^

FOR THEH^EOPIE

FOR EDVCATION

FOR SCIENCE

LIBRARY

OF

THE AMERICAN MUSEUM

OF

NATURAL HISTORY

THE

ANATOMY OF VERTEBRATES.

VOL. 11.

Works hj the same Author.

LECTURES on the COMPAEATIVE ANATOMY and

PHYSIOLOaY of the INVERTEBRATE ANIMALS, delivered at the
Royal College of Surgeons. Second Edition (1855), illustrated by
numerous Woodcuts 8vo. 2\s.

On the CLASSIFICATION and GEOGEAPHICAL DIS-
TRIBUTION of MAMMALIA, being the Lecture on Sir R. Reade's
Foundation, delivered before the University of Cambridge, in the
Senate House, May 1859. To which is adder" an Appendix on the Gorilla,
and on the Extinction and Transmutation of Species. With 9 Figures
on Wood 8vo. 55.

INSTANCES of the POWER of GOD as manifested in His
Animal Creation : a Lecture delivered before the Young Men's Christian
Association, November 1863. With 11 Figures Crown Svo. I*.

London: LONGMANS, GREEN, and CO.

CENTMl PARK *■'

ANATOMY OF VEETEBRATES.

VOL. II.

BIRDS AND MAMMALS.

BY

EICHARD OWEN, F.R.S.

»

SUPEmNTEXDBNT OF THK KATtlRAL HISTORY DEPARTJrSNTS OF THE RRITieH MUSEUAf,
FOREIGN ASSOCIATE OP THK INSTTrUTE OF FRANCE, KfC.

LONDON :
LONGMANS, GREEN, AND CO.

1866.

.OA^

LOXDOS

PRINTED BY SPOTTISWOODE AND CO.

NEW-STBEET SQUARE

\o^':

CONTENTS, OE SYSTEMATIC INDEX.

CHAPTER XIII.
CHARACTERS OF H^MATOTHERMA.

SECTIOX

121. Thermogenous organic conditions .

122. Its results

123. Characters and orders of the class Ares

PAGE

1
3
5

CHAPTER XIV.
OSSEOUS SYSTEM OF AYES.

124. G-eneral characters of the Skeleton

125. Dorsal vertebrse and sternum

126. Sacral Tertebrse, pelvis, and tail

127. Cervical vertebrae

128. The skuU ....

129. Scapular arch and limbs

130. Pelvic limbs ...

14
14
29
39
41
65
75

CHAPTER XV.

MUSCULAR SYSTEM OF AYES.

131. General characters 84

1C2. Muscles of the vertebrae ......... 86

133. Muscles of the wings 94

134. Muscles of the legs 99

135. Muscles of the skin 109

136. Locomotion of Birds 112

CHAPTER XVI.
NERVOUS SYSTEM OF AYES.

137. Myelencephalon of Birds

138. Nerves of Birds .

139. Sympathetic system of Birds

117
121
127

VI

CONTENTS.

SECTIOX PAGE

140. Organs of Tmieh in Birds 128

141. Organ of Taste in Birds 129

142. Organ of Smell in Birds 130

143. Organ of Hearing in Birds 133

144. Organ of Sight in Birds 135

CHAPTER XVII.
DIGESTIVE SYSTEM OF AVES.

145. Beaks of Birds

145

146. Tongues of Birds

151

147. Salivary glands of Birds ....

154

148. Alimentary canal of Birds ....

166

149. Liver of Birds

174

150. Pancreas of Birds

.... 178

CHAPTER XVIII.
ABSORBENT SYSTEM OF AVES.

151. Absorbents of Birds

180

CHAPTER XIX.
CIRCULATING SYSTEM OF AVES.

152. Blood of Birds 184

153. Heart of Birds 185

154. Arteries of Birds 189

155. Veins of Birds 204

CHAPTER XX.
RESPIRATORY SYSTEM OF AVES.

156. Lungs of Birds 209

157. Air-cells of Birds 211

158. Air-passages in Birds 217

159. Lower larvnx in Birds .......... 220

CHAPTER XXI.
URINARY SYSTEM AND DUCTLESS GLANDS OF AVES.

160. Kidneys of Birds 226

161. Adrenals of Birds 229

162. Spleen of Birds 230

163. Pecidiar Secretions of Birds 230

CONTENTS. VU

CHAPTER XXII.
TEGUMENTARY SYSTEM OP AVES.

SECTION PA6B

164. Compositiou of the Tegument 231

165. Appendages of the Tegument 233

166. Development of Feathers 236

CHAPTER XXIII.
GENERATIVE SYSTEM OF AVES.

167. Male organs and semination 242

168. Female organs and ovulation 246

169. Fecundation and structure of the laid egg . . . . . . 251

170. Accessory generative structures and external sexual characters . . 256

CHAPTER XXIV.
DEVELOPMENT OF AVES.

171. Development and peculiarities of the Chick 259

CHAPTER XXV.
CHARACTERS AND PRIMARY GROUPS OF THE CLASS MAMMALIA.

172. Class characters 266

173. Mammalian sub-classes 270

174. Mammalian orders 274

CHAPTER XXVI.
OSSEOUS SYSTEM OF MAMMALIA.

175. General characters of the Skeleton 297

176. General characters of the Skull 300

177. General characters of the Limbs 305

178. Special homologies of the skull-bones of Mammals .... 310

179. Skeleton of Monotremata 314

A. Vertebral Column 314

B. Skull 318

C. Bones of the Limbs 323

180. Skeleton of Marsupialia 328

A. Vertebral Column 328

B. Skull 334

C. Bones of the Limbs 350

181. Skeleton of Rodentia 364

A. Vertebral Column 364

B. Skull . 367

C. Bones of the Limbs . . . 378

VUl

CONTENTS.

182. Skeleton of Insectivora 385

A. Vertebral Column 385

B. Skull 387

C. Bones of the Limbs . 390

183. Skeleton of Bruta . 392

A. Vertebral Column 392

B. Skull 403

C. Bones of the Limbs ....... 407

184. Skeleton of Cetacea 4l5

A. Vertebral Column 415

B. Skull 419

C. Bones of the Limbs 426

185. Skeleton of Sirenia 429

A. Vertebral Column 430

B. Skull 433

C. Bones of the Limbs 435

186. Skeleton of Probosciclia 437

A. Vertebral Column 437

B. Skull 438

C. Bones of the Limbs 441

187. Skeleton of Perissodactyla 444

A. Vertebral Column 444

B. Skull 448

C. Bones of the Limbs 454

188. Skeleton of Artiodaety la 457

A. Vertebral Column 457

B. Skull 465

C. Bones of the Limbs 479

189. Skeleton of Camivora 487

A. Vertebral Column 488

B. Skull 496

C. Bones of the Limbs 506

190. Skeleton of Quadrumana 511

A. Vertebral Column 512

B. Skidl 526

C. Bones of the Limbs 538

191. Skeleton of Bimana 553

A. Vertebral Column 553

B. Skull 558

C. Bones of the Limbs 672

D. Kelations to Archetype 681

Table I. Synonyms of the Bones of the Head, according to their general homo-
logies.

Table II. Synonyms of the Bones of the Head of A^ertebrates, according to their

special homologies.

Table III. Synonyms of the Elements of the typical Vertebrae ... 587

ERRATA.

Page 133, note ^ for ' vol. i. p. 208,' read ' ccxxxvi, vol. i. p. 173,'
258, note '^for ' old' read ' odd.'
260, note 'for ' LXix- ' read ' Lix*.'

333, twenty-three lines from top, /or ' met- apophyses,' read ' par-apophyses.'
4.52, two lines from bottom, /or ' fig. 303,' read ' fig. 304.'
470, fifteen lines from bottom, /or ' promixal,' read ' proximal.'

THE

AMTOMY OF YERTEBRATES.

CHAPTER XIII.

CHARACTERS OF H^MATOTIIERMA.

§ 121. Thermogejious Conditions. — Life is attended \\\\\i con-
stant molecular change ; and such vital motion becomes converted
directly, or through intermediate modes of chemical or electrical
force, into that of heat ; the chief chemical action preceding or
producing the calorific force being due to the introduction of oxy-
gen by air or food into the body, where it operates in a manner
analogous to combustion.

The evolution of animal heat more directly relates to the
amount of air inspired in a given period, and to the rapidity with
which the oxygenated blood is conveyed to the tissues.

In these the molecular changes are governed by the nervous
system, and whatever tends to paralyse the nervous force operates
in the same degree in arresting those molecular movements on
which more directly depends the evolution of heat. In this act
the nervous system is accordingly concerned, in so far as it
influences the exercise of the muscular movements.

In the Hoimatotherma, or Warm-blooded Vertebrates, the at-
mosphere is directly inspired and applied to a vascular surface
Avhich, in proportion to the bulk of the body, is much more exten-
sive than in any of the HcEmatocrija. For mechanical convenience
the respiratory surface is closely packed, in small compass, by
subdivision of the pulmonary ca^dty into countless minute cells,
giving to the lung a spongy texture, obliterating all trace of a
visible or conspicuous cavity.

The whole of the venous blood is propelled over this extensive
but compactly disposed capillary area by successive contractions
of a special ventricle, receiving it from a distinct auricle, and the

VOL. II. B

2 ANATOMY OF VERTEBRATES.

blood, changed by the resph'atory action, is conveyed to another
distinct auricle and propelled by a second distinct ventricle over
the entire system.

Thus a four-chambered heart and spongy lungs are the chief
anatomical characteristics by which the ^ warm-blooded ' are dis-
tino-uished from the ^ cold-blooded ' Vertebrates, although respira-
tion and circulation are subsidiary or auxiliary, not immediate,
thermoo-enous functions.

Whatever tends to obstruct the flow of blood to a part of the
body, as ligature of an artery, e. g., lowers in a certain degree the
heat of that part ; and whatever augments such flow of blood, as,
exercise, e. g., or increases the quantity of blood in a part, as
where the capillaries dilate through paralysis of the vaso-motory
filaments from a ganglion of the sympathetic nerve, raises the heat
of such part; temporarily, at least, in the latter case.^

In all HcEmatotlierma the mass of nervous matter constituting
the cerebral portions of the prosencephalon is relatively larger
both to the rest of the brain and to the bulk of the body than in
Hcpmatocrya, although the degrees of this predominance in the
warm-l)looded series relate to other functions than the evolution
of heat.

Concomitantly with the advance of the circulating and respira-
tory organs in HcEmatotlierma is that of the blood itself, in quantity,
in the proportion of organic {proteine) principles to the water in it,
and in depth of colour due to the more abundant blood-discs.
The voluntary muscular fibre shows, in most Hcematotherma, by
its deeper colour than in Hcematocrya, the influence of this more
abundant, richer, and redder blood ; and the longer duration and
greater energy of the contractions have relation to the ha^mato-
thermal conditions of the nervous, respiratory, and circulating
systems.

In every muscular contraction some molecules of the fibre
may be said to be burnt, and heat is evolved. Needles of a deli-
cate thermo-electrical apparatus, thrust into a living muscle, indi-
cate a rise of temperature at each act of contraction. ^ The heat-
producing results of the sum of such actions is a matter of common
experience, and a loss of animal heat results from the cessation of
such actions. So, Hunter writes : ^ When a man is asleep he is
colder than when he is awake ; and I find, in general, that the
difference is about one degree and a half (of Fahr.)^

' V. p. 377.

- As in the ' biceps flexor ciibiti ' of the man so experimcntctl on, in i-. p. 402.

^ xciv. p. U-4. Sec also ir.

CIIARACTEKS OF II^EMATOTIIERMA. 3

The molecular movements and changes in the organs of vege-
tative life constitute a more unintermitting source of caloric. The
blood which returns from the extensive seat of such operations
aiforded by the mucous intestinal tract is warmer than before it
enters that tract : the blood of the hepatic vein after its passage
through the portal circulation, and its work in the liver, shows a
more marked rise of temperature. Urine in mammals, before its
escape, is hotter than blood ; ^ and the rich supply of nerves to the
adrenals may relate to the calorific functions of the kidneys.

The production of heat from the actions of organic life depends
on the amount of material for the support of such actions — on the
quantity of oxidizable substance introduced as aliment into the
body. The greater vigour, activity, waste, or wear and tear, in
the warm-blooded machinery necessitate, while they ena])le, a
greater energy, and more regular and rapidly recurring perform-
ance of the digestive functions ; and the warm-blooded differ from
the cold-blooded vertebrates in the greater amount of food which
they consume, and the shorter intervals between the times of
eating. Warm-blooded animals exemplify this influence; — ^ I
weakened,' says Hunter, ' a mouse by fasting, and then intro-
duced the ball of the thermometer into its belly : the ball being
at the diaphragm, the quicksilver rose to 97° ; in the pelvis to
95°, being two degrees colder than in the strong mouse.' ^ The
difference of beinsj ^ full ' or ^ fastins^ ' in resistino; cold is a matter
of common experience.

§ 122. Thermogenous Results. — The more active and unremit-
ting vital combustion, due to the above-defined advanced con-
ditions of the nervous, respiratory, circulating, digestive, and
muscular systems, keeps up a constant temperature, as a general
rule, in the Hmmatotherma, Avhich is usually so much higher
than that of the surrounding medium as to cause the sensation
of warmth to the hand touching the body. In man the mean
temperature of the interior of the body is 100° Fahr. ; in the dog,
101°; in the ox, 100°; in the mouse, 99°; in the whale, 105°.
In Birds ^ the mean temperature ranges in different s})ecies from
106° to 112°.

The heat-producing powers in healthy IIcBmatotlterma are more
active as the surrounding medium is cooler; and cold, much
below freezing, is long resisted, and habitually, by the wann-

' iir. 100° or 101° Fahr. as against 97° Falir.; (39.5, as against 37 or 30 Cent.)
- xciv. p. 145. See also p. IG, for a similar illustration of loss of heat ihrongli
starvation in ducks. ■' JV-.

15 2

4 ANATOMY OF VERTEBRATES.

blooded denizens of arctic and antarctic zones. The nature of
the external covering has much influence in this resistance,
whether it be the thick layer of subcutaneous fat in the whale-
tribe, the fur and hair of the quadruped, or the down and feathers
of the bird. Save in the case of mankind and the whalekind,
the warm-blooded Vertebrate may be distinguished at a glance
from the cold-blooded one by the non-conducting, heat-preserving,
nature of its clothing, which is ^ hair,' as a general rule in Mam-
mals, and ' feathers ' in Birds.

There are, however, gradations of the heat-maintaining power
in the Hcematotherma. Some Mammals, e. g. the Alpine Marmot,
the Hamster, the Squirrel, the Dormice (3I?/oxus), the Porcupine,
the Virginian Opossum, at the approach of winter- cold, seek a
retreat, fall into a deep sleep, and lose from ] 0° to 20° Fahr. of
heat. In the Squirrel, e. g., the heat of the body has been found
to sink from 98° to 78°. Respiration is continued, though slowly,
in these winter-sleepers. The Hedgehog (^Erinaceus) and the
Bat ( Vespertilio, Linn.) fall into a dee2:)er and more lasting
torpor ; in which breathing is suspended, and a slow and languid
circulation is the sole sign of animation. In the Bat, the heart's
pulsations fall from 200 in a minute, as when in active wake-
fulness, to 30 in a minute, during torpidity ; the blood being
then in a dark venous state, and the temperature of the body
down to 40°. In this condition these Insectivora survive the
season during which their allotted food is unattainable. In the
tropics some allied species, e. g. the Tenrecs ( Centetes) fall into a
similar torpidity, without the excitement of a freezing cold, during
the season unfavourable to the presence of their food.

The feeble and inactive young Hcematotherma use up less
oxygen than adults ; and, when exposed to cold, lose their heat,
and also their sensibility, differing in this latter respect from the
hybernators. The least touch to a spine of a torpid Hedgehog
rouses it to draw a deep sonorous inspiration : the merest shake
induces respiration in the torpid Bat.

In all these instances of loss of power to preserve the average
mammalian temperature, the physiological conditions of the
species approximate more or less to those of the cold-blooded
animals ; and it is interesting to observe that the Avinter-sleeping
and torpid Mammals are those which most resemble reptiles in
their cerebral organisation : they are also of small size. Whether
the Edentata and Monotremata would become torpid, and so
accommodate themselves to other than their native climates is a
question well worthy of experimental determination.

CHARACTERS OF TITEMATOTHERMA. 5

"No approach to torpidity with loss of animal temperature has
been determined to take place in any bird. The insectivorous
kinds migrate — Smfts and Swallows, e. g., to and fro between
England and Africa; and migration is performed by numerous
other birds in relation to localities furnishing the food most
appropriate for the nourishment of their newly-hatched young.
Experiments have failed to induce torpidity in birds through
artificial cold.

§ 123. Characters and Orders of Birds. — The two H^mato-
thermal classes Aves and Mammalia, are defined in vol. i. p. 6 ;
and I here proceed to a fuller exposition of the avian charac-
teristics, and of the modifications on which the class has been
divided into orders or other primary groups.

Birds constitute a class of oviparous vertebrate animals, with
warm blood, a double circulation, and a covering of feathers.
They are organised for flight, and as this, the fleetest and most
vigorous kind of locomotion, demands the greatest energy in the
contractility of the muscular fibre, so the respiratory function

finds its highest developement in the present class. Not only the
ramifications of the pulmonary artery, but many of the capillaries
of the systemic circulation, from the singular extension of the
air-cells through the body, are submitted to the influence of
the atmosphere, and hence Birds may be said to enjoy a double
respiration.

Although the heart resembles in some particulars that of the
Reptilia, the four cavities are as distinct as in the Mammalia, but
they are relatively stronger, their valvular mechanism is more
perfect, and the contractions of this organ are more forcible and
frequent in Birds in accordance Avith their more extended resi)i-
ration and their more energetic muscular actions.

As Birds exceed Mammals in the activity of those functions on
which the waste and renovation of the general system more
immediately depend, so they possess, as has been shown, a higlicr
standard of animal heat.

G ANATOMY OF VERTEBRATES.

The modification of the tegiimentary covering characteristic of
the present class is to be regarded rather as dependent upon,
than occasioning, this high degree of internal temperature, which
requires for its due maintenance against the agency of external
cold an adequate protection of the surface of the body by means
of non-conducting down and imbricated feathers ; and this warm
clothing is more especially required to meet the sudden variations
of temperature to which the bird is exposed, when soaring in the
liigher regions of air and stooping to the earth, during rapid and
extensive flights.

The generative product is excluded from the oviduct in an
undeveloped state, inclosed, in a liquid form, within a calcareous
case or shell. Collision of tw^o brittle coco's in transitu is obviated
by the female organs being developed only on the left side of the
body. The ovum is subsequently perfected by means of incuba-
tion^ for which action the bird is especially adapted by its high
degree of animal heat.

Birds form the best characterised, most distinct, and natural
class in the whole animal kingdom, perhaps even in organic
nature. They present a constancy in their mode of generation
and in their tegumentary covering, which is not met with in any
other of the vertebrate classes. Xo species of Bird ever deviates,
like the whales among Mammals, the serpents among Reptiles,
and the eels among Fishes, from the tetrapodous type charac-
terisino; the vertebrate division of animals.

The anterior extremities are constructed according to that plan
Avhich best adapts them for the actions of flight ; and although, in
some few instances, the developement of the wings proceeds not
so far as to enable them to act upon the surrounding atmosphere
with sufficient power to overcome the counteracting force of
gravity ; yet, in these cases they assist, by analogous motions,
the posterior extremities : either, as in the ostrich, by beating
the air while the body is carried swiftly forward by the action of
the powerful legs ; or, as in the penguin, by striking the water
after the manner of fins, and by the resistance of the denser
medium carrying the body through the water in a manner analo-
gous to that by Avhich the birds of flight are borne through the
air. In a few exceptions, as the cassowary and apteryx, the wings
are outwardly represented by a few quills or a small claw In no
instance do the anterior extremities take any share in stationary
support or in prehension.

Birds are therefore biped, and the operations of taking the
food, cleansing the plumage, &c., are almost exclusively performed

CIIAKACTErtS OF IliKMATOTIIERMA. 7

by means of the mouth, which consists of two lipless and tooth-
less jaws, sheathed with horn. To facilitate the prehensile and
other actions thus transferred to the head, the neck is elono-ated,
and the body generally inclined forward and downward from the
hip-joints. The thighs are accordingly extended forward at an
acute angle from the pehis toward the centre of the trunk, and
the toes are lengthened and spread out to form an adequate base
of support. The actions of perching, walking, hopping, running,
scratching, burrowing, wading, and swimming, require for their
perfect performance different modifications of the posterior extre-
mities. The mandibles, again, present as many varieties of form,
each corresponding to the nature of the food, and in some degree
indicative of the organisation necessary for its due assimilation.
Ornithologists have, therefore, founded their divisions of the class
chiefly on the modifications of the bill and feet. Since, however.
Birds in general are associated together by characters so peculiar,
definite, and unvarying, it becomes in consequence more difficult
to separate them into subordinate groups, and these are neces-
sarily more arbitrary and artificial than are those of the other
vertebrate classes.

A binary division of the class ^ may be founded on the condition
of the newly-hatched young, which in some orders are able to
run about and provide food for themselves the moment they quit
the shell (Aves prcecoces) ; while in others the young are excluded
feeble, naked, blind, and dependent on their parents for support
(^Aves altrices).

Nitzsch^ grouped together the feathered tribes under three
series, according to the great divisions of the terraqueous globe
which form respectively the principal theatres of their actions.
The first order consists of the birds of the air, Aves aerecB (Luft-
vogeln) ; the second embraces the birds of the land, Aves terrestres
(Erdvogeln); the third includes the birds which frequent the
waters, Aves aquaticcB (Wasser-vogeln). The eagle and lark
exemplify the first ; the ostrich and common foAvl the second ;
the heron and the gull the third, of these extensive divisions of
the class.

Vigors ^ proposed a more definite system upon a similar prin-
ciple, distributing Birds into five orders. The first includes
those which soar in the upper regions of the air, which build their
nests and rear their young on high cliffs or lofty trees ; they are
the chief of aerial birds and form the order termed Raptorcs,

' vir. p. 2G5. 2 yj,i._ s ^•^.

8 ANATOMY OF VERTEBRATES.

from the rapacious habits and animal food of the species so
grouped together.

The second order affects the lo\ver regions of the air : the birds
composing it are peculiarly arboreal in their habits, and are,
therefore, termed ' Perchers,' Insessores,

The third order corresponds with Nitzsch's Aves terrestres, and
is denominated Basores, from their general habit of scratching up
the soil in quest of food.

By dividing his Aves aquaticce into those which wade to obtain
their food, and into those which swim, we get the two remaining
orders of the quinary arrangement — viz. the Grallatorcs and
Natatores, The merit of this system mainly lies in the endeavour
to trace the natural affinities of the several families, and show
how they pass one into another to form a connected circular
whole.

The Raptores of Vigors ansAvers to the Accipitres of Linnaeus
and Cuvier ; the Inses sores to the Passer es and Pici of Linnseus,
and to the Passeres and Scansores of Cuvier ; the Rasores to the
GallincB of Linnaeus, jo/w^ the Columhce, and to the Gallinacece, of
Cuvier; the Or allatores to the Grallce of Linnaius and Cuvier;
the Natatores to the Anseres of Linnaeus, and the Palmipedes of
Cuvier.

AVES (Birds).

Class-characters.

Ajiimal, vertebrated, oviparous, biped.
Pectoral ^ limbs oro-anised for flig-ht.
Integument, plumose.
Blood, red, warm.

Respiration and circulation, double.
Lungs, fixed, perforated.

Negative Characters, no ear-conchs, lips, teeth, epiglottis, dia-
phragm, fornix, corpus callosum, scrotum.

The following are the orders, with their characters and sample
families, adopted as most convenient for the purpose of the present
work ; —

^ CCCXLVIII.

CHARACTERS OF HiEMATOTHERMA.

Order I. NATATOEES.

Swimming Birds. Toes united by a membrane, fig. 2. Legs
placed behind the equilibrium, and body covered with a thick coat
of down beneath the feathers.

Fam. 1. BrevipennatcB. Ex. Penguin, Auk, Guillemot, Grebe.

2. LoiKjipennatcB. Ex. Skimmer, Tern, Mew, Gull, Petrel,

Albatross.

3. Totipalmat(B. Ex. Pelican, Gannet, Cormorant, An-

hinga. Frigate Bird, Tropic Bird.

4. Lamellirostratoi. Ex. Duck, Goose, Swan, Flamingo.

Webbed foot of Pelican.

Head and wading leg of the Curlew.

Order II. GKALLATORES.

Wading Birds. Legs long, naked from above the distal extre-
mity of the tibia downwards, fig. 4.

Fam. L Macrodactyli. Ex. Coot, Rail, Crake, Screamer,
Jacana.

2. Cidtrirostres. Ex. Boatbill, Crane, Heron, Ibis, Stork,

Tantalus, Spoonbill.

3. Longirostres. Ex. Gambet, Avocet, Snipe, Ruff, Turn-

stone, Sandpiper, Godwit, Curlew, fig. 3.

4. Pressirostrcs. Ex. Oystercatcher, Thicknee, Plover,

Lapwing, Bustard, Courser.

10

ANATOMY OF VERTEBRATES.

rintado or Guiuea-fowl

Order III. RASOllES.

Scratching Birds. Feet strong, provided
with obtuse claws for scratching np grains,
etc. Upper mandible vaulted ; nostrils
pierced in a membranous space at the base,
and covered by a cartilaginous scale, fig. 5.
Nest rude. Sternum with four, rarely two,
deep fissures.

Suborders.

Gallinacei or Clamatores \ Polygamous. Ex. Megapode, Pea-
fowl, Partridge, Quail, Pheasant, Ganga, Grouse,
Pintado, Tinamu, Turkey, Curassow, Guan.

CoJun/haccI or Gemitores ; Monogamous. Ex. Dove, Gourn,
Yinao'O.

Order IV.
Sino^ino' Bh'ds.

CANTORES (Oscines).

Legs short and slender, with three toes before
and one behind, the two external toes being
united by a very short membrane, fig. 6. Ster-
num vnth one hind-notch on each side, manu-
brium bifurcate, fig. 15 ; larynx 5 — muscular.
The brain arrives in this order at its greatest
proportional size, and the organ of voice here
attains its utmost complexity. Nests complex ;
eggs usually coloured. Monogamous.

Fam. 1. Dentirostres. Ex. INIanakin, Shrike, Wren, Wagtail,
Warbler, Thrush.

2. Conirostres. Ex. Paradise Bird, Crow, Starling, Bun-

ting, Tit, Lark, Finch, Grosbeak.

3. Tenuirostres. Ex. Sunbird, Nuthatch, Creeper.

4. Fissirostres. Ex. SAvallow, Martin.

Foot of Perchcr.

Order V. VOLITORES.

Moving solely by flight. Skeleton light and highly pneumatic ;
sternum with a simple manubrium, and a deep keel ; in some en-
tire, fig. 18, in most with two hind-notches on each side, fig. 20 ;

CIIARACTErvS OF IIiI^:MATOTHERMA. 11

larynx trimuscular ; intestinal caica usually absent, or laro-e ;
wings powerful, in some long and pointed ; legs small and weak,
with few exceptions not used in locomotion; with the back toe
i short, sometimes turned forward ( Cypselus), or wantino-
( Ceijx) ; the outer toe iv is reversible in some ( Trogon), in
others united to the mid-toe in, as far as the penultimate joint,
fig. 7. Many nidificate in holes of trees, or in the earth ; the
eggs are white and subsphcrical. They are monogamous. The

Syudactyluus foot of Kingflslier.

Scansorial foot of Woodpecker.

head is large, and in most the beak is remarkable for its length or
width, or both. The gape is A^dde ; the food taken on the wing.

Fam. 1. CijiiselidcB. Ex. Swift.

2.. Trochilidce. Ex, Humming-bird.

3. Caprimulgid(B. Ex. Xightjar.

4. Trogonidoi. Ex. Trogon.
Ex. Mot-mot.

Ex. Bee-eater.
Ex. Jacamar.
Ex. Roller.
Ex. Puff-bird.
Ex. Kingfisher.
Ex. Hornbill.

5. Prionitidce.

6. Meropidce.

7. Galhulidce.

8. Coraciadce.

9. Copitonidce.

10. AlcedinidcB.

11. BucerotidcB.

Order. VI. SCAXSORES.

Climbing Birds. Toes arranged in pairs, two before and two
behind, fig. 8. Most oviposit in holes of decayed trees. Larynx

trimuscular.

Monogamous.

12 ANATOMY OF VERTEBRATES.

Fam. 1. Ramphastidce. Ex. Tucan.

2. Bucconidce. Ex. Barbet.

3. CuculidcB. Ex. Cuckoo.

4. PicidcB. Ex. Woodpecker.

5. 3Iusophagid(B. Ex. Touraco or Plantain-eater.

6. Coliidce. Ex. Coly.

7. Psittacidce. Ex. Parrot.

Order VII. EAPTOPvES.

Rapacious Birds. Beak, strong, curved, sharp-edged, and
sharp-pointed, fig. 9 ; legs short and robust, Avith three toes before
and one behind, armed with long, strong, crooked talons, fig. 10.

10

Head of Eagle.

Raptorial foot of Eagle.

Fam. 1. Nocturnes. Ex. Owl.

2. Diurnes. Ex. Hawk, Eagle, Vulture.

An eighth group of birds has been characterised under the name
CuESOEES, Coursers, or * Running-birds,' ^ by the arrested deve-
lonement of the wings unfitting them for flight, and by the com-
pensating size and strength of the legs, by which they are enabled
to run swiftly on the ground. This is not, however, a natural
order ; some of its exponents have demonstrably closer aflfinities to
other groups of which they are wingless members, just as the
Peno;uins and Auks bear relation to families of the Natatorial
order. Thus the Notornis is a modified Coot. The Ostrich bears
the same relation to the Bustards. The extinct Didus and Pezo-
phaps are most nearly allied to the Columbaceous group of
Rasores. Apteryx and the allied extinct Dinornis and Palapteryx,
bear aflBnity to the Megapodial family of Gallhice.

* Piuceri, Illi<

CHARACTERS OF IliEMATOTIIERMA. 13

In all the Cursorial genera the sternum is devoid of keel.

Struthio is the only genus of birds in which
the toes are reduced to two, fig. 11.

In like manner the web-footed order is an
artificial one, including derivatives from dif-
ferent natural groups or types ; and the same
may be said of the order including the birds
that have the leo;s lono; and naked above the

tarsal joint. ^ ^ cursorial foot of Ostnch.

Derivatively the class of Birds is most
closely connected with the Pterosaurian order of cold-blooded air-
breathers. In equivalency it is comparable rather with such a
group than with the RejJtilia in totality, or with the Marnmalia ;
and, hence, the corresponding inferiority of value of the avian
^ orders ' to the subdivisions so called of those larger classes.

In relation to time, indications of Aves date as far back as those
of Pterosauria, in the ' ornithichnites ' or foot prints of the New-
Red Sandstones, for example.^ The lithographic slates of a later
mezozoic period have revealed a true feathered bird,^ wanting
only the adaptive modification of the caudal vertebro3 charac-
teristic of all neozoic birds, even those of the oldest tertiary
strata, in which fossil remains of representatives of nearly all the
present orders of Aves have been found.'^ The most recent in-
stances of extinction of species are of the birds that have lost the
power of flight; as, e.g., the gigantic ^loas {Di?iornis, Palapten/x,
Aptoi'nis, Ciiemiornisy of New Zealand ; the equally gigantic
Epyornis of Madagascar ; the Dodo (^Didus) of the Mauritius ;
the Solitaire {^Pezopliaps) of Rodriguez ; the Gare-fowl (^Alca
impennis) of Northern shores or islands.

Notwithstanding the characteristic powers of locomotion of the
class generally, it is amenable, most suggestively, to laws of geo-
graphical distribution and limitation.

' xvn-. pp, 5 and 324. - xv. ^ CLr. and xviii". p. 549.

' XV1-.

14 ANATOMY OF VEUTEBKATES.

CHAPTEE XIV.

OSSEOUS SYSTEM OF AVES.

§ 124. General Characters. — The skeleton of Birds is remark-
al)le for the rapidity of its ossification and the light and elegant
luechanism displayed in the adaptation of its several parts. The
osseous substance is compact, and exhibits more of the laminated
and less of the fibrous disposition than in the other vertebrate
classes. This is more especially the case in those parts of the
skeleton which are permeated by the air. The bones which pre-
sent this singular modification have a greater proportion of the
phosphate of lime in their composition than is found in the osseous
system of the mammalia, and they are whiter than the bones of
any other animal. In the bones where the medulla is not displaced
by the extension of the air-cells into their interior, the colour is of
a duller white. In the Silk- or ' black-boned ' fowl of the Tropics
( Gallus Morio, Temminck), the periosteal covering of the bones is
of a dark colour ; but this is a peculiarity of the cellular rather
than of the osseous texture, which does not difier in colour from
that of other birds ; indeed the thin aponeurosis covering the
lateral tendons of the gizzard of the Silk-fowl has the same dark
hue as the membrane which invests the bones.

§ 125. Dorsal Vertehrce. — The modifications of the common
vertebrate type of skeleton required by the exigencies of the pre-
sent class are extreme. Anchylosis so fetters the vertebral column
that from no part can a single segment with all the elements be
detached without using the saw. The skull includes four, the
sacrum a greater number, of vertebras, of more or less of which
the haimal portions alone retain freedom. The remaining segments
may be classified as ^ cervical,' * dorsal,' and ' caudal ' : in the first
and last the pleurapophysis, if present, is confluent with the
neural arch : in the dorsal series, the pleur- and hajm-apophyses
are flexibly articulated, but the hasmal spines are connate, and
represented by a single bony plate.

OSSEOUS SYSTEM OF AVES.

15

First tlirce dorsal vertebnv and scapular
arch of a bird, in diagrammatic side view.

Ill fig. 12, is given a sketch of three dorsal segments, i, 2, 3,
with the hiemal arches, 52, 58, of
two others. In the first and se-
cond dorsals the pleurapophyses (i
and 2) terminate in a free pointed
end, like the ' false floating ribs,' of
Anthropotomy ; in the third, the
plenrapophysis, pi, .s, articulates
with the haiinapophysis, h ; and this
Avith the expanded spine, h s, which,
in connation with its homotypes,
constitutes the bone called ' ster-
num,'/*. Every succeeding dorsal
segment has the ha3mal arch com-
pleted by bone.

Fig. 13, gives a diagrammatic front view of the connate dorsal
or thoracic ha3mal spines, c, s; the ha^mapophyses, d, of five
corresponding segments, and also a modified pair, A, h, of the ha3m-
apophyses of an antecedent segment.

The pleurapophyses, pZ, «,
of the dorsal segment are
shown in connection with the
centrum, c, and neural arch,
71 ; it is to this part of the
segment that the term ' verte-
bra,' is commonly restricted.

The dorsal vertebra?, thus
defined, rarely form more than
a fourth part of the entire
column, and in some of the
long-necked Grallatores, as
the Stork and Flamingo, fig.
14, form only an eighth part ;
they have not been observed
to be fewer than four (in some
Vultures), nor more than nine
throughout the class ; the lat-
ter number obtains in the Ap-
teryx : the most common numbers are six or seven.

The dorsal vertebra? are shorter than most of the cervicals, and
Avith broader neural arches, in consequence of the greater devc-
lopcinent of the transverse processes ; but their bodies become mucli
compressed, and in some Birds are reduced almost to the form of

1 tenor vertebra, witii other iKvmal arches of dorsal
or thoracic region, in diagrammatic front view.

IG

ANATOMY OF VERTEBEATES.

vertical lamina3 towards the sacral region {Ajitenodytcs, Catar-
rhactes) ; but, in the Ostrich, the bodies of the dorsal vertebra)
retain their breadth throughout the series.

The bodies are united by capsular ligaments and synovial mem-
branes; the anterior articular cartilaginous surface is convex in

14

Skeleton of Flamingo. A. Corax Mitis. 13. Tinamou (T. ro&Hs«Hs). C. Plicenicopterus.

the vertical direction, and concave in the transverse ; the posterior
surface is the reverse. The Penguins and Auks, however, present
an exception to this rule : the posterior surface of the second or
third dorsal vertebra is concave, to which the opposed end of the
succeeding vertebra presents a corresponding convexity ; the
' opisthococlian ' ball-and-socket-joint is continued between the
centrums to the last dorsal.^ In many Birds the bodies of some of
the middle dorsal vertebra3 are anchylosed together ; and in gene-
ral those which are nearest the sacrum. In the Flamingo, fig.

' VII. p. 270, and x. pi. 52, figs. 50, 51.

OSSEOUS SYSTEM OF AVES. 17

1-4, the anchylosis extends from the second to the fifth dorsal ver-
tebra. In the Sparrow-hawk, tlie same vertebra3 are consolidated
into one piece, while the sixth enjoys considerable lateral motion,
both upon the fifth and seventh, which last is anchylosed to the
sacrum ; so that the body can be rapidly and extensively inflected
toward either side during the pursuit of prey.

From some or most of the dorsal centrums inferior processes
(hypapophyses) are sent down, for extensive and favourable origin
of the flexor muscles, longi colli and recti antici, of the neck. In a
vulture {Gi/ps fulvus) the hypapophysis is a low median ridge in
the first and second dorsals ; to this, in the third dorsal, is added
a pair of outstanding depressed plates : in the fourth the pair of
plates are smaller, and, mth the medial ridge, are supported on a
common stem: in the fifth dorsal, the hypapophysis is again
reduced to a median compressed plate, but it is expanded at the
end ; the vertebra, which by anchylosis has become the foremost
sacral, has a similar but stronger and slightly bifurcate hypapophy-
sis. In both Vultures and Eagles the parial hypapophyses are seen
to be due to modified parapophyses, which descend and are pro-
gressively lost in the median hypapophysis of the fourth and fifth
dorsals {^Harpcya, Cuv.) ; the sixth and seventh liave only tlie
low median ridge. The parapophysial pairs of inferior processes
are broad divergent plates in the anterior dorsals oi Aptenoclyfcs^
and Alca^, and subside upon the large and long compressed median
hypapophysis wdiich characterises the posterior dorsals. Tlie
unusual developement of these inferior processes relates to the size
and strength of the subvertebral muscles, which combine w^th
other muscles of the trunk in the shuffling movement by which
the Penguin, like the seal, makes progress, prone, upon dry Land,
In the anterior dorsals the parapophysis, besides forming the arti-
culation for the head of the rib, sends ofi" a muscular process sub-
ject to the modifications above mentioned: the diapophysis is
larger and more constant in character ; it is extended from before
backward, is horizontally flattened, and forms the surface for the
joint of the tubercle of the rib at a small part of its outer border :
a metapophysial ridge is developed from the upper surface, and is
frequently produced into filaments coalescing with those of conti-
guous dorsals. The pneumatic foramina are at the back part of
the base of the diapophyses. The zygapophyses are small, the front
pair look upward and inward; the back pair outward and downward ;
the latter often support anapophysial ridges. The neural spine is a

' X-. pi. 51, fig. 48, h, h. 2 XH-.

VOL. II. C

18 ANATOMY OF VERTEBRATES.

compressed quadrate plate, its truncate summit is often thickened,
sometimes produced forward and backward to fix the vertebra?
from their highest points ; ossified tendons of spinal muscles, also,
aid the coalesced spinous and transverse processes in fixing part of
the dorsal region, but only in birds of powerful flight, and not in
all such. The partial anchylosis of the dorsal region is associated
in Falcons with their ' hovering ' action. The pleurapophyses
or ' vertebral ribs ' articulate moveably to the dorsal vertebras, as
also to the anterior sacral, Avhen developed there to form part of
the compages of the ' chest.' In the first, and usually the second
dorsal, they are free, pointed, floating ribs, fig. 12, i, 2, fig. 13, pi ;
they articulate with bony ' hasmapophyses ' or ' sternal ribs,'ib.,/i,
d^ in the remaining dorsals. As the vertebral ribs are placed more
backward, the neck or pedicle supporting the head elongates, and
this articulates with the parapophysial surface or tubercle, close
to the anterior border of the centrum ; rarely, as in the Penguin ^
and Ostrich, encroaching upon the intervertebral space. The
tubercle of the rib is, in most, supported on an elongate compressed
base, and articulates by a synovial joint with the diapophysis.
The body of the rib, where formed by the union of the two arti-
cular processes, is compressed, or tliin from side to side, but broad
from within outward; but the outer margin soon expands both
forward and backward beyond the compressed part of the body of
the rib ; this part, as the rib extends down, subsides, the outer
margin maintaining or increasing its breadth, and forming the rest
of the rib, giving to it a flattened surface externally. This is the
common but not constant character of the dorsal pleurapophyses.
These ribs are broadest in proportion to their length in the
^/>^^r?/x,^ narrowest and also longest in the Guillemots and Auks^;
they are slender in most Lisessores ; broad and strong in Raj)tores.
The second, third, and fourth ribs are partially and remarkably
expanded in Wood-peckers. In all birds the end of the vertebral
rib articulatino; with a sternal one is thickened to form the sub-
convex surface of the synovial joint. There may be several mi-
nute pneumatic foramina, but the most constant and conspicuous
is below the tubercle.

An ' epipleural ' appendage, fig. 12, «, is attached to most, if not
all, the moveable pleurapophyses between the first and last, and
consequently may be found in the pair of which the centrum has
become part of the sacrum. These appendages are oblong flat
bones, varying in tlie proportions of length and breadth in dif-
ferent species, and also in their mode of union to their rib : they
' X-. pi. 52, fig. 48. 2 xr. pi. 54. ^ xii-.

OSSEOUS SYSTEM OF AVES. 19

are directed upA\ ard and backward, usually overlapping the suc-
ceeding rib. In the Apteryx they occur in the second to the
eighth pair of ribs inclusive, and are articulated by a broad base
to a fissure in the hind border a little below the middle of the
rib : those belonging to the third — sixth ribs are the largest and
overlap. The articulations of the appendages persist in other
wingless birds, including the Penguins and Auks ; also in some
birds of flight : the RajJtores well exemplify the coalescence of the
appendage Avith its rib. The appendages to some of the ribs in
Picus are broader than they are long : the length much exceeds
the breadth in some Natatores ( Uria, Larus) and Grallatores
(^Hcematojms , PhoenicojHerus, jjI. 14).

The moveable hsemapophyses, or sternal ribs, usually begin at
the third, sometimes the second, rarely, as in the Emeu, at the
fourth pair, more rarely, as in the Cassowary, at the fifth pair, of
the moveable pleurapophyses ; a pair of sternal ribs may also
exist answerino' to the seo-ment succeedino- the last of those which
have the long and moveable vertebral ribs ( Vultur\ The
common number of such htemapophyses is six pairs, of which the
first five articulate with the sternum ; the last usually having its
sternal end attached to the antecedent one. The lia3mapophyses
are longest, most slender and most numerous in the Guillemots
and Auks. There are eight pairs in Phalerus, Temm. ; seven
pairs in Uria. In Rhea and Dinornis elephantopus but three pairs
of haimapophyses articulate Avith the sternum. The sternal ribs
progressively increase in length from the first to the penultimate,
and converge towards the costal border of the sternum, where
they articulate with transverse elevations divided by narrow
depressions. Their upper end is but little, if at all, expanded,
and its articular surfiice is subconcave ; their lower or sternal end
is expanded from within outward, subcompressed from before
backward, and here is usually found the pneumatic foramen. In
the ostrich the sternal end supports two distinct articular surfaces,
each ha\dng its own capsular and synoA^al articulation with part
of the costal eminence.^ The joint between the pleur- and ha^m-
apophyses is also synovial and capsular. This is the main centre
upon which the respiratory movements hinge, the angles between
the vertebral and sternal ribs and between these and the sternum,
becoming more open in inspiration when the sternum is de-
pressed, and the contrary when the sternum is approximated to the
dorsal region in expiration. In some birds, chiefly of the terres-
trial or aquatic kinds, the vertebral and sternal portions of one or

' XX-. i. p. 54, no, 254.
O 2

20

ANATOINIY OF VERTEBRATES.

more of the last pairs of thoracic ribs are iinconuected with each
other, in the skeleton ; such sternal ribs resembling the abdominal
hasmapophyses in Saurians, or the ' intersections,' ossified, of the
rectus abdominis muscle in Mammals.

The modifications of the sternum in Birds relate to their
faculty of flight ; more directly, to the adequate origin of the
muscles acting upon the pectoral limb, less directly to the me-
chanism of respiration needed by the conditions of the lungs ; also,
in Perchers, to sustaining the body in sleep.

The sternum of the Bird is the bony ventral wall of the trunk,
fig. 18, 60, s, r; it is not, however, the
homologue of the plastron of the Tortoise,
fig. 53, p. 63, vol. i., but of the series of
haemal spines forming the episternum and
sternum of the Crocodile (fig. 56, p. 68,
ib.) ; it is developed, in most Birds, from
one pair of ossific centres, wdiich, coalescing
in the midline, usually consolidate the car-
tilaginous basis of the keel by continuous
ossification therein.

The chief parts to be noted in the Bird's
sternum are the ' body,' fig. 15, a, mth its
notches or holes, f, f; the 'keel,' fig. 18,
s; the 'costal processes,' fig. 15, d; the
' costal borders,' Avith their articular sur-
faces, fig. 15, <? ; the ' coracoid grooves,' figs.
15 and 16, b; and the ' manubrium,' fig. 15,
e, 59.

The body may be almost flat, as in
Apteryx and Dlnornis ; or very concave,
the sides being bent upw^ard at an acute angle, as in Aqnila ;
it is commonly less concave toward the trunk. It varies
greatly in the proportions of length and breadth : the latter
dimension is in excess in Apteryx and Dinoniis ; the breadth
nearly equals the length in other Struthionidce, the Albatross,
and the Pelican. The length progressively gains in other birds,
until it becomes four times the breadth of the sternum in Tina-
mus, fig. 14, B. Extreme length is associated wdth ordinary
l)readth in the sternum of the Anserines, Auks, Guillemots,
many Waders, diurnal Baptores, and some Volitores, reaching to
the pelvis, and occasionally to the pubic bones, fig. 18, s,p', and
requiring removal for exposure of the abdominal cavity.

Examples of an ' entire ' sternal body, i. e., neither notched nor

Cantorial sternum, Sbrike.

OSSEOUS SYSTEM OF AVES.

21

perforated, are afforded by Swifts, Humming-birds, iig. 18, some
Eagles {Aqidla, Pandion, HalicBtus) and Petrels ( Thalassidroma),
in connection with excessive developement of the bone and great
powers of flight ; also by the Emeu, Rhea, Cassowary, and Notor-
nis, fig. 16, where the bone stops short of the parts exhibiting the
notches or grooves in birds of flight, and retains almost the small
lacertian proportions, fig. 17, a. The oblong and not very large
sternum of some Cockatoos {Cahjiytorlujnclms) is entire; in the

16

17

Cursorial steniuni, Notoniis.

Lacertiau sternum, Iguaua.

Balearic and Demoiselle Cranes, in the Ibis ( Tantalus Ibis) ; in
the Agami [Psophia), the sternum is long, narrow, and entire.
The broad sternum of the Frigate-bird ( Tachypetes) and the long
sternum of the wingless Auk (Alca impc?inis) are also entire.^

The anterior margin of the sternal body is impressed by the arti-
cular ca\^ties for the coracoids. In Notornis, fig. 16, b, Dinornis
and Apteryx they are small shallow depressions, near the outer
angles : they are similarly situated, but longer and deeper, in the
Rhea and Cassowary ; are more extended and with a sliorter inter-
space in the Ostrich. In birds of flight they are deep grooves,
with the upper or hinder border thickened and convex in many,
affordino; a concavo-convex surface for the broad end of the coracoid.
They mostly meet at the midline; they are continuous, perforating
the base of the manubrium, in some Gallince (Perdix) ; and have
their medial ends decussating, extending one in advance of the

' xn:

22 ANATOIMY OF VERTEBRATES.

other across the midline in some GrallcG {Ardea) ; and in a slight
degree in some diurnal Raptores. The borders of the coracoid
grooves show modifications characteristic of genera and species.^
In the Albatross the coracoid grooves extend to the outer ano'les
of the sternum, between li and s, fig. 13. In most Birds with
a like extent of groove the upper or inner border is developed
behind and beyond it into a ^ costal process : ' but the coracoid
grooves do not reach the outer angle in many Birds, and the
angle itself is then j)roduced to form the process, figs. 15, 19 and
20, d. It is long and slender in some Rasores {Perdix) ; short
and broad in most Raptores : but, in many birds it is represented,
as in the Eagles, merely by the angle between the anterior and
costal borders. On an average about half of the lateral margin
of the sternum is adapted for articulating with the dorsal htema-
pophyses, figs. 13, h d and 15, h: but, when the sternum is long,
the ' costal border,' fig. 15, c, is shorter; and when the sternum is
short it occupies a larger extent of the lateral margin. The part
of the bird's sternum answerino; to that of Mammals is included
between the costal borders, fig. 16, c, c : the rest corresj^onds with
the ' xiphoid ' prolongation. Thus the Apteryx, Emeu, and Ostrich
most resemble Mammals in the projoortions of the costal and non-
costal parts of the sternum ; whilst in most birds of flight the non-
costal part, fig. 15, a,f, extends along that part of the great visceral
cavity, which would be similarly defended were the xiphoid car-

m X

Skeleton of the Topaz Humming Bird ir>'oclnlus Pella, Cuv.).

tilage to be produced and expanded in the same degree in Man.
In the Crocodile, where it is so produced, without expanding,

' The value of these and other sternal characters in Palfeontology may be estimated
by reference to my 'British Fossil Mammals and Bird?,' p. 549 {Lithornis), and p.
236 {Cahhates).

OSSEOUS SYSTEM OF AVES. 23

the costal borders are co-extended therewith, fig. 56, p. 68, vol. i.
In most Gallince the lateral margins of the sternum are deeply-
concave : in the Guan {Penelope) almost angularly incised, with
the costal border on the anterior slope. In the Tinamou, fig. 14,
B, the long marghi beyond the short costal border is convex : in
many Waders (Platalea, Phoenicopterus, fig. 14, c) and Swimmers
(Procellaria, Diomedcea) the lateral borders are straight and paral-
lel, or nearly so: in Rhea, Casuarius, Dromaius, Notorms, fig. 16,
they converge to the hind border : in most birds the lateral borders
are moderately concave and diverge, figs. 15 and 20. The costal
border is thickened, and divided by the transverse articular ridges
for the hasmapophyses into hollows, which usually show pneumatic
foramina. The modifications of the posterior border will be noticed
in connection w^ith the sternal characteristics of orders, or other
groups, of Birds.

The part of the sternum bearing the most direct relation to the
force with which the pectoral limbs are worked is the 'keel,'
figs. 18 and 19, s. In order to afford origin to the accumulated
fasciculi of the pectoral muscles, which otherwise would become
blended together over the middle of the sternum, this osseous crest
is extended downward, analogous to the cranial crest which inter-
venes to the temporal muscles in the carnivorous mammalia ; and
which, in like manner, indicates the power of the bite.

The keel varies in depth, length, contour of the front and lower
borders, and degree of production, freedom, or otherwise of the
angle between those borders. The keel is long and deep in the
wino;less Auk and Penouin, relatins; to the mass of muscle
working the fore limbs as fins in.these excellent and habitual divers :
in the Penguin both the free borders are straight, and meet at
rather an acute angle, fig. 19. The keel is deep, descending ante-
riorly far below the furculum in most GallincB : it is remote from
the furculum in Limosa, Ibis, Scolopax ; but touches it in many
other Grallatores {Otis, Psophia, Ciconia). It coalesces with the
furculum in Griis Virgo and Grus Antigone ; in the stilted Vul-
ture {Gypogeranus)\ in the Frigate-bird {Tacliypetes)', also in
the Pelican {Onocrotalus), Grannet (^Sula), and in old Cormorants
( Carbo), the fore part of the keel being much produced in these
Totipalmates. The keel is thick in the few birds in wdiich a
fold of the windpipe penetrates it ; the anterior border being
excavated to admit the fold. In the larger Rcq^tores the front
border of the sternum is rather thick and subcarinate. The outer
surface of the sternum shows in many birds a ' carinal ' ridge, a
' subcostal ' ridge and a ' pectoral ' ridge, the latter defining the

24 ANATOMY OF VERTEBRATES.

origin of the ' pectoralis secundus.' The subcostal ridge ^'aries
in its distance from the costal border, being more remote in Aquila,
e. g. than in Uria : the pectoral ridge varies in position, direction,
and extent. In the Eao-le it reaches from the outer end of the
coracoid groove to the middle of the base of the keel. In the
Razor-bill (AIca tor da) it extends from the costal border to the
posterior sternal notch ; these differences relate to the form and
proportion of the pectoralis secundus. The ' manubrium ' forms
but a small portion of the sternum, and is often absent or rudi-
mentary : it may be compressed, spatulate, long and simple, or
bifurcate; the latter is its character in all Contores, fig. 15, e.

The parts of the sternum of the Lizard, fig. 17, homologous
with parts of the sternum of the Bird are those forming the
' coracoid groove,' ib. h, the ' costal border,' ib. c, c, and the
median bone, 59, passing forward to join the clavicles, ib. 58.
The broad flat bone, including the first two parts, exists in all
birds ; the third, or ' episternal ' part, is wanting as a distinct
element, but its positions and connections are repeated by the
exogenous keel and ' manubrium.' The episternum, moreover, is
not present in all Lizards : it is wanting in the Chameleons, e. g.,
in which the sterninn partakes of the simplicity of that in the
Notornis, fig. 16, the Apteryx and Emeu.

In the Apteryx the anterior border of the sternum between
the coracoid grooves is concave, and the posterior border has a
deep and Avide emargination on each side. In the Emeu the
coracoid grooves meet at the middle of the anterior border ; and
the sternum contracts posteriorly to an obtuse point. The ster-
num is rhomboid, also, in the Cassowary : it is broader in pro-
portion to its length, and subquadrate in the Ostrich. In
Notornis, fig. 16, the costal borders converge posteriorly, as in
Lizards, and the narrow breast-bone is continued as a ' xiphoid '
part, gradually contracting to a blunt point. The depressions, 60, a,
for the pectoral muscles are separated by a narrow median tract,
expanding anteriorly, 59, and showing the beginning of the ' keel.'
In Brachypteryx^ the keel is rather more prominent : two obtuse
ridges diverge from its fore-part to the coracoid grooves, between
which the fore margin is deejjly concave, as in the Apteryx.
There is no distinct ossific centre for the keel in Brachypteryx,
any more than in its feebler rudiment in Notoimis. In all these
keel-less sternums ossification begins, as in the Ostrich^, by a
pair of centres expanding until they meet and coalesce in the

' XLiv. p. 238, no. 128U. - lb. p. 264, no. 136G.

OSSEOUS SYSTEM OF AVES.

25

middle line, and thence, according to the stimnlus of the growth
and pressnre of the pectoral muscles, extending, as a keel, into
the interspace. A separate ossification answering to the epi-
sternnm in Lizards and Crocodiles is not formed : but the body of
the sternum with the keel has a centre distinct from that of the
long bifurcate side-processes, exceptionally, in GallincB.

In the Penguins, fig. 19, the sternum is long and narrow, with
a deep fissure,/*, on each side of the posterior border: the free
borders of the well-developed keel are straight, and meet at an
acute angle, which almost touches the furculum. There is a
short manubrium, e, behind which the coracoid grooves, h, meet.

19

sternum, scapular nrcli, and limb. Penguin {Aptenodijtes).

In the Auks and Guillemots the sternum ' is very long and
narrow ; the lower border of the keel is convex, the front one
concave ; the manubrium is short and wedge-shaped ; the sternum
is entire in Alca imjiennis ; but has a narrow notch on each side
the posterior border in Alca tarda, to which the pectoral ridge ex-
tends from the costal border ; the notches are converted into fora-
mina in Uria and PJialeris lyygmcEa, The Loons ( Cohjmhus) have
a similar two-notched sternum, but with larger costal borders.
In the Grebes (^Podiceps), the sternum is broader ; and there is a
median notch between the two lateral posterior ones. In the

26 ANATOMY OF VERTEBRATES.

Skimmers, Gulls, and Terns, the sternum has two shallow notches
on each side the posterior margin. In the Petrels and Albatross
the posterior border is feebly incised or entire and the sternum ac-
quires great breadth, especially in the Albatross. The keel reaches
the furculum in all the Longipennate family. In the PelecanidcB,
confluence of the two bones usually here occurs ; there is a pair of
shallow posterior emarginations. In the Lamellirostrals the ster-
num is both large and long, boat-shaped, with extensive costal
borders ; the keel is of moderate depth, with almost straight free
borders, excavated for tracheal folds in some swans ; there is a
short notch or small foramen on each side the broad posterior
margin in all the Sifters ; the manubrium curves downward in
many. The Flamingo's sternum is given in fig. 14, c. The fore-
Q-oino- diversities of sternal structure in the web-footed birds indi-
catc from how many types they have been derived, and shows the
artificial character of the webbed-foot.

The same testimony is borne by the breast-bone of the long-
legged birds, from which, in some instances, the species have
been detached when the truer affinities were sufficiently strongly
marked, as, e. g., the Flamingo to the Sifters or Lamellirostrals ;
the Secretary Bird to the Vultures ; and the Couas to the Cuc-
koos. In the long and narrow sternum of the Coots and Rails
the two posterior notches are deep, with the outer boundary the
longest, and Bracliyiiteryx shows a third intermediate shallow
notch.

The Ibis and Spoonbill have a four-notched sternum ; the Ad-
jutants and Herons have a two-notched one ; the notches are short
in both. Peculiarities in the breast-bone of certain Cranes have
already been noticed. The Woodcock (^Scolopax) has a pair of
notches, mth the outer boundary slender and shorter than the
broad intermediate tract ; the Gambets ( Totamis), Avocets, Sand-
pipers (^Trinf/f(), Curlews (^A^umc7iius), Pratincoles (^Glareola),
have the four-notched sternum. In the Godwits {Limosa, Helias),
the medial notches are almost obsolete, and the lateral ones wide.
The ^ Thiok-kwdQ^^ (^(Edicnemus) and Bustards (Otis) have the
four- notched sternum, the notches beiug small.

In the Gallinaceous group of Basores, the four posterior notches
are so wide and deep as to reduce the bony parts of the sternum
almost to five slender processes, diverging from a short and
broad anterior stem, and the points of ossification are multi])licd
accordingly. The middle process is the broadest, and from it is
developed the keel, of which, in some ( Ortyx, Perdix), it seems
to be almost wholly composed. As the median pair of notches

OSSEOUS SYSTEM OF AVES. 27

is usually deepest, the processes on each side the mid one appear
as unequal, styliform, terminally expanded, prongs of a fork, the
outer prong being the shortest. The costal border is very short,
and is continued upon the costal process, which is long : the
manubrium is compressed and terminally dilated and deflected,
often perforated transversely by confluence of the short cora-
coid grooves. The fowls {Gallus), pheasants (Phasicmus), par-
tridges (^Perdix, Francolinus), quails (^Coturnix, Ortijx, Loph-
ortyx\ grouse ( Tetrao), exemplify the gallinaceous type of the
sternum.

In the Turkeys {Meleagris)^ Pea-fowl {Pavo), and Kaleeges
(Polyplectron, Lophophorus, Oreophasis), the sternum is more
ossified, and the lateral processes are shorter and broader ; in the
Curassows {Crax, Ourax), they present the proportions shown in
fig. 14, A. In the Gangas or Sand-grouse {Pterocles^ Syrrhaptes),
the outer pair of notches are chiefly present, the inner pair
nearly obsolete ^ ; in the Tinamous ^ they are wanting, the outer
notches are of extreme length, and the whole sternum is reduced
to a trifid form, as in fig. 14, B. The sternum of Columha coronata
resembles that of the Curassow, with the median pair of notches
shorter and narrower. In Columha magnificat ^ the four notches
are more equal in size, and the whole sternum is broader. In the
Columha livia the median pair of notches are often converted into
small foramina.

The transitional steps in the foregoing series from the type-
sternum of CralliiKB to that of the swiftest of the doves indicate
the natural character of the order Rasores.

In diurnal Raptores the sternum is a large elongate paral-
lelogram, convex outwardly both transversely and longitudinally.
The manubrium is short and trihedral ; the lower border of the
keel is convex ; the front border concave ; their angle of union
rounded off. The instances where the sternum is entire have
been cited: in other birds of prey the arrest of ossification is
limited to very small parts of the hind border ; usually a fora-
men, rarely a notch (^SarcorampJius), on each side; one of
which may be filled up, wholly or partially. Eyton"* figures
two small notches on each side the posterior border in Hierax
hengalensis ; and both hole and notch on each side in Cathartes
aura. In the Nocturnal Raptores the sternum is relatively
shorter, the keel less deep, its lower margin less convex and not
thickened, the costal border is shorter. The posterior margin
usually presents two notches on each side, the outer one the

' xiir. p. 2-28, fig. 109. - lb. p. 230, iig-. 110. ^ xiv. pi. 2 c. -■ lb. pi. 16.

28

ANATOMY OF VERTEBRATES.

deepest; but the Barn-OAvl (^Strix Jiammeci) has but one on each
side; while Strix praticola shows a third intervening notch. ^

In the Cantores the sternum, fig. 15, is broadest behind, with
the lateral margins slightly concave, the costal, c, usually meeting
the rest of the margin at a very open angle. The keel has a
convex lower border meeting the concave front border at a sharp
anole : the manubrium <?, is bifurcate : the costal jjrocesses, d, are

broad and flat: the posterior border
has a notch, f, usually of angular form,
on each side, near the lateral margin,
and with this outer boundary termi-
nally dilated.

Among the Scansores the Toucans,
Barbets, Touracos, and Woodpeckers,
fig. 20, have a four-notched sternum :
the Cuckoos have but one pair of short
notches ; many Parrots (^Psittacus pro-
per, Pezo2)orus) have one pair of small
foramina, and Calyptorhynchus has the
sternum entire : it is keel-less in Stri-
(jops. In most parrots the costal border
is extensive ; the manubrium is trihe-
dral and truncate. None of the Scan-
sores have the manubrium bifurcate ; it
may be notched ; in most it is small ; in
some (^Cuculus, Painphastos) obsolete.
In the Volitores, as a rule, the
posterior border of the sternum has a
pair of notches on each side : the Eurylaim and Hoopoe have
one notch or foramen on each side. The Hornbills, Swifts, and
Hummino-birds have the sternum entire. In none of this
group is the manubrium bifurcate : it is wanting in Podarcjus,
Harpactes, Todus: the costal process is Avanting in some. In
the Swifts ( Cypsebis) the sternum corresponds in its proportional
magnitude with the superior length and power of wing A^'hich
characterizes the genus : the depth of the keel equals the breadth
of the entire bone. The manubrial process is wanting, but the
costal ])rocesses are moderately long and pointed.

In the Humming-birds, which sustain themselves on the wing
during the greater part of the day, and hover above the plant
while extracting its juices, the sternum, r, s, fig. 18, is still

Stermuu and scapular arcli, Woodpecker,

a'icus).

pl. 4, fig. 5.

OSSEOUS SYSTEM OE AVES.

29

21

Front view of pelvis, Partridge.

further developed as compared with the body ; it approaches to a
triangular form, expanding posteriorly,
where the margin is entire, and convex.
The depth of the keel exceeds the entire
breadth of the sternum. The coracoid
depressions are deeply trochlear: the
manubrial process is small, and directed
upward ; the costal processes are also pre-
sent, but of small size : the costal border
is short. In these pre-eminently volant
Vertebrates, the breast-bone reaches the
maximum of developement.

§ 126. Sacral Ferfe/^r^.- -In vertebrate
anatomy the term ' sacrum ' is applied to
the centrum and neural arch of the ver-
tebra, having its haimal arch complete, as
in the thorax, but with its ap])endage de-
veloped into a hind-limb (vol. i., figs. 101,
D and 114). If two or more vertebras coalesce beyond the thorax,
they are likewise said to form ^ a sacrum,' although but one may
be typically complete, and the rest support only stunted pleura-
pophyses. In all warm-blooded Vertebrates the sacrum, when
present, is so characterized, and confluence is carried to an
extreme in birds, converting a large proportion of the vertebral
column into a '^sacrum,' fig. 21, .9, «, c, which in the Ostrich may
include seventeen or more vertebras. Thirteen is the average
number in Natatores, twelve in Grallatores and Rasores, eleven in
Altrices or the higher birds of flight.'

In analyzing this most complex of all compound bones, in a
young Ostrich ^, I find the centrum of the first sacral vertebra
distinct, although its neural arch and spine have coalesced with
those of the second vertebra and with the ilia. Traces of the
articulation between the centrum of the second and third sacral
vertebra remain : they are obliterated in the remaining vertebras,
and the bodies of all are cellular and permeated by air.

The pleurapophysis of the first sacral retains its moveable
articulation to the par- and di-apophyses of its vertebra ; it is
long, slender, and terminates in a free point. That of the second
sacral vertebra is styliform, half the length of the preceding, and
terminates in a free point projecting downward and backward ;
its head and tubercle, free in the young bird, become confluent

» See the Table in vii'. p. 273.

2 Nos. 1835 and 1837, Osteol. Scries, Mus. Coll. Chir.

30 ANATOMY OF VERTEBRATES.

in the full-grown. The third sacral has no pleurapophysis : its
l)arapophysis is a stumpy process ; its diapophysis is longer and
abuts against the ilium. In the fourth sacral both par- and
di-apophyses abut against the ilium.

The neural arch of the fifth sacral vertebra has advanced and
rests over the interspace between its own and the preceding
centrum : this interlockino- relation continues to the eleventh
vertebra, where the arch resumes its normal position and con-
nections. The pleurapophyses of the fifth to the eleventh sa-
cral vertebrre inclusive have undergone a corresponding change
of position, and are synchondrosed by an expanded head to a
rough flat surface formed by the base of the neurapophysis and
by a portion of their own and of the preceding centrum : their
distal extremities expand and coalesce, forming a broad abutment
applied to the iliac bones. The diapophyses are directed upward
and outward against the same part, and are of considerable
length, especially in the ninth to the fifteenth sacral vertebra.
The dilated part of the neural canal is formed by the increased
breadth and flatness of the centrums, and by the wide expanse of
the neural arches at the middle of the sacrum. In the seventh
to the ninth of these arches there is a wide aperture in each
between the diapophysis and the base of the spine. The outlets
for the nerves are single and at the interspace of the neural
arches, but those at the middle of the canal show two grooves for
the separate exit of the motor and sensory roots.

The spines of all the vertebra? are lofty, and already confluent
with each other at the middle of the sacrum. They are com-
pressed from before backward, consist of little more than a lace-
work of osseous tissue, and diverge in curves from the neural
arches, through the interspace between the iliac bones, with both
of which their lateral margins are confluent, and which they
thus serve to bind firmly together. By the peculiar cellular
and pneumatic structure of the parts, not more osseous texture
is expended in performing the oflfice of tie-beams across the
elongated roof of the pelvis than is absolutely required. The
last seven vertebrae are seen between the narrow parts of the
ilia produced backward beyond the acetabula, until full-growth,
when ossification extends from the summits of the spines bridging-
over the interval, leaving only a linear fissure on each side, fig. 24.
In the Cassowary a few pairs of foramina similarly indicate the
last three or four sacral-vertebras.

In the Apteryx the first four sacral vertebrae send outwards
parapophyses which abut against the ilia, and progressively

OSSEOUS SYSTEM OF AVES. 31

increase in length and thickness. The breadth of these vertebra?
also gradually increases ; but it diminishes in the four succeeding
vertebra?, in which the parapophyses are wanting : then the ninth
and tenth sacral vertebra? send outward each a pair of strong
parapophyses to abut against the inner surface of the ossa inno-
niinata immediately behind the acetabulum : the anchylosis of the
bodies is continued through the four succeeding vertebras, which
are of a very simple structure, devoid of transverse or oblique
processes, becoming gradually more compressed and more extended
vertically, so as to appear like mere bony lamina? ; the line of the
articulation between the bodies of these posterior sacral vertebra?
is obvious, but their spines coalesce to form a continuous bony
ridge, which is closely embraced by the posterior extremities of
the ilia. The foramina for the nerves are pierced in the sides of
the bodies of the sacral vertebrte ; they are double in the anterior
ones, but single in the posterior compressed vertebra?, where they
are seen close to the posterior margin.

The species of Dinornis show from 17 to 20 sacral vertebni?.
In D. rohustus the pleurapophyses of the first retain their move-
able articulations : those of the second and third are anchylosed,
but project freely beyond the ilia : those of the fourth to the
eighth abut as parapophyses against the ilia, the last, which is oppo-
site the acetabula, being the thickest : those and the four following
sacrals, which have no parapophyses, are very short : from the thir-
teenth to the twentieth sacral the parapophysial buttresses reap-
pear, and the vertebra? increase in length. A continuous bony
roof of the pelvis extends from the sacral spines to the ilia. When
vertically and longitudinally bisected, the sacrum shows the great
expanse of the canal for that part of the myelon in connection with
the nerves of the large and strong hinder extremities. All traces
of the original joints between the bodies of the vertebras, wdth the
exception of the last, are obliterated. The primitive distinction
of the neural arches is indicated by undulating transverse folds of
the roof of the spinal canal : the motor and sensitive roots issue
separately, as in other birds.

In the Penguins (yAiJtenodytes) the sacrum forms the middle
third of the upper surface of the pelvis : in Podiccps and Colymhus
the ilia converge to the summits of the posterior sacral spines : in
Uria, Diomedea, Procellaria, and the AnatidcB they converge to
the anterior ones, fig. 22, b. Pairs of foramina usually indicate the
sacral vertebrae, forming a broader posterior sacral roof (ib. a, c),
of the pelvis : but in the Petrels ossification obliterates them. In
most Grallatores the ilia come near to the neurospinal ridge, ib. />»,

32

ANATOINIY OF VEETEBEATES.

of the anterior sacral vertehra? ; whilst the posterior ones form a
broad middle tract of that part of the pelvic roof: usually perforated
by pairs of foramina, as in the Duck, but becoming obliterated

more or less in Scolopax, Ptili-
nopus, Psopliia, Scojys, Ibis, and
perhaps in others Avith age. In
most Gallinacea, including the
Doves, the ilia converge to a
less proportion of the anterior
sacral spines, and the space at
the middle and posterior part
of the pelvis formed by the sa-
crum, fig. 21, «, c, is both broad
and long. In the Tinamus
hrasiliensis, figured by Eyton,
this part of the roof is almost
wholly ossified, as it likewise is
in Oreophasis derbianus, where
n pair of oblique grooves lead
forwards, deepening, to ' ilio-
neural ' canals beneath the an-
terior sacro- iliac bony roof on
each side the neurospinal ridge.
In Hemipodius, Columba, and
Goura, the pairs of foramina in
the sacral part of the pelvic roof
are very small ; in Crax Mitu
they continue large to a late
period. The ilio-neural grooves and canals are seen in most
Gallince as in Oreophasis.

In Cantores, Volitores, Scansores, and Raptores, the proportion
of the hind-part of the pelvic roof formed by a neural expanse of
the sacrum is less than in Gallince : the ilioneural grooves are
commonly wanting. The bony roof is entire in Ncomorpha,
Centropus, Psittacus, Falco, Aquila: and the parial foramina are
very small in Cypsehis, Trocliilus, Cassicus, Fregilus, and most
Cantores : the ileoneural grooves are present in Turacus gifjas,
and are open canals in Cypsirhina and some others. In the
diurnal Raptores the pelvic roof, of which the sacrum contributes
a broad medial tract to about a third of the hinder portion, is
strongly and very completely ossified, fig. 23. The ribs of the
first two vertebra^ retain their moveable joints : in the third to the
sixth vertebra? they abut as parapophyses against the lower border

Back view of pelvis, Duck.

OSSEOUS SYSTEM OF AVES.

33

of the ilia ; the seventh to the tenth vertebrae have no parapo-

physes ; the eleventh to the fourteenth have them long and strong,

thickest in the last. All

these abutments, with the ^^

expansions from the neural

spines, coalesce with the in-

nominata and convert the

pelvis into one complex

mass of bone.

The iliac, ischial, and
pubic elements are deve-
loped as distinct bones, but
speedily coalesce at their
point of junction around
the acetabulum and usually
elsewhere : their indepen-
dence is longest maintained
in the Cursores.^ Ossifi-
cation begins in each from
a single point, even in the
much elongated ilium of
Struthio and Dromaius.
This bone is, in fact, a
single vertebral element,
or rather part of one ; it is
homologous -with the pelvic
bone, 62, in figs. 43 and
101, D (vol. i.), and with
62 in fig. 28, p. 159, of my
work on the ^ Archetype
Skeleton' (cxL. vol i.),
where it is shown to com-
plete the pleurapophysial element of the pelvic haemal arch ;
the ischium being the hfemapophysis of the same arch. The
ilium in Birds, figs. 21 and 22, d, h, fig. 23, b, fig. 24, h, c, c\
is remarkable for its developement in the direction of the
axis of the vertebral column, extending its connections with
many more segments than its own: it is accordingly long and
narrow, thickest midway, fig. 22,/, where it contributes the upper
wall of the acetabulum, ib. z, in front of Avhich, rZ, it is outwardly
concave ; behind the acetabulum, ib. g, U, it is convex. It differs

Side view of pelvis, Eagle.

VOL. II.

' XLiv. vol. i. p. 267. Nc. 1386

D

34 ANATOMY OF VERTEBRATES.

in the proportions of the pre-acetabular and post-acetabular exten-
sions, and in the degree of divergence of the latter from the sacrum.
The longest and narrowest ilia are seen in certain Natatores (Po-
diceps, Colymhus, fig. 34, a, d, Uria) and in Cursores {^Struthio,
fig. 24, h, c , Dromaius) : the shortest and broadest ilia are seen
in certain Volitores, Scansores, and Insessores. In the Grebe and
Loon the ilia unite with the summits of the sacral spines behind
the acetabula, and diverge for a broader interposed neural expan-
sion anteriorly : in most birds the divergence is shown at the post-
acetabular portions, as in fig. 22, g, g^ the pre-acetabular plates
d, d, converging to the summits of the sacral spines, ib. h. A few
birds {Podargus^ Tachypetes) retain the extent of sacral interpo-
sition which obtains at an early stage of pelvic developement in all
birds. ^ In the old Apteryx the ilia almost meet along the summit
of the sacral ridge to mthin a short distance of their hind end,
where an epiphysial piece of bone is sometimes found wedged
between this end and the anterior caudal vertebrae. The anterior
border of the ilium is usually more or less convex : in Tinamus,
Crax, Ojiocrotalus, it is almost straight : in Geococcyx, Corythaix,
Scolephagus, it is emarginate or concave, the external angle being
produced outw^ard : in Limosa it is angular ; the point being
formed by the commencement of the ^gluteal ridge:' this, which
is well-marked in most birds, describes a curve, concave down-
ward, and terminates above or behind the acetabulum, as atjf,
fig. 22, marking off the post-acetabular convex part of the ilium,
g, h. This part is the longest in Grebes, Loons, fig. 34, d, and
the Ostrich, fig. 24, c' : it is the shorter division in Petrels, Gulls,
Cranes, and most smaller Grallatoi-es, in the Apteryx^ in most
Insessores, and especially in diurnal Raptores, fig. 23, g, i : in
many birds it forms half the length of the ilium. In some birds
( Cursores) it is narrower than the fore part of the ilium ; in
others, especially Geococcyx, it is broader : in most the breadth is
about equal, although the ilium may seem broadest behind from
its coalescence with the horizontal expansions from the sacral
spines. The upper is divided from the outer surface of the post-
acetabular part of the ilium by a prominent ridge in most birds,
fig. 22, g, which generally overhangs the outer surface ; in
Geococcyx to a remarkable extent, like a wide pent-house, pro-
ducing a deep concavity in the outer and back part of the ilium
where it coalesces with the ischium. This coalescence, converting
the ischiadic notch into a foramen, fig. 22, I, fig. 23, h, is common

' XV. p. 45, pi. iii. fig. 6.

OSSEOUS SYSTEM OF AVES. 35

to most birds. It does not take place in Ajiteryx, Dinornis,
Struthio, fig. 24, c\ The ilium forms an angular projection above
the posterior ischial junction in the Albatross, Skimmer, Duck,
fig. 22, n. Ibis, Spoon-bill, Woodcock, Pigeon, most Volitores
and Insessores. The principal pneumatic foramen of the ilium
is on the outer and under part of the post-acetabular division.
The ilium developes an oblong articular surface on the pro-
minence extending from the upper and back part of the aceta-
bulum.

The ischium, fig. 24, 63, fig. 22, ^, m, fig. 23, c, i, is a long, nar-
row, flattened bone ; thickest where it forms the back part of the
acetabulum, becoming thinner and broader as it extends back-
ward, with the lower border turned slightly outward; generally
placed parallel with its fellow, but diverging in the Ostrich ; of
nearly uniform breadth in this wingless bird, fig. 24, and in
the Apteryx, but usually expanding to its hinder end, and
there coalescing with the ilium. Just beyond the acetabular
part the ischium contracts, presenting a smooth and thick upper
border to the ischiadic notch or foramen, fig. 22, Z, fig. 23, h, and
a similar lower border to the foramen or notch, ib. o, fig. 24, /,
which transmits tlie tendon of the obturator internus muscle ; it
then becomes lamelliform, with thin margins, usually increasing
in depth, and often bent down at its termination to join the
pubis, and circumscribe, as in fig. 24, the obturator foramen, o.
In the Ostrich, the ischium does not join the ilium posteriorly,
and the ischiadic notch remains open; its coalescence with the
ilium, beyond the ischiadic foramen, is usually extensive, as in
figs. 22 and 23.

The most singular modification of the ischia is seen in the
Rhea, in which they meet below the sacrum and coalesce with
each other for some extent, almost obliterating here the bodies of
the sacral vertebra?.

The pubic bones, fig. 21, /?, fig. 24, 64, present an analogous
exceptional condition in another member of the Cursores, viz.
the Ostrich, in which they unite together at their hind ends,
forming a ^ symphysis,' which is curved downward and forward,
fig. 24, h ; in Gyps fulvus the same ends curve toward and
almost touch each other. In other birds the pubic bones are
directed backward, with usually a curve convex outward, and
terminate freely, or are united to the ischium above, as in
fig. 34, h, the pelvis being thus an open one, as a rule, in
Birds. The pubis forms the lower and front portion of the
acetabulum, beyond which it quickly contracts, exchanging its

D 2

ANATOMY OF VERTEBRATES.

trihedral for a subcompressed form, and is more slender than
the ischium. The shortest pubis is seen in certain Eagles,
in which it terminates after forming the lower boundary of the
obturator foramen; its extremity there projecting freely, as in
fig. 23, d, or being joined by ligament to the ischium, as in the
Harpy Eagle, in which it is an inch in length, whilst the ilium is

six inches long. The opposite ex-
treme may be seen in the Guillemots
and Grebes ; and in the latter the
pubic styles diverge from the aceta-
bula with a slight outward bend, the
interspace of their extremities being
twice the breadth of the fore part of
the pehds : they are usually longer
than the ischia, figs. 24 and 34 ; but
in the Apteryx they equal that bone
in length, and in the Emeu they are
shorter. The pubis coalesces with the
ilium and ischium at the acetabulum ;
usually again mth the ischium, as at
k, fig. 22, to close the tendinal fora-
men, and, in some birds, a third time
Avith the end of the ischium, as in
fig. 24, to circumscribe the obtura-
tor vacuity, o. In Doves, the pubis
after uniting with the ischium to close
the tendinal foramen, extends back-
Avard parallel with and close to its lower
margin, sometimes contracting a bony
union therewith and obliterating the
^ obturator ' interspace. The pubic
bones as they extend backward in the
Apteryx are nearly parallel ; in the
EmeUi Neomorpha, Cassicus^ Podiceps, they diverge. In most
birds the fore part of the acetabular portion of the pubis forms
a ridge or tuberosity, figs. 24, m, and 22, §'; in some it is
produced to a greater extent (^Geococcyx, Corythaix, Tinamus,
Oreophasis).

In accordance with the above-stated differences in the form and
proportions of sacrum, ilium, ischium, and pubis, the pelvis of the
Bird varies in its general form and proportions. From that of all
cold-blooded Vertebrates it differs in the greater number of ver-
tebral segments entering into its composition, and in their bony

Pelvis of Ostricl

OSSEOUS SYSTEM OF AVES. 37

confluence ; from that of Mammals by being unclosed^, and by the
widely perforate acetabulum, fig. 22, i.

The lars^e size and brittle shell of the eo-jT are the teleoloo^ical
conditions of the open pelvis, and the transference of the weight
of a horizontal trunk upon a single pair of legs necessitates an
extensive grasp of its segments. When the legs require to be
pulled far and strongly back, as in diving and cursorial motions,
the origins of the requisite muscles are extended far behind the
limbs' centre of motion, as in the pelvis of the Grebes, Loons,
Guillemots, Ostriches, Emeus ; when the bird slowly stalks, or
hops, or climbs, or uses the legs chiefly in grasping and perching,
the pelvis is short and broad, especially behind, and its breadth
may exceed its length (^Cyclarius guanensis).

The caudal vertebrje are few, short, not produced into a con-
spicuous appendage, the so-called ' tail ' of birds being due to the
feathers attached to the terminal vertebrae ; these, in birds of
flight, coalesce to the number of two or more, and form a com-
pressed vertically extended bone, like a plough-share,^ fig. 23, «,
presenting a concave surface to the antecedent centrum ; rising
above as a sharp crest, anteriorly perforated by the termination of
the neural canal ; expanding below and there perforated by the
haemal canal which terminates by one inferior and two lateral ori-
fices. This compound bone, ' os en sec de charrue,' supports the
coccygeal oil-glands, and gives attachment to the ^ rectrices ' or
rudder-quill-feathers, which are disposed fan-wise. In the Wood-
peckers the hasmal part extends far in advance of the articular
surface of the centrum, and expands into a broad subquadrate
plate concave below ; the neural part forms as large a vertical
plate ; this relates to the use of the stifl" tail-feathers in climbing.
The horizontal developement prevails in the Peacock. Reckoning
the terminal bone as one, the common number of caudal vertebra3
is nine. The anterior ones have vertically extended transverse
processes including di- par- and pleur-apophysial elements ; the
neural arch has prezygapophyses, very small postzygapophyses,
and a short and thick neural spine. In the third or fourth ver-
tebras caudal hjemapophyses appear, increase in length, and in
the fifth or sixth inclose a hasmal canal. The transverse pro-
cesses in many birds increase in length to the antepenultimate ;
in a few (^Ibis, Uria) they gradually shorten to the last ; the
caudal centrums are joined by ligament and are procoelian. In
the Toucan the joint between the sixth and seventh vertebrae

> XII. vol. i. p. 208.

38 ANATOMY OF VERTEBRATES.

has a capsule and synovial fluid, and the neural spine is shortest
in the sixth, where the tail has the greatest extent of motion ver-
tically, the transverse bend being checked by the size and length
of the transverse processes. The neural spines can be brought
by dorsal inflection into contact Avith the sacrum ; and in this mo-
tion the side-muscles, which at first tend rather to oppose the
elevators, become, as the motion proceeds, themselves elevators,
and complete it by a jerk ; this throwing up the tail upon the
back, as if operated on by a spring, is a conspicuous characteristic
of the living bird.^ In most birds of flight the caudal series are
habitually curved upward, as in fig. 23 ; in the few birds that can-
not fly the tail is straight, and the terminal centrum is not ex-
panded. In the Apteryx there are nine caudal vertebrae, which are
deeper, and project farther below the posterior portions of the iliac
bones than in the other birds : as they recede, they increase in
lateral and diminish in vertical extent ; the spinal canal is conti-
nued through the first five, and they are all moveable upon each
other, excepting the last two, homologous with the expanded ter-
minal mass in other birds, but which here exceeds the rest only in
its greater length, and gradually diminishes to an obtuse point.
In the Ostrich the coiTesponding vertebra is expanded for the
support of the caudal plumes, but in the Apteryx it offers the
same inconspicuous developement as in the Rhea and Emeu. In
the ' rumpless ' breed of domestic fowl the coccyx is reduced to
a single stumpy bone. In some bre^dpennate sea-birds I have
found as many as eleven free caudal vertebra3 ; only in the extinct
Archeopteryx of the upper oolitic period was the tail a conspicuous
appendage to the trunk, formed by about twenty elongate ver-
tebrae, each of which supported a pair of small and slender quill-
feathers.

The terminal vertebrae, ungrasped by the pelvis in the embryo
bird, may equal in number those of the ancient feathered fossil ;
and if such vertebras participated in the ratio of growth of other
parts of the skeleton, without subsequent stunting and con-
fluence, they would more or less repeat the strange and unique
feature in the skeleton of Archeopteryx ; but the metamorphosis
of the tail which has taken place in the bird's skeleton in the
transition from the mesozoic to the neozoic life-periods of the
class, is analogous to that from the protocercal to the homocercal
type of tail, which marks the progress in fishes from the palaeo-
zoic to the mesozoic periods.''^

' XX-. 2 XV. p. 45, pis. i. and iii.

OSSEOUS SYSTEM OF AVES. 59

§ 127. Cervical Vertebra. — As the prehensile functions of the
hand are transferred to the beak, so those of the arm are per-
formed by the neck of the bird ; this portion of the spine is
therefore composed of numerous, elongated, and freely moveable
vertebrae, and is never so short or so rigid but that it can be
made to apply the beak to the coccygeal oil-gland, and to every
part of the body for the purpose of oiling and cleansing the
plumage. In birds that seek their food in water it is in general
remarkably elongated, whether they support themselves on the
surface by means of short and strong natatory feet, as in the
Swan, or wade into rivers and marshes on elevated stilts, as in
the Flamingo, fig. 14.

The articular surfaces of the bodies of the cervical vertebrae,
like those of the dorsal series, are concave in one direction and
convex in the other, so as to lock into each other, and in such a
manner that the superior vertebras move more freely forward, the
middle ones backward, while the inferior ones again bend forward ;
producing the ordinary sigmoid curve observable in the neck of
the bird.

This mechanism is most readily seen in the long-necked waders
which live on fish and seize their prey by darting the bill A\dth
sudden velocity into the water. In the common Heron, for
example (^Ardea cinerea), the head can be bent forward on the
atlas or first vertebra, the first upon the second in the same direc-
tion, and so on to the sixth, between which and the fifth the for-
ward' inflection is the greatest; while in the opposite direction
these vertebras can only be brought into a straight line. From
the sixth cervical vertebra to the thirteenth the neck can only be
bent backward ; while in the opposite direction it is also arrested
at a straight line: from the fourteenth to the eighteenth the
articular surfaces again allow of the forward inflection, but also
limit the opposite motion to the straight line.

An inter-articular cartilage is inclosed between reduplications
of the synovial membrane in most of the joints between the
bodies of the cervicals, as in the joint of »the lower jaw in mam-
malia. The zygapophysial articulations are simply synovial. The
par- and di- apophyses are at the fore part of the vertebras, and,
usually at the third cer\ical, coalesce with a styliform pleurapo-
physis projecting backward. The vertebrarterial canal, thus
formed, is large, and gives passage to both the vertebral artery
and the sympathetic nerve.

The inferior processes from the cervical centrums are of two
kinds ; one single, developed from the mid-line, usually toward

40

ANATOMY OF VEETEBRATES.

the back part, and answering to the ^ hypapophysis ' in lizards ;
the other parial, developed from the under part of the vertebrar-
terial canal, answering to parapophyses, bent or directed down-
ward, after coalescing with the pleurapophysis. In a Vulture
( Gyps fulvus), the latter inferior processes begin at the sixth cer-
Adcal, and are continued to the thirteenth ; the hypapophysis
begins at the second, and is continued to the fifth, where it is
reduced to a low ridge. In the Guillemot the hypapophysis
exists as a ridge or process in all the cervicals. In the Apteryx
the single hypapophysis for the attachment of the longus colli
anticus is present in the last three vertebrae, as in the contiguous
dorsals. The parapophysial arch for the protection of the carotid
arteries is most complete in the twelfth cervical, but the two sides
of the arch are not anchylosed together ; the interspace progres-
sively increases in the eleventh, tenth, and ninth vertebrae, and
the groove widens and is lost at the fifth vertebra. In many
birds the parapophyses after forming the sides of a wide canal in
the middle cervicals, converge and unite to
inclose a haemal canal, as in the lower cervical
vertebra of the Pelican, fig. 25.

The neural arch in most of the cervicals
developes, in addition to the spine, ib. ns,
zygapophyses, ib. z, and diapophyses ib. t,
also anapophyses, or tubercles, above the pos-
terior zygapophyses. The arch is, in some
A^ertebra, strengthened by bony plates, one
of which may be specified as ' interzygapo-
physial,' and this may be perforated vertically, as in the second,
third, and fourth cervicals of the Hornbill {^Biiceros), and in
the third and fourth cervicals of the Vulture, and many other
birds ; the neural arch thus becomes remarkable for its breadth,
and the square or quadrate platform of bone from which the
small and short neural spine rises. In one or more succeeding
vertebrae the incomplete ' interzygapophysial' bar projects back-
ward as a process or tubercle from the prezygapophysis. The
prezygapophyses look upward and inward ; the postzygapophyses
downward and outward ; the neural spine is feebly developed,
if at all, in the middle of the cervical region ; it is most con-
spicuous in the second to the fifth, and again in the last two or
three cervicals. In the Apteryx it is thick and strong in the
second, but progressively diminishes to the seventh, cer\dcal,
where it is reduced to a mere tubercle ; from the eleventh it
progressively increases to the last cervical, in which it presents

Cervical vertebra, Pelican.

OSSEOUS SYSTEM OF AVES. 4t

the strong quadrate figure which characterizes the same process
in the dorsal vertebrae. The neural canal, ib. n, varies in form
and diameter in the same vertebras. If, e.g., the sixth cervical
of a Stork be sawed lengthwise vertically, the diameter is great-
est in the middle, least at the ends ; but if it be sawed length-
wise horizontally, the transverse diameter is the reverse, being
narroAvest at the centre and widest at the ends. In the Ostrich,
the Swan, and many other birds, the canal widens in every direc-
tion at its extremities ; and on the dorsal or posterior aspect of
the spine, the canal remains open for some extent in the intervals
of the vertebrae, the myelon being there protected only by mem-
brane and the elastic ligaments which connect the neural spines
together. This modification subserves the prevention of compres-
sion of the myelon during the frequent, varied, and extensive
inflections of the neck in birds.

The atlas and axis speedily effect a partial coalescence; the
body of the first, e.g., as an ^odontoid process' to that of the
second, and usually presenting a pair of small facets to articulate
with its own neurapophyses, which are mainly supported by the
' hypapophysis ' simulating the entire centrum of the atlas. The
back part of the hypapophysis offers a flat surface to the centrum
of the axis, beneath which it is slightly produced, being here
wedged into a notch between the true bodies of the atlas and
axis. The fore part of the hypapophysis combines ^viih the neura-
pophyses to form the major part of the cup for the condyle of the
occiput, which is completed by the * odontoid.' The atlantal
neurapophyses usually diverge as they rise, and are joined toge-
ther above by a broad plate slightly arching across from one to
the other ; in some {Ajjtenodytes, Dhwrnis) they do not meet :
rarely is a neural spine developed. The centrum of the axis is
sometimes carinate below mth a slight posterior production (Alca
impennis), sometimes produced into a hypapophysis, as long as
the neural spine above {Aptenodi/tes, most Baptores.) Postzyga-
pophyses of the atlas articulate with the prezygapophyses of the
axis. In a Hornbill (Buceros) I have seen complete coalescence
of the atlas and axis.

§ 128. The Skull. — The neural and haemal plates of the embryo-
nic trace become modified in the head of the chick by the early ex-
pansion of the cerebral part of the neural axis, and by the almost
contemporary appearance of the capsules of the organ of hearing,
which are speedily followed by the rudiments of the eyeballs.
The neural plates are dilated by the primitive vesicles of the
ep- mes- and pros-encephalon, the latter speedily showing its

42 ANATOMY OF VERTEBRATES.

greater size and bending down. The notocliord extends into the
hind part of the future basis cranii, its gelatinous axis terminating
at the bend ; but the blastemal capsule — the true seat of the
histoloo^ical chano^es resultina- in vertebral structure — is continued
forward, expanding, di^dding below the part of the vertical cere-
bral canal called ' infundibulum,' and again uniting anteriorly to
form a vertical plate extending between the eye-capsules and be-
coming lost in the deflected fore part of the cephalic blastema. At
this stage neural segments are not shown. The haemal ones appear
as the so-called ' visceral arches ' of the head. The foremost is in-
complete below at the M^lastemic' stage, and is represented by a
pair of obtuse lobes or buds beneath the eyes ; the next is larger
and becomes closed below : a third, a fourth, and a feeble indi-
cation of a fifth, correspond mth the primitive vascular arches,
and are more truly ' visceral ' than ' vertebral.' Of the latter
sio:nificance is that which descends on each side the heart itself,
and is soon indicated by the buds of the appendages which become
articulated with such * scapular' arch.

The cartilage formed round the fore part of the notocliord,
extends neurad, and attains great thickness at the sides of the
cranium in connection with that of the acoustic capsules ; it
becomes thinner as it rises, and the primitive tissue closes the ex-
panded cranial cavity. The cartilage behind the ear-capsule is of
the liindmost neurapophysis : that in front of the capsule is of the
next ; that which is formed at the optic foramen is the third in
advance : these latter neurapophysial cartilages are formed in the
blastemal walls of the cranium distinct from the notochordal car-
tilage. This, advancing along the base of the skull, follows the
disposition of the extensions of the notochordal capsule, and
bifurcates into the so-called 'trabecul^e' (vol. i. figs. 58-60, 5, 5),
which again unite to form the basis of the neural arch and apex
of the haemal arch of the foremost segment of the skull ; it becomes
compressed betAveen the eyes, and expands in advance of them,
the end of the ha3mal closing up to that of the neural arch in a
Avay which reminds one of the modification of the vertebral axis at
the opposite end of the column. Here, however, the nature of
the Bird overrides that of the Vertebrate, and every subsequent
step in cranial developement relates to adaptive conditions of ver-
tebral elements and appendages. Distinct cartilages in the buds
or piers of the foremost haemal arch form the basis of the palato-
maxillary bones. The palatine cartilage arches outward and
backward, like that marked 24 in fig. 60, voL i., and in it is
developed the pterygoid. The cartilage in the second arch forms

OSSEOUS SYSTEM OF AVES.

43

the basis of the tympanic and mandible ; that of the third arch
forms the stylo-hyal, rarely ossified in birds, and in connection
Avith it is developed the ^ stapes.' The product of the fourth is
homoloo-ous with a branchial arch in the fish: but further evi-
dence of such conformity with the segmental structure of the
trunk-skeleton as is discernible in the much modified anterior
termination of the body is given by the ossific centres established
in the primordial cartilages ; and by the special homologies, de-
terminable prior to confluence, of the bones developed therefrom,
with the skull-bones of the lower cold-blooded Vertebrates, which
retain their distinctness and depart less from the archetypal
arrangement.

Although, as a general rule in the class Aves, the separate
cranial bones can be discerned only at an early period, yet in
those birds in which the power of flight is abrogated, the indica-
tions of the primitive centres of ossification endure longer ; and
in the species here selected for the illustration of the cranial

26

Side view of disarticulated cranial vertebra and sense-capsules. Ostrich.

segments, the constituent bones of the skull, with the exception
of the basioccipital, i, the basi-pre-sphenoid, 5, 9, and the bones
2, 6, and 8, which coalesce with the petrosal, 16, have been sepa-
rated by maceration merely in the half-grown bird.

The basioccipital, figs. 26, and 27, i, developes the major part
of the single articular condyle, and sends down a process, more
marked in the Struthious genera, and especially in Aptornis, than
in most other birds : in all respects this primitively distinct bone
retains the character of the centrum of its vertebra.

44

ANATOMY OF VERTEBKATES.

97

The exoccipitals, figs. 26 and 27, 2, contributing somewhat
more to the occipital condyle than in the Crocodile, develope, as
in that reptile, the paroccipital, figs. 27 and 28, 4, as an out-
standing exogenous ridge or process : but it is lower in position
than in the Crocodile (vol. i. p. 135, fig. 93). The superoccipital,

figs. 26,27, 28, 3, as compared with
that of the Crocodile, ib., mani-
fests more strongly the flattening
and developement in breadth, by
which the spinous elements lose
the formal character from which
their name originated, and are
converted from long into flat
bones. It always protects the
cerebellum ; is absent in the Frog,
where this organ is a mere rudi-
ment ; and is present in the Cro-
codile in the ratio of the superior
size of the cerebellum. The fur-
ther developement of the cere-
bellum is the condition of the
superior breadth of the spine or
crown of the epencephalic arch,
fig. 26, N I, in the Bird.

Of the three bones above de-
fined, 2 is developed in the back
part of the cartilage inclosing the
ear-capsule, and all bear the same
relation thereto, in the primordial

cranium.

as Nos. 1, 2, 3, 4j

m

(P

Base of skull, Ostrich. Clieloiiia (p. 131, fig. 92), aud

as Nos. 1, 2, 3, in the Crocodile
135, fig. 93). No. 2, in the Bird, as in the Crocodile, in-
cludes, connately developed therewith, the bone 4, in the Emys.
A basal view of the epencephalic arch is given in the young
Ostrich, fig. 27, showing the proportions in which the centrum,
\x, the neurapophyses 2, 2, and the neural spine, 3, enter into the
formation of the neural canal or ^foramen magnum,' 1. The
connate element, 4, stands out, like 4 in figs. 81 and 92, as the
transverse process of the neural arch.

The second segment of the skull has for its central element
a bone, figs. 26, 27, 5 (basisphenoid), ossified, like some trunk-

OSSEOUS SYSTEM OF AVES.

4S

centrums, from three points,* and in the Bird, as in other Ovipara,
becoming confluent with that, 9, which stands in the same relation
to the third cranial segment ; the pit for the pituitary body marks
the boundary ; but the essential distinction of these centrums is
given by the neural and hfemal arches. The neural arch of the
parietal vertebra retains the same characters which it first mani-
fested in Fishes. Besides the neurapophyses, 6 (alisphenoids),
impressed by the mesencephalic ganglia and transmitting the chief
part of the trigeminal nerves, besides the vastly expanded and
again, as in Fishes, divided neural spine, 7 (parietal bones), the
parapophysis, 8 (mastoid) is originally distinct. It has a similar
proportional size to that in the Crocodile (vol. i. figs. 93, 95, g) ;
but OAving to the raised dome of the neural arch, is relatively
lower in position ; it extends apophysially downward and outAvarcl,
is ossified with the petrosal, and forms a large proportion of the
outer wall of the otocrane. Owing to the breadth and shortness
of the bird's brain, and the displacement of the optic lobes, the
neurapophyses of the mesencephalon, 6, converge toward each
other anteriorly, and support part of the neural spine of the
prosencephalon, ii, as well as their own, 7. On comparing a side

Skull of young Ostrich.

view of the cranium of the Bird, fig. 28, with that of the Tortoise
(vol. i. fig. 91), and Crocodile (fig. 95), the greater developement
of the epencephalon brings its neural arch, 2, 3, into view, which is
obscured by the growth of the apophysial part of 8, in the cold-
blooded Ovipara : but the connections of 8 with 2 behind, with 7
above, and with the ear-capsule within, are the same ; the latter,
however, being ossified in the Bird, but retaining its gristly state
in the Tortoise.

' cccxxx. and xxiii.

46 ANATOMY OF VERTEBRATES.

The ha3mal arcli of the parietal vertebra, fig. 26, 40, 43, is
more reduced than in the Crocodile, and owes much of its appa-
rently typical character to the retention of the thyrohyals, 46, 47,
borrowed from a branchial arch of the visceral system, which
arches are transitorily manifested in the embryo bird. These
spurious cornua project freely or are freely suspended.

The bones, lo (orbitosphenoids), of the third neural arch coa-
lesce with each other, and with the centrum below, protect a
smaller proportion of the prosencephalon than in the Crocodile,
but maintain their neurapophysial relation to it and to the
optic nerves, below the exit of which they begin to ossify. The
neural spines, ii (frontal), cover a larger proportion of the
hemispheres, and, with their homotypes, 7, exhibit a marked
increase of developement in conformity with that of the cerebral
centres protected by their respective arches. The parapophysis
of the frontal vertebra, 12 (postfrontal), is relatively smaller
in the Bird than in the cold-blooded Vertebrates, and is rarely
ossified from an independent centre, as it is in the Emeu. The
hagmal arch of the frontal vertebra, receding from its typical posi-
tion as the HcBmatocrya advanced in time and in developement, is
now wholly transferred to the parietal one ; its pleurapophysis (28,
the ' tympanic '), which is simple, as in the Crocodile, articulates
with the parietal parapophysis, 8 (mastoid), though this in some
Birds unites with that of the frontal vertebra, 12. The bone, 28,
is the chief and most direct osseous developement from the proxi-
mal portion of the cartilage of the tympano-mandibular visceral
arch : the special appendages of the acoustic organ are developed,
as in the Lizards and Snakes (vol. i. fig. 444, b, e), in connection
Avith, but not in or from that cartilage. In the young Ostrich
and many other birds traces of the composite character of the
ha^mapophysis (mandibula) are long extant; and bear obviously
a homological relation to the teleologically compound character
of the same element in the Crocodile : the pieces, Nos. 29, 29', so'
and 31, first coalesce with each other, and then with the haemal
spine (32, ' dentary element '), the halves of which are confluent
at the symphysis.

The centrum, (1.3, ' vomer') of the nasal vertebra is single, and
usually coalesces Avith the neurapophyses (prefrontals), 14, and
pleurapophyses (palatines), 20, of its OAvn segment, and with the
rostral production of the frontal centrum, 9 : it is elongated and
pointed at its free termination, and deeply grooved above where it
receives the above-named rostrum ; indicating both by its form
and position that it owes its existence, as bone, to the ossification

OSSEOUS SYSTEM OF AVES. 47

of the under and outer part of the anterior production of the
notochordal capsule. In the young Ostrich the presphenoidal
rostrum intervenes between the vomer^ is, and prefrontals, 14.
These latter bones manifest the essential neurapophysial rela-
tions to the rhinencephalon and olfactory nerves : but they early
coalesce together and with the rhinal capsules, as in the tail-
less Batrachians. The anterior contraction of the cranial cavity,
which affects the orbito-sphenoids, influences still more the pre-
frontals, and, in connection with the large relative size of the eye-
capsules, becomes the condition of the extreme modification of the
neurapophyses of the foremost cranial vertebra. The neural spine
(nasals), 15, is divided along the middle line; but in most Birds
the suture becomes obliterated and the spine coalesces with its
neurapophyses, with the frontal spine, and with those parts of the
hasmal arch of the nasal vertebra with which it comes in contact.

The pleurapophyses (palatines), 20, of this inverted arch retain
their typical connections with the nasal centrum and neurapophy-
ses at one end, and with the haimapophysis (maxillary), 21, at the
other end, and they also support the constant element of the di-
verging appendage of the arch (pterygoid), 24. The ha3mapophy-
sis (maxillary), 21, resumes in birds more of its normal proportions
and elongated slender form, as such : but the haemal spine (premaxil-
lary), 22, is largely developed though undivided, and sends upward
and backward from the part corresponding to the symphysis of
the spine, a long pointed process, 22', which joins and usually
coalesces with the neural spine, 15, and divides the anterior outlet
of the haimal canal into two apertures called the nostrils. The
modification of the haemal arch of the nasal vertebra in the Lizard
tribe is here repeated. The pleurapophysial appendage (pterygoid),
24, connects the palato-maxillary arch with the tympanic, and in
the Ostrich and some other birds, also with the basisphenoid, 5,
and fig. 27,/: the second or ha3mapophysial ray of the diverging
appendage (malar and squamosal) is developed in all Birds, as in
the squamate Saurians, combining the movements of the haiinal
arch of the nasal vertebra with that of the frontal vertebra, and
consisting of the two styliform ossicles (malar, 20, and squamosal,
27), which extend from the ha^mapophysis, fig. 28, 21, 21'', to the
pleurapophysis, 28 : the essential relationship of the compound
ray, 26 and 2:, with the nasal vertebra, is indicated by their
becoming confluent with its hiismapophysis, at 21'', whilst they
maintain an arthrodial articulation ^vith the pleurapophysis, 2s, of
the succeedinoj vertebra.

The bones of the splauchno-skeleton intercalated with ihc

48 ANATOMY OF VERTEBRATES.

segments of the endoskeleton in the bird's skull are the petrosal,
16, between the neural arches of the occipital and parietal verte-
brae, connate or co-ossifying with the elements of those vertebrae
with which it comes in contact ; the sclerotals, 1 7, interposed be-
tween the frontal and nasal neural arches ; and the thyrohyals,
47, retained in connection with the debris of the haemal arch of the
parietal vertebra. The olfactory capsule may be represented by
ethmoturbinal and turbinal processes in the skull ; but chiefly
remains cartilaginous. The dermal bone (lacrymal), 73, is Avell
developed and constant : one or more superorbital dermal bones
are occasionally present.

As the characters of the occipital segment of the bird's cranium
are so obviously those of the vertebral neural arch as to compel
acceptance of the interpretation of its elements according to the
terms of general homology, there is a priori probability in the
segmental type being continued to the front end, as it is to the
hind end, of the vertebral axis, notwithstanding the modifying
influences of the large intercalated sense-capsules, and of the
special uses to which certain of the lower bony arches are des-
tined in the head. Developement, obedient to these demands,
gives such evidence as it can in favour of the presumption, while
relative position and connections afford the proof. In the fore-
going description I have, therefore, explained the chief constitu-
tion of the bird's skull in the terms of general homology, and I
proceed to point out some of its principal modifications in those of
special homology.

The occipital condyle is single in Birds, varying from the
hemispheroid to the transversely elliptic form, with sometimes a
median notch or pit, and in the extent to which it projects; being
pedunculate in Dinornis,^ but sessile as a rule. The foramen
mao-num varies from a subcircular to a full transverse ellipse,
and to a vertically oval {Di?ior?iis giganteus) form, ^\i\\\ lateral
encroachments as in Aptomis"^ and Didus;^ its plane may be
vertical (ib.), but as a rule is oblique from above downward and
forAvard, thus departing further from the reptilian character.
The basioccipital in the extinct Aptornis sends down, as in the
Crocodile, a deep plate below the condyle : it descends in a less
degree in Dinornis, in both swelling out laterally into a pair of
tuberosities, completed by ossifications in the basisphenoid carti-
lage which afterwards coalesce.'' As a rule the condyle is on a
level with the basis cranii. The paroccipitals in the low flat cra-

• XVI-. vol. iv. pi. 24, fig 2. ^ lb. vol. iii. p. ?50.

2 lb. vol. iii. pi. .52, fig. 4. ^ lb. fig. 1, 5'.

OSSEOUS SYSTEM OF AYES. 49

nium of Dinornis retain much of their crocodilian position, but
they hold a lower one in the loftier domed crania of other birds :
they vary in the developement of their apophysial part, standing
further out, e.g., in Rhea and Struthio, than in Dromaius. The
occipital region is bounded above by the arched ridge formed by
the insertion of the muscles longus colli posticus and complexus,
in large and powerful birds ; and is bisected, as, e. g., in the Eagle,
by a median-vertical ridge dividing the transverse one into a pair
of arches : in Dinornis a prominence between the insertions of
the longus colli jjosticus and complexus subdivides the transverse
ridge into four arches; and, here, a lower transverse ridge,
bounding the insertions of the ?^ecti cap. postici and traclielo-
mastoidei, overarches the foramen magnum. ^ In smaller and less
robust birds a cerebellar prominence marks the middle of the
occipital region : in some species the pressure of the brain from
within, and the muscles from without, reduces the thin, bony
wall in some places to its membranous lining, leaving openings in
the dry skull commonly on each side of the cerebellar prominence.
These have been termed ' fontanelles,' as if they were due to
original arrest of cranial ossification, but the latter explanation
applies to openings, usually reduced to a venous outlet, between
the exoccipital and mastoid. In certain Doves, Owls, Parrots,
and the Dodo, there is a median ^ superoccipital ' foramen, usually
accompanied by a pair of venous foramina.

The basisphenoid chieily differs in the presence or absence of
^ pterapophyses.' ^ They are longest in the StruthionidcB, fig. 27,j,^
are short and thick in Dinornis and Apteryx, and abut against the
tympanic end of the pterygoids ; they are shorter in Grallatores
( Vanellus) and Rasores ( Columha, Tinamus, Syrrhaptes), and
their abutment is nearer the middle of the pterygoids ; they are
absent, or are too short to reach the pterygoids, in the Dodo,
Owls, Diurnal Kaptores, and most other Birds. In the Emeu,
Apteryx, and Dinornis, the basisphenoid shows a median perfora-
tion. The sides of the basisphenoid, obliquely grooved by the
Eustachian canals {Dinornis) and excavated to form the base of
the tympanic cavity, in some birds extend outward to the tym-
panic process of the mastoid, and with it grasp the hinder condyle
of the tympanic.

The mesencephalic fossa and the ' foramen ovale ' for the transit
of the fifth or trigeminal nerve indicate the alisphenoid, fig. 28, 6,

* xvr. vol. iii. pi. 52, fig. 4.

"^ First indicated as such in xvi*. vol. iii. p. 351 (January, 1848); see also xliv. p.

303, no. 1601. » xliv. p. 259.
VOL. II. E

50 ANATOMY OF VERTEBEATES.

and its general homology as a ' neurapophysis ; ' its extent and
connections are shown in fig. 8, p. 22, of CXL, and in the speci-
men, No. 1363, of XLIV ; it articulates below mth the basi-
sphenoid, behind with the mastoid, 8, and petrosal, above wath the
parietal, 7, and frontal, n, in front with the orbitosphenoid, lo,
combining with it to form the foramen lacerum anterius, through
which orbital portions of the fifth nerve pass ; and which usually
blends with the common foramina optica, encompassed in great
part by the orbitosphenoid.

The homology of 8, figs. 25, 28, 31, Avith the bone so numbered,
and called ' mastoid' in voL i. figs. 75, 81, 91, 92, 93, 95, and 97,
is plain ; it forms part of the cavity for the otic capsule, as in
Fishes, and part of the tympanic cavity, as in the air-breathing
Hsematocrya. As in Reptiles, it offers the articular cavity to 28,
a relation partially fulfilled in Fishes ; it sends oiF the second,
counting fonvard, of the great outstanding processes for the in-
sertion of muscles from the trunk and neck ; it is developed in
and from the thick lateral cartilaginous mass of the primordial
cranium, connately mth the otic capsule (petrosal). Besides the
^mastoid process,' figs. 27, 29,8, a second so-called 'tympanic
process' is developed in some Birds. ^ The articular canity for
the bone, 28, is single in Apteryx, Dinornis, Struthio, and a few
other birds, but double in most ; in Aptornis there are three
articular surfaces.^ The mastoid process varies in shape and size ;
in a few birds, as in Calyptorhynchus and Aptornis, it repeats
the secondary character more commonly seen in Reptiles by unit-
ing with the third cranial diapophysis, 12, and forming an upper
zygomatic arch across the temporal fossa.^ The optic foramina
indicate the orbitosphenoids, wdiich, like neurapophyses of the
trunk, in certain instances, coalesce below and di\ide their seg-
ment of the neural axis from the vertebral centrum. In Birds
they are uplifted, as in the Perch (vol. i. fig. 85, 10), far above
the representative, 9, of their centrum. The divergence of the
neural laminaj above the median confluence, to support the pros-
encephalon, is Avell shown in CXL. fig. 8, and in the specunen.
No. 1363, XLiv., p. 262. In the antecedent neurapophyses, 14,
the tendency to median confluence increases, and they become
confluent not only below, but above their segment, encompassing
the canal, foramen, or foramina, for the olfactory nerves (rhi-

* Bustard, xviir. vol. iii. p. 352, pi. 52, fig. 9, 8'. ^ lb. p. 352.

3 lb. p. 352, pi. 52, fig. 1, 8, 12; CXL'. pi. 1, fig. 1, 8, 12. In the memoir above
cited this skull is described as belonging probably to X>. Casuarinus, ib. p. 376;
it is, however, of D. didiformisy since generically separated as Aptornis.

OSSEOUS SYSTEM OF AVES.

51

29

iienceplialic prolongations of the neural axis), and in some birds
expanding above, and appearing, as in Batrachia, on the exterior
of the cranium, as between ii and 15, in fig. 29, and at 14, fig. 31.
The confluent prefrontals, fig. 28, u, support the fore part of the
frontals, 11, and a greater proportion of the nasals, 15; they are
in most birds raised far above the (hypa-
pophysial) ossification of the lower cor-
tical part of their centrum, called the
' vomer,' fig. 32, 13, the large eyeballs,
and their thin but deep interorbital sep-
tum, being interposed ; this septum is
ossified in different degrees in different
birds. The typical position of the pre-
frontals is retained in Aj)teryx and Di-
nornis. The condition of the prefrontals
in some fishes (^Xiphias)^ will aid the
comprehension of the developement of
the prefrontals between the orbits in
these ivingless birds. The frontals are
large, triangular (fig. 29, 11), or sub-
rhomboid, plates. The post-frontal ap-
pears as a distinct bone in some birds
(Emeu)^ fig. 31, 12; it varies much in
length ; it bends down, and is the longest
of the three cranial diapophyses in the
Eagles ; it curves forward, meets, and
coalesces, w^ith a backward production of
the lacrymal in some Parrots, fig. 30, 0 g.

The nasal bones rarely unite Avith each other in any proportion,
fig. 29, 15 ; in most birds they are separated by the union of the
nasal process of the premaxillary, 22',
with the frontal or prefrontal : save in
the Emeu, fig. 31, 15,^ and some other
Struthionidce, the nasal bifurcates ante-
riorly to form the hind boundary of the
nostril, and the hinder prong descends
to join the maxillary, dividing the
nostril from the antorbital vacuity.

The premaxillary, figs. 28 32, 22,
upon which the upper mandible is moulded, follows, in a minor
degree, aU the varieties of that much diversified part in Birds : it

Skull of young Ostrich.

Skull of Parrot.

' CXL-. p. 52, pi. 1, fig. 5. U. 2 XV1IT-. vol. iii. pi. 39, figs. 1 and L>, li\

=* xviir. vol. iii. pi. 39, 14.

E 2

52

ANATOMY OF VERTEBRATES.

is a single bone, expands from before backAvard, and divides into
a superior and medial nasal process, ib. 22', and a pair of infero-
lateral maxillary processes, ib. 22 ; the interval between the nasal
and maxillary processes being the fore part of the outer bony
nostril. The nasal process indicates by a median slit or groove the
typical duality of the bone in the Gallince and a few other birds :
the maxillary process usually sends oif a ' palatal ' plate, fig. 32, 22.

Skull of Emeu (Bromahis).

The maxillary, figs. 27-32, 21, is a small and usually slender
bone, anteriorly expanded and engrained into the notch be-
tween the maxillary and palatal processes of the premaxillary :
usually imiting also with the nasal, and in some birds with the
lacrymal, 73, and vomer, 13 ; it then bifurcates posteriorly on the
horizontal plane to join the malar, 26, and the palatine, 20. The
palatine process sometimes developes from its upper surface a
turbinal structure. In the Rhea the palatine plate of the maxil-
lary is perforated : in the Emeu, Ostrich, Apteryx, and in most
birds, it is entire : it is of great breadth in the Night-jars ( Capri-
mulgus, Podargus), and is both long and broad in the Ajpteryx,
In Striithio and Rhea the maxillary sends upward a process to-
wards the nasal, the descending maxillary process of which is
wanting.

The palatines, fig. 32, 20, articulate by a longitudinally grooved
mesial surface to the vomer, 13 {Emeit), more commonly to both
this bone and the presphenoid, or to the latter only : they give at-
tachment posteriorly to the pterygoids, 24 : they diverge as they
extend forward, developing a ' meatal ' plate mesially, which par-
tially bounds the posterior nostril, and a "^ muscular ' plate externally
for the attachment of the entopterygoideus ; they then extend for-
Avard, parallel or converging, to join the maxillaries, and some-
times also the vomer, and there complete the roof of the mouth.
In the StruthionidcB the ' palatal ' part is short aud broad ; arti-

OSSEOUS SYSTEM OF AVES. 53

culates laterally with the maxillary, and, as it retrogrades, ex-
pands, mesiad, to abut upon the presphenoid {Struthio) or hind
part of the vomer (^Dromaius, fig. 32, is), and to articulate with
the pterygoids : the palatines nowhere meet in the median line,
and the meatal process is wanting. In the Apteri/x the palatines
coalesce anteriorly with the maxillaries, posteriorly with the pte-
rygoids, have a straight outer and a concave inner border, from
wliich, posteriorly, is continued the ^ meatal ' plate curving inward

Skull of Emeu iDroviaiiis).

and forward, obliquely, about the hind part of the meatus, and
applying itself mesiad to the vomer and presphenoid. In Nata-
tores, and most Grallatores, the palatines meet each other poste-
riorly, for a short extent, before diverging as they advance to
bound posteriorly the palatine nostril. In the PelecanidcE the
mesial union is extensive beneath the 2:)resphenoid and vomer.
In Tinamus the palatines join behind; they there touch each
other for a shorter extent in ColumhidcB ; but in most Gallinacea
they are kept apart by the presphenoid. In Podargus and some
other Fissirostrals the palatines are short and broad, and exten-
sively joined together behind the small palatal nostril. In Rap^-
tores the palatines meet behind beneath the presphenoid and
vomer : the meatal plate developes a ridge, descending, to increase
the concavity of the entopterygoideal surface, the outer border of
which also descends ; and these carinal boundaries of that surface
are found in many birds. The extent of the palatine plate varies
in diiFerent birds ; it is largest in StruthionidcB, large in Raptores,
and least in the Gallin(E : in the Tinamous and Pigeons it is of
moderate size. In the Emeu it has a large vacuity ; ^ it is per-
forate in Tinamus, and in some Grallatores.

The pterygoids, figs. 27, 32, 24, articulate with the outer
and hinder angles of the palatines by a squamous overlapping

' XTi-. vol. iii. pi. 39, fig. 2, 20.

54 ANATOMY 01- VERTEBRATES,

suture in Struthio, where they are wide apart, and j^ass ahnost
parallel backward to join the pterapophyses of the basisphenoid
and the tympanies ; developing a broad plate mesially to abut
upon the presphenoid : their palatine ends are nearer each other,
and their course to the tympanies more divergent, in the Emeu,
Apteryx, Hemipode : they touch each other anteriorly in some
birds ; and, in a few {Podicejjs, Sula, Ibis, Argala, Scolopax),
have a short extent of mutual junction before diverging. In
Rliea the fore part of the pterygoid is slender, is attached to the
vomer and presphenoid, traverses obliquely the upper surface of
the palatine plate, with which it ultimately coalesces, and becomes
engrained between the pterapophysis and orbital process of the
tympanic before abutting upon the inner and lower condyle of
that bone. In general the pterygoids are straight and slender;
they diverge at an open angle in Rajytores, at an acute angle in
Colymhiis, are nearly parallel and longitudinal in Struthio, with
intermediate relative positions in other birds. In Raptores their
connections are limited to the essential terminal ones with the
palatines and tympanies : in some other birds they articulate,
occasionally by a distinct process, with pterapophysial extensions
of the basisphenoid, limiting the movement of the tympanic, and
adding strength and fixity to the upper mandible : in most birds
there is a prominence or process from the hinder border for liga-
mentous attachment to the basisphenoid. In Rhea there is an
articular process for the orbital plate of the tympanic. The
tympanic joint is double in Pheasants and Plovers.

The bone, figs. 28-32, 26, answering to that so numbered in
figs. 91, 92, 93, 95, vol. i., is a straight, slender, usually triedral,
style in birds, articulating with 20 by one end and mth 27 by the
other, and in some birds being joined by a descending process
from the lacrymal. It combines all the essential homological
characters of the ' malar,' those, viz., derived from relative position
and connections ; and exemplifies the unimportance of configura-
tion : showing the opposite extreme to the scale-like shape of the
bone in the Turtle, fig. 91, 26, vol. i. The malar of the Crocodile,
fig. 95, 26, offers an intermediate modification of form. The
malar in the bird overlaps the maxillary by an oblique suture, as
in the Keptiles.

The zygomatic connection between the maxillary and tympanic
is completed by the bone, figs. 28-32, 27, which has the same
slender figure as 26, with Avhich it early coalesces ; but preserves
a moveable articulation with 28 by a convex condyle adapted to
the acetabulum on the outer side of the tympanic. The two

OSSEOUS SYSTEM OF AVES. 55

bones, 26 and 27, which become blended together in young
Struthionidce before the confluence with the maxillary is complete,
extend backward in all adult birds, usually in a straight line,
from the maxillary to the tympanic. In the Cassowary the zygo-
matic arch presents a slight expanse and outward bend of the
squamosal ; in Didus it shows a slight downward as well as
outward bend. In some Parrots and in Hornbills (^Buceros),
the malo-squamosal zygomatic style, fig. 30, Z, has a moveable
cotyloid joint at both ends ; in some Caprimidgi it is anchylosed
at both ends.

In the birds in which the upper mandible is moveable, either,
as in Parrots, by articulation, or as in many other birds by
flexibility of the nasal process of the premaxillary, the movements
of the tympanic, to and fro, upon its proximal joint, are transferred
by the zygoma to the maxillary, and by the pterygoid to the
palatine : and thus by the forward rotation of the tympanic the
upper jaw is raised, at the same time that the lower jaw by the
action of the digastricus may be depressed.

Before anatomy had reached its homological phase, ornitho-
tomists called the zygomatic styles ^ ossa communicantia,' and the
pterygoids ^ ossa homoidea, seu interarticularia ; ' the folloAving
bone was termed ^ os quadratum.'

In the tympanic, figs. 28, 31, 28, are to be noticed the ^ mastoid '
and ^ mandibular ' ends, and the intermediate body giving attach-
ment at its back part to the ear-drum, and sending from its fore
part the ' orbital ' process. The mastoid articular end is obliquely
extended from behind forward and outward: the body slightly
contracts below ; then expands and becomes triedral at the set-
ting off of the broad compressed angular orbital process : below
this process the mandibular end is much expanded, chiefly trans-
versely : it presents two articular surfaces ; the outer one, elon-
gate or reniform, partly concave, partly convex ; the inner one
a shorter elliptic or oblong convexity ; the intermediate non-
articular tract varies in diflerent birds. On the outer side of the
mandibular end is a hemispheric articular cavity for the ^squa-
mosal.' In most birds the mastoid condyle is divided into two,
the inner and posterior encroaching upon the paroccipital, and
shomng, in an interesting way, the course of retrogression of the
tympano-mandibular arch from the fish to the Avarmblooded ovipara.
Most Cur sores and Rasores, Apteryx^^ Pezus, Rhynchotis, have
but one condyle, as in Lizards. The ear-drum is attached to the
back part of the pedicle obliquely from its outer margin above to
' XVI-. torn. iii. pi. 39, figs. 8, 9, and xxiv,

5Q ANATOMY OE VERTEBRATES.

the inner one below, whence the membrane is continued to the
basisphenoid, paroccipital, and round by the mastoid to the tym-
panic again. A part of the periphery of the drum may show an
epiphysial bony rim. In some birds there is a well-defined flat
oval surface on the outer side of the pedicle for a corresponding
surface on the mastoid process : ' most show a distinct articular
surface^ on the inner side of the lower part of the base of the
orbital plate for the pterygoid : thus, including the squamosal pit
and two mandibular condyles, there may be not fewer than seven
articular surfaces in the tympanic bone of the Bird. Its orbital
process is a greater developement of the anterior lamina of the
Crocodile's tympanic, fig. 93, 28, vol. i. ; the size of the process
is one of the chief characteristics of the tympanic in the Bird, and
shows much variety of shape and proportion in the class.^ Its
apex may be truncate {Dichis),'^ or rounded (^Dinorids), or pointed
(Aquila). A large pneumatic foramen may be situated on the
inner side of the pedicle; or on the hinder facet below and be-
tween the upper condyles, or in both situations.

The mandible or lower jawbone is ossified usually from nine
centres ; the anterior being the first to appear, forming the
chief and characteristic part, fig. 25, H. iii, of the bone. It
bifurcates as it extends backward to form the homologues of the
dentary elements, fig. 31,32, which are thus ' connate ' at their
symphysis. The Pelicans are an exception, and exemplify the
normal separate ossification of each dentary, becoming subse-
quently confluent for a small extent anteriorly.^ The ^suran-
gular,' ib. 29^ speedily unites, if it be not connate, with the
* articular,' 29 : the angular, so, remains longer distinct, but co-
alesces first with the articular : the splenial element, 3i, coalesces
first mth the dentary, and retains longest its primitive indepen-
dence posteriorly.

In the Garefowl (^Alca impennis), each dentary retains its bi-
furcate hind end distinct, the upper prong overlapping the sur-
angular, the lower one the angular ; and these two latter elements
are divided by an oblong space partly closed within by the sple-
nial : there is also a foramen at the back part of the surangular.
The splenial retains its distinctness posteriorly, and a groove on
the lower margin of the ramus indicates the extent of its for-
ward production to its confluence with the dentary. A vacuity
between the angular and surangular remains in many birds,

' xvr. vol. iii. p. 3.56, pi. 53, fig. 9,/. ^ lb. fig. 10, g.

^ Compare ib. pi. 39, figs. 7, 8, 9, a, and pi. 53, figs. 8, 9, k.
* Ib. vol. iii. p. 35. ^ xxiii*.

OSSEOUS SYSTEM OF AVES. 57

e.g. Cracticus, Aiithochcera, Lanius, amongst Cantores, but chiefly
in the aquatic, wading, and terrestrial orders ( Tetrao, Dinor-
nis, Didus, Notornis,^ Porphyrio, Tantalus, Rhyncops, JJria^.
The Coots show a second elliptical vacuity at the base of the
coronoid rise of the surangular.^ In Rhyncops, the long com-
pressed symphysial part of the mandible descends below the
level of the angular, the lower border of the mandible having a
deep notch there. The symphysial part partakes in a minor
degree of all the various modifications of the lower mandible.
The angular is chiefly extended transversely, and to the inner
side of the ramal axis, to form the surfaces adapted to the tympa-
nic condyles, a deep and smooth depression usually dividing
them : the inner joint, in Parrots, is a longitudinal groove ; the
outer one is a longitudinal convexity. An angular process
extends from the inner or medial side of the articular expansion ;
there is also, in some birds, a similar process from its back part,
and this, in the Grouse tribe, especially the male Urogallus, is
much elongated and bent up. The temporal muscles are inserted
into an elongate rough tract, or slight elevation of the upper
border of the surangular : it is rarely raised into a ' coronoid '
process ; but this is conspicuous in the conirostral Cantores, and
especially in the Grosbeak and Crossbill. The latter bird shows
a want of symmetry in the mandibular rami ; and there is a large
sesamoid, wedged into the back and inner part of the joint of the
lower jaw.^

Through the arrested developement of tlie hyoid arch (cerato-
and stylo-hyals), the tongue of Birds is not suspended by attached
inverted piers, but is slung to the cranium, when its branches are
suflficiently long, by ^ thyro-hyals,' usually including the hypo-, figs.
26, 31, 46, and cerato-, ib. 47, branchial elements; they are long
and slender. The basihyal, figs. 26, 31, 33, 4i, hh, is subcylindrical
and expanded at the ends ; the front end usually presenting a
trochlear articular surface, convex transversely, concave vertically,
for the glossohyal, or for the ceratohyal, or for both elements.
The ceratohyal, ib. 4o, ch, is always short, usually extending for-
ward from its attachment as well as backward, and the forAvard
production often unites with its fellow, so as to form the basal
part of the direct support of the tongue. In this case the glosso-
hyal, ib. 42, articulates with the ceratohyals ; rarely also ^^Ai\\
the basi-hyal, hh, as in tlie Crane, fig. 33, c. The basihyal is of

* XV1-, vol. iii. pi. 53, fig. 1. ^ Ib. figs. 1 and 7, w.

3 VII-. p. 277.

53

ANATOJIY OF VERTEBRATES.

extreme length and tenuity in tlie Woodpeckers, ib. hh, D, and
supports at its fore end the barbed glossohyal, ib. gh. Sometimes
the urohyal, fig. 31, 43, is confluent with thebasihyal(^Zc« impennis,

Vanellus, Cohanha); more often
articulated therewith, or with
both basi- and thyro-hyals, fig. 33,
C,uh( Grus cinerea). The ' thyro-
hyals ' usually retain the two ele-
ments of the branchial arch above
cited, and shown in figs. 26 and
31, 46 and 47, fig. 33, hh, ch.

Only in a skull of the extinct
A'ptornis have I seen an ossified
' stylohyal : ' it was anchylosed as
a styloid process to the side of
the inferiorly produced basisphe-
noid.^

The bone, figs. 26, 28, 29, 31,
73, situated at the fore part of the
orbit and pierced or grooved by
the lacrymal duct, articulates,
when not anchylosed, to the
frontal, nasal, and prefrontal ; it
usually sends one process from
its upper part arching over the
upper and fore part of the orbit ;
and a second process, from its un-
der part, downward to abut upon
the maxillary, di^dding the orbital
from the antorbital vacuity.

Like the lacrymal in Fishes,
this bone in some birds is con-
nected with a suborbital frame
extending to the post-frontal
(^Macrocercus, Strigops), fig. 30,
o, g^ and even with the mastoid
( Calyptorhynchus, Plyctolophus,
Licmetes, Microglossus aterrimus^
Lathamus).

The superorbital part of the lacrymal is broad and flat, in Aquila,
and articulates mth a similar superorbital derm-bone : in Vultur

^-^

Hyf.id. C Gru», D Ficiis.

xvr. vol. iii. pi. 52, fig. 3, 38.

OSSEOUS SYSTEM OF AVES. 59

it is longer and more slender. In Casuarius the lacrymal coalesces
with the frontal, prefrontal, and nasal, but retains its freedom
in other StruthionidcB. The lacrymal is very large in Dacelo
and Ti'ochilus, fig. 18, Z.

The skull in the Raj^tores, especially in the nocturnal division,
is short, broad, and high, in proportion to its length, and the
cranium is large compared with the face. The occipital foramen
is almost horizontal. The superoccipital muscular depressions are
well defined. The temporal fossa3 are not very deep, and are
wide apart superiorly. The cerebral convexities are not strongly
marked; the frontal region is flat. A longitudinal furrow
extends along the whole upper surface of the cranium in some
Owls.

The cranium of the Warblers presents a more regular sphericity,
but the interorbital space is very concave. The anterior parietes
of the orbits are large, from the size of the lacrymal bone and
of the transverse lamina of the prefrontal ; the internal and pos-
terior orbital parietes are defective ; the optic foramina are com-
monly blended into one, and continuous vvith the larger fissures
above.

In the Parrots the upper surface of the cranium is flattened or
slightly convex, and greatly extended in breadth between the
orbits for the articulation of the naso-premaxillary bone, fio-.
30, n.

In the Toucans the cranium slightly increases in breadth to
the anterior part where it is joined to the enormous bill. Its
superior surface presents an equable convexity. The temporal
fossae, like those of the Parrots, are small, and wholly confined to
the lateral aspects of the cranium. The posterior surface, which
is absolutely concave in the Macaws, from the backward exten-
sion of the paroccipitals, is slightly convex in the Toucans, where
it is separated from the upper surface by a regularly arched ridge.
The cerebellar prominence extends over the occipital foramen, the
plane of which inclines forward and downward from the horizontal
line at an angle of 45°. The circumference of the orbit is un-
inclosed by bone at the posterior part, the postorbital processes
of the frontal not being developed as in most Parrots. The
septum of the orl^its is very incomplete. The nostrils open on the
posterior part of the upper mandible, which presents a smooth
entire surface formed by the thin parietes of the dilated cellular
osseous tissue.

In the Helmeted Hornbill (Buceros galeatus) the outer sur-
face of the skull is sculptured with irregular furrows and risings,^

60 ANATOMY OF VERTEERATES.

recalling the surface of the skull m the Crocodiles. The occiput
is concave, and separated by a strongly developed ridge from the
temporal fossie, which almost meet at the vertex. The bony
septum of the orbits is complete, and formed by two strong plates,
separated by an intermediate cellular diploe, except at the pos-
terior part. The optic foramina are distinct ; each is directed
transversely outwards.

In the Woodpeckers the cranium is rounded, the temporal
fossa3 shallow, the internal wall or septum of the orbits incom-
plete, but the anterior boundary is well developed. The posterior
facet of the cranium is raised. The superior surface is traversed
by a wide furroAv extending longitudinally forward, generally to
the right, but sometimes also to the left, as far as the lacrymal bone.
In some of the larger species of Woodpecker, as the Picus major,
L., the cranial furrow is more symmetrical. In the Humming-
birds it is double, the hyoidean furrows being separated at first
by the cerebellic protuberance, and afterwards by a mesial longi-
tudinal ridge.

The skull is remarkable for its length in the majority of the
Waders. In the Herons and Bitterns the occipital region is low,
and inclines from below upward and forward; it is separated
from the upper and lateral regions by a well-developed, sharp,
lambdoidal crest ; and it is divided into two lateral moieties by a
slight longitudinal ridge. The temporal fossae are deep and wide,
and extend upward to the sagittal line, along Avhich an osseous
crest is developed. The cranium is expanded anteriorly to the
above fossae, for the lodgment of the cerebral hemispheres, the
interspace of which is indicated by a deep longitudinal furrow.
The roof of the orbits is expanded laterally, which gives great
breadth to this part of the head, but the posterior orbital walls
are very imperfect, and the internal Avails or septum almost wholly
Avanting. The optic foramina are blended with each other and
with the smaller foramina, which in other birds represent the fora-
men lacerum orhitale.

Woodcocks, Snipes, Curlews, and LapAA^ngs resemble Herons
in their defective bony orbits ; but they AA-ant the extended
superior parietes of those cavities, and differ much in the almost
spherical form of the cranium, AAdiich is smooth and devoid of the
muscular ridges characteristic of the fish-feeding Grallce. In
this order the premaxillary bones present some of their most
eccentric forms. They are narroAv, elongated, and curA^ed doAAai-
Avard in the Ibises and CurlcAvs; bent upAvard in the contrary

OSSEOUS SYSTEM OF AVES. 61

direction in the Avosets ; extended in a straight line in the
Snij)es ; singularly widened and hollowed out in the Boatbills
( Cmicroma, Balceniceps) ; widened, flattened, and dilated at the
extremity in the Spoonbill ; thickened, rounded, and bent down-
wards at an obtuse angle in the Flamingo, fig. 14.

Among the Natatores, the Divers (^Coli/mbus), Grebes (^Podl-
ceps), and Cormorants ( Carbo) show a defective condition of the
bony orbits, and of the anterior parietes of the cranium; the
septum of the orbits is almost entirely wanting ; in place of the
posterior orbital parietes, there are two lacunae leading directly
into the cranial cavity, one superior, of large size, and one inferior,
smaller ; they are, in general, separated by a narrow osseous bar,
but in the Coulterneb {Fratercula arctica) this is also wanting,
so that all the orbital and optic nerves escape by a common open-
ing. In the Petrels and Albatrosses, the internal and posterior
walls of the orbits are more complete. In the Diomedea exulans
the optic foramina are separated both from each other and from
the neighbouring outlet. The occipital region is low, and divided
into a superior and an inferior facet, tlie latter being concave
from side to side. The plane of the occipital foramen is almost
vertical. The occipital or lambdoidal crista is well-marked, and
the temporal fossie nearly approximate in the middle line. In
these Sea-birds and in the Gulls, the lateral lacuna3 in the bony
parietes of the face are very considerable.

A most remarkable characteristic of the cranium of both the
Brachypterous and Macropterous Sea-birds is the presence of the
two deep, elongated, semilunar glandular depressions extending
along the roof of the orbits. In the aquatic birds which frequent
the marshes and fresh waters, as the Anatidce or Lamelllrostres,
these glandular pits are wanting, or very feebly marked, as in
the Swans. They are, however, again met mth of large size,
though shallow, in the Curlews (^Numenius) and Avosets {Recur-
virostra) ; and are also found, though of smaller size, in the
Flamin2:o.

The cranial cavity has but a limited range of size in the class
of Birds, although an extreme one in relation to the bulk of
the body : that of the smallest Humming-bird is proportionally
greater than in any other animal, while that of the great Dlnornis
is almost crocodilian in its contracted area : the size of the
cranium, small as it is in relation to the trunk and legs in the
giant bird, being expanded to the requisite extent for muscular
and other attachments by a thick pneiunatic cellular diploe be-

62 ANATOI^IY OE VERTEBRATES.

tween the outer and inner tables.^ The owls have a similar de-
velopement of diploe : in most birds the free cranial wall is thin
and compact. The cavity is closely moulded to the brain, and
shows well-marked fossae for the cerebellum, medulla oblongata,
optic lobes, hypophysis, cerebral hemispheres, and, in Dinornis
and Apteryx, for the olfactory lobes. Some birds show also a
depression upon the petrosal, which is deep in the Heron. In
Dinornis an upper transverse ridge divides the pros- from the
ep-encephalic compartment, and a lower one divides the pros-
from the mes-encephalic compartment, which ' tentorial ' ridges,
being on nearly the same vertical parallel, almost equally bisect
the cranial cavity into a wider front and narrower hind division.
The roof of the prosencephalic compartment sinks a little into the
interspace of the hemispheres, and is here usually grooved by
the longitudinal sinus : but in a few birds it developes a bony
' falciform ' ridge, which, in Buceros galeatus, e. g., bisects the
fore part of the prosencephalic compartment.

The principal foramina observed in the cranium are, in the
epencephalic fossa, one or more minute ' precondyloid,' the large
foramen for the ' vagus ' and internal jugular vein, the meatus
auditorius internus ; in the mesencephalic fossa the ' foramen
ovale ' for the third and second division of the ' fifth,' the ^ carotid,'
which opens into the deep ' sella,' the * foramina,' which trans-
mit nerves to the orbit, not always distinct from the wide foramen
opticum ; this also being blended with its felloAv in many birds ;
in the prosencephalic compartment, are the rhinencephalic fora-
mina, which, in Apteryx and Dinornis, from the backward exten-
sion and interorbital position of the enormous olfactory chambers,
become ' rhinencephalic fossas,' distributing thereto olfactory
nerves by a * cribriform ' plate.

The tympanic cavity is formed by the paroccipital, basi- and
ali-sphenoids, petrosal, mastoid, and tympanic. It presents the
stapedial canal leading to the '^ fenestra ovalis ; ' and pneiunatic
apertures by which the air from the Eustachian tube is conducted
to the pericranial diploe. The ^ petrosal ' as the osseous capsule
of the acoustic organ, and the ' stapes,' mth the cartilaginous
' incus ' and ^ malleus,' as appendages thereof, will be noticed in
connection mth the sense-organs.

The orbits are large and lateral, but encroach upon the anterior
wall of the cranium, the eyeballs moulding it into a pair of con-
cavities looking forward and usually a little downward and out-

' xvr. vol. iv. pi. 24, fig. 4.

OSSEOUS SYSTEM OF AVES. 63

ward, with extreme tliinning and sometimes partial loss of bone.
The roof of the orbit is formed by the frontal, prefrontal, and
lacrymal ; the hind wall by the frontal, ali- and orbito-sphenoids ;
there is no bony floor ; but the eyeball rotates on a sort of air-
cushion resting upon the palatal, the pterygoid, and the orbital
process of the tympanic. The bony septum is usually more or
less incomplete, and the orbital freely communicates with the
temporal vacuity. Only in a few species is the periphery of the
orbit completed by bone, as in certain Maccaws and Cockatoos
(^Macrocercus, fig. 30, Plyctolophus, Calyptorhynchus) \ the la-
crymal extending to the postfrontal as a continuous suborbital
bar. In the Woodcock the large lacrymal so extends the front
wall of the orbit as to cause it to look a little backward as well as
outward : and the orbits are so large as to push the brain-case to
the lower and back part of the cranium. In the Owls the post-
frontals have the form of broad thin plates, compressed from
before backward, and unusually produced downward to increase
the wall of the large orbit and give it a more anterior aspect. In
most diurnal Raptores the upper wall of the orbit is supple-
mented by a dermal oblong flat superorbital bone, ligamentously
connected with the lacrymal. The orbits are smallest and worst
defined in the nocturnal small-eyed Apteryx : there are no super-
orbital ridges, no antorbital or postorbital processes, and the inter-
orbital septum is complete and thick, the optic foramina being
wide apart. In Dinornis the orbits are small, and also divided
by the rhinal chamber : but the superorbital ridge is present and
developes a strong postorbital process. The interorbital septum,
as a rule, is very thin, even when entire, as in T achy petes,
Coracias, Eury stomas \ it may have a small vacuity (^Aquilci) or
a very large one {Buceros^, or two or three as in most birds.

The olfactory cerebral crura emerge from the cranium at the
upper angle between the hind wall, roof, and septum of the orbit ;
groove the upper part of the septum as they pass forward to
penetrate the prefrontal and expand into the rhinencephalon,
dispersing the olfactory nerves to the turbinal membranes. The
frontal olfactory foramen, in the Raptores, is smaller than the
prefrontal one. Between the Vulture and the Crocodile the dif-
ference is that the rhinencephalic crura extend along a common
canal above the interorbital space in the Reptile, while in the
Bird the ossification of the septum divides the rhinencephalic
fossa into two : but many birds resemble the Crocodile in this
respect. The bones which hold the neurapophysial relation to
the rhinencephala, anterior to the frontals, are the same, or homo-

64 ANATOMY OF VERTEBRATES.

logons, in both Ovipara : but in the Bird the secondary peripheral
developments of the prefrontals are suppressed as in Batrachians
and some fishes (Xiphias),^ in which they form the anterior wall
of the orbit, occupying the anterior part of the interorbital space,
joining each other at the median line by an extensive vertical
cellular surface, and dividing the orbital from the rhinal cavities.
In the Apteri/x and Dinoi-nis the latter cavities are so developed
as to extend backward between the orbits to the cranium, the
front wall of which forms the back wall of the rhinal, instead of
the orbital, cavities.

In most birds, however, the orbits intervene : tlie rhinal
chambers are small, and communicate with the upper and back
part of the nasal passages on each side of tlie prefrontal septum.
The passages are partly divided by bone developed from the
vomer. They usually extend obliquely backward from the outer
to the inner or palatal nostrils : but in the Toucans and Hornbills
the nasal passage descends vertically at the base of the huge bill.
The outer nostril is formed in front by the premaxillary, be-
hind by the nasal — each bone bifurcating to include the area,
into the lower part of the circumference of which the maxillary
usually enters. In the Rhea and Emeu, fig. 31, the outer bony
nostril is incomplete behind, the maxillary process or prong of
the nasal not being developed. In the Ostrich it does not reach
the maxillary. The external nostril is near the apex of the bill in
the Cassowary. In the Apteryx the external nostrils are minute
and subterminal ; but a linear groove extends back and widens
into a large triangular Aacuity, on each side the base of the
upper mandible in the skull. In the Petrels the nostrils are
pierced at the end of a tube upon the upper mandible. In the
PelecanidcB there is no outer nostril. The bony septum between
the nostrils is rarely entire. The nasal passage is continued
backward between the vomer and palatine, or betAveen the pre-
sphenoid and palatine, to open, usually by a single median fora-
men or fissure, or by a pair of such, divided, as in Dromaius, by
the vomer, fig. 32, 13, or, as in Struthio, by the vomer and pre-
sphenoid, upon the palate.

Amongst the cranial peculiarities in Birds may be noticed the
bony style attached to the occiput in the Cormorant: the light
cellular bony core or support of the thick horn or horny crest,
in Casuarius galeatus ; which is expanded and flattened behind
in Casuarius Mooruk : the longer and narrower horn-core, re-

' XVI-. p. 52, pi. 1, fig. .5, 14.

OSSEOUS SYSTEM OF AVES. 65

stricted to the space above the orbits, in Oreophasis Derhyanus :
the bony extensions of the upper part of the premaxillary in
certain Hornbills, especially Buceros galeatus : the elevated base
of the short and thick upper mandible in Ourax Pauxi; the
multiplied superorbitals in Tinamus, Nor, perhaps, should the
spherical bony cyst above the fore part of the cranium in a
variety of common fowl be omitted, though this, like the stunted
mandibles of some varieties of pigeon, may rather rank among
the phenomena of pathology.

§ 129. Scapular Arch and Appendage. — The simplest condition
of this arch is manifested in Apteryx and Dinornis, It consists
of scapula and coracoid, uncomplicated by connection with the
liiBmapophysis of any other segment : moreover, the pleur- and
haem-apophyses of the occipital rib have coalesced. A man must
shut his eyes, and with a tight squeeze, to escape recognising the
significance of the propinquity of the scapular arch to the
hyoidean one in the embryo bird. As developement proceeds,
segment after segment is added to the cervical series, and the
occipital ribs, with the myelonal centres supplying their appen-
dages recede far back from the typical jx)sition they maintain in
the Fish (vol. i. figs. 34, ^5, 5i, 52). In Dinornis, as in Murcena
and Any ids, the arch has no appendages. The scapula is rib-
like, compressed, slightly bent, measuring but 4J inches long in a
species (Z). robustiis) with a tibia a yard long ; it is barely an inch
across its broadest end where it coalesces with the coracoid, and
the breadth of the opposite free end is but 5 lines. The coracoid
is straight, 2 inches 10 lines long, ^ inch broad, becomes thicker
to its sternal end, which is convex and adapted to the small
' coracoid ' fossa at the angle of the sternum. There is no trace
of glenoid cavity at the confluence of the two bones, but the
confluent part is here produced into a ridge, showing that there
was no humerus, and that the fore-limb, or appendage of the
scapular arch, was wholly absent in Dinornis,

In Apteryx the scapula is relatively more expanded where it
coalesces with the coracoid, and the bone is broader in proportion
to its length, and shows a vascular perforation near the humeral
articulation, as in the Monitor (vol. i. p. 174). The glenoid
cavity is very small, but of the usual shape in Birds. In these
the scapular arch includes on each side a scapula, fig. 19, 51, a
coracoid bone, ib. f 2, and a clavicle, ib. 58 — the clavicles, coalescing
in most birds at their mesial extremities, constitute a sino^le
bone, which, from its peculiar form, is termed the os furcatorium
ov furculum. In the Ostrich the two clavicles are distinct from

VOL. II. F

66 ANATOMY OF VERTEBRATES.

each other, but are severally anchylosed with the coracoid and
scapula, so as to form with them one bone on either side. In the
Frigate-bird the clavicles coalesce with the coracoids, as well as
with each other and Avith the sternum. In almost every other
species of bird the scapula, coracoid, and clavicle are moveably
articulated to each other throughout life. In Rliea and Casuarius
the acromial element or clavicle is anchylosed with, or rather is
a continuous ossification from, the scapula ; but the coracoid bone
is free, a condition which the bones of the shoulder present in
the Chelonian Reptiles (vol. i. p. 172, fig. 106).

In the Emeu {Dromaius) it is interesting to observe that each
clavicle commences by a distinct ossification, and long continues
separate from the scapula ; it does not reach the sternum, but holds
the same relative situation as the continuous acromial or clavicular
process of the scapula in the other Struthious birds. The cla-
vicles are distinct from each other and from the coracoid in some
Ground Parrots and carpophagous Doves (^Columha galeata, e. g.).

The scapula, fig. 19, 5i, is broader and flatter in the Penguins
(Aptenodytes) than in other birds. In the rest of the class it is a
long and narrow sabre-shaped bone, increasing in thickness as it
approaches the joint of the shoulder ; there it is extended in the
transverse direction, forming externally the posterior half of the
glenoid cavity, and being internally more or less produced, acro-
mially, to meet the clavicle, while it is strongly attached in the
remainder of its anterior surface to the coracoid. The blade of
the scapula may expand towards the free end {^Gallin(E)\ and
this may be obliquely truncate {Gallince), or taper to a point
(most Avcs), Avhich point maybe decurved {Columha) ; it is rarely
obtuse ( Tetrao, Apteryx, Dinornis). The position of the scapula
is longitudinal, being extended backward from the shoulder,
parallel to the vertebral column, towards which, however, it
presents a slight convexity. In some birds it extends over the
ribs to, or even above, the fore part of the ilium ; while in the
Emeu and Apteryx it crosses over two ribs only. In the Hum-
ming-bird {Trochilus), fig. 19, t, its posterior third is bent down-
ward at a slight angle. In birds where the scapula is pneumatic,
the perforations are at the base of the acromial process.

The coracoid, fig. 18, u, figs. 16, 19, 20, 52, is the strongest of
the bones composing the scapular arch : its expanded extremity is
securely lodged below in the transverse groove at the anterior
part of the sternum, from which it extends upward, outward, and
forward, but sometimes almost vertically, to the shoulder-joint,
wliere it is articulated usually at an acute angle with the scapula

OSSEOUS SYSTEM OF AVES. 67

and commonly also with the clavicle. It thns forms the main sup-
port to the wing, and point of resistance to the humeri during the
downward stroke of the aerial oar. The humeral end of the bone
is commonly bifurcate; the outer process is the strongest, and
forms the fore part of the glenoid cavity {I, fig. 19), above which
it rises, to a greater or less extent, and usually affords, on its
inner side, an articular surface for the clavicle : the inner process
is short and compressed, articulates with the scapula, and is also
joined by ligament to the end of the clavicle. The coracoid is
perforated at the base of the inner process. The coracoid is of
great breadth in the Albatross, fig. 13, h, h ; and is both long
and strong in the Penguin, fig. 19, 52. It is pneumatic in Aves
aerecB and in Rasores ; in some GrallcB (Psophia), and in most
longipennate Palmipeds. The sternal ends of the coracoids join
each other in Tachypetes, decussate in Herons, send up a process
above the mesial end in Aptenodytes and above the lateral or
outer end in Tachypetes : the outer angle of the sternal end is
produced in Raptores. The glenoid cavity resulting from the
union of the coracoid and scapula is not equal to the reception
of the entire head of the humerus. In Raptores, Scansores, and
Cantores, an ossicle (O5 humero-scapulare) lies between the
scapula and humerus at the upper and back part of the glenoid
cavity. In Rasores, Grallatores, and Natatores, there is, in
place of this bone, a strong elastic ligament or fibro-cartilage
extended between the scapula and coracoid, against which that
part of the head of the humerus rests, which is not in contact
with the glenoid cavity.

The clavicles, figs. 15, 16, 18, 19, 58, are the most variable
elements of the scapular apparatus. In the Ground Parrots of
Australia (Pezopliorus, Illiger) they are rudimentary or wholly
deficient ; they are slender styles in Columha galeata ; they are re-
presented by short processes in the Emeu, Phea, and Cassowary ;
they do not come in contact inferiorly in the Ostrich, although
they reach the sternum. In the Toucans they are separate, and
do not reach the sternum. In the Hornbills and Screech Owl
{Strix Ulula) they are united at their inferior extremities by car-
tilage. In the rest of the class they are anchylosed together
inferiorly, and so constitute one bone, the furculum or * merry-
thought.' From the point of confluence a compressed process ex-
tends downward in the Diurnal Raptores, the Conirostral Cantores,
the Rasores, most of the Grallatores, and Natatores, in which a
ligament extends from its extremity to the ento-sternum. The
process itself reaches the sternum, and is anchylosed therewith

F 2

68 ANATOMY OF VERTEBRATES.

in the Pelicans, Cormorants, Grebes, Petrels, Frigate-bird, and
Tropic-bird ; also in the Gigantic Crane, and Storks in general.
In the Humming-birds, where the sternum is so disproportionately
developed, the furculum terminates ahnost opposite the commence-
ment of the keel, but at some distance before it ; it is of equal
length with the coracoid. As the principal use of this elastic
bony arch is to oppose the forces which tend to press the humeri
toward the mesial plane during the downward stroke of the mng,
and restore them to their former position, the piers of the arch
are stronger, and the angle of their union is more open, as the
powers of flight are enjoyed in greater perfection : of this adjust-
ment the Swifts, Goat-suckers, and Diurnal Birds of Prey afford
the best examples. In the Eagle the clavicles are arched both
forward and outward, much expanded above, with an articular
surface for the fore part of the outer prong of the coracoid. The
arch becomes narrower, and the bone itself weaker, as flight
is feebler or less sustained ; in the GallincB the U- is changed
to the V-shape ; and at the point of confluence of the straight
and slender piers a process is continued, usually compressed,
sometimes styliform ( Crax), becoming almost obsolete in Hemi-
jwdius ; in the Lapwing the process is at right angles to the arch.
In Tacliypetes the upper ends of the clavicles coalesce with the
coracoids ; and the lower confluent ends expand into a triangular
plate coalesced with the sternal keel. In the crested Pintado the
apex of the furculum is dilated and hollowed into a cup opening
forward and receiving a fold of the windpipe.^

In Birds the humerus has a smooth shaft, sub-elliptic in trans-
verse section, with expanded ends, the proximal^ one being the
broadest. Lengthwise the bone is gently sigmoid, the proximal
half being convex palmad, the distal half concave, with the plane
of the terminal expansions vertical, as the bone extends along the
side of the trunk from its scapulo-coracoid articulation backward,
in its position of rest.

The head of the humerus is an elongate, semi-oval convexity
Avith the lono; axis transverse from the radial to the ulnar sides
(vertical, as naturally articulated), and with the ends continued

' XLiv. no. 1411, p. 271.

^ I here avail myself of the terms indicative of aspect and position proposed by
Dr. Barclay, in his 'Anatomical Nomenclature.'

Proximal signifies the upper, distal the lower, end of the bone, as it hangs in Man;
anco7ial is the posterior, palmar the anterior, surface, as when the palm of the hand is
directed forward ; radial is the outer, ulnar is the inner, side, according to the same
position of the human arm and hand. Proximad, palmad, are adverbial inflections,
meaning towards the proximal (upper) end, and towards the palmar (anterior) side.

OSSEOUS SYSTEM OF AVES. 69

into the upper and lower crests. Of these, the upper one, in the
natural position of the bone, is on the same side as the radius, the
lower more tuberous one is on the same side as the ulna ; the
one marks the ^ radial ' side, the other the ' ulnar ' side, of the
bone. The side of the humerus next the trunk answers to that
called ' anconal,' the opposite side to that called ^ palmar.' The
expanded, proximal part of the shaft on the palmar side, fig. 6,
is concave across, convex lengthwise : on the anconal side it is
convex across to where the ulnar ridge bends anconad near the
pneumatic orifice. The radial crest answers to the ^greater
tuberosity,' and to the '^pectoral' and ^ deltoidal ridges' in mam-
mals ; the ^ ulnar ' crest to the ^ lesser tuberosity ' and to the ridge
for the ^ latissimus dorsi,' in mammals. In a few exceptions the
shaft of the humerus is almost cylindrical ; in still fewer {Apteno-
dytes) it is flat ; in the Albatross it becomes triedral toward the
distal end.

In the Vulture ( V. monachus) the ulnar crest forms a thick
tuberosity at its proximal end, projecting anconad, and over-
arching the ^ pneumatic ' foramen ; it descends a short way ob-
liquely palmad, decreasing in breadth, but still thick, convex, and
terminating obtusely. The radial crest better merits the name ;
it extends twice the length of the ulnar one, down the shaft, to
the palmar side, towards which the whole crest is slightly bent ;
its margin describes a very open or low, obtuse, angle at its
middle part. A ridge u23on the palmar side of its distal half
indicates the boundary of the insertion of the pectoralis major
into the crest. At the middle of the anconal surface of the
proximal part of the shaft there is a low, longitudinal ridge. The
tuberosity at the proximal part of the ridge gives insertion to the
middle pectoral.

At the distal part of the humerus a ridge on the radial side of
the palmar surface, and a rising of the bone on the ulnar side of
the same surface, diverge to the opposite angles or tuberosities
of the expanded end of the bone ; they include a shallow, sub-
triangular concavity above the articular surfaces. These are
two, and are convex. The radial surface is a narrow, sub-
elongate convexity, extending from near the middle of the palmar
surface obliquely to the lower part of the radial tuberosity, where
the convexity subsides ; it is very prominent at its palmar end,
with a groove on each side, the deeper one dividing it from the
ulnar articular convexity. This is of a transversely oval or
elliptical shape, most prominent palmad ; all the part of the end of
the humerus forming the two articular convexities is as if bent

70 ANATOMY OF VERTEBRATES.

toward tlie palmar aspect. The ulnar end of the ulnar convexity
is continued anconad to that end of the ulnar tuberosity. An
oblique, longitudinal channel divides the anconal end of the
radial tuberosity from an almost longitudinal ridge, which is
nearer the middle of the anconal side of the distal end of the
humerus ; a similar, but shorter, longitudinal ridge or rising of
bone, terminates in the anconal part of the ulnar tuberosity.
Between the above almost parallel ridges the anconal surface is
nearly flat transversely ; it is traversed along the middle by a low,
narrow, longitudinal ridge. Lengthwise the bone is here convex.
The differences in the humerus of different birds are seen
chiefly in the forms and proportions of the proximal crests ; the
radial one in the Columhidce, e. g., is shorter and more produced
than in most birds of flight. The humerus in the Swift is very
short and thick, with strong pectoral and deltoid processes, and
with a trochlear groove on the back of the outer condyle : the
proximal processes are still further developed in the humerus of
the Humming-bird ; a distinct ulnar sesamoid plays upon the
anconal trochlea in both. The pectoral process is much produced
and is angular in Tachypetes : also in Sterna where it is deflected.
The bone maintains its general ornithic character when the pro-
cesses have subsided, with the abrogation of the power of flight.
In the Apteryx the humerus is a slender, cylindrical, styliform
bone, 1 inch 5 lines in length; slightly expanded at the two
extremities, most so at the proximal end, which supports a trans-
verse oval articular convexity, covered -with smooth cartilage, and
joined by a synovial and capsular membrane to the scapulo-
coracoid articulation. A small tuberosity projects beyond each
end of the humeral articular surface. The distal end of the
humerus is articulated by a true but shallow ginglymoid joint
with the rudimental bones of the antibrachium, and both the
external and internal condyles are feebly marked.

The humerus is not always developed in length in proportion
to the powers of flight ; for, although it be shortest in the
Struthious Birds and Penguins, it is also very short in the Swifts
and Humming-birds. In the latter, however, it is characterised
by its thickness and strength, the size of its muscular processes,
and the consequent transverse extension of its extremities ; while
in the Cursores it is as attenuated as it is short, and in the
Peno-uins the shaft is reduced to a mere lamina of bone resem-
bling the corres})onding part in the paddle of the turtle. In the
Rasores it rarely equals half the length of the trunk (thorax and
pelvis) ; it equals it in the Argala and Pelican ; exceeds it in the

OSSEOUS SYSTEM OF AVES, 71

Frigate-bird and Albatross. In this and some other sea-birds,
as the Gulls, Awks, and Petrels, the humerus presents a notable
' ectocondyloid ' process on the radial side, near its distal extremity.

A sesamoid bone is found attached (like the fabella of Mar-
supials) to the capsular ligament and the tendons of the extensor
muscles, in many of the Raptores, in the Swifts and Hum-
ming-birds; it is double in the Guillemots and Penguins, fig. 19,
n, n.

There is a deep depression beneath the tuberosity at the ulnar
side of the proximal expansion of the humerus in the Penguins,
Ostrich, Awks, and other birds which have no air in that bone ;
and it is here that the air-cells are continued into the bone in the
majority of the class which have the humerus pneumatic.

A section of the humerus of the Penguin ^ shows it to be solid ;
that of the Awk (Alca) shows a small medullary cavity mth
dense and rather thick walls ; that of a pneumatic humerus, as of
the Argala,^ e.g., exposes the extreme thinness of the compact
wall of a very large cavity, and the loose cancellous lacework at
the extremities of the bone : osseous filaments shoot more or less
obliquely across different parts of the cavity, serving to strengthen,
like tie-beams, the thin walls, and also, being hollow, to convey
minute blood-vessels. The proximal half of the bone is divided
longitudinally by a loose cancellous partition ; the decussation or
anastomoses of the delicate hollow columns give an open reticulate
structure to the inner surface of the air-cavity at the two ex-
tremities of the bone, which is highly characteristic of the long-
bones of birds.

The radius, fig. 19, />, and ulna, ib. o, are present in all birds,
and co-extended between the joints of the elbow and wrist. The
antibrachium, so formed, is short where flight is abrogated ; it is
but one-third the length of the humerus, e.g., in the Ostrich : it is
rather shorter in Guillemots, Divers ( Colymbus), and Gannets
{Sula); is about equal in length in Gallince, Psophia, Cariama ;
but exceeds the length in most birds of flight. However, in some
of the best flyers, e.g. the Albatross where the humerus is ex-
tremely long, and in the Smfts and Humming-birds w^here it is
very short, the antibrachium is of the same length therewith.
Its two bones are so articulated to each other and to the humerus
as to be restricted to flexion and extension : scarcely any degree
of rotation is admitted, and this adds to the firmness and resistance
required for the action of flight. Owing to the obliquity of the

• XLiv. p. 219, no. 1137. See also, no. 1373, Ostrich. ^ ji_,_ „(j, uos.

72 ANATOMY OF VERTEBRATES.

humeral tubercle for the radius, the fore-arm moves in a plane
not quite perpendicular to the palmar surface of the humerus.
When the fore-arm is flexed and the wing is folded, the distal
end of the antibrachium is near or in advance of the proximal end
of the humerus ; the radius being sui:)erior and the ulna a little
external as well as inferior.

The radius is always the more slender bone of the two, some-
times in a remarkable degree: its proximal end is expanded,
subelliptic, ^^dth a concavity for the oblique tubercle, and a
thickened convex border next the ulna for articulation with that
bone : a little beyond that articular expansion is the tubercle for
the insertion of the biceps. The shaft here becomes slender,
usually subcompressed, with a slight bend, convex upward from
the ulna ; the rest of the shaft, which becomes subtriedral, showing
an opposite flexure toward the ulna, though very slightly marked.
The distal end is rather more, though less equally, expanded,
from the radial to the ulnar side : rather flattened with one or two
tendinal grooves on the anconal side, with a terminal transverse
convexity for the scaphoid, produced palmad to articulate "v^dth the
ulna ; with a tuberosity (^Aquila) or ridge ( Tachypetes) on the
radial side of the expansion. The orifice of the medullary artery
in the non-pneumatic radius is on the ulnar side of the shaft about
one-fourth from the proximal end.

The ulna is straio:ht or with a sino-le and slight curve, more
marked in the shorter antibrachium of Gallince than in the long
one of long-^^dnged waders and smmmers. The proximal end is
most expanded, and is obliquely truncate for the articular exca-
vation adapted to the ulnar tubercle of the humerus : the obtuse
angular production of the ulna, behind or anconad of the cavity,
represents in different degrees in different birds the olecranon,
but is always short : an extension of the bone radiad is obliquely
excavated for the head of the radius. The shaft of the ulna
gradually decreases to near the distal end, where the subtriedral
is exchanged for the subcylindric shape. A ridge is developed
below the head on the ulnar side in Raptores. In birds ( Tachy-
petes ^ e.g.) in which the ulna is pneumatic, the foramen is on the
palmar surface a little below the head. On the ulnar and anconal
sides of the shaft are the two rows of quill-knobs (in Raptores)
for the ' secondaries ; ' the anconal row is most marked in longi-
pennate Natatores ; and is the only row in many birds. But
this character of the bird's ulna is wanting in the flightless and
some other birds. The distal end of the ulna slightly expands
into a trochlear joint very convex from the radial to the

OSSEOUS SYSTEM OF AVES. 73

ulnar side, rather concave from the anconal to the pahnar side,
and this chiefly at .the ulnar part of the trochlea. On the
radial side of this trochlea, supported by a tuberosity, is the small
surface for the radius. The interosseous space, OAving to the
greater bend of the ulna, is widest in GallincB ; it is narrower and
chiefly seen at the proximal half of the antibrachium in most
other birds. The ulnar trochlea articulates mth the two free
carpal bones, one — the ' scapho-lunar ' — being wedged into the
radial part, the other — ^ cuneiforme ' — into the ulnar part, leaving
a small intermediate tract for the ' magnum ' which is confluent
^vith the base of the mid-metacarpal.

In the young Ostrich the metacarpus consists of three bones.
The one on the radial side answers to that of the index-finger ; it
is very short, and supports a digit of two phalanges, the second
phalanx being armed with a long curved and pointed claw. The
second metacarpal is the longest and largest, its base being in-
creased by the confluence therewith of the * magnum,' which
presents a trochlear surface to the two proximal carpals and to
the part of the ulnar joint not occupied by them. The third
metacarpal, answering to that of the digitus annularis, is bent, its
extremity resting against that of the large and straight middle
metacarpal, mth which it subsequently becomes anchylosed.
The middle digit consists of three phalanges ; the outer one of
two phalanges. In aU birds the three metacarpals, here seen to be
distinct, coalesce with one another and form a single bone, having
an interesting analogy to the metatarsus, wiiich Like^^^se consists
in all birds of a coalescence of the three bones supporting the
corresponding toes, namely, those answering to the second, third,
and fourth in the pentadactyle foot.

The bones of the hand are developed in length, but contracted
in breadth. The wedge-like adjustment of the free carpals is
such as to restrict the movements of the hand upon the arm to
abduction and adduction, or flexion in the ulno-radial plane,
requisite for the outspreading and folding up of the wing. The
hand of the bird moves thus in a state of pronation, without the
power of rotation or of proper flexion or extension, i.e. in the
ancono-palmar direction ; so that the wing strikes firmly and vnXh.
the full force of the depressor muscles upon the air.

The following state of anchylosis commonly exists in the meta-
carpus : — The short ' index ' metacarpal coalesces with the base of
the * medius ' : the slender ' annularis ' metacarpal anchyloses by
its two ends with those of the medius which it equals in length.
The ^ index ' supports one phalanx, usually terminating in a point

74 ANATOMY OF VERTEBRATES.

about the middle of the ' medius ' metacarpal. This supports two
phalanges, fig. 19^ 5, 5: the proximal oue singularly expanded by
a lamelliform growth from its whole ulnar side, excavated out-
wardly for the attachment of primaries: the next phalanx is
smaller and ends in a point. The ' annularis ' metacarpal supports
a short and slender pointed phalanx, which in the Frigate-bird is
closely joined, length^vise, to the contiguous expanded phalanx
of the mid-digit.

The hand-segment is the longest of those of the pectoral limb
in Swifts and Humming-birds: exceeding by three times the
length of the humerus : and the bones have a proportionate thick-
ness. The mid-metacarpal shows a series of large impressions
for the distal * primaries ' in Rajytores, and also a longitudinal
tendinal groove on the anconal side. The metacarpal, fig. 19, r,
and phalangeal, ib. 5, t, bones, in the Penguin are flattened, like
the antibrachial bones.

The index digit in Struthio and the medius digit in Apterijx,
support each their claw. The claw or spur, when present
in other birds, e. g. Syrian Blackbird {Merula dactyloptera),
Spur-winged Goose {Anser Gamhcnsis), Knob-winged Dove {Di-
dunculus), Jacana {Parra Jacana), Mound-bird (Me(/apodius),
Screamer {Palamedca), is developed from the radial side of
the metacarpus or from the index digit. The Screamer has two
spurs, the homotypes of the metatarsal ones in Pavo hicalcaratus.
The claw upon the index digit of Archeopteryx was curved and
sharp ; and the remains of the unique example of this ancient
fossil bird make it probable that the hand had a second free
unguiculate digit, perhaps the homologue of the pollex.^

Although the instances of these weapons and the occasional use
of the wings in Birds not so armed, e. g. the Swan, show them in
the light of means of attack, the bones of the pectoral limb in
Birds are modified mainly for volant action ; the articulations
restrict the movements of the several segments to the service of
wings, and the processes for muscular attachments relate to such
development and disposition of the moving forces as flight requires.

The larger feathers which overlie, in a series, the humerus, are
termed, in ornithology, ' scapularies : ' those still larger which
overlie or are attached to the ulna are the * secondaries ' or ^ wing-
coverts ; ' those which are attached to the manus are the ' pri-
maries,' they are the longest : a group of feathers attached to the
stunted index digit are the ^ spurious ' or ' bastard ' feathers.

' XV. p. 39, pi. 2, fig. 1.

OSSEOUS SYSTEM OF AVES. 75

The primary quill-feathers being the chief direct mechanical
instrument in the displacement of the air, the segment of the
limb supporting them is the longest and strongest in the most
powerful flyers, e.g. Swifts and Hummers, in which the pri-
maries are proportionally longer and stronger than in other birds :
but the various habits, habitats, and food of the feathered tribes
are associated with different kinds of aerial motion and call for
corresponding modifications of the instrument : thus the Frigate
and Tropic birds. Albatrosses, Terns, and other ablest flyers
among the Natatores, contrast strangely with the above-cited
Volitores in the proportionate length of the brachial and anti-
brachial segments of the pectoral limb : whilst the powerful
Kaptorial flyers show an intermediate more harmoniously ba-
lanced proportion of the several segments. All these are rela-
tively short and feeble in the heavier land birds which take but
brief and occasional flights ; and, as circumstances have rendered
this exertion less and less necessary, so the wings and their frame-
work have wasted away to the diminutive rudiments in the
Apteryx, and to zero in Dinornis.

§ 130. Bones of the pelvic limb. — The segments of this limb
do not wholly correspond with those of the pectoral one, the
tarsus being absent or blended with the tibia or the metatarsus,
which immediately succeeds it.

The femur, fig. 34, 65, has a cylindrical shaft, which, when not
straight, is slightly bent forward : it nearly equals the pelvis in
length in the Apteryx and some Ground-cuckoos {Geococcyx),
but is usually shorter ; it is very short in Dinornis elephantopus ;
shortest of all and most bent in Colymbus : it is always shorter than
the tibia, but in a minor degree in most Easores, Scansores, Voli-
tores, Cantores, some Natatores ( Tachypetes), and the Apteryx. The
head is hemispherical, proportionally small, and largely scooped
out above for the round ligament which fills up the vacuity in the
acetabular wall : it is sessile, with its axis nearly at right angles
to that of the shaft ; the articular surface is continued upon the
upper end of the bone which expands as it recedes from the head,
and usually rises above its level to form a trochanterian ridge
extending from behind forward and there produced and continued
a short way down the shaft. The outer (fibular) side coextensive
with this ridge is rather flattened and impressed by insertion-
marks of muscles. Rarely is there, as in Aptornis, a trochanter
minor, situated a little below the head on the inner (tibial)
side of the bone, or represented by a round rough surface, more
anterior, as in Dinornis. Assuming its cylindrical or subcylin-

76 ANATOIVIY OF VERTEBRATES.

drical form below the great trochanterian ridge, the shaft at its
lower half expands transversely, and, in forming the distal con-
dyles, also from before backwards, with a bend in that direction.
The inner condyle begins anteriorly as a ridge, expanding into
a convexity which attains its greatest breadth posteriorly, where
it becomes more flattened. The outer condyle, commencing in
the same manner, is indented at its broad lower end by an angular
groove, which, widening, divides the back part of the condyle into
two convexities. The inner of these is the broadest and most pro-
duced, is applied to the outer facet of the tibia, and represents
the ordinary outer condyle : the more external convex ridge and
the groove dividing it from the outer condyle are adapted to the
head of the fibula. This is the most characteristic part of the
bird's femur. The space between the anterior beginnings of the
condyles is the * rotular ' channel : it is usually broad and mode-
rately concave transversely, convex lengthwise ; sometimes divided
from, commonly continued into, the intercondyloid fossa which is
marked with pits for ligamentous attachment. The inner side of
the inner condyle is flattened, with a tuberosity at its mid-part,
and sometimes a second just above the hind part of the condyle.
There is usually a tuberosity above the hind end of the fibular
ridge, exterior to which the surface is sometimes flattened, some-
times prominent, in Dinornis impressed by a deep fossa. ^ At the
lower part of the outer condyle before the ^ fibular ' groove begins,
there is usually a small pit. The popliteal depression is divided
by a ridge from the intercondyloid one. The shaft shows inter-
muscular linear ridges : in Aquila one extends from the fore and
outer angle of the epitrochanterian articular surface to near the
beginning of the inner condyle ; a second extends from the inner
and back part of the upper third of the shaft to the tubercle above
the back part of the inner condyle : the third shorter * linea aspera '
is at the back part of the middle third of the shaft near its outer
side. In Dinornis a ridge continued from the anterior trochan-
terian one bifurcates at the middle of the fore part of the shaft
diverging to the beginnings of the two condyles. In Aj)teryx the
two posterior lineai aspera? approximate at the middle of the shaft
and then diverge to the condyles : in Dinornis they expand into
tuberosities, or the inner one alone is continued as a ridge, but
interrupted above the condyle : the inner ridge is strongly marked
and continued to the condyle in Aptornis. The orifice of the
medullary artery is at the back part of the shaft above its middle.

' In Dinornis maximus the femur is 16 inches in length, and 6| inches across the
distal end.

OSSEOUS SYSTEM OF AVES. 77

VYhen the femur is pneumatic the proximal orifice is commonly
anterior, near the trochanterian ridge : but in the Ostrich it is
behind : the distal orifices when present are in the popliteal fossa.
Of the two condyles the outer one is most prominent posteriorly,
and, when the femur is held vertically, descends the lowest. In
the flexion of the leg on the thigh this puts the ligaments on the
stretch ; and, as they are partly elastic, the fibula enters its fossa
at the conclusion of the bend with somewhat of a jerk.

The tibia, fig. 34, 66, is the chief or longest bone of the hind limb,
showing its extreme character in this respect in most Stilt-birds,
especially the Argala and Flamingo, fig. 14, and its smallest propor-
tions in Volitores, fig. 18, and the Frigate-bird, in Avhich the tibia is
not lialf the length of the skull. The shaft is straight and mainly
subtriedral, expanded at both ends and most so at the upper one.
This presents a semi-oval surface not quite transverse to the
shaft, but with the truncate margin raised toward the fore part of
the bone, and more or less developed above the level of the un-
dulating articular part. Of this the least marked is the almost
flat reniform ^ entocondylar ' surface for the inner condyle, feebly
hollowed near its back part which projects in that direction over
the shaft ; it is divided from the smaller and less defined ' ecto-
condylar ' surface for the outer femoral condyle by an ' inter-
condylar ' convexity. In advance of these the head of the tibia
extends into a ' rotular ' process, usually extended transversely
and truncate. From the fore or outer part of this process there
descend two vertical ridges or plates : the one from near the inner
or tibial angle of the rotular process is the ^ procnemial ridge,'
the other from the outer or fibular angle is the ' ectocnemial
ridge ; ' they subside more or less gradually upon the shaft, and
intercept a deep triangular concavity. On the outer side of the
intercondylar tuberosity is a single surface for ligamentous union
with the head of the fibula, and a little way below this there is a
vertical ridge for close attachment to part of the shaft of that bone :
below and behind the ' fibular ' ridge is the orifice of the medul-
lary artery. From this point the tibia maintains a uniform size
usually to its lower third, where along a rough tract, in a line
Avith the above ridge, the styliform end of the fibula terminates
by close union or anchylosis. There the tibia begins to gain
in transverse breadth, exchanging the triedral for a transversely
oval section, and it gradually expands in both directions to the
distal condyles, which are most developed from behind forward,
in advance of the shaft. The inner condyle is the largest, usually
in fore-and-aft, sometimes {Aquila) in transverse, extent. A

78

ANATOMY OF VERTEBRATES.

groove commencing near the lower end of the fore part of the
shaft leads, deepening, toward the intercondyloid space : it is
bridged over by a strong ligament, which becomes ossified in
most birds : Parrots, Hornbills, and existing Ciirsores are ex-
ceptions. The position — median or submedian and direction —
straight or oblique — of the precondylar groove, the presence and
direction — transverse or oblique — of its bony bridge, the re-
lative breadths, anteroposterior and transverse, of the distal end,
the relative size of the intercondyloid space to the anterior parts
of condyles, — help in the determination of bird-affinities, when
they have to be deduced from a fossil tibia.* The distal condyles
commencing behind as ridges bounding an articular surface con-

34

Pelvis and bones of the leg, Loon {Colynibus).

cave across, increase in breadth and convexity as they curve to
their anterior ends : these are more prominent than their posterior
ridged beginnings, but in different degrees in different birds ;
and the inner condyle is usually the most prominent anteriorly :

' Sec X1X-. p. 204, pi. 3, for the illustration and application of the characters of
the tibia in the determination of the affinities of birds indicated by that bone fossil.

OSSEOUS SYSTEM OF AVES. 79

thus the distal end of the tibia is like that of the femur mth
the back of the condyles turned forward, and without the notch
in either.

Among the modifications of the proximal end of the tibia may
be noted the production of the rotular process in the axis of the
shaft two inches above the knee-joint in the Divers ( Colymbus),
fig. 34, /i; both pro- and ecto-cnemial ridges descend from the
fore part of the base of this process, the former extending half-
way down the shaft of the tibia. In the Albatross the pro- and
ecto-cnemial ridges are much developed ; but are still more so in
the extinct Cnemiornis, without corresponding production of the
rotular or ' epicnemial ' process. In the Ostrich this process
extends forward, without rising above the level of the proximal
surface, and contracting to its termination there divides into small
pro- and ecto-cnemial processes; the latter the shortest and
tuberous. The distal condyles are less produced anteriorly, com-
mence more abruptly and are more produced posteriorly, than in
other birds : their articular surfaces are so continuous as to leave
no ' intercondylar ' space ; there is no tendinal groove or bridge :
but a tuberosity above the middle of the confluent condyles.
The articular surface of these being concave in one direction,
convex in the other, forms a ' trochlea,' and the same in the con-
joined parts of the distal condyles in other birds. It limits the
movements of the next segment of the limb to one plane.

The Jihula, fig. 34, 67, is a styliform bone ending in a point below
at various distances down the tibia in different birds. The articular
head is subcompressed, convex in the longer axis, slightly curved
backward, hollowed on the inner (tibial) side : rather convex
externally : the shaft shows the rough linear tract for attachment
to the tibia: and there are sometimes tuberosities for tendinal
insertions on the opposite side.

The femur is ossified from one centre: the tibia has an epiphysis
for the distal condyles ; the proximal end of the metatarsus is
ossified from one centre, forming an epiphysis which caps the ends
of the three metatarsals that coalesce, first with each other, then
A^dth the epiphysis, to form the single compound bone.

The trochlear epiphysis of the tibia most resembles the astra-
galus in those mammals (Ruminants, e.g.) in which the meta-
tarsals coalesce. The term ' tarso-metatarse ' applied by some
ornithotomists to the present segment, fig. 34, 68, implies the tarsal
homology of the epiphysis ; the same might, more probably, be
predicable of the distal one of the tibia ; but neither being demon-
strated, I prefer to call the present segment the ' metatarse.' It

80 ANATOMY OF VERTEBRATES.

consists of the foot-bones of three digits coalesced, and often of a
fourth ligamentously joined thereto. This always small and
short seeming appendage is the distal end of the metatarsal of the
* hallux ' or innermost digit of the pentadactyle foot. The three
coalesced bones are the metatarsals of the second (ii), third (iii), and
fourth (iv) toes, fig. 34. In their original position the proximal end
of the third metatarsal is behind those of the second and fourth
which meet in front of it. A fossa below the meeting shows,
afterwards, two fore-and-aft canals which diverge to outlets at
the back part indicative of the breadth there of the middle meta-
tarsal. When, as in Aquila, there are two foramina in front of,
as well as two behind, the upper part of the metatarse, the inter-
space of the former shows the extent to which the mid-metatarsal
intervened between the others anteriorly, and this structure is
concomitant with a great excess of the transverse over the fore-
and-aft diameter of the proximal end of the metatarse. In most
birds a fore-and-aft canal also remains to indicate the primitive
distinction of the outer (iv) from the middle (iii) metatarsal near
their distal ends.

The metatarse, fig. 34, 68, presents a proximal end with two
articular cavities (^ ento- ' and ' ecto-condylar ') and the intercon-
dylar space, a shaft with its processes, grooves, and perforations,
and a distal end divided (save in Struthio) into three trochlear con-
dyles for the three principal (ii, iii, iv) toes : in most birds, also,
there is a rough depression on the distal half of the inner meta-
tarsal, for that end of the innermost or first (i) metatarsal. The
proximal end varies in the proportions of its transverse and antero-
posterior diameters, in the depth of its articular surfaces, and
configuration of the intercondylar surface. As a rule the ento-
condylar surface is largest and deepest ; the ectocondylar surface
is nearly flat in the Eagle. A tuberosity rises from the fore part
of the intercondylar space in birds which sleep standing on one
leg (Gr«Z/<s and some others): it passes into the corresponding
space of the tibia, the bar anterior to which affords so much
resistance to flexion of the leg as counteracts the effect of oscilla-
tions of the body : it requires a muscular effort to bring the
tuberosity over that bar, and the elastic lateral ligaments are
then put on the stretch ; but as soon as the bar is passed the
tuberosity slips into the depression above with a snap or jerk.
One or more longitudinal ridges at the back of the upper end
of the metatarsal are called ' calcaneal ; ' they intercept or bound
tendinal grooves which, in some instances, are bridged over by
bone and converted into canals : the ridges may be expanded and

OSSEOUS SYSTEM OE AVES. 81

flattened.' In the Birds of Prey the metatarsal is most modified
by the muscles and tendons operating upon the raptorial toes.
There are three calcaneal processes, the innermost large, the
two outer ones small and approximate. The fore part shows
a tuberosity for the insertion of the strong ' tibialis anticus '
(fig. 35, 48) : below this is the process on the inner margin
extending the surface of attachment for the metatarsal of the
back toe (z). The trochlear ends of the three confluent meta-
tarsals are nearly on the same level, the inner one is the
broadest, the outer one the narrowest : each is produced, at an
opposite angle, so as to bound the wide concavity behind this
end of the metatarsal. In the King- Vulture {Sarcoramphus),
the mid-trochlea is broadest and most produced: in the Snake-
Vulture ( Gypogeranus) with a metatarsal of stilt-like length, the
inner trochlea is shorter than the others and further apart. In
most Owls the metatarsal is shorter in proportion to its breadth
than in diurnal Raptores ; a bony bridge overspans the beginning
of the tendinal canal on the fore part : the outer trochlea is the
shortest and is bent backward and inward. In most Cantores
and Volitores the distal end of the metatarsal is little expanded,
and the three trochlea? are of nearly equal length : in Podargus
and Dacelo the outer trochlea is the shortest. In Cypselus the
trochlea terminate on the same transverse line : in Trochilus the
middle one is a little more prominent. In the short and strong
metatarsal of the Parrot-tribe, the middle trochlea extends wholly
below the others, which are oblique and twisted, especially the
outer one, backward and inward : a like twist is noticeable in
most Scansores, especially the Woodpeckers and Cuckoos. In
the spurred Gallince the weapon is supported on a conical process
from the back part of the metatarsal ; sometimes there are two,
as in Pavo bicalcaratus. In all Rasores the mid-trochlea is
longest; in Pigeons and Curassows the outer (iv) is shorter or
higher than the inner {ii) trochlea : in the Tinamou and Syrrhaptes
it is longer. In the Apteryx and tridactyle Cur sores the mid-
trochlea is largest, and extends by almost its whole length beyond
the other two which are nearly on a level. In Struthio the inner
metatarsal (ii) terminates in a point near the base of the great
trochlea (m): the outer trochlea (/v) is comparatively small and
short. In Grallatores the mid-trochlea is lono^est, the other two
of equal or nearly equal length in most : the inner (ii) trochlea is
the shorter in the Demoiselle Crane ( Scops Virgo) ; the outer one

VOL. II,

XVI-. vol. iii. part iv. (184G), pp. 321, 322; xliv. p. 274, &c.

82 ANATOMY OF VERTEBRATES.

{iv) in the Woodcock (Scolopax). In the Spoonbill (Platalcea)
and Flamingo {Plioenicopterus) the mid-trochlea is but little pro-
duced beyond the others. The surface for the attachment of the
innermost metatarsal (z) is raised well above the trochlear end of
the next {ii) in most of those Waders that have the back-toe.
Amono'st Natatores the Albatross has the three trochlea3 nearlv
on the same level : in others the mid one is usually most pro-
duced : in the Gannet and Pelican the outer trochlea is the
shortest and furthest from the middle one. In the Guillemot
( Uriel) the inner trochlea {ii) ends at the base of the mid one,
whilst the outer trochlea is of nearly equal length with the mid
one : in the Grebe (Podiceps) the inner trochlea is the longest of
the three : in the Loon ( Columbus) it is the shortest : the meta-
tarsal in this bird is much compressed, and the outer and inner
trochlea are bent backward. The Penguins show the most in-
structive modification of the metatarsal : it is very short and
broad ; but the primitive divisions are to a great degree retained,
especially on the fore part of the compound bone. The stunted
or abortive metatarsal supporting the backwardly directed toe
consists of a trochlear articulation supported on a compressed
stem, twisted, and obtusely pointed above, with one margin
thickened and rough for syndesmosis with the next anchylosed
metatarsal. This bone is best developed in the Raptorial birds
and the Dodo,^ in which its length may exceed a fourth part
of the leno;th of the metatarsal seo-ment : in Pigreons it is about
the fifth or sixth part that length : by the twist the bone forms a
pulley upon which the flexor tendon of the back toe plays. In
the Dodo the distal expansion is increased by an obtuse process
from the outer side of the trochlea ; and this character is repeated
in the Cohimhidce.^ In GallincE the trochlea is less expanded
and the twist is feebly shown : it disappears in the still smaller
loose metatarsal of Apteryx, Palapteryx^ and in many Natatores,
in some of which it is represented by the ligamentous matter
tying the short back toe to the metatarse.

Both this {i) and its metatarsal are undeveloped in the larger
existing Cursores, the Bustards ( Otis), the Plovers ( Charadicus),
the Thick-knees (^(Edicnemus), the Oystercatchers {Hcematopus),
the Coursers ( Tacliydromus), and the Albatrosses {DiomedcBa and
Haladromci).

The toes of birds never exceed four in number, and of these,
three are usually elongated and directed forward, diverging, Avhile

' XXVI'. 2 XXV1I-, pi, 11. 3 XVI-. vol. iii. p. 307.

OSSEOUS SYSTEM OF AVES. 83

one is sliort and directed backward. The hind toe articulates
on the same plane as the otliers in grasping and perching birds,
but on a higher level in terrestrial and aquatic kinds. By the
analogy of the number of the phalanges of these toes with those
in Lizards (vol. i. p. 192, fig. 122) the back toe, fig. 34, z, is the
innermost, answering to ^ hallux ; ' the inner of the front toes, ib.
ii, is the second ; the middle one, ib. Hi, is the third : the outer
one, ib. iv, is the fourth : it will be seen that the number of
phalanges progressively increases from two to five. The fifth
toe of the four phalanges in the Monitor is not developed in any
bird. The constancy of the numl^er of phalanges in each toe is
such that the toes retained in a tridactyle bird, e. g.. Emeu, are
seen to be the second, third, and fourth; those in a didactyle
bird, e. g., Ostrich, to be the third and fourth : and, although the
latter is much the smaller and shorter toe, it retains its superior
number of joints. Among the very few" exceptions to this rule
may be cited the outer toe of the Caprimulgus and of the Swift,
which has but four phalanges ; in the Swift, also, the innermost
toe is directed forward like the rest. The last phalanx in each
toe is pointed, and usually curved, corresponding in some measure
with the shape of the claw it supports : the articular ends of the
phalanges are slightly expanded and coadapted with trochlear
joints limiting motion to one plane.

The chief of the sesamoid bones in the hind limb is the patella :
it is of unusual size in the Penguin, is ossified from two centres,
and articulates with the procnemial process of the tibia: it
coexists with the long rotular process in the Loon, fig. 34, / ; it
is large and of an angular form in the Musk-duck {Biziurd) : in
the Merganser the patella is largest and deeply notched ; in the
Coot it is elongate. In most aerial birds a patella is wanting.
A calcaneal sesamoid is wedged into the outer and back part of
the ankle-joint in the Apteryx, and plays upon the back part of
the tibial trochlea in the Turkey, Guan, Curassow, and some
other Rasores.

Ossification normally extends into the tendons of some of the
muscles in most birds : e. g., of the deep seated spinal ones of the
back ( Uria Troile and many others) ; of the muscles of the foot
and toes (^GaUince). The bony plates at the corneal margin of
the sclerotic tunic of the eye, and the columelliform stapes of the
ear, are appendages to sense-organs. Mr. William Home Clift
discovered small ossifications at the attachments of the semilunar
valves of the aorta and pidmonary artery in some Birds. ^

' VTT-, p. 331.
g'2

84 ANATOaiY OF VERTEBRATES.

CHAPTER XV.

MUSCULAR SYSTEM OF AVES.

§ 131. General Characters. — The muscular system of Birds is
remarkable for the distinctness and density of the fasciculi or
visible fibres, the deep red colour of those chiefly employed in
vigorous action, and their marked separation from the tendons,
which are of a pearly shining colour, and have a peculiar
tendency to ossification. This high degree of developement re-
sults from the rapid circulation of very warm and rich blood,
highly oxygenated through the extent of the respiratory system.
The energy of the muscular contraction in this class is in the
ratio of the activity of the vital functions, but the irritability of
the fibre rapidly goes after death. The elementary fibres are
much smaller and less sharply angular than in Reptiles ; the
blood-vessels being more abundant and occupying more space in
their intervals.

These characteristic properties are manifested in the greatest
degree in the muscles of the Volitores, and of those Cantores that
take their food on the wing, as the HirundinidcB ; in those of the
Diurnal Raptores and the long-winged Palmipedes, as the Alba-
tross, Tropic Bird, &c. In the more heavy and slow-moving
Herbivorous families, the muscles resemble those of the Reptilia
in their softness and pale colour. In birds of flight the me-
chanical disposition of the muscular system is admirably adapted
to the aerial locomotion of this class ; the principal masses being
collected below the centre of gravity, beneath the sternum, beneath
the pelvis, and upon the thighs, they act like the ballast of a
vessel and assist in maintaining the steadiness of the body during
flight, Avhile at the same time the extremities require only long
and thin tendons for the communication of the muscular influence
to them, and are thereby rendered light and slender.

§ 132. Muscles of the vertebrcB.—Tha muscles of the cervical re-
gion are the most developed, as might be expected from the size
and mobility of this part of the spine ; the muscles which are situ-
ated on the dorsal and lumbar regions are, on the other hand, very
indistinct, feeble, and but slightly carneous ; they are not, how-

MUSCULAR SYSTEM OF AVES.

85

35

ever, entirely wanting. In the Struthious and short-winged sea
birds, in which the dorsal vertebrae are unfettered by anchylosis,
these muscles are more fleshy and
distinct, most so in the Apteryx,
and will here be described as seen
in that bird.^

The sacro-lumbalis is the most
external or lateral of the muscles
of the back, and extends from the
anterior border of the ilium to the
penultimate cervical vertebra. It
arises by short tendinous and car-
neous fibres from the outer half of
the anterior margin of the ilium,
and by a succession of long, strong,
and flattened tendons from the an-
gles of the fifth and fourth ribs,
and from the diapophyses of the
third, second, and first dorsal verte-
bra3 ; also by a shorter tendon from
that of the last cervical vertebra;
these latter origins represent the
musculi accessorii ad sacro-liimba-
lem ; to bring them into view, the
external maro-in of the sacro-lum-
balis must be raised. These acces-
sory tendons run obliquely forward,
expanding as they proceed, and are
lost in the under surface of the
muscle. It is inserted by a fleshy
fasciculus with very short tendinous
fibres into the angle of the sixth
rib, and by a series of correspond-
ing fasciculi, which become progressively longer and more ten-
dinous, into the angles of the fifth, fourth, third and second
ribs, and into the parapophyses of the first dorsal and last two
cervical vertebrae: the last insertion is fleshy and strong; the
four anterior of these insertions are concealed by the upper and
outer fleshy portions of the sacro-lumbalis, which divides into five
elongated fleshy bundles, inserted successively into the diapo-
physes of the first three dorsal and last two cervical vertebra?.

Muscles of a Hawk.

1 XXIV. vol. iii. p. 280, pis. 32 and 33.

86 ANATOMY OF VERTEBRATES.

These last insertions seem to represent the continuation of the
sacro-lumhalis in Man, which is termed the cervicalis descendens
or ascendens.

The longissimus dorsi is blended posteriorly both with the
sacro-lumhalis and the multifidus spince, and anteriorly with the
outer portion of the spinalis dorsi. It extends as far forward as
the thirteenth cervical vertebra. It arises from the inner or mesial
half of the anterior margin of the ilium ; from a strong aponeu-
rosis attached to the spines of the eighth, seventh and sixth dorsal
vertebrae ; and from the diapophyses of the sixth, fifth, fourth and
third dorsal vertebrae. The carneous fibres continued from the
second origin, or series of origins from the spinous processes, in-
cline slightly outward as they pass forward, and are inserted into
the anapophyses of the first three dorsal vertebra, receiving ac-
cessory fibres from the spinalis dorsi. The fasciculi from the
diapophyses incline inward, and are also inserted into the anapo-
physes of the vertebras anterior to them ; they receive fibres from
the iliac origin, and soon begin to form a series of oblique carneous
fasciculi, which become more distinct as they are situated more
anteriorly ; they are at first implanted in the vertebra next in front
of that from which they rise, and then into the vertebra next but
one in front : the most anterior of these tendons of insertions, to
which can be traced any of the fibres of the main body of the
longissimus dorsi is that which is implanted into the thirteenth
cervical vertebra ; it is this fasciculus which is joined by the first
or most posterior of ihQ fasciculi ohliqui of the long us colli posticus,
Ohliquus colli, a series of oblique carneous fasciculi, evidently
a continuation of, or part of the same system with those in which
the longissimus dorsi terminates anteriorly, is continued between
the diapophysis of one cervical vertebra to the anapophysis or
posterior zygapophysis of the next vertebra but one in advance,
as far forward as the fourth cervical vertebra. This series of
muscles seems to represent the transversalis colli, which is the
anterior continuation of the longissimus dorsi in Mammalia, but
it differs in being inserted into the oblique, instead of the trans-
verse processes. In the direction of their fibres these fasciculi
resemble the semispinalis colli, but they are inserted into the
oblique processes instead of the spines of the vertebra?. There
are no other muscles with which they can be compared in the
Mammalia than these two, witli neither of which, however, do
they precisely correspond ; they seem to represent the second
series of oblique muscular fasciculi in the trunk of Fishes.

The fasciculi ohliqui which rise from the first two dorsal and

MUSCULAR SYSTEM OF AVES. 87

five lower cervical vertebrae are joined near their tendinous termi-
nations by corresponding oblique fasciculi of the long us colli
jyostlcus, and the strong round tendons continued from the points
of convergence of these fascicles are inserted successively into the
posterior oblique processes of the twelfth to the sixth cervical
vertebra inclusive ; the two fasciculi next in succession receive
no accessory fibres from the longus colli posticus ; the anterior
one derives an extensive origin from the upper transverse pro-
cesses of the eighth, seventh, and sixth cervical vertebrae. It
must be observed, however, that the whole of each fasciculus is
not expended in the strong round tendinous insertion above de-
scribed ; the portion which arises from the anterior ridge of the
diapophysis passes more directly inwards than the rest, and is
attached to the tendon which terminates the fasciculus imme-
diately behind ; at the middle of the neck these accessory fibres
approach to the character of distinct origins. The tendons of
insertion, moreover, severally receive accessory fleshy fibres from
the base of the zygapophysis of the two vertebrae next behind ;
and thus they become the medium of muscular forces acting from
not less than five distinct points, the power of which is augmented
by each tendon being braced down by the oblique converging
series of muscles immediately anterior to it. The fasciculus from
the eighth cervical vertebra, besides its insertion by the ordinary
tendon, sends off externally a small pyramidal bundle of muscular
fibres which soon terminates in a long and slender tendon which
is inserted into the oblique process of the third cervical vertebra.
Corresponding portions of muscle are detached from the two
anterior fasciculi, Avhich converge and terminate in a common
slender tendon inserted into the posterior oblique process of the
fourth cervical vertebra ; and thus terminates this complex muscle
or series of muscles. It is partially represented by the muscle
8, in fig. 35 (Hawk).

The longus colli posticus is most internal or medial of the super-
ficial muscles of the dorsal aspect of the thoracic and cervical
regions. At its posterior part it seems to be a continuation of the
longissimus dorsi ; its medial and anterior part ofi^ers a strong
analogy with the hiventer cervicis ; it is the homologue of the
first, or medio-dorsal series of oblique fibres of the muscular
system in Fishes. It commences by long and slender, but strong,
subcompressed tendons from the spines of the sixth, fifth and
fourth dorsal vertebroe : these tendons gradually expand as they
proceed forward and downward, and send oflT from their under
surface muscular fibres which continue in the same course, and

88 ANATOMY OF VERTEBRATES.

begin to be grouped into distinct fasciculi at the base of the neck :
the first of these bundles joins a fasciculus of the longissimus dorsi,
which is inserted into the anapophysis of the thirteenth cervical
vertebra; the succeeding fasciculi derive their origins from a
broad and strong aponeurotic sheet attached to the spines of the
fourth, third and second dorsal vertebra? : the second to the
eighth fasciculi inclusive are compressed, broad, and fleshy, and
are inserted in the strong round tendons described in the pre-
ceding muscle, and attached to the zygapophyses of the twelfth to
the sixth cervical vertebra^ inclusive : the ninth fasciculus, which
forms the main anterior continuation of the longus colli ijosticus^
is larger than the rest, and receives, as it advances, accessory
fibres from the spinous processes of the seventh to the third
cervical vertebras inclusive, and is inserted, partly fleshy, partly
by a strong tendon, into the side of the broad spine of the vertebra
dentata, A slender fasciculus is detached from the mesial and
dorsal margin of the longus colli j^osticus, near the base of the
neck, which soon terminates in a long round tendon, fig. 35, a&:
this tendon is braced down by short aponeurotic fibres to the spine
of the fifth, fourth, third and second cervical vertebras inclusive,
immediately beyond which it again becomes fleshy, and expands
to be inserted into the occipital ridge : this portion is the digas-
trique or hiventer capitis of Cuvier, ib. c, 6,

In Raptores the carneous exceeds the tendinous part of this
muscle. The displacement of the dorsal portion of the preceding
muscle and the longissimus dorsi brings into view the sjnnalis
dor si, which is a well-developed and distinct muscle in the
Apteryx. It arises by two long, narrow, flattened tendons from
the spines of the eighth and seventh dorsal vertebra : these pass
obliquely downward and forward, expanding as they proceed,
and terminate in two fasciculi of muscular fibres : the posterior
bundle passes forward beneath the anterior one, and inclining
inward and upward, divides into two portions, inserted by long
tendons into the spines of the second and first dorsal vertebra? ;
it then sends a few fibres forward to join the outer and anterior
fasciculus, which is partly inserted by a slender tendon into the
spine of the last cervical vertebra : the rest of the fibres of the
second fasciculus join the portion of the longissimus dorsi which
is implanted into the posterior oblique process of the last cervical
vertebra. The three inserted tendons of the spinalis dorsi are
also the medium of attachment of fibres continued from the inul~
tifidus spinoi, beneath them.

The series of muscles called multJjidus spince arises by fleshy

MUSCULAR SYSTEM OF AVES. 89

fibres from the diapopliyses of the five last dorsal vertebrae, which
pass upward, forward, and inward, to be inserted by four flat
tendons into the spines of the seventh to the third dorsal vertebra?
inclusive, and by the tendons of the spinalis dorsi into the two
anterior dorsal spines.

OhliquO'Spinales. The removal of the multifidus sjiincE brings
into ^dew a series of long, narrow, flat tendons, coming ofl" from
the spines of all the dorsal vertebraa, and slightly expanding as
they proceed forwards and obliquely downwards and outwards ;
they become fleshy half-way from their origin, and are inserted
into the posterior oblique and transverse processes of the six
anterior dorsal vertebra?, and into the posterior oblique processes
of the three last cervical vertebrae.

The inters-pinoles muscles do not exist in the region of the back,
unless we regard the preceding oblique fibres as a modified repre-
sentation of them. The most posterior fasciculus of muscular
fibres, which is directly extended between the spinous processes,
commences at the interspace of the spines of the two last cer^dcal
vertebra?, and the series is continued as far as the vertebra dentata.

Inter articular es. The muscles which form the more direct
continuation of the ohliquo-spinales are continued from the pos-
terior zygapophysis of one vertebra to that of the next in front.

Obliquo-transver sales. A third series of deep-seated interver-
tebral muscles is situated external to the preceding, and passes
obliquely between the diapophysis and the posterior zygapophysis
of the vertebra in front. These fasciculi appear to be a con-
tinuation of the multifidus spince in the neck.

The intertransver sales are two series of short carneous fasciculi
passing the one between the diapophyses, and the other between
the parapophyses.

Levatores costarum. The first or most anterior of this series of
muscles seems to represent the scalenus medius ; it arises from
both the di- and pleur-apophysis of the last cervical vertebra, and
expands to be inserted into the first rib, and into the upper and
outer part of the second rib. The remaining levatores successively
diminish in size as they are placed backwards ; they come ofi:'
from the diapophyses of the first six dorsal vertebra? ; those from
the first and second expand to be inserted into the rib attached to
the same transverse process and to the one next behind ; the rest
have a single insertion : the angle and the part of the rib imme-
diately beneath are the situations of their attachments.

Complexus, fig. 35, 7. This strong triangular fleshy muscle
arises from the met- and di-apophyses of the fourth, third and

90 ANATOMY OF VERTEBRATES.

second cervical vertebrae, and gradually expands as it advances
forward to be inserted into the occipital ridge, from the outer side
of the insertion of the hiventer cervicis to the mastoid process.

Recti cajntis postici. These small muscles are concealed by
the preceding; they rise successively from the spines of the
third, second and first cervical vertebrae, and expand as they
advance to be inserted into the occiput.

Trachelo-mastoideus. This strong, subdepressed carneous
muscle arises from the diapophyses of the fifth, fourth, third
and second cervical vertebras, and is inserted into the parocci-
pital.

Longus colli. This large and long muscle, which appears
simple when first exposed, is found to consist, wdien unravelled
by further dissection, of a series of closely succeeding long, narrow
fasciculi, arising from the hypapophyses of the sixth dorsal to the
first dorsal, and from the ten posterior cervical vertebrae ; and
sending narrow tendons which increase in length as they are
given off more anteriorly, obliquely forward and outward, to be
inserted into the pleurapophyses of all the cervical vertebrae save
the first two : the highest or foremost tendon is attached to the
tubercle at the under part of the ring of the atlas ; but this
tendon is also the medium of insertion of five small fasciculi of
muscular fibres arising from the diapophyses of the sixth, fifth,
fourth, third and second cervical vertebra.

The rectus capitis anticus major is continued, or arises by as
many distinct tendons, from the five superior tendons of insertion
of the preceding muscle ; these origins soon become fleshy, con-
verge, and coalesce pre\dous to their insertion into the base of the
skull.

The rectus capitis anticus minor is a strong fleshy compressed
triangular muscle arising from the anterior part of the body of
the first four cervical vertebra), and inserted into the basi-
occipital.

The rectus capitis lateralis arises from the diapophyses of the
sixth to the second cervical vertebrae inclusive ; it is inserted into
the lateral ridge or tubercle of the basioccipital.

The ohliquus externus ahdomiiiis arises, fleshy, from the second
and third ribs, and by a strong aponeurosis from the succeeding
ribs near the attachment of the costal processes, and from those
processes. The fleshy fibres are continued from this aponeurotic
origin to nearly opposite the ends of the vertebral ribs ; they run
almost transversely, very slightly inclined towards the pubis, to
within half an inch of the linea alba, and there terminate, by an

MUSCULAR SYSTEM OF AVES. 91

almost straight, parallel line, in their aponeurosis of insertion.
The fibres of this aponeurosis decussate those of the opposite side,
and adhere to the tendinous intersections of the rectus beneath.
The aponeurosis from the last rib passes to be inserted into a
strong ligament extending between the free extremities of the
pubic bones, leaving the abdomen, behind the last rib, defended
only by the internal oblique and transversalis.

The ohliquus internus abdominis arises from the whole of the
anterior and outer surface of the pubis; aponeurotic from the
upper part, fleshy for half an inch from the lower or ventral
extremity : the carneous fibres run longitudinally, and cannot be
distinctly defined from the intercostales on their outer border, or
from the rectus abdominis on their inner or mesial border, which
forms the medium of the insertion of the internal oblique.

The rectus abdominis is the medial continuation of the pre-
ceding muscle, which arises by a strong, flat, triangular tendon
from the lower or ventral extremity of the pubis and from the
inter-pubic ligament : it soon becomes fleshy ; the carneous por-
tion is interrupted by three broad, oblique, but distinct aponeu-
rotic intersections, and is finally inserted into the sternum.

Transversalis abdominis. A layer of loose, dark-coloured cel-
lular tissue divides the internal oblique from the transverse abdo-
minal, except at its origin from the pubis, and for half an inch
anterior to that part. The transversalis then proceeds to derive
carneous fibres from the inner surface of the ribs near their lower
third; they pass obliquely upward and forward, and terminate
by a regular, slightly concave line midway between their origins
and the extremities of the ribs ; a strong aponeurosis passes thence
to the linea alba, but becomes thin at the pubic region, where a
mass of fat is interposed between it and the peritoneum.

The diaphragm presents more of its mammalian character in
the Apteryx ' than in any other known bird. It is perforated by
vessels only, in consequence of the non-developement of the abdo-
minal air-cells. The origin corresponding to that of the lesser
muscle in Mammals is by two strong and distinct, short tendinous
pillars from the sides of the body of the last costal vertebra ; they
are united by a strong tendon or fascia, forming the anterior
boundary of the aortic passage. The tendinous pillars may be
traced forward for some way in the central aponeurosis, expanding
without crossing ; they are then lost in that aponeurosis, which is
perforated by the gastric arteries and veins, divides anteriorly to

1 XI-. vol. ii. pi. 52 ; vol. iii. pi. 36, p. 287.

92 ANATOMY OF VEKTEBRATES.

give passage to the gullet and the apex of the heart, expands
over the anterior part of the thoracic air-cells, and becomes, at its
lateral circumference, the point of attachment of muscular fibres
arising from the inner surface of the anterior ribs, and forming
apparently a continuation of the transversalis ahdominis.

The appendico-costales^ arise from the posterior edge and ex-
tremity of the costal processes, and run down to be inserted
severally into the rib posterior to that to which the process
affording them origin is attached. These processes are supported
by strong triangular aponeuroses continued from their anterior
and upper margins, severally, to the rib anterior to them.

The levator caudcB arises from the posterior and superior ex-
tremity of the ischium ; it is inserted into the spines of the caudal
vertebrae. In birds with a posteriorly expanded sacrum, that
bone affords the chief origin to this muscle, fig. 35, lo.

The adductor caudcB superior is smaller than the preceding,
with which it runs parallel; it rises below from the posterior
extremity or tuber of the ischium, and is inserted into the pleura-
pophyses of the caudal vertebrae.

The adductor caudce inferior arises from the tuber ischli and
the ligament connecting this with the posterior extremity of the
pubis. It is inserted into the diapophyses of the caudal vertebrae.

The depressor caudcB arises, ib. 15, from the under part of the
middle line of pelvis ; it is Inserted into the inferior spines of the
caudal vertebrae.

In birds of flight the ' rectrices,' or rudder-quills attached to
the coalesced and modified terminal vertebras call for moving
powers not developed in the Apteri/x.

The quadratus coccijgis, fig. 35, ii, arises from the diapo-
physes of the coccygeal vertebra?, and is inserted into the shafts
of the tail-quills, which it separates and raises. On the lateral
aspect the puho-coccygeus, ib. 12, arises from the posterior margin
of the pubis, and inserted also into the shafts of the exterior rec-
trices ; it is by means of these muscles in conjunction with the
quadratus and levator caudal, that the Peacock raises the gorgeous
plumes overlying the true tail-feathers.

The ilio-coccygeus, ib. 13, extends from the posterior margin of
the ilium to the last coccygeal vertebra, and to the small inferior
tail-feathers.

On the ventral or inferior aspect of the tail, the muscles are in
general more feebly developed than on the opposite side, except

' X1-. vol. iii. pi. 32, //» p. 287.

MUSCULAR SYSTEM OF AVES. 93

in the Woodpeckers, where the tail, by means of its stiff and
pointed qnill-feathers, serves as a prop to support the bird on the
perpendicular trunks of trees on which it seeks its food. In these
the ischio-coccygeus, ib. 14, is of large size, extending from the
lower edge of the ischiadic tuberosity, and from the diapophyses
of the anterior caudal vertebrae to the hajmapophyses of the pos-
terior ones, and to the sides of the ploughshare bone.

Of the Muscles of the head, those which are attached to it for
its general motions have already been described ; the remaining
muscles of this part are devoted to the movements of the jaws, the
tongue, the eye, and the ear.

The muscles of the jaws are chiefly modified in relation to the
moveable condition of the upper mandible and tympanic bone,
and the subserviency of the latter to the actions of these parts.

The temiioralis, fig. 35, 17, fills the temporal fossa, which con-
sequently indicates the bulk of that muscle in the dry skull. It
arises from a greater or less extent of the temporal and parietal
bones, and, as it passes within the zygoma, becomes closely
blended with the masseter ; the united muscles derive an acces-
sion of fibres from the lower part of the orbit, and are inserted
into the raised superior margin, representing the coronoid process ;
and into the sides of the lower jaw from the articulation as far
forward as the commencement of the horny bill. In the Cormo-
rant, the osseous style, moveably articulated to the superoccipital,
affords to the temporal muscles a more extensive origin. This,
indeed, is its essential use,^ for the muscles of the upper part of
the neck are inserted into the occipital bone, and glide beneath
the posterior or superadded fasciculi of the temporalis.

The biventer maxlllce, ib. 18, arises by two portions, the one
from the lateral depression, the other from the lower part of the
paroccij)ital ; they are inserted into the back part and angle of
the lower jaw.

The openers and closers of the mandibles present very slight
differences of bulk in relation to the developement of the parts they
are destined to move ; their disproportion to the bill is, on the
contrary, truly remarkable in the Horn-bills, Toucans, and Pe-
lican, and the bill is but weakly closed in these in comparison
with the shorter-billed birds.

The upper mandible when moveable is acted on by three
muscles on either side. The first is of a radiated form, arises,
from the septum of the orbits, the fibres converging to be inserted

> XXIV. p. 234.

94 ANATOMY OF VERTEBEATES.

into the pterygoid near its articulation with the tympanic. It
draws forward the pterygoid bone, wliich pushes against and raises
the upper jaw.

The entotympanicus, or levator tympanicus, arises from the side
of the basisphenoid and is inserted into the fossa, on the inner
surface of the tympanic bone : in adducting that bone it pushes for-
ward the pterygoid, and, consequently, the upper mandible in the
same way as the preceding muscle, and assists in opening the bill.
The pterygoideus externus arises from the outer side of the
orbital process of the tympanic, and is inserted into the mandible in
front of the outer articular cavity. The pterygoideiis internus
arises by a tendon from the fore part, and by fleshy fibres from
the rest, of the depression upon the palatine bone, and is inserted
into the inner part of the inflected angle of the mandible. This
muscle draws forward the lower jaw.

In the Cross-bill {Loxia curvirostra) there is a remarkable want
of symmetry in the muscles of the jaws on the two sides of the
head corresponding to their peculiar position. Those of the side
towards which the lower jaw is drawn in a state of rest (which
varies in diflerent individuals) are most developed, and act upon
the mandibles with a force that enables the bird to dislodge the
seeds of the fir-cones, which constitute its food.^

The articulation of the lower jaw is strengthened and its move-
ments restrained by two strong ligaments ; one of these is extended
from the squamosal to the outer protuberance near the joint of
the lower jaw. The second ligament extends from the hind end
of the squamosal directly backward to the posterior part of the
inner articular depression of the lower jaw, and guards against
the backward dislocation of the lower jaw.

§ 133. Muscles of the icings. — Some of those inserted into the
humerus, are prodigiously developed, and form the most charac-
teristic part of the myology of the Bird. The muscles of the
shoulder, however, are but small, and those of the distal segments
of the wing still more feeble.

The Trapezius, fig. 35, 20, arises from the spines of the lower
cervical, and a varying number of the contiguous dorsal ver-
tebras, and is inserted into the dorsal margin of the scapula and
the corresponding extremity of the coracoid.

The rUomhoideus lies immediately beneath the preceding, and
is always single ; it passes in a direction contrary to the trapezius
from the spines of the anterior dorsal vertebras to the dorsal edge
of the scapula. It has no representative in the Apteryx.

' XXVI1-. p. 459.

MUSCULAR SYSTEM OF AVES. 95

The levator scapulce arises by digitations from the pleura-
pophyses of the last cervical, and the first two dorsal vertebraj ;
it is inserted into the posterior part of the dorsal edge of the
scapula, which it pulls forwards. In the Apteryx it seems to be
the most anterior portion of the series of fasciculi composing the
serratus magnus anticus. This muscle, ^^. 35, 21, is most de-
veloped in birds of prey ; it arises by large digitations from three
or four of the middle ribs, and converges to be inserted into the
extremity of the scapula.

The serratus parvus anticus arises by digitations from the first
and second ribs, and is inserted into the commencement of the
inferior margin of the scapula. This is the largest of the muscles
of the scapula in the Penguins.

A muscle, which may be regarded either as a portion of the
pectoralis minor or as the analogue of the suhclavius muscle,
arises from the anterior angle of the sternum, and is inserted into
the external margin of the sternal extremity of the coracoid bone.

The sujira-spinatus, ib. 22, arises from the anterior and outer
part of the humeral end of the scapula, and is inserted behind
the largely developed radial crest of the humerus.

The muscle which seems to represent both the infraspinatus
and teres major, ib. 23, has a more extensive origin from the
scapula, and is inserted into the ulnar tuberosity of the humerus,
where it is closely attached to the capsule of the shoulder-joint.

The subscapularis arises from the anterior part of the inner sur-
face of the scapula, and is inserted into the ulnar humeral tubero-
sity. It is divided into two portions by the pectoralis minor.

The latlssimus dorsi, ib. 24, is but a feeble muscle in Birds, and
is constantly divided into two distinct slips. The anterior portion
arises, more superficial than the trapezius, from the spines of the
four or five anterior dorsal vertebrae, and is inserted near the
tendon of the deltoid into the outer side of the humerus. The
posterior slip comes from the spines of the dorsal vertebrae above
the origin of the broad abductor femoris, ib. 40, and sometimes
from the anterior margin of the same muscle, and is inserted
by a broad and thin tendon immediately in front of the pre-
ceding portion.

The deltoides, ib. 26, arises from the anterior part of the scapula;
also in Volitores and Cantores from the acromial end of the furcu-
lum and the coraco-furcular ligament : a distinct fasciculus from
the inner angle of the humeral end of the scapula passes over
the OS humero-scapulare, or the humero-scapular ligament, to be
inserted into the angle of the pectoral ridge ; this portion is large

96 ANATOMY OF VERTEBRATES.

and distinct in Doves ; ^ where the humero-scapular ossicle exists,
a fascicuhis therefrom, large in Owls, appears as a distinct origin
of the deltoid, the main mass of which muscle is inserted into the
pectoral ridge from its angle distad. The deltoid raises and
retracts the wing.

Birds have the iiectoralis muscle divided, as in many Mammals,
into three portions, so distinct as to be regarded as separate
muscles ; they all arise from the enormous sternum, and act upon
the proximal extremity of the humerus.

The first or great jjectoral muscle, ib. 25, is extraordinarily de-
veloped, and is in general the largest muscle of the body. In
birds of flight it often equals in weight all the other muscles of
the body put together. It arises from the anterior part of the
outer surface of the clavicle or furculum, from the keel of the
sternum, and from the posterior and external part of the lower
surface of that bone ; it is inserted by an extended fleshy margin
into the palmar surface of the pectoral crest of the humerus. It
forcibly depresses the humerus, and, consequently, forms the
principal instrument in flight.

This muscle is very long and wide in the Natatores generally,
but in the Penguin, its origin is limited to the external margin of
the subjacent pectoral muscle, which is here remarkably developed.
The great pectoral is very long, but not very thick in the Rasores.
In the Herons it is shorter, but much stronger and thicker. Its
size is most remarkable in the Humming-birds, Swallows, and
diurnal Birds of Prey, where it is attached to almost the whole
outer surface of the sternum and its crest, and has an extended
insertion. In the Ostrich its origin is limited to the anterior and
external eighth part of the sternum, and it is inserted by a
feeble tendon into the commencement of the pectoral crest of the
humerus, to which it gives a strong rotatory motion forwards.
In the Apteryx the pectoralis major - is represented by two thin
triano-ular layers of muscular fibres attached to the under and
lateral part of the sternum, and converging to be inserted into the
proximal third of the minute humerus.

The second pectoral muscle is situated in birds of flight beneath
the great pectoral ; it has the form of an elongated triangle : it
arises from the base of the crest of the sternum and from the
mesial part of the inferior surface of that bone ; it increases in
size as it ascends, then again becomes suddenly contracted, passes
upward and backward round the coracoid, between that bone and

• XLXIII-. p. 400. - xr. vol. iii. p. 289, pis. 31, 32, p.

MUSCULAR SYSTEM OF AVES. 97

the clavicle, then turns downward and outward, and is inserted,
fleshy, above and in front of the great pectoral, into the upper ex-
tremity of the humeral crest.

The interspace between the clavicle, coracoid, and scapula,
through which its tendon passes, serves as a pulley, by means of
which the direction of the force of the carneous fibres is changed,
and although these fibres ascend from below toward their inser-
tion, yet they forcibly raise the humerus, and thus a levator of the
wing is placed without inconvenience on the lower part of the
trunk, and the centre of gravity proportionally depressed.

In the Penguins, Guillemots, and Gulls, this muscle is almost
the largest of the three, occupying the whole length of the ster-
num. It is remarkable for the length and strength of its tendon,
which is inserted so as to draw forwards the humerus with great
force. It is proportionally the smallest in the Raptores ; and is
very small and slender in the Struthious birds.

We have already alluded to the use which the Penguin makes
of its diminutive anterior extremities as water-wings, or fins ; to
raise these after making the down-stroke obviously requires a
greater effort in water than a bird of flight makes in raising its
wings in air : hence the necessity for a stronger developement of
the second pectoral muscle in this and other diving birds, in all
of which the wings are the chief organs of locomotion, in that
action, and consequently require as powerful a developement of
the pectoral muscles as the generality of birds of flight.

The third pectoral 7?iitscle, ^vhicli is in general the smallest of
the three, arises from the anterior part of the sternum at the angle
between the body and keel, and also by a more extended origin,
from the posterior moiety of the inferior surface of the coracoid
and the coraco-clavicular membrane ; it is directed forward,
rising, to pass through the scapulo-coracoid trochlea ; its tendon
glides through a sheath, attached to the capsule of the shoulder-
joint, and in some birds to the os humero-scapulare ; and is inserted
into the radial tuberosity of the humerus which it helps to raise.

It is proportionally large in the Penguins and Gulls, but attains
its greatest developement in the Gallinaceous order.

Above the preceding muscle there is another longer and more
slender one, analogous to the coraco-hrachialis, which arises
from the middle of the posterior surface of the coracoid ; its direc-
tion upward is less vertical than that of the third pectoral, along
the outer side of which it is attached to the anterior tuberosity
of the humerus. This muscle is wanting in the Struthw?iidce, is
of small size in the Heron and Goose, is much more developed m

VOL. IT. PI

98 ANATOMY OE VEKTEBRATES.

the Raptores and many Natatores^ especially tlie Penguins, and
attains its greatest relative size in the Masoresj where it arises
from almost the whole of the coracoideum.

Birds in general possess t\NO flexors 31 and one extensor, fig. 35,
27, of the fore-arm. They have also muscles corresponding to
pronators and supinators, but their action is limited in the feathered
tribes to inflexion and extension of the fore-arm, and to adduction
and abduction of the hand.

A remarkable muscle, partly analogous in its origin to the cla-
vicular portion of the deltoid, but differently inserted, is the ex-
tensor plicce cdaris, ih. 3o, a^, b, and forms one of the most powerful
flexors of the cubit. It is divided into two portions, of which the
anterior and shorter arises from the internal tuberosity of the
humerus ; the posterior and longer from the clavicular extremity
of the coracoid bone. In the Ostrich and Rhea, however, both
portions arise from the coracoid. The posterior muscle, b, sends
down a long and thin tendon which runs parallel with the hu-
merus, and is inserted, generally by a bifurcate extremity, into
both the radius and ulna. The anterior muscle, a, terminates in
a small tendon which runs along the edge of the aponeurotic ex-
pansion of the wing. In this situation it becomes elastic; it
then resumes its ordinary tendinous structure, passes over the
end of the radius, and is inserted into the short confluent meta-
carpal, u. It combines with the preceding muscle in bending the
fore-arm ; and further, in consequence of the elasticity of its
tendon, puckers up the soft part of the fold of the wing.

A lesser flexor of the fore-arm, and stretcher of the alar mem-
brane, ib. 31, arises, as a portion of the serratus magnus from the
ribs, and terminates in an aponeurosis inserted into the alar
membrane and fascia of the fore-arm ; it is represented in fig. 35
as turned aside.

The extensor metacarpi radialis longus, ib. 32, is the first
muscle which detaches itself from the external condyle of the
humerus, s, and it forms the radial border of the muscular mass
of the fore-arm ; it terminates in a large tendon about the middle
of the fore-arm, and this tendon passes along a groove of the
radius, over the carpus, to the phalanx of the metacarpal, s, into
the radial margin of which it is inserted. It raises the hand, draws
it forward toward the radial margin of the fore-arm, and retains
it in the same plane. In the Penguin this muscle is extremely
feeble, and the tendon is lost in that of the tensor jjlicce alaris.

The extensor metacarpi radialis brevis, ib. 33, arises below the
preceding from the ulnar edge of the radius, and is inserted into

MUSCULAR SYSTEM OF AVES. 99

the phalanx of the thumb immediately beyond the tendon of the
preceding muscle. The two tendons are quite distinct from one
another in the birds of prey, the Ostrich and Parrots, but unite
at the lower end of the fore-arm in the Anatidcs, PhasianidcE, and
Grid dee.

The extensor carpi ulnaris. ib. 34, comes off from the inferior
extremity of the outer condyle of the humerus, passes along the
middle of the exterior surface of the fore-arm, and its tendon,
after passing through a pulley at the distal end of the ulna, is
inserted into the ulnar phalanx. It draws the hand toward the
ulnar edge of the fore-arm, and is the principal abductor or folder
of the pinion.

The flexor metacarpi radialis, ib. 35, is a short and weak
muscle, which arises from the inferior part of the ulna, descends
along the internal side of that bone, winds round its lower extre-
mity and the radial edge of the carpus, passes beneath the tendon
of the radial extensors, and is inserted, external to the latter,
high up into the dorsal aspect of the radial phalanx of the meta-
carpus. In the Ostrich it arises from the lower third of the
ulna. In the Peno-uin it is wantino;.

The flexor metacarpi ulnaris, ib. 36, arises beneath the fore-
arm from the internal pulley of the ulna, continues fleshy to the
pinion, and is inserted, first into the ulnar carpal bone, then into
the ulnar phalanx. The latter insertion is wanting both in the
Ostrich and Penguin.

The muscles of the pinion or hand are few, and very distinct
from one another ; the index or spurious wing is moved by four
small muscles, viz. two extensors, an abductor, which draws the
digit forward, and an adductor. The middle digit receives three
short muscles, two of which are extensors, and the third an
abductor ; in this action it is aided by one and opposed by another
of the extensors. The outer digit receives an abductor, which
comes from the ulnar edge of the preceding phalanx.

§ 134. Muscles of the Legs. — The muscles of the pelvic limb are
here described chiefly as they exist in the Apteryx, in which they
present their full developement. The most superficial of the
muscles on the outer side of the leg is that very broad one which
combines the functions of the tensor vaginai and rectus femor is, but
which, in the opinion of Cuvier^ and Meckel,^ is the homologue
of the tensor vagijicc and glutcBus maximus (seu externus) : since,

^ XII'. torn. i. p. 502. 2 xlvi*. th. iii. p. 361.

H 2

100 ANATOMY OF VERTEBRATES.

however, it is exclusively inserted into tlie leg, it is here described
with the other muscles moving that segment of the pelvic ex-
tremity. The removal of this muscle, of the sartorius, and the
hiceps cruris, is requisite to bring into view the true glutm.

Gluteus externus^ is smaller than the middle glutmis, but is
relatively larger in the Apteryx than in birds of flight. Besides
its orio-in from the outside of the pelvis, it overlaps part of the
(jlutmis medius, and has its insertion into the femur at some
distance below the great trochanter, all of which are marked
characteristics of the glutcBus magnus. It takes its origin from
the superior margin of the os innominatum, extends along an inch
and a quarter of that margin, directly above the hip-joint, and is
chiefly attached by distinct short tendinous threads, which run
down upon the external surface of the muscle : it rises also by
carneous fibres from the external surface of the os innominatum
for three lines below the superior margin. The fibres converge
and pass into a tendinous sheet, beginning on the external surface
of the muscle half-way down its course, which ends in a broad,
flat, strong tendon, inserted into a rising on the outer side of the
femur nearly an inch below the great trochanter. It abducts and
raises the femur.

The gluteus medius'^ is a large, triangular, strong and thick
muscle, which has an origin of three inches' extent from the
rounded anterior and superior margin of the ilium, and from the
contiguous outer surface of the bone for an extent varying from
an inch to eight lines. Its fibres converge to a strong, short,
broad and flat tendon, implanted in the external depression of the
oreat trochanter, having a bursa mucosa interposed between the
tendon and the bony elevation anterior to the depression.

The glutcEus minimus^ rises below and internal to the preceding
muscle from the anterior and inferior extremity, and from one
inch and three-fourths of the inferior and outer margin of the
ilium, and contiguous external surface, as far as the origin of
the glutceus medius ; also by some fleshy fibres from the outside
of the last rib. These fibres slightly converge as they pass back-
ward to terminate in a broad flat tendon which bends over the
outer surface of the femur, to be inserted into the elevation ante-
rior to the attachment of the glutceus magnus.

A muscle * which may be regarded either as a distinct accessory
to, or a strip of, the preceding one, arises immediately behind it
from half an inch of the outer and inferior part of the ilium ; its

' xr. vol. iii. p. 290, pi. 32, a - lb. pi. 32, b. ^ j^ j,]. 32, c. '' lb. pi 32, d.

MUSCULAR SYSTEM OF AVES. 101

fibres run nearly parallel with those of the glutcBus minimus^ and
terminate in a thin flat tendon^ which similarly bends round the
outer part of the femur, to be inserted into the outer and under
part of the trochanter immediately below the tendon of the glutcsus
medius. This muscle and the preceding portion, or glutcBus mini-
mus, are described by Prof. Mayer ^ under the names of c/lutceus
quartus and glutcBtis quintus, in the Cassowary ; one of them is
absent in most Birds.

Use. All the preceding muscles combine to draw the femur
forward, and to abduct and rotate it inward.

Iliacus inter nus. This is a somewhat short thick muscle, of a
parallelogrammic form, fleshy throughout ; rising from the tube-
rosity of the innominatum in front of the acetabulum immediately
below the glutcBus minhmis, and inserted at a point corresponding
to the inner trochanter, into the inner side of the femur near the
head of that bone, which it thus adducts and rotates outwards.
This muscle is present both in the Ostrich and Bustard.

Pyramidalis. The same kind of modification which aflects the
iliacus internus, viz. the displacement of its origin from the inner
surface of the ilium to a situation nearly external, aflects this
muscle. It arises fleshy from the outer surface of the ischium for
the extent of an inch, and converges to a broad flat tendon which
is inserted into the trochanter femoris opposite, but close to, the
tendon of the glutceus minimus, which it opposes, abducting and
rotating the femur outwards.

The adductor hrevis femoris ^ arises from the innominatum im-
mediately behind the acetabulum, passes over the back part of
the great trochanter, becomes partially tendinous, and is inserted
into the back part of the femur in common with the following
muscle.

The adductor longus^ is a long, broad and thin muscle, sepa-
rated from the preceding by the ischiadic nerve and artery. The
origin of this muscle extends one inch and a quarter from near
the upper margin of the innominatum which is behind the aceta-
bulum ; it is joined by the preceding strip, and is inserted into
the whole of the lower two-thirds of the back part of the femur.

The adductor magnus^ is a broad and flat muscle, which has
an extensive origin (two inches) from the outer edge of the
ischium and the obturator fascia ; its fibres slightly diverge as they
pass downward to be inserted into the back part of the lower
half of the femur, and into the upper and back part of the tibia.

' XX1X-. p. 12. 2 xr. vol. iii. pi. 32, e. ^ jb.pls, 32, 35, r.

* lb. pi. 35, G.

102 ANATOMY OF VERTEBRATES.

The ohdurator inter nus arises from the inner side of the oppo-
site margins of the pubis and ischium, where they form the
posterior boundary of the ohturatoy^ foramen, and from the corre-
sponding part of the obturator fascia ; the fleshy fibres converge
in a shghtly penniform manner to the strong round tendon which
glides through the notch, separated from the rest of the foramen
by a short, strong, transverse, unossified ligament, and is inserted
into the posterior part of the base of the trochanter. In its length
and size this muscle resembles the corresponding one in the
Ostrich and other Struthious birds.

The gemellus is represented by a single small fleshy strip
arising from the margin of the obturator foramen, close to the
emer2:ence of the tendon of the obturator internus, with which it
is joined, and co -inserted into the femur.

The quadratus is a broad fleshy muscle which arises from the
pubis, below the obturator foramen, and which increases in breadth
to be inserted into the femur internal and posterior to the obtu-
rator tendon.

Abductor magnus} The largest and most remarkable of the
muscles which act upon the bones of the leg is that already
alluded to as the most superficial of those on the outer side of the
thigh. It has a broad, thin, triangular form, and arises from the
spines of the sacrum by a strong but short aponeurosis which
soon becomes fleshy ; the carneous fibres converge as they de-
scend," and pass into a thin aponeurosis at the lower third of the
thigh : this is closely attached to the muscles beneath {vastus
externus and crurcsus), then spreads over the outer and anterior
part of the knee-joint, is inserted into the patella, and into the
anterior process of the head of the tibia.

Owing to the great antero-posterior extent of the origin of this
muscle, its anterior fibres are calculated to act as a flexor, its
posterior ones as an extensor, of the femur : all together combine
to abduct the thigh and extend the leg, unless when this is in a
state of extreme flexion, when a few of the posterior fibres glide
behind the centre of motion of the knee-joint.

Sartorius.^ The origin of this muscle is characterised by an

* xr. vol. iii. pi. 31, ii.

* They are not divided into a superficial and deep layer, as in the Ostrich, but
forin a simple stratum, as in the Cassowary. Meckel regards the rectus femoris jis
entirely wanting in the Cassowary, supposing, with Cuvier, the present muscle to be
the analogue of the glutceus vmximus and tensor vagivte united. lie says that Profes-
sor Nitzsch observed a like absence of the rectus femoris in the Emeu. Cuvier calls
that muscle rectus anticus femoris, which is here described as the ^ pectineus.'

^ X1-. vol. iii. pis. .31 and 3.5, i.

MUSCULAR SYSTEM OF AVES. 103

unusual extension, like that of the preceding, with which it is
posteriorly continuous : it comes off aponeurotic, from the anterior
and superior margin or labrum of the ilium; the fibres soon
become fleshy, and the muscle diminishes in breadth and increases
in thickness as it descends ; it is inserted by short and strong
tendinous filaments obliquely into the anterior part of the tendon
of the broad rectus, and into the anterior and inner part of the
head of the tibia. Its insertion is partly covered by the internal
head of the gastrocnemius. It bends and adducts the thigh, and
extends the leg.

The homologue of the biceps flexor cruris^ is a unicipital
muscle, corresponding with the abductor magnus, by the removal
of which it is exposed, in the characteristic modification of its
extended origin, in relation to the great antero-posterior develope-
ment of the pelvic bones. Orig. By a broad and thin aponeurotic
tendon, which at first is confluent with that of the abductor, but
soon becomes distinct, from the posterior prolongation of the
ilium : there is no second head from the femur. Ins. The fleshy
fibres converge as they descend along the back and outer part of
the thigh, and finally terminate in a strong round tendon, which
glides through a loop formed, as in the common Fowl, Ostrich,
&c., by a ligament extended from the back of the outer condyle
of the femur to the head of the tibia, and is inserted into the
process on the outside of the fibula. By means of the loop the
weight of the hinder parts of the body is partially transferred,
when the leg is bent, to the distal end of the femur ; and the
biceps is enabled, by the same beautiful and simple mechanism,
to effect a more rapid and extensive inflection of the leg than it
otherwise could have produced by the simple contraction of its
fibres.

The semimembranosus'^ arises from the side of the caudal
vertebrae, and from the posterior end of the ischium ; it crosses
the superficial or internal side of the semitendinosus. It is in-
serted into the fascia covering the gastrocnemius and the inside
of the tibia : through the medium of the fascia it acts upon the
tendon of the internal gastrocnemius.

The semitendinosus^ arises from the posterior and outer part
of the sacrum and the aponeurosis connecting it with the ischium :
it is a flattened triangular muscle, which receives the square
accessorius muscle from the lower and posterior part of the femur.
It gradually diminishes as it descends, and having passed the

' xr. vol. iii. pis. 31, 32, k. ^ lb. pis. 32, 35, l. ^ lb. pis. 32, 3.5, m.

104 ANATOMY OF VERTEBRATES.

knee-joint, sends off at right angles a broad and square sheet of
aponeurosis, which glides between the tAVO origins of the gastro-
cnemius interims, and is inserted into the lower part of the angular
ridge continued from the inside of the head of the tibia. The
terminal tendon, continued from the apex of the muscle, then
runs along the outer or fibular margin of the internal head of the
gastrocnemius, and becomes confluent with the tendon of that
muscle.

The crurccus ^ is a simple but strong muscle : it commences at
the upper and anterior part of the thigh by two extremities, of
which the outer and upper one, representing the vastus externus,
has its origin extended to the base of the trochanter ; the inner
and inferior comes off from the inner side of the femur, beneath
the insertion of the glutceus magnus ; the two portions blend into
one muscle much earlier than in the Ostrich. It is inserted by
the ligamentum patellie into the fore-j^art of the head of the
tibia.

The gracilis- lies on the inner side of the crurceus, but more
superficially ; it rises by two heads, one from the anterior and
upper part of the femur, the other from the os pubis ; both soon
become blended together and transmit a broad thin tendon to be
inserted into the lower and lateral part of the patella with the
crurcEus.

Two other muscles succeed the j)receding, and rise beneath it
from the inner and anterior part of the femur ; they have a
similar insertion, and obviously represent the vastus internus^^
The fibres converge to a middle aponeurosis, which increases to a
strong short tendon, inserted into the uj)per and anterior projec-
tion of the tibia.

Popliteus. This small muscle is brought into view when the
superficial muscles of the leg which are inserted into the foot are
removed. Its carneous fibres extend from the fibula inward and
downward to the tibia. It is of relatively smaller extent than in
the Cassowary.

Gastrocnemius. This complex and powerful muscle consists,
as in other Birds, of several distinct portions, the chief of which
correspond with the external and internal origins of the same
muscle in Mammals. The gastrocnemius externus'^ arises by a
strong, narrow, rather flattened tendon from the ridge above the
external condyle of the femur, which, about an inch below its

' XI-. vol. iii. pis. 32, 35, o. - lb, pi. 35, P. ^ lb. pi. 35, Q.

^ lb. pis. 31, 32, R.

MUSCULAK SYSTEM OF AVES. 105

origin, becomes firmly attaclied to the strong ligamentous loop
attached by one end to the femur above the preceding tendon,
and by the other to the outer ridge of the fibula. This trochlear
loop is lined by synovial membrane, and sujoports the tendon of
the biceps cruris, which glides through it. The carneous fibres
of the external gastrocnemius come ofi" from the outer side of the
tendon, and from the fascia covering the outer surface of the
muscles of the leg : they are continued in a somewhat penniform
arrangement two-thirds down the leg, upon the inner surface of
the muscle, where they end in a strong subcompressed tendon.
This joins its fellow-tendon, from the internal gastrocnemius,
behind the ankle-joint, and both expand into a thick, strong liga-
mentous aponeurosis, which extends over three-fourths of the
posterior part of the tarso-metatarsal bone. The lateral margins
of this fascia are bent down under the flexor tendons behind the
joint, and become continuous with a strong ligamentous layer
gliding upon the posterior surface of the distal condyles of the
tibia, and attached to the tendons of the yeroneus and tibialis
anticus : the conjunction of the thickened tendons of the gastro-
cnemii with this deeper-seated layer of ligamento-tendinous sub-
stance constitutes a trochlear sheath lined by synovial membrane,
through which the flexor tendons of the toes glide. The synovial
membrane of the ankle-joint is continued upward, half an inch
above the articvdar surface of the bone, between it and the fibro-
cartilaginous pulley. Below the joint the margins are inserted
into the lateral ridges of the tarso-metatarsal bone, becoming
gradually thinner as they descend, and ending below in a thin
semilunar edge directed dowuAvard.

The gastrocnemius internus ^ has two powerful heads, one from
the femur, the other from the tibia ; the first arises fleshy from
the internal condyle of the femur, expands as it descends, and
receives additional fibres from the lower edge of the accessorius
semitendinosi. About one-fifth down the tibia this muscular origin
in the right leg terminated in a flattened tendon which became
attached to the inner side of the tibial portion of the gastrocnemius
internus. The second head, which is separated from the pre-
ceding by the insertion of the semitendinosus, arises partly from
the internal and anterior part of the strong fascia of the knee-
joint by short tendinous fibres, which almost immediately become
fleshy, and partly from a well-defined triangular surface on the
inner and anterior aspect of the head of the tibia : the fleshy fibres

' xr. vol. iii. j 1. 35, e.

106 ANATOMY OF VERTEBRATES.

converge, receive the tendinous slip from the femoral portion, and
end on the inner side of the muscle in a strong flattened tendon,
about two-thirds down the leg : this joins the tendgn of the gas-
trocnemius externus and is inserted as described above.

The soleus ^ is a slender flattened muscle arising from the
posterior part of the head of the tibia, the tendon of which joins
that of the gastrocnemius internus, behind the tarsal joint.

The flexor perforans digitorum ^ lies immediately anterior to
the external gastrocnemius ; it arises fleshy from the outer con-
dyle of the femur, below the tendinous origin of that muscle, and
terminates in a slender flat tendon half-way down the leg. Its
tendon, fig. 35, 5i, glides behind the tarsal joint through the
sheath of the gastrocnemius, expands beneath the metatarsus and
bifurcates, sending its smallest division to the inner toe, ib. 5 2, and
its larger one to blend with the tendon of the peroneus medius.

Flexor perforatus of the outer toe.^ This arises by very short
tendons from the proximal end of the fibula, and from the liga-
ment forming the bicipital pulley ; it continues to derive a thin
stratum of fleshy fibres from the fascia covering the anterior sur-
face of the muscles of the leg : the fleshy fibres terminate half-
way dowm the leg in a flattened tendon, which, after entering the
gastrocnemial sheath, pierces the tendon of the first perforatus of
the middle toe, then runs forward to the outer toe, expands into a
thick ligamentous substance beneath the proximal phalanx, and
sends off two tendinous attachments on each side, one to the
proximal, the other to the second phalanx, and is continued to be
finally inserted into both sides of the third phalanx.

Flexor perforatus digitorum ^ is the strongest of the three ; it
arises fleshy from the posterior part of the distal extremity of the
femur, above the external condyle, and also by a distinct flattened
tendon, one inch in length, from the proximal end of the tibia,
fig. 35, 50 : this tendon, moreover, receives the long slender
tendon, ib. 4i, sent oif obliquely across the front of the knee-
joint from the pectineus, by which its origin is extended to the
pelvis. This accessory tendon perforates the inner fleshy surface
of the muscle, and is finally lost about half-way down the car-
neous part. Before the flexor perforatus is joined by the tendon
of the pectineus, it subdivides posteriorly into four muscular
fasciculi. The anterior division receives principally the above
tendon, and this division of the muscle becomes wholly tendinous
two-thirds down the leg ; its tendon passes through the posterior

' xr. vol. iii. pi. 35, S. - Ib. pis. 31, 32, 35, 1. ^ ^o. pis. 31, 32, 35, 2.

^ Ib. pis. 32, 35, 3, 4, 5, 6.

MUSCULAR SYSTEM OF AVES. 107

part of the pulley of the gastrocnemius, and expands as it passes
along the metatarsus : a thick ligamentous substance is deve-
loped in it opposite the joint of the proximal phalanx of the second
toe, into the sides of which it is inserted, dividing for that pur-
pose, and giving passage to the two other flexor tendons of that
toe. The second portion of the present muscle terminates in a
tendon situated behind the preceding, which passes through a
distinct sheath behind the tarsal joint, expands into a sesamoid
fibro-cartilage beneath the corresponding expansion of the previous
tendon, which it perforates, and then becomes itself the perforated
tendon of the second phalanx of the second toe, in the sides of
which it is inserted. The third portion of this muscle ends in a
somewhat smaller tendon than the preceding, which forms the
second perforatus Jiexor of the third or middle toe. The fourth
and most posterior portion soon becomes a distinct muscle ; its
fleshy fibres cease on the inner side, one-fourth down the leg, but
on the outside they are continued three-fourths down the leg ; its
tendon passes through the gastrocnemial pulley behind the ankle-
joint, and divides to form a sheath for the Jiexor perforatus of the
fourth toe ; it is then joined by the tendon of the peroneus, which
passes through a pulley across the external malleolus, and finally
becomes the perforated tendon of the first phalanx of the middle
or third toe.

Pectineus (^rectus anticus femoris of Cuvier ^ and Meckel ^). —
This is a long, thin, narrow strip of muscle arising from the spine
of the pubis, anterior to the acetabulum, and passing straight
down the inner side of the thigh ; it degenerates into a small
round tendon near the knee, which tendon, fig. 35, 41, traverses
a pulley, formed by an oblique perforation in the strong rotular
tendon of the extensors of the leg, and thus passing across the
knee-joint to the outer side of the leg, finally expands, and is lost
in \hQ Jiexor perforatus digitorum last described. It is this muscle
which causes the toes to be bent when the knee is bent, as in the
act of perching.

Peroneus longus ^ arises, tendinous from the head of the tibia,
and by carneous fibres from the upper half of the anterior margin
of the tibia ; these fibres pass obliquely to a marginal tendon,
which becomes stronger and of a rounded form where it leaves
the muscle. The tendon gives off a broad, thin, aponeurotic
sheath to be inserted into the capsule of the tarsal joint ; it is
then continued through a synovial pulley on the side of the outer

* xir. p. 523. 2 XLV1-. th. iii. p. 365. " xi'. vol. iii. pis. 32, 35, 7.

108 ANATOMY OF VERTEBRATES.

malleolus, and is finally inserted or continued into the perforated
tendon of the middle toe.

The tibialis anticus, ' fig. 35, 48, is overlapped and concealed
by the peroneus ; it arises partly in common with that muscle,
and partly by separate short tendinous threads from the outer
part of the head of the tibia ; it gradually becomes narrower, and
finally tendinous two-tlnrds of the Avay down the leg ; its strong
tendon glides through the oblique pulley^ in front of the distal
end of the tibia, expands as it passes over the ankle-joint, and is
inserted into the anterior part of the proximal end of the tarso-
metatarsal bone, sending off a small tendinous slip to the aponeu-
rosis covering the extensor tendons of the toes, and a strong
tendon which joins the fibular side of the tendon of the following
muscle.

Extensor longus digitorum.^ This lies between the tibialis
anticus and the front and outer facet of the tibia, from which it
derives an extensive origin ; its tendon commences half-way down
the leg, runs along the anterior part of the bone, first under the
broad ligamentous band representing the anterior })art of the
annular ligament, then through a ligamentous pulley, and inclines
to the inner or tibial side of the anterior surface of the metatarsal
bone, where it expands and divides into three tendons. Of these
the innermost is given off first, and subdivides into two tendons,
one of which goes to be inserted into the base of the last phalanx
of the second toe; the other portion is principally inserted into
the middle toe, but also sends off a small tendon to the inner side
of the proximal phalanx of the second toe. The second tendon
is inserted by distinct portions into the second, third, and last
phalanges of the middle toe. The third tendon supplies the outer toe.

The extensor brevis digitorum "^ is a small extensor muscle which
arises from the insertion of the tibialis anticus and sends its tendon
to the outer side of that of the great extensor digitorum.

Extensor pollicis brevis.^ This extensor of the small innermost
toe arises from the upper and inner side of the tarso-metatarsal
bone.

Peroneus medius, Cuv., Accessorius flexor is digitorum, Yicq.
d'Azyr.^ This strong 2:)enniform muscle arises fleshy from nearly
the Vvdiole of the outer surface of the fibula, also from the posterior
part of the tibia and the interosseous space ; the tendon of the
biceps perforates its upper part in passing to its insertion. It

' xr. vol. iii. pis. 32, 3.5, 8. '^ This is ossified in most Birds. ^ lb. pi, 35, 9.

* lb. pi. 35, 10. ^ lb. pi. 35, 1 J. ^ lb. pis. 32, 35, 12.

MUSCULAR SYSTEM OF AVES. 109

ends in a strong flat tendon at the lower third of the leg, which
tendon runs through a particular sheath at the back part of the
tarsal pulley, becomes thickened and expanded as it advances
forwards beneath the tarsus, joins the tendon of the flexor perfo-
ratus, and forms with it the expansion which finally divides into
three strong perforating tendons, which bend the last joints of the
three long toes.

In the outer, or fourth toe, both the perforans and perforatus
tendons are confined by a double annular ligament ; the exterior
one being continued from the adjoining toe, the inner and stronger
one from the sides of the proximal phalanx of the outer toe. The
second and third toes have two perforated tendons ; one inserted
into the sides of the first, and the other into the sides of the second
phalanx.

The chief modification of the skeleton of the hind limb of Birds,
in respect of size and proportion, is manifested in its central
segment ; the ossa innominata being anomalously expanded in
order to include, as it were, in their grasp the whole of the very
long sacrum required for the support of the horizontal trunk
upon a single pair of extremities. The principal modification of
the muscles of the leo' attached to the ossa innominata mijiht
be expected, therefore, to be found in their origins. In the at-
tachment of the fibres of a superficial muscle to the aponeurosis,
continued from the outer part of the thigh, over the knee-joint, to
the head of the tibia, we recognise the corresponding insertion of
the tensor vagincB femoris of Man and Mammals ; and no Com-
parative Anatomist appears to have thought the anomalous de-
velopement and extensive origin of this muscle, in Birds, to be
any objection to the homology indicated by its insertion, which is
the attachment that mainly governs the function of a muscle,
Now besides the attachment to the femoral fascia, we find this
broad superficial muscle, and especially its middle and posterior
fibres, terminating in a strong tendon, implanted into the upper
part of the patella, and receiving fibres from the crurceus and vasti
muscles which it immediately covers, and with which it concurs in
constituting a quadriceps extensor of the leg. Here, therefore,
we perceive the normal insertion, the normal function, and the
true relative position of the rectus femoris. In calling this
complex muscle ' abductor mognus^ it is to be understood as
including the homologues of the tensor vagince femoris and rectus
feinoris in Mammals.

§ 135. Muscles of the Skin. — In the Apteryx the cutaneous
system of muscles presents a distinct and extensive developement

110 ANATOMY OF VERTEBRATES,

connected with the peculiar thickness of the integument, and
probably ^Yith the burrowing habits of this species, which thereby
possesses the power of shaking off the loose earth from its plum-
age, while busy in the act of excavating its chamber of retreat
and nidification.

The whole of the neck is surrounded by a thin stratum of
muscular fibres, constrictor colli,^ directed for the most part
transversely, and extending from an attachment along the median
line of the skin at the back of the neck, to a parallel rajyhe on the
median line of the opposite side : this muscle is strongest at its
commencement or anterior part, where the fibres take their origin
in a broad fasciculus from the outer part of the occipital ridge ;
these run obliquely downward and forward on each side of the
neck, but are continued uninterruptedly with those arising from
the dorsal line of the skin above mentioned ; the direction of the
fibres insensibly changing from the oblique to the transverse.
The outer surface of this muscle is attached to the integument by
a thin and dense layer of cellular tissue, devoid of fat ; the under
surface is more loosely connected with the subjacent parts by a
more abundant and finer cellular tissue.

Use, To brace the cervical integument, raise the neck feathers,
and in combination with the following muscle to shake these
parts. This muscle is well developed in the emeu, and acts when
the drum-like dilatation of the windpipe is sounded.

The sterno-cervicalis ^ arises fleshy from the posterior incurved
angular process of the sternum, from the ensiform prolongation
and middle line of the outer and posterior surface of the same
bone. The fibres pass forward, and, diverging in gently curved
lines, ascend upon the sides of the broad base of the neck, and are
inserted by a thin but strong fascia into the median line of the
dorsal integument. This muscle is a line in thickness at its
origin, but becomes thinner as it expands ; the anterior part is
covered by the posterior fibres of the constrictor colli.

Use, To retract the skin of the neck, and brace that portion
Avhich covers the base of the neck ; when these are the fixed
points, it will depress and protract the sternum, and thus aid in
inspiration.

Ohs. In its position and the general course of the fibres, this
muscle is analogous to that which supports and assists in empty-
ing the crop in the common foAvl; but the oesophagus presents no
partial dilatation in the Apterjjx,

' XI •. vol. iii. pis. 31, 34, or. - lh.T^\. ^\, b.

MUSCULAR SYSTEM OF AVES. HI

The sterno-maxillaris ^ appears at first view to be the anterior
continuation of the preceding, but is sufficiently distinct to merit
a separate description and name. It arises lleshy from the
anterior part of the middle line of the sternum, passes directly
forward along the under or anterior part of the neck, expanding
as it proceeds, and gradually separates into two thin symmetrical
fasciculi, which are insensibly lost in the integument covering the
throat and the angle of the jaw. It adheres pretty closely to the
central surface of the constrictor colli, along which it passes to its
insertion. It retracts the fore-part of the skin of the neck, and
also the head. Each lateral portion acting alone would incline
the head to its own side : the whole muscle in action would bend
the neck ; but the movements of the head and neck are more
adequately and immediately provided for by the appropriate
deeper-seated muscles, and the immediate office of the present
muscle is obviously connected with the skin. Nevertheless, in so
far as this muscle acts upon the head, it produces the same move-
ments as the sterno-mcistoideus in Mammalia.

The skin covering the dorsal aspect of the lower two-thirds of
the neck, besides being acted uj^on by the constrictor colli, is
braced doAvn by a thin stratum of oblique and somewhat scattered
fibres, dermo-transversalis^ which take their origins by fasciae
attached to the inferior transverse processes of the sixth to the
twelfth cervical vertebrae inclusive ; the fibres pass obliquely
upward and backward, and are inserted by a thin fascia into the
median line of the skin, covering the back of the neck.

The representative of the platysma myoides^ is a thin trian-
gular layer of muscular fibres, taking their origin from the outer
side of the ramus of the jaw, and diverging as they descend to
spread over the throat, and meeting their fellows at a middle
raphe of insertion beneath the upper larynx and beginning of
the trachea, which they thus serve to compress and support.

The dermo-spinalis arises by a thin fascia from the ends of the
spinous processes of the three anterior dorsal vertebrae. The
fibres slightly converge to be attached to the integument covering
the scapular region.

The dermo-iliacus arises fleshy from the anterior margin of
the ilium. The fibres pass forward and slightly converge to be
inserted into the scapular integument.

The dermo-costalis is a muscle resembling the preceding in
form. It arises fleshy, from the costal appendages of the seventh

> XT.- vol. iii. pi. 34, e. - lb. pi. 34, fig. 1, (/. ' lb. pi. 31, e.

112 ANATOIMY OF VERTEBRATES.

and eighth ribs. The fibres pass forward and join those of the
preceding muscle, to be inserted into the scapular integument.

The three preceding muscles are broad and thin, but Avell-
defined; they would appear to influence the movements of the
rudimentary spur-armed wing through the medium of the integu-
ment, as powerfully as do the rudimental representatives of the
true muscles of that extremity.

There are also two muscles belonging to the cutaneous series,
and inserted directly into the bones of the wing. One of these,
the dermo-ulnaris, is a small, slender, elongated muscle, which
takes its origin from the fascia beneath the dermo-costalis ; its
fibres pass backward, and converge to terminate in a very slender
tendon which expands into a fascia, covering the back part of the
elbow-joint. It extends the elbow-joint and raises the wing.

The dermo-humeralis is also a long and narrow strip, deriving
its origin from scattered tendinous threads in the subcutaneous
cellular tissue of the abdomen : it passes upward, outward and
forward, and is inserted fleshy into the proximal part of the
humerus, which it serves to depress.

The cutaneous muscles which spread the plumes of the peacock
and raise the hackles of the cock are unusually developed in these
birds.

§ 136. Locomotion of Birds. — Upon land, the trunk is ba-
lanced horizontally on an axis traversing the acetabula perpen-
dicidarly to the plane of the medial section. The centre of
gravity is brought within the base of support by the advanced
position of the thigli-joints in the pelvis, and by the transference
of the weight from the femoral heads by the shafts inclining for-
ward to the heads of the tibia?. The area of the base of support
is adjusted to the same end by the anterior extension and diver-
gence of the three longest toes. On this base the stilt-like leg
of the crane, rising like a straight slender column to the capital
formed by the head of the tibia, is capable, by an outward as
well as backward course of the femur to its joint-cup, of sus-
taining the l:)ody singly : the neck of the bird being so bent, and
the head so disposed, as to throw the centre of gravity over the
vertical line passing through the base of support. Thus sleep
the GrallcB and allied Palmipeds (Flamingos, Anserines), adjusting
by reflex action the superincumbent weight as they may be
swayed by the wind on the long and taper pedestal. In standing
on two feet, the tibia and metatarse are usually, in Birds, bent at
an open angle.

Progression on land is effected in most Birds by alternate ad-

LOCOMOTION OF BIRDS.

113

■vancement of the right and left leg ; the body is supported and
pushed forward by one as the other leg is raised and swuno-
forward to the step in advance ; the centre of gravity oscillatino-
laterally, in a degree corresponding with the breadth of the pelvis
and shortness of the legs, and which is such as to cause the 'waddle'
of the Duck. The forces acting on the centre of gravity are
preserved in equilibrio, during the w^alk, by movements of the
neck and head, conspicuous in poultry ; and, in Kails and Coots,
also by movements of the tail. Most Cantor es advance both legs
at once, and progress by leaps or hops, the joints being first
flexed and the body propelled by their sudden extension. In
Volitores the legs merely support or suspend the body, and loco-
motion is wholly performed by the wings. Some birds derive
assistance in rapid terrestrial progression by the flapping of the
wings, and this is especially the case with the Ostrich, which
runs by the alternate advancement of its legs.

The act of climbing is performed by means of a peculiar dis-
position of the toes, the fourth usually being bent back like the
first ; but sometimes, as in Trogons, the first and second toe are
opj)osed to the third and fourth. The grasp of such ' scansorial '
foot may be aided by prehension mth the beak, as in the Mac-
caws and Parrots ; or by the prop formed by the stifl* tail-feathers,
as in the Woodpeckers.

Birds float by the specific levity of their body, arising from
the extension of the air-cells and the lightness of the plumage ;
but to swim requires an expanse of sole, either by marginal
membranes of the toes (Water-rails, Coots), or by the extension
of webs between and uniting the toes. In such true swimmers
the under side of the trunk is boat-shaped, the down is thick and
covered by closely imbricated well-oiled feathers, the bulk of the
bird being enlarged and its specific gravity diminished by the
air intercepted in the plumage. Much of the body is thus sus-
tained above the w^ater by hydrostatic pressure, and muscular
action is needed solely for the horizontal movements. The broad
oars, acting at the end of a long lever, strike the w^ater backward
wdth great force, the webs being fully expanded ; but they
collapse, the toes coming together, in the forward movement, and
in some of the best swimmers {Colymbus e.g.) the metatarsal is
compressed to further diminish the resistance in preparing for the
next effective stroke. The oar-like action of the hinder legs is
still further favoured by their backward position in Nntatores ;
and by the metatarse and toes being placed almost on the same
perpendicular line with the tibia, an arrangement, however^ which

VOL. II. I

114 ANATOMY OF VERTEBRATES.

is unfavourable for walking. Swans partially expand tlieir wings
to the wind while swimming, and thus move along the water by
means of sails as well as oars. The act of diving is performed
by the feet striking the water backward and upward, assisted by
the compression of the air-cells : the habitual divers (Penguins,
Awks) move in and through the water by the rapid and forcible
action of wings, shortened and shaped like paddles, and beating
the water as in flight.

Flight, the chief and characteristic mode of locomotion in birds,
results principally from the construction and form of the anterior
extremities. The form of the body has reference thereto, the
trunk being an oval with the large end forward : being also short
and inflexible, the muscles act with advantage, and the centre of
gravity is more easily changed from above the feet as in the
stationary position, to between the wings as during flight. The
long and flexible neck compensates for the rigidity of the trunk,
and alters the poise according to the required mode of progression,
by simply projecting the head forward, or drawing it back. The
head of the bird is generally small, and the beak pointed, which
is a commodious form for dividing the air. The position of the
great pectoral muscles tends to keep the centre of gravity at the
inferior part of the trunk. The power which birds enjoy of
raising and supporting themselves in the air is aided by the
lightness of the body. The large and usually air-filled cavities
in the bones diminish their weight without taking away from their
strength, — a hollow cylinder being stronger than a solid one of
the same weight and length. But the specific levity principally
depends on the great air-cells which occupy almost every part of
the body. The air which birds inspire distends these cells, and is
rarified by the heat of the body. Lastly, the feathers, and espe-
cially the quills, from their lightness and elastic firmness, contri-
bute powerfully to the act of flying by the great extent which
they give to the wings, the breadth of which is further increased
by the expanded integument situated in the bend of the arm and
in the axilla.

When a bird commences its flight it springs into the air, either
leaping from the ground, or precipitating itself from some elevated
point. During this action it raises the humerus, and therewith the
entire wing, as yet unfolded ; it next spreads the wings horizon-
tally by an extension or abduction of the fore-arm and hand : the
greatest extent of surface of the wing being acquired, it is
rapidly and forcibly depressed : the resistance of the air thus sud-
denly struck occasions a reaction on the body of the bird, which is

LOCOMOTION OF BIRDS. 115

thereby raised in the same manner as in leaping from the ground.
The impulse being once given, the bird folds the wings by bending
the different joints, and raises them preparatory to another stroke.

Velocity of flight depends upon the rapidity with which the
wing-strokes succeed each other ; and the ratio of the resist-
ance of the air is not as the velocity simply, but as the square
of the velocity. A downward stroke would only tend to raise
the bird in the air ; to carry it forward the wings require to be
moved in an oblique plane, so as to strike backward as well as
downward. The turning in flight to the right or to the left is
principally effected by an inequality in the vibrations of the wings.
To wheel to the rio;ht the left
wing must be plied with greater
frequency or force, and vice versa.

The outspread tail contributes
to sustain the posterior part of
the body ; and, its plane being
horizontal, serves chiefly by its
movements to lift or lower the
head. If a bird, flying in the
direction of its axis, q, f, fio;. 36, , ^. ,,.,.«.,, ,.,.,.,

y J y J y O ^ ^ ? Action of tail in flight, cxxxi.

brings the tail into the position

h h, parallel to o n, the resistance of the air will depress h toward
k, and, causing the bird to rotate on its centre of gravity c, mil
raise the head from a towards Z. If the tail be moved into the
position h i, parallel to I k, the resistance of the air mil raise the
point b toward Ji and depress the head toward o. By partially
folding the fan, or bending the tail to one side, it may be made
to act like a rudder in the manifold modifications of the course of
flight. In Waders and Anserines the tail, represented by the
caudal quill feathers, is very short, and the office of the rudder is
transferred to the legs, which are extended backward in flight,
and counterbalance the long outstretched neck and head.

In descending from a great height birds usually incline the
axis of the body obliquely downward, as in fig. 1, the resistance
of the air in a vertical direction upAvard equilibrating the force
of gravity acting upon the body vertically downward, so that the
motion of the bird becomes uniform without requiring any move-
ment of the wings. ' Another mode of descent is performed with
greater celerity by elevating the wings at an angle of nearly 45°
above the plane of the horizon, as in fig. 37, by which the resist-
ance of the air, compared with the resistance to the wing when
horizontal, is diminished in the ratio of the radius to the cube of

I 2

116 ANATOