harderian gland, into
which a black bristle has been inserted.

0. C. 1771. Huntei

E. 1235. The right eye of the same Crocodile, with the eyelids
and the muscles of the globe prepared, particularly to show
the mechanism for the moveTnent of the nictitating mem-
brane.

The muscle by which this membrane is drawn upwards
and backwards across the surface of the eye arises from an
area of the sclerotic just below the insertion of the internal
rectus. From this origin it jiasses round the globe above

3G2

PHYSIOLOGICAL SEUIES.

the Optic nerve and retractor bulbi and below the insertion
of the external rectus to be inserted to the lower angle of
the nictitating membrane. 0. C. 1770. Jlunleiian.

John Hunter, Essays and Observations, edit. B. Owen»
1861, vol. ii. p. 342.

E. 1236. The right eye of a Crocodile (Crocodilvs americanus)
in position, showing the muscles of the globe and eyelids,
and the Harderian gland. The upper and under lids have
been divided at their posterior end to show the nictitating
membrane more clearly. Black bristles have been inserted
into the puncta lachrymalia. Jn addition to the normal
recti and obliqui there is a well-marked retractor bulbi
surrounding the optic nerve. A description of tlie nicti-
tator muscle is given for the previous specimen. The
upper lid is raised by a strong levator muscle inserted
into its outer corner. The depressor of the lower lid forms
a muscular floor to the orbit ; in action it probably not
only lowers the eyelid but also slightly protrudes the
<?yeball. O.C.I 7 70 b.

E. 1237. The left eye and part of the snout of a Crocodile
(Crocodilus americanus), showing the origin and course of
the lachrymal duct. The eyelids have been separated from
the eyeball and reflected outwards, and black bristles have
been inserted into the puncta lachrymalia — three small
orifices situated in a row just within the margin of the
lower lid near its anterior limit — and passed thence along
the lachrymal duct into the nose. The single duct formed
by the union of the three passages from the puncta lachry-
malia is broad and much flattened dorso-ventrally ; it
opens into the nose under cover of the turbinal by a wide
mouth. At its ocular and nasal ends it is dilated, forming
respectively a saccus lacbrymalis, which receives the three
ducts from the puncta lachrymalia, and a saccus naso-
lachrynialis, remarkable for its thick glandular walls. The
lachrymal sac, the flattened portion of the duct, and the
saccus naso-lachrymalis have been opened. 0. C. 1770 a.

ORGANS OF SrECIAL SENSE. — VEUTEBllATA.

303

CHELONIA.

E. 1238. The eyeball, eyelids, and lachrymal glands o£ a Turtle
{Chelone mydas). The upper and under lids are well
developed and are both capable of movement. The third
lid is situated vertically at the anterior canthus o£ the eye
and has a horizontal motion over the cornea : it is here slit
across to show the orifice of the duct (indicated by a black
bristle) of the Harderian gland, of which the secretion is
expressly destined to facilitate its movements. This gland,
however, is of small size compared with the true lachrymal
gland, which consists of the thick and broad conglomerate
mass surrounding the outer and upper parts of the eyeball :
its duct (into which a quill has been inserted) is short and
wide, and terminates just below the outer canthus of the
eye. The gland is made up of a number of sharply
defined conical lobules that convero-e towards a central
duct. The secreting epithelium (PI. III. fig. 9) of the
tubular acini of the gland is composed towards the centre
of the lobules of slender cells, which are fluted longi-
tudinally and separated from one anoiher by spaces filled
with an intercellular substance. The basal part of each
cell breaks up into a number of delicate root-like pro-
cesses. Towards the periphery of the lobule the cells
of the secreting epithelium are nearly cubical in form.

0. C. 1766. Hunterian.
Stewart, Monthly Microsc. Jour., vol. xviii. 1877, p. 241.
John Hunter, Essays and Observations, edit. E. Owen,
vol. ii. 1861, p. 353.

E. 1239. The right eye of a female Turtle {Chelone mijdas),
with the eyelids, glands, and muscles shown. The
Harderian gland can be seen more clearly than in the
previous specimen. Its opening into the conjunctival sac
beneath the nictitating membrane is indicated by a pale
blue rod. A dark blue rod has been passed into the duct
of the true lachrymal gland. The several lobes of the latter
have been slightly separated. The muscles of the globe
can be better seen in the following specimen.

0. G. 1767 a.

Presented hj the Manager of the Westminster Aquarium.

rilYSlOLOGICAL .SERIES,

E. 1240. Loft cyo of a Turtle {Chelone mj/das) with the oycHds
and the muscles of the globe. In addition to the six
usual muscles of the globe, which have the normal
positions, there is a strong retractor bulbi surrounding the
o[)tic nerve. The superior oblique divides just before its
insertion into two well-defined slips — one passes beneath
the superior rectus to be inserted towards the hinder part
of the globe about its meridian ; the other is inserted in
common with the superior rectus. The external rectus is
partly double and sends slips of insertion to the conjunctival
sac. The muscle of the third lid is very similar in form
and position to that of the Crocodile, but at the point where
it passes above the optic nerve it is crossed by and forms a
connection with a depressor of the upper lid. This latter
nmscle arises from the surface of the globe just below the
nictitator, crosses superficial to it, passes upwards to the
posterior canthus of the eye, and is inserted by tendon into
the corner of the upper lid. In consequence of the con-
nection between these two muscles, the nictitating membrane
and upper lid move together. In the specimen part of the
conjunctival sac has been removed at the anterior canthus
to show the insertion of the nictitator muscle to the third
lid. A black bristle has been placed beneath the point of
union of the nictitator and depressor palpebra3 superioris
muscles and a blue rod into the duct of the lachrymal gland.
A small part of the orbital wall has been retained to preserve
intact the origins and mutual relations of the external,
superior, and internal recti and of the two obliqui.

0. C. 1767 B.
Presented hy H. Power, Esq.

Power, I. c, p. 338.

E. 1241. Lids from the left eye of a Leathery Turtle {Dermo-
chelys coriacea), seen from the inner aspect. In general
form the lids closely resemble those of Chelone. But the
mucous membrane upon the deep surface of the upper lid
and of the nictitating membrane, and to a less degree that
upon the lower lid, is thrown into numerous deep plications,
giving to these areas a strongly laminate appearance. A
similar though very much less marked plication is present

ORGANS OF SPECIAL SENSE. — VERTEBUATA.

in Chelone. The niclitator muscle is labelled B, the
depressor o£ the outer corner of the upper lid A, and a
black bristle has been passed through one of the ducts of
the Harderian gland.

AVES.

E. 1242. The right eye and eyelids of an Ostrich (^Strutldo camelus).
The horizontal lids are well defined, the lower being the
larger and capable of most movement. They are beset
along their margins by a fringe of irregularly placed
bristle-like feathers resembling the eyelashes of Mammals.

0. C. 1794. Hunterian.
John Hunter, Essays & Observations, edit. R. Owen,
1861, p. 297.

E. 1243. The right eye of an Emeu (Drommis novcE-liollandict),
dissected to show the muscles of the globe and third
eyelid, and the Harderian gland. The normal six muscles
of the globe are present, their insertions only being retained.
The muscles of the nictitating membrane are two in
number — the quadratus and the pyramidalis. The former
arises from an extensive area of the dorsal surface of the
globe beneath the insertions of the superior rectus and
superior oblique. Its fibres converge towards the optic
nerve, just short of which the muscle terminates in a
tendinous border channelled to lodge the tendon of the
pyramidalis muscle. The pyramidalis arises from the
lower surface of the eyeball, just in front of the insertion
of the inferior rectus. From its origin, where it is some
10 mm. in breadth, its fibres converge to form a round
tendon that plays within the fibrous selvage of the
quadratus. It then winds over the optic nerve and is
inserted into the lower angle of the free margin of the
third lid, along which it is continued for some distance
and is gradually lost. By the simultaneous contraction of
these two muscles, the third lid is drawn forcibly and
rapidly outwards and with an oblique inclination down-
wards over the fore part of the eye. The tendon of the
pyramidalis gains a suitable direction by winding round

PHYSIOLOGICAL SERIES.

the optic nerve, and is restrained from pressing upon the
nerve by the counteracting force of the quadratus, whicli
thus increases the pull of the pyrainidalis upon the lid,
whilst at the same time obviating any injurious pressure on
the optic nerve. The nictitating membrane returns, on the
relaxation of its muscles, by virtue of its own elasticity to
the inner corner of the orbit, where it lies folded up when
not in use. The Harderian gland, the secretion of whicli
lubricates the third lid, lies upon the anterior surface of the
globe. It is pear-shaped and compared with that of some
Birds of quite small size. It communicates with the con-
junctival sac by a long and wide duct, into which a black
bristle has been placed. 0. C. 1797 b

E. 1244. Right half of the head of a Goose (Anserferus). The
median and upper walls of the orbit have been removed to
show the glands and muscles of the globe. The lachrymal
gland is small and lies at the outer and upper border of the
eye, connected with the conjunctival sac just above the
insertion of the external rectus. The superior oblique has
been cut short ; beneath its cut end can be seen the
quadratus muscle. The Harderian gland forms a con-
spicuous rounded mass at the inner and lower angle of
*heeye. O.C. 1795a.

E. 1245, The opposite eye of the same Goose, removed from the
orbit to show the insertions of the muscles of the globe and
the mechanism of the third lid. Black bristles have been
placed beneath the pyramidalis muscle and its tendon.
The quadratus is relatively about twice as large as in
JDromceus (No. E. 1243). 0. C. 1795 b.

E. 1246. Left half of the head of a Black Swan {Chenopis atrata)
showing the lachrymal duct. The eyelids have been reflected
forwards and black bristles have been inserted into the two
large puncta lachrymalia, which are situated upon the inner
surface of the lids just in front of their anterior point of
union. The lachrymal duct is a broad membranous tube
that runs forward over the outer surface of the lachrymal

ORGANS OF SPECIAL SENSE. — VERTEBRATA. 3G7

bone to the hinder edge of the nasul. At this point it dips
towards the nose-cavity, into which it opens beneath the
maxillo-turbinal by a vertical slit-like aperture.

Presented hy W. B. Tegetmeier, Esq.

E. 1247. Right eye of a Stork (Ciconia ciconia) removed from
the orbit and dissected to show the insertions of the muscles
of the globe, the mechanism of the third lid, and the
Harderian gland. The superior oblique, although thin, is
at least twice the breadth of any other muscle of the globe.
The muscles of the third eyelid, except for the greater
development of the quadratus, resemble those of the Emeu
(No. E. 1243). The Harderian gland is relatively small ;
it is connected by a long duct with the conjunctival space
beneath the nictitating membrane. 0. C. 1796 A.

Presented hy the Zoological Society of London,

E. 1247 a. Left eye of a Rough -billed Pelican {Pelecanus
erythrorhyncJius) showing the muscles and glands of the
eyeball. The muscles have the disposition and general
characters normal for Birds, but the Harderian gland is
unusually large, being almost equal in size to the globe of
the eye (measuring 27 X 23 X 10 mm.). The lachrymal
gland is relatively quite small. Upon the sclerotic, in the
angles between the pyramidalis muscle and the optic nerve
and quadratus muscle, are two small masses of congested
blood-vessels. These are retia mirabilia, into which the
ciliary arteries divide before traversing the sclerotic.
The mass of gland tissue beneath the Harderian is part
of the nasal gland.

E. 1248. Left side of the head of a Spanish Imperial Eagle
{Aquila adalberti) dissected to show the eyelids with their
muscles, the Harderian gland in its natural relations to the
globe, and the insertions of the ocular muscles. Black
bristles have been inserted beneath the tendon of the
pyramidalis. The tarsal cartilage in the lower lid is
exposed from the outside, as. also is a similar though more
elongated plate of cartilage that lies in the substance of
the upper lid. 0. C. 1797 a.

•5^'^^ rilYSIOLOGICAL SEIHES.

E. 1249. The eyeball of an Eagle, with the nictitating membrane
and anterior parts of the horizontal lids. The latter are
fringed by stout bristle-like feathers. Bristles have been
inserted into the puncta lachrymalia and beneath the third
eyelid into the duct of the Harderian gland.

O.C. 179G. IJunterian.
John Hunter, Essays & Observations, edit. R. Owen,
18G1, vol. ii. p. 271.

E 1250. Lids of the right eye of an Eagle {Aquila sp.) seen
from within, to show the position of the nictitating membrane
and the large round tarsal cartilage in the lower lid.

0. C. 1797. Iluntenan.

E. 1251. Left half of the head of a Horned Owl {Asio otus),
showing the lids. The margins of the horizontal lids are
beset by plumose feathers, analogous to the eyelashes
of Mammals. The third lid is very large, and is sjtuated
mainly under cover of the upper lid : its low*er angle
lying slightly below the inner corner of the eye, and its
outer angle reaching nearly to the outer canthus. It
sweeps over the eye downwards as well as outwards and is
usually accompanied in its movements by the upper lid.
A black bristle has been inserted into one of the puncta
lachrymalia and thence to the nose ; and a white bristle
(seen on the reverse of the specimen) into the duct of the
Harderian gland. 0. 0. 1799. Hunterian.

John Hunter, Essays & Observations, edit. E. Owen,
.1861, vol. ii. p. 278.

E. 1252. The left eye of a Great Horned Owl {Bubo bubo), with.
the lower lid, parts of the nictitating membrane, and the
Harderian ghmd. The round tarsal cartilage can be
clearly seen on the inner surface of the lower lid (cf.
Varanus, No. E. 1230). Bristles have been placed in the
puncta lachrymalia and into the duct of the small Harderian
gland. 0. C. 1798. Hunterian.

John Hunter, Essays & Observations, edit. R. Owen,
1861, vol. ii. p. 279.

E. 1262 a. The cranium and right eye of a Raven (Corvus corax)
dissected from the venti'al aspect to show the depressor of

«

ORGANS OF SPECIAL SENSE. — VEUTEBRATA.

369

the lower eyelid. This is a flat fan-shaped muscle, that
arises from the skull in the fundus of the orbit close in
fi-ont of the optic foramen, and passes outside the lining
membrane of the orbit to the lower lid. The levator of
the upper lid, though present, is relatively very feeble.

MAMMALIA.

Eggeling, Jena. Zeits., Bd. xxxix. 1905, p. 1 Qids).
MONOTEEMATA.

E. 1253. The right eye and surrounding integument of a Spiny
Anteater {TacliygJossus [Ecliidna] aculeatus), showing the
muscles of the globe and eyelids and the Harderian gland
from the inner aspect. The superior oblique is in a
condition transitional between that of other Mammals and

Fig. 53.

I.R

The right eye of Tachyglossus aculeatus.

A.R., I.E.. Anterior and inferior recti. L.P. Levator palpehrse. P. Its slip
to lower lid. P.R. Posterior rectus. S.O. Superior oblique. S.O.' Its
attachment to the connective tissue of the orbit. S.R. Superior rectus.

that of lower Vertebrates. The greater part takes origin
at the anterior part of the orbit from a mass of fibrous
tissue, but its deeper fibres pass on and at the same time
turn towards the fundus of the orbit lying external to
the anterior rectus. Their actual point of origin is not
shown, but Goppert states that this part of the muscle
arises from the orbital wall in front of the origin of the
recti. Both obliques are inserted far round the eyeball,

VOL. III. 2 B

370

PHYSIOLOGICAL SEHIEF!.

one above and one below the insertion o£ the posterior
rectus. The Harderian gland is large and loose in texture
and, like that o£ Snakes, envelops the hinder part o£ the
globe and the optic nerve. There is a strong levator
of the uppor lid, and a peculiar palpebral muscle that
runs from the depth o£ the orbit to the posterior angle
of the lids, where it is inserted into the lower lid. Its
contraction closes the lids. 0. C. 1771 A.

Goppert, Morph. Jahrb., Bd. xxi. 1894, p. 278.

MAESUPIALIA.

E. 1254. The left eye of a Black Wallaby {Flahnaturus ualdbatus)
showing the lachrymal and Harderian glands and the
presence of a small retractor bulbi around the optic nerve.

O.C. 1772 a.

EDENTATA.

E. 1255. The left eye of a Hairy Armadillo {Dasypus villosus)
with its associated glands. The globe of the eye, which is
peculiarly small for the size of the animal, is mounted
separately above the lids. The latter are seen from the
inner side. The lachrymal and more especially the Harderian
glands are of great size, and the latter, as in Braclypxis,
has a looser texture than in most Mammals.

E. 1256. The left eye of a Three-toed Sloth {Brady pus fn-
dactt/lus), with the muscles and glands displayed. The
line of insertion of the retractor bulbi can be seen between
the optic nerve and the insertions of the recti and obliqui.
The Harderian gland is large and much lobulated, semi-
isolated lobules extending along the conjunctival reflection
as far as the levator palpebrse superioris. The true lachrymal
gland is small and occupies the usual position at the posterior
corner of the eye.

E. 1257. The eyes of an Anteater (MyrmecopJiagajuhata), showing
the muscles and glands of the eyeball. The Harderian gland
is remarkable for its enormous size. It consists of two
definite lobes — one above the eyeball and one encircling its
posterior, ventral, and anterior parts. Ducts from these
two lobes enter the conjunctival space by a single orifice at

ORGANS OF SPECIAL SENSE. — VERTEBRATA.

371

the base of the third eyelid. (The opening is not shown.)
In addiiion to this, which may be called the true Harderian
gland, the outer surface of the third eyelid is covered by
a glandular mass similar in position to the nictitating
gland upon the third eyelid of the Pig and some other
Mammals. The lachrymal gland lies above the postero-
dorsal parts of the eyeball, between the two lobes of the
Harderian gland. The usual ocular muscles are present
(lower specimen). The superior, inferior, and anterior
recti, in addition to their usual insertions upon the sclerotic,
give ofE slips to the upper, lower, and third eyelids, the first
two of which are indicated by blue rods in the upper speci-
men. There is also a well-developed levator palpebrse
superioris. A retractor bulbi of moderate size surrounds
the optic nerve.

. Pouchet, Memoire sur le Grand Pourmilier, 1874,
pp. 55, 60.

CETACEA.

John Hunter, Phil. Trans., vol. Ixxvii. 1787, p. 438.

E. 1258. The eyeball and surrounding muscles, with the eyelids,
of a Porpoise (PJioccena phoccena). The eyelids consist of a
continuous fold of the skin, leaving a circular opening
in front of the eye with a narrow margin unprovided with
cilia. The palpebral opening is closed by an orbicular
sphincter, and expanded by four broad and almost con-
fluent muscles. In the specimen their cut ends can be
seen close below the section surface of the skin. The
eyelid has been cut at its inner side, showing the depth of
the conjunctival sac. Black bristles have been inserted
into two of the ducts of the glands that cover the reflection
of the conjunctiva. 0. C. 1774. Hunterian.

E. 1259. The eyeball of a Porpoise {FJioccena plioccena), isolated
to show the muscles of the globe. The obliqui are ill-
developed in comparison with the recti. The superior
oblique becomes slightly tendinous in its passage through
the trochlea ; the retractor bulbi is well marked.

0. C. 1773. Hunterian.
2b 2

372

PHYSIOLOGICAL SERIES.

E. 1260. The cyo oL' a Doljiliin {Delpldnvs tur.sio), sliowin^ a
zone of glandular tissue situated upon the reflection of the
conjunctiva. Bristles have been inserted into the ducts of
these glands. A larger and more definite mass of this tissue
lies at the inner side of the eyeball ; its ducts are distin-
guished by thicker bristles. 0. C. 1776. Jluntenan.
John Hunter, Essays & Observations, edit. R. Owen,
1861, vol. ii. p. 108.

E. 1261. The left eye and eyelids of an adult male Dolphin
{DelpUnus tiirsio). The muscles have been cut short.
The recti and obliqui are poorly developed in comparison
■with the retractor bulbi. The eyeball has been artificially
retracted, to show clearly the circle of glands attached to
the conjunctiva along its line of reflection. At the inner
and lower angle of the eye the amount of glandular tissue
is much increased and forms a very definite lobe. The
muscle by which the lids are opened forms a continuous
sheet inserted into the entire circumference of the lids ; it
has here been cut short, its cut edge standing up like
a frill outside the circle of glands. The sheath of the
optic nerve is extremely thick. 0. C. 1775 b.

Presented hy the Manager of tlie Westminster Aquanum.

E. 1262. The eye and skin of the right side of the head of the
same Dolphin. The muscles of the eyelids and globe of
the eye and the conjunctival glands are shown, the several
parts being less displaced than in the previous specimen.
Posterior to the eye lies the long and narrow external
auditory meatus, traversed by a black bristle.

0. C. 1775 a.

Presented hy the Manager of the Westminster Aquarium.

E. 1263. A portion of the circular eyelid, with the conjunctival
glands, of a Piked Whale {Balwnoptera acuto-ro strata)
Bristles have been inserted into the ducts of the con-
junctival glands. 0. 0. 1777. Ilunterian.
Carte & MacAlister, Phil. Trans., vol. clviii. 1868,
p. 255.

OKGANS OF SPECIAL SENSE. — VERTEBRATA.

373

SIEENIA.

E. 1264. The eyeball of a yonng Dugong (IMicore dugong),
showing the presence of a nictitating membrane, and the
small size of the cornea. 0. C. 1777 a.

Presented hy Sir Everard Home, Bart.

UNGULATA.
HYRACOIDBA.

E. 1265. Right eye of a Hyrax {Procavia capensis). The large
nictitating membrane is supported by a T-shaped cartilage
whose shaft runs inwards parallel to the anterior surface
of the globe. This process of the nictitating cartilage is
covered at its free end by a dense mass of gland-tissue
corresponding in position and appearance to the nictitating
gland of other Ungulates. It serves also as a point of
attachment for two strands of muscle-fibres that branch
respectively from the upper and lower paits of the
orbicularis palpebrarum and in action tend to thrust
the nictitating membrane backwards across the surface of
the eye. Between these muscle-strands lies another small
mass of gland-tissue. The lachrymal gland is flat and lies
at the lower outer angle of the eye. The muscles attached
to the anterior and upper surfaces of the globe and the
levator palpebrse stiperioris are peculiarly weak. The eye,
as a whole, is small compared with that usually found iu
animals of about the same size.

PROBOSCIDEA.

E. 1266. The nictitating membrane, with its muscles and glands,
of an Elephant {Elephas indicus). The fibres of the
nictitator muscle pass at first in a regular curve (seen
on the reverse of the specimen) over the base of the
membrane, but afterwards deviate from the curve and
form an angle to include the extremity of the cartilage
of the nictitating membrane. This is in consequence
moved in the direction of the resultant of the contracting
forces and drags the membrane backwards and outwards
over the front of the eyeball. A bristle has been inserted
into the duct of the gland of the third eyelid. This gland

374

PHYSIOLOGICAL SERIES.

closely resembles that just described in a similar position in
Procavia and is most probably a combination of nictitating
and true Harderian glands. 0. C. 1780. Ilunterian.

John Hunter, Essays and Observations, edit. R. Owen,
18G1, vol. ii. p. 173.

E. 1267. The nictitating membrane with its associated gland
from the opposite eye o£ the same Elephant, isolated.
The membrane is supported by a thin, flattened, and
slightly curved cartilage, that broadens and thins out
towards the free edge of the membrane. Its distal end
is narrower and is partially embedded in the surface of the
gland of the third eyelid. The duct of the latter opens
beneath the nictitating membrane ; it is indicated by a
black bristle. 0. C. 1779. Ilunterian.

PERISSODACTYLA.

E. 1268. The right eye of a Horse (Equus cahallns), showing
the eyelids and the accessory organs of the globe. Eye-
lashes are fully developed only on the upper lid, those on
the edge of the lower lid being quite insignificant, although
upon its outer surface are several irregularly scattered
tactile vibris?ae. Blue rods have been placed in the puncta
lachrymalia in either lid and can be seen at the cut edge of
the specimen in the lachrymal canal. A green rod is
inserted into one of the ducts of the nictitatlngr o-land
which open under cover of the third eyelid, and black
bristles are passed into the openings of the lachrymal
gland. The lachrymal gland occupies the normal position
■upon the upper and outer surface of the eyeball, but is of
exceptionally large size. The nictitating gland on the
other hand is relatively small and of more compact texture.
The direct and oblique muscles of the globe have been cut
short to expose the strong retractor bulbi, indistinctly
separable into four bundles. 0. C. 1780 b.

Presented hij Henry Power, Esq.
Ellenberger & Baum, Handbuch der vergleichenden
Anat. der Hausthiere, 1903, p. 857,

E. 1269. The eyelids of a Horse {Eqmis cahallus) removed by
dividing the conjunctiva along its reflection and seen from

ORGANS OF SPECIAL SENSE. — VERTEBRATA.

375

within. The lachrymal and nictitating glands are shown,
and preen rods and black bristles have been inserted into
their ducts as in the previous specimen. 0. C. 1780 c.

Presented by Henry Power, Esq.

E. 1270. Left nictitating membrane of a Horse (Equus cahallus),
isolated, to show its supporting cartilage and the nicti-
tating gland. The cartilage is roughly triangular in form,
with its base lodged within and supporting the membrane
and its elongated apex buried in the tissue of the nictitating
gland. 0. C.1780D.

Presented by Henry Power, Esq.

E. 1271. Eight half of the face of an Ass (Equus asinus),
showing the contents of the orbit from the median aspect
and the entire course of the lachrymal duct. The duct,
which is filled with a blue injection, passes along the roof
of the antrum to the base of the maxillo-turbinal. It
follows the line of attachment of this turbinal to the
boundary between the nostril and false nostril, and at this
point bends sharply outwards to open finally just within
the outer lip of the false nostril, the opening being
indicated in the specimen by a white rod. The muscles
of the globe, including the strong retractor bulbi, are
clearly displayed. The superior oblique is fleshy through-
out, with no intermediate tendon where it passes through
the trochlea. 0. C. 1780 f.

Presented by Henry Power, Esq.

ARTIODACTYLA.

E. 1272. The left eyelids and nictitating membrane with the
Harderian and nictitating glands of a Boar {Sus scrofa).
The Harderian gland is of large size ; the opening of its
single large duct upon the lower part of the inner surface
of the nictitating membrane is marked by a bristle. The
nictitating gland is only partly exposed ; it appears as
a rounded mass protruding from the cut edge of the
conjunctiva close to the duct of the Harderian gland.
A black bristle is passed through the single punctuni
lachrymale in the upper lid (vestiges of the lower canali-

376

rHYSIOLOGICAL SERIES,

cuius and occasionally the lower punctum are said also
to be present : Ellenberger & Baum. Anat, der Hausthiere,
1903, p. 885). The same lid is provided with a fringe o£
stifE long cilia, beneath which may be observed the orifices
of the Meibomian glands. The lower lid has no eyelashes.

0. C 1781. Hunterian.

E. 1273. Dissection of the right orbit of a Pig {Sus scro/a),
showing the ocular glands and muscles and the course of
the lachrymal duct. The lachrymal gland is well developed,
and in general form and position resembles that of the
Horse. The relative positions of the Harderian and
nictitating glands in the floor of the orbit are clearly
shown. The superior oblique does not become tendinous
till after it has passed through the trochlea. There is a
strong retractor bulbi. A bristle has been passed through
the punctum lachrymale in the upper lid and along the
lachrymal duct. Its extremity can be seen emerging into
the nose below the line of attachment of the maxillo-
turbinal. O.C. 1781a.

E. 1274. The right eye of a Pig (Sus serofa), showing the
nictitating membrane with its glands, the lachrymal gland,
and the muscles of the eyeball : below is mounted an
isolated specimen of the glands and supporting cartilage of
the nictitating membrane. In the Pig the separation
of the gland of the third eyelid into two parts— the true
Harderian and the nictitating glands — is more clearly
marked than in other species in which this separation
occurs. The Harderian gland is an oval compact body lying
■upon the floor of the orbit ; a large duct arises from its
ocular surface and opens into the conjunctival sac between
the third eyelid and the globe. The nictitating gland is
closely applied to the outer (convex) surface of the nicti-
tating cartilage and opens by four main ducts (Lowenthal)
upon the inner surface of the third lid. The histological
structure of these two glands of the third eyehd is shown in
PI. III. figs. 10, 11. The supporting cartilage of the nicti-
tating membrane is T-shaped as in other Ungulates, with

ORGANS OF SPECIAL SENSE. — VERTEBRATA. 377

the cross of the T in the free border of the membrane
and the shaft embedded in the nictitating gland.

Miesner, Arch. f. Thierheilk., Bd. xxvi. 1900, p. 135.

E. 1275. Right eye of an old female Hippopotamus {Hippo-
potamus ampUbius), showing the muscles of the globe,
cut short, and the nictitating membrane with its glands.
The retractor bulbi is strongly developed. As in the Pig,
there are two glands in connection with the nictitating
membrane — the Harderian and nictitating glands. In
their relative positions they resemble those of the Pig, but
the Harderian gland is more broken up into lobules. The
sheath of the optic nerve is peculiarly thick.

O.C. 1781b.

E. 1276. The eyeball of a Dromedary {Camelus dromedarius) ,
with the horizontal lids removed to show the small
nictitating membrane. 0. C. 1782. Hunterian.

E. 1277. The nictitating membrane and glandula nictitantis of
a Dromedary [Camelus dromedarius). The latter opens
into the conjunctival sac beneath the nictitating mem-
brane by four ducts, into which bristles have been
introduced. 0- C. 1784. Hunterian.

John Hunter, Essays & Observations, edit. R. Owen,
1861, vol. ii. p. lo3.

E. 1278. The right eye of a Javanese Chevrotain (Tragulus
javanicus). The accessory structures of this eye show a
marked degree of degeneracy compared with those of
Ungulates previously described. The muscles are through-
out peculiarly slight and feeble, the lachrymal and nicti-
tating glands fairly developed, and the Harderian very
small. The latter is apparently represented by a mass of
glandular tissue attached by a pedicle (its duct ?) to the
upper border of the nictitating gland. 0. C. 1786 A.

Presented hij J. AhraJiams, Esq.

E. 1279. Part of the right side of the face of a Sambur Deer
[Germs aristotelis) showing the ^contents of the orbit, the

378

niYSIOLOGICAL SERIES.

eyelids with the puncta kchrymalia, and the nasal ex-
tremity of the lachrymal duct. The muscles of the globe
are very clearly shown and conform to the normal type.
The superior oblique narrows slightly and becomes partly
tendinous where it passes through the trochlea. Both
Harderian and nictitating glands are strongly developed.
The eyelashes are most marked on the upper lid. As in
the Horse, the outer surface of the lower lid is beset by a
number of long tactile vibrissas. There is a punctum
lachrymale in each lid. 0. C. 1785 E.

E. 1279 a. The right eyelids of an Axis Deer (Cervus awis) seen
from within and prepared to show the follicles of a number
of tactile vibrissas upon both lids. 0. C. 1965 c.

E. 1280. Eight eye of Cervulns reevesii, showing the eyelids
with their glands, and the muscles of the globe. The
Harderian and nictitating glands are clearly separable ;
the lachrymal gland is large ; the muscles of the globe
are normal in arrangement and moderately developed.

0. C. 1786 A a.
Presented hy Sir E. G. Loder, Bart.

E. 1281. The nictitating membrane and anterior part of the left
eyelids of a Cow {Bos taurus). Bristles have been placed in
the puncta lachrymalia and into five of the openings of the
ducts of the lachrymal gland. The lachrymal caruncle —
an elevation at the inner canthas of the eye composed
mainly of sebaceous glands— is well seen in this specimen.
The eyelashes although stronger on the upper than on the
lower lid are present on both. There are no tactile vibrissse
on the surface of the lower lid, as in the Horse and Deer.

0. C. 1785. Ilunterian.

E. 1282. The eyelids and nictitating membrane of the left eye
o£ an Ox (Bus taurus) with the Harderian and nictitating
glands seen from within. The free margin of the nicti-
tating membrane is stiffened by the cross-piece of a T-shaped
supporting cartilage. The shaft is flattened and expanded,
and lies imbedded in the nictitating gland. The latter
communicates by three ducts, into which black bristles have

ORGANS OF SPECIAL SENSE. — VERTEBKATA.

379

been inserted, with the conjunctival sac beneath the nicti-
tating membrane. The Harderian gland is a compact
rounded body partly enveloped by the aboral end of the
nictitating gland. An isolated specimen oE the nictitating
cartilage is shown below. Blue rods are inserted into the
puncta lachrymalia. 0. C. 1785 B a.

Peters, Arch. f. mikr. Anat,, Bd. xxxvi. 1890, p. 198.

E. 1283. The contents of the left orbit of a Calf {Bos taiirus).
Blue rods have been inserted into the pimcta lachrymalia, a
green rod into the duct of the nictitating gland, and black
bristles into the ducts of the lachrymal gland. The passage
of the superior obhque through the trochlea is particularly
well shown in this specimen. 0. C. 1785 B.

E. 1284. Right side of the face of a Calf (Bos faurus), dissected
to show the contents of the orbit, the eyelids, and the course
of the lachrymal duct. The lachrymal duct has much the
same course and general relations as in the Sheep (E. 1286).
As in that specimen, it is filled with blue injection and its
openings are marked by blue rods. It runs almost directly
forwards from the anterior margin of the orbit, passing
through the lachrymal bone and close beneath the maxilla
and prsemaxilla to its nasal opening close within the nostril.

O.C. 1785 a.

E. 1285. The left eye of a Sheep (Ocis aries), showing the lids
and other accessory organs of the eye. The anterior and
superior recti, the superior oblique, and the levator palpebr^
superioris have been cut short to expose the powerful re-
tractor bulbi. The lachrymal gland is large. The nicti-
tating gland is finger-shaped and compact, but with its
surface broken up by minor lobulations. There is no true
Harderian gland. Blue rods have been inserted into the
puncta lachrymalia and along the first part of the lachrymal
duct. 0- C. 1785 D.

Lowenthal, Internat. Jour. Anat., 1896, p. 42.

E. 1286. Right side of the head of a Sheep (Ovis aries), dis-
sected to show the contents of the orbit and the course of
the lachrymal duct. From the two puncta lachrymalia
(indicated by blue rods) the canaliculi run inwards

;580

PHYSIOLOGICAL SERIES.

to the orbital margin of the lachrymal bone. Here they
unite to form a small sacculiis, from which the lachrymal
duct is continued forwards through the lachrymal bone to
the deep surface of the maxilla and finally opens into the
noso close within the nostril at the anterior end of the
maxillo-turbinal. The opening is marked by a blue rod.
The lachrymal duct has been filled with blue injection.
The position of the duct in different parts of its course can
oe seen in the series of transverse sections of the nose,
No. E. 140, it is there marked by green rods.

0. C. 1785 c.

E. 1287. The eyelids of a Sheep {Ovis aries), dissected to show
the follicles of a series of vibrissse arranged in two rows
along the lower lid below its margin. These help in the
protection of the eye by giving warning of approaching
danger. 0.0.1965 b.

EODENTIA.

E. 1288. Head of a Rat (Mus decumanus). There are two glands
in connection with the conjunctival sac, in addition to the
lachrymal and Harderian. They lie behind the orbit close
under the skin — one (the extraorbital) in front of the ear
close above the parotid and communicating with the con-
junctival sac by a long duct that accompanies the temporal
artery; the other (infraorbital) below the ocular end of
the duct of the first close outside the conjunctival sac.
The ducts of the two glands unite before entering the
conjunctival sac.

Lowenthal, Arch. f. mikr. Anat., Bd. Ivi. 1900, p. 538.

E. 1289, The eyelids of a Rabbit (Lepus cunkulus). The hori-
zontal lids have been propped open to show the well-
developed nictitating membrane in the inner angle of the
eye. 0. 0. 1787. Hunterian.

Krause, Anatomie des Kaninchens, 1868, pp. 126-132.

E. 1290. Part of the right side of the head of a Rabbit {Lepus
cuniculus). The lower eyelid has been turned outwards to
show the punctum lachrymale on its inner surface (there is
no punctum in the upper lid). A bristle has been passed
through it along the lachrymal duct. The termination in

ORGANS OF SPECIAL SENSE. — VERTEBRATA.

381

tlie nasal cavity can bo seen on the reverse of tlie specimen
below the attachment of the maxillo-turbinal.

0. C. 1787 c.

E. 1291. The left side of the head of a Rabbit (Lepus cuniculvs)
with the lachrymal, Harderian, and orbital glands exposed.
The lachrymal gland lies at the tipper and outer part of the
orbit, extending backwards some little way outside the
orbital cavity. The Harderian gland forms a solid whitish
mass (divisible into two parts by a difference in colour and
structure [PI. III. fig. 12 ]) situated at the anterior and
lower part of the orbit closely applied to the muscles and
globe of the eye. The lower and posterior part of the
orbital floor is occupied by a large glandular mass (orbital
gland) apparently continuous with the lachrymal. In
reality it belongs to the salivary series, and is separated
by membrane from the orbital cavity. 0. C. 1787 A.

E. 1292. Left eye of a Hare {Lepus europceus) showing, from the
deep aspect, the retractor bulbi surrounding the optic
nerve, and the ocular and orbital glands. The lobules of
the several glands have been separated, showing very
plainly the pink and white portions of the Harderian
gland and the arrangement of their main collector ducts,
and the loose texture of the lachrymal and orbital glands.

0. C. 1787 ca.

E. 1293. The right eyelids and part of the nasal wall of a Hare
(Lepus europceus) with the lachrymal duct exposed. There
is only one punctum lachrymale, which is very large (1 mm.
diameter) and lies at the extreme anterior limit of the
conjunctival sac upon a level with the margin of the lower
lid. A short canaliculus leads from it into a saccus
lachrymalis that opens at the anterior border of the orbit
into the lachrymal duct. The latter passes downwards and
forwards in the bones of the lateral wall of the nose and
opens by a vertical slit-like mouth into the nose-cavity
15 mm. in front of the molar teeth. The terminal part of
the duct is not encased in bone. A black bristle has been
passed through the punctum lachrymale into the saccus
and also along the lachrymal duct.

382

PHYSIOLOGICAL SERIES.

riNNIPEDIA.

E. 1294. The left eye of a Seal {Phoca vitulina). The horizontal
eyelids have been removed to shovi^ the vertical nictitating
membrane at the inner corner of the eye. Its border is
supported by the cross-piece of a T-shaped cartilage, whose
shaft extends horizontally around the anterior curve of the
globe of the eye and is partially embedded in the substance
of the gland of the third eyelid. The muscles of the globe
and particularly the retractor oculi are poorly developed.
The sphincter muscle (orbicularis palpebrarum) by whicb
the eyelids are closed is most clearly shown on the outer part
of the eye beneath the lachrymal gland. The latter is very
small, as in other aquatic mammals. 0. C. 1778 A a.

E. 1295. The injected eyelids of a Common Seal {Phoca vitulina),
seen from within. 0. C. 1778 a.

E. 1296. The eyeball and eyelids of a Sea-Lion ( Otona sp.).
The posterior parts have been removed to show the extent
of the conjunctival sac and to expose the small nictitating
membrane, at whose base can be seen the gland of the third
eyelid. The skin at the inner can thus of the eye is longi-
tudinally grooved, indicating that originally the lids were
disposed horizontally as in terrestrial Mammals.

0. C. 1778. Hunterian,
John Hunter, Essays and Observations, edit. R. Owen,
1861, vol. ii. p. 98.

oaenivora.

E. 1297. Left part of the nose of a Dog (Cams familiaris) with
the eyelids of the same side, prepared to show the course
of the lachrymal duct. The puncta lachrymalia, of which
there is one in each lid, are connected by long (10 mm.)
canaliculi to a saccus lachrymalis lying upon the orbital
border of the lachrymal bone. From the saccus, the lachry-
mal duct runs in the bones of the face to the lower border
of the attachment of the maxillo-turbinal. Here it emerges
upon the deep surface of the bone and passes forward in
the mucous membrane following the line of attachment of
the maxillo-turbinal for 30 mm., and then communicates

ORGANS OF SPECIAL SENSE. — VERTEBRATA.

383

-with the nose-cavity by an oval aperture in its mesial wall.
Beyond this opening the duct still continues for another
20 mm., and finally opens within 10 mm. of the point of
the snout just within the pigmented area of the nostril.
This opening is marked by a black bristle.

Ellenberger u. Baum, Anat. des Hundes, 1891, p. 582.

E. 1298. The skin of the head of some species of Cat, shortly
after birth, with the eyelids still closed. During the de-
velopment of the lids, their edges become apposed and
actually grow together by proliferation of their epithelium.
Either shortly before (Man) or after (Cat, Dog, Eabbit)
birth the lids again become disunited, probably owing to
the breaking down of the cells in the centre of the epi-
thelial layer of union. 0. C. 1778 B.
Minot, Human Embryology, 1892, p. 726.

E. 1299. The head of a Kitten {Felis domestica), at birth. On
the left the closed eyelids have been cut through and their

Fio-. 54.

0 C
9

' — Old-**"*

Section of tlae united eyelids of a Kitten.
C. Conjunctiva. E. Line of fusion between the epidermis of either lid.

conjunctival and section surfaces shown by the reflection
of part of the skin.

384

PHYSIOLOGICAL SERIES.

E. 1300. The right eyelids of a Cat (Fdis domestica), removed
by dividing the conjunctiva along its line of reflection and
seen from within. The lachrymal gland and that of the
third eyelid have been retained showing their respective
positions and the close attachment of the latter to the shaft
of the nictitating cartilage.

INSEOTIVORA.

E. 1301. The right eye of a Hedgehog (Erinaceus europcens),
showing the globe, the muscles, and the glands. The
lachrymal gland is large and has the usual loose texture.
It can be readily separated into an outer part wholly super-
ficial to the superior rectus and an inner that lies chiefly
on the deeper side of that muscle. These parts may
perhaps be compared with the superior and inferior portions
of the gland in Man. The gland of the third eyelid is also
large, but has a very compact texture. Its histological
structure, which in some points appears to be peculiar, is
described fully by Lowenthal (Anat. Anz., Bd. vii. 1892,
p. 48).

CHIROPTERA.

E. 1302. Right eye of a Bat (Pteropus poliocephalus), showing
the muscles and glands. Bristles have been inserted throuofla
the puncta lachrymalia into the lachrymal sac.

PRIMATES.

E. 1303. A vertical section of the left eye and eyelids of a Monk ev.
showing the pigmentation of the conjunctiva, the extent of
the conjunctival sac, and the vestigeal character of the
nictitating membrane (plica semilunaris).

0. C. 1788. Hunteriaii.
John Hunter, Essays and Observations, edit. R. Owen,
1861, vol. ii. p. 11.

E. 1304. Part of the face with the right eye of a Brown Capu-
chin {Cebus fatuellus), showing the eye and its muscles
from the inner and posterior aspect.

The inferior oblique arises from the floor of the orbit
near its central point (directly below the Rectus inferior)
and runs upwards and slightly backwards and inwards to

ORGANS OF SPECIAL SENSE. — VEBTEBRATA.

385

its insertion upon the hinder border o£ the globe near the
optic nerve. The other muscles show no great difference
from those of Man.

E. 1305. Left eye of a Gibbon (Hi/lohates sp.), with parts of the
eyelids removed to show the nictitating membrane, which
for that of an Anthropoid Ape is peculiarly large.

E. 1306. Right eye of a young Orang-utan (Simia satyrus),
dissected to show the lids, the muscles of the globe, and
the lachrymal gland. The arrangement of the several parts
closely resembles that found in Man. 0. C. 1787 F.

Presented by Sir Victor Horsley.

E. 1307. Two specimens of the eye of an Orang-utan {Simia
satyrus). The specimen on the left shows the left eyelids,
with the tarsal plate of fibrous tissue in the upper lid
exposed. In the inner can thus the pigmented lachrymal
caruncle can be seen and behind it the vestigeal nictitating
membrane (plica semilunaris). In the other specimen the
right eye is seen from the posterior aspect. The levator
palpe'bree superioris has been reflected upwards. Posterior
to it lies the lachrymal gland. There is no Harderian gland.

E. 1308. The eyelids of a Negro. The upper lid is divided and
the two parts are separated to show the white conjunctiva
(c/. E. 1303), the two puncta lachrymalia indicated by white
bristles, the glandular caruncula lacrymalis lodged between
them, and behind this the plica semilunaris or vestige of
the nictitating membrane. 0. C. 1789. Hunterian.

E. 1309. The left eyelids and neighbouring parts of the face,

showing the separation of the lachrymal gland into two lobes

—the pars superior and pars inferior. The superior portion

forms an isolated lobe above the upper and outer region of

the eye ; it is separated from the conjunctiva by the inferior

portion. Each part of the gland has its own ducts, which

open together or separately into the upper and outer part

of the conjunctival sac. The skin of the eyebrow and

upper lid has been reflected forward showing the sphincter

muscles (orbicularis) by which the Hds are closed.

0. 0.1790 A a.

2c

VOL. III.

386

PHYSIOLOGICAL SERIES.

1310. Part of the ri<.ht side of the face, with the lachrymal
duct exposed from outside. Blue rods have been inserted
into the puncta lachrymal ia, and the saccus lachrymalis and
lachrymal duct have been filled with dark injection. Upon
the reverse of the specimen the opening of the duct into
the nose beneath the maxillo-tnrbinal is shown by the
insertion of a glass rod into the orifice and by the i)artial
removal of the turbinal. 0. C. 1793 b.

SENSE-OEGANS OP UNKNOWN FUNCTION.

Organs of the Lateral Line.

Cole, Trans. Liun. Soc, vol. vii. 1896-1900, p. 115.
Parker, Bull. Bureau Fish. Washington, vol. xxiv. 1904,
p. 185.

The integumentary sense-organs of the Lateral line are con-
fined to Fishes and aquatic Amphibia. At present their function
is obscure, though what evidence there is points to their being
specially sensitive to vibrations of the water of low frequency
(6 per second), such as those caused in the deeper water by
ripples on the surface, or by a solid body falling into the water.
This function is in harmony with the fact that the nerves to
these organs belong to the same category as those that supply
the ear, which is essentially an organ for response to material
vibrations. In structure the organs of this system resemble taste-
buds, each consisting of a bunch of hair-cells surrounded by an
envelope of indifferent supporting cells. The buds are most
numerous on the head and differ considerably in their arrange-
ment and relations to the surrounding skin. They may occur
isolated as " pit organs " sunk in little depressions upon the
surface of the head and trunk, or lodged in the walls of a system
of gutter-like or tubular canals that lie in very constant and
definite positions upon the head and trunk, or at the blind
swollen extremities (Lorenzini's ampullje) of mucous-containing
tubes that open upon the surface of the head in Elasmobranchs
and Holocephali, or finally in the Torpedo in closed vesicles
(Savins vesicles).

The Pit organ is the simplest and probably the most primitive

ORGANS OF SPECIAL SENSE. VEHTEBKATA,

387

of these varieties, Lorenzini's ampullae being simple or coinpouiid
pit-organs sunk be'ow the skin at the end of tubes of various
length, and the organs of the lateral line canals being pit-organs
sunk in or beneath the skin and connected together into one
complex system of canals or gutters. The canals of this system
have practically in all cases the following fundamental plan of
arrangement. The chief canal, known as the lateral line, runs
upon the side of the body from the tail to the hinder part of the
head, and there joins a system of thi*ee chief cranial canals, one
above and one below the orbit (supra- and suborbital) and
one following the lines of the hyoid arch and mandible
(hyomandibular) .

The nerves that supply this system of sense-organs form with
the auditory a separate group, the branches of which leave the
brain in conjunction with the viith and xtli cranial nerves and
sometimes also with the ixth. The branches of the viith and
ixth supply the sense-organs in the cranial cana's and in the
Elasmobranchs and Holocephali those in the ampulla?. The
lateralis branch of the xth is confined to the lateral line and pit-
organs upon the trunk.

PISCES.
ELASMOBEANOHII.

Forssell, Zeitschr. wiss. Zool., Bd. Ixv. 1899, p. 725.
E. 1311. A piece of skin from the side of a Porbeagle Shark
(Lamna cornuhicd) showing the lateral line canal (into
which a green rod is passed) and the numerous apertures
(indicated by black bristles) that pass obliquely from it to
the surface. Blue and yellow rods are placed in large
vessels that accompany the lateral line canals.

From an animal, 8 ft. long, taken at Rye in 1871.

0. C. 2107 a.

E. 1312. A portion of the skin of the side of the snout of the
same Fish, showing the openings of the mucous tubes.

0. C. 2107 b.

E. 1313 The termination of the snout of a Spotted Dog-fish
(Scijllium canicula) prepared " to show the manner of the
nerves ramifying, as also their apparent termination in this

388

PHYSIOLOGICAL SERIES.

])art, each ultimate nerve appearing to terminate in the
bottom of a tube or duct, the sides of which wc may
suppose to secrete, contain, and convey a thick mucous to
the skin." The nerves, which are not very clear in the
specimen, terminate in the sense-organs of the ampullae of
Lorenzini. The tubes by which these ampullae communicate
with the surface can be seen in section beneath the skin at
several parts of the specimens and also where bristles have
been inserted into them. Their walls, as Hunter says,
secrete the mucous by which they are filled.

0. C. 1395. Hunterian.
John Hunter, Essays and Observations, edit. R. Owen,
1861, vol. ii. p. 399.

E. 1313 a. A piece of skin from the head of a Greenland Shark
(LcBmargus horealis), upon the deep surface of which a
nerve-trunk belonging to the lateral line system has been
exposed to show the innervation by it of some ajnpullae of
Lorenzini and the sense-organs in a short portion of one of
the lateral line canals. The canal and the tubes connecting
it with the exterior have been cut open. The sense-organs
form a thickened cushion along the floor of the canal.
Their number as shown by the number of nerves connected
with them is far in excess of the external openings.
Several ampullae of Lorenzini are shown upon the left side
of the specimen, each with a fine nerve in connection with
its blind extremity. Further down several ampullae have
been cut across, showing that the blind end of each is
divided into separate chambers by radiating septa. Near
the lower edge of the specimen one of the mucous canals
leading to an ampulla is cut across obliquely, showing its
wide calibre and sudden narrowing towards its external
opening.

E. 1314. A wax model * of a group of ampullae with their tubes
of communication with the exterior and their nerves and
blood-vessels, and a row of five Savi's vesicles, from a

* One of a series of wax models prepared by Prof. Calamai, of Florence,
to illustrate the anatomy of the Torpedo, and preserved in the Rail Case of
Eriom V. (lower gallery).

ORGANS OP SPECIAL SENSE. — VERTEBEATA.

389

Torpedo ( Torpedo galvanii) x 15 ; also a wax model of a
single ampulla x 120 showing a network of nerve-fibres
upon its surface.

Savi's vesicles are oval bodies situated beneath the skin
upon the ventral surface of the Torpedo united together by
a fibrous cord. They probably represent degenerate lateral
line canals which are otherwise absent on the ventral
surface of fishes of this genus.

CooD-i, Arch. Ital. Biol., t. xvi. 1891, p. 216.

E. 1315. A small Starry Eay (Raia radiata), with the skin
removed from the left side of the back to show the arrange-
ment of the lateral line canals and the mucous tubes.

The canals are narrow and relatively thick-walled tubes
that branch out close beneath the skin over the surface of
the head and expanded pectoral fins and along the sides
of the body to the tail and open at intervals by short
branches to the exterior. The usual four chief canal-
systems are present— the lateral canal upon the body and
hinder part of the pectoral fin, the supra- and suborbital
canals above and below the eye, and the hyomandibular
canal external to the suborbital and connected to the lateral
canal by a long backwardly directed loop that follows the
anterior margin of the pectoral fin. The majority of the
mucous tubes radiate to the margin of the pectoral fin and
to the shoulder from a cluster of ampullae situated just
external to the spiracle. Black paper has been placed
beneath the mucous tubes, and the lateral line canals are
injected with blue. ^- ^ 1437 c.

Ewart & Mitchell, Trans. R. Soc. Edinburgh, vol. xxxvn.
1895, p. 87.

E. 1316. A similar specimen showing the lateral line canals a.nd
the mucous tubes upon the ventral surface. The lateral
line canals, which, as in the previous specimen, are injected
with blue, are direct continuations of those upon the dorsal
surface, but differ from them in having a much greater
calibre and more delicate walls. The limits of each canal
and its branches can best be traced in the two following
specimens by reference to their innervation. The ampullso

PHYSIOLOGICAL feElllE.S.

of the mucous tubes are collected into three main clusters,
one beneath the snout between the sub- a;id supraorbital
canals, one external to the nasal capsule, and one (the same
as that seen in the previous specimen) in front of the outer
end of the first gill-cleft. The mucous tubes radiate from
these centres and open irregularly upon the ventral surface
of the head and fore-part of the body and fins.

0. C. 1437 D.

E. 1317. The l()ft half of the fore part of a Skate (Raia hatis)
dissected from above to shovir the innervation of the lateral
line and ampuUary sense-organs upon the ventral surface of
• the head. The sense-organs of the lateral line are arranged
at fairly regular intervals along the canals, each being sup-
plied by a small nerve-filament derived froin one of the lateral
line branches of the facial. Thus, the supraorbital canal is
innervated by the superficial ophthalmic vii, the suborbital
by the buccal vii, aud the hyomandibular by the hyoman-
dibular VII. The three clusters of ampullae are also supplied
by the same three branches.

Black paper and bristles have been placed beneath the
clusters of ampuUse aud under many of the nerve-filaments
that supply the individual organs of the lateral line canals.

0. C. 1437 E.

Ewart & Mitchell, I. c, p. 94.

E. 1318. A similar preparation of the right half of the same
Fish, showing the innervation of the canals and clusters of
ampullae upon the dorsal surface. In this specimen the
nerve-supply to the anterior part of the lateral canal by
a branch of the lateralis vagi is shown. The innervation
of the cranial canals and clusters of ampullae is the counter-
part of that sliown in the previous specimen, the several
canals being the main trunks, of which those on the
ventral surface are branches. 0. C. 1437 f.

HOLOCEPHALI.

E. 1319. The head and shoulders of a Sea-Oat {Chimcei'a medi-
lerranea), showing the course of the lateral line canals and
the position of the openings of the mucous tubes. The

ORGANS OF SPECIAL SENSE. — VERTEBRATA. 391

lateral canal runs forward along the side of the body to a
point about 2 era. behind the eye and then branches towards
the dorsal and ventral surfaces of the head, arching forward
above and below the eye to form supra- and suborbital
canals. A transverse connection unites the supraorbital
canals across the crown of the head. Immediately below
the eye the suborbital canal gives origin to the hyomandi-
bular, which consists of two branches, one running down-
wards towards the edge of the gill-cover, the other passing
forwards. This latter again branches below the eye and
upon the surface of the snout, and in the. mid-anterior line
unites with the suborbital canal. In Chimcera the canals
are gutter-shaped and not tubular. Upon the swollen
gelatinous snout they are considerably enlarged and at
intervals their margins widen out to form large diamond-
shaped openings, between every Iwo of which lie the sense-
organs. The openings of the mucous canals are marked by
red rods. 0. C. 1437 b.

Cole, Trans. R. Soc. Ediuburgh, vol. xxxviii. 1896,
p. 63.

X M-O.C3
Roy

\l<yL.3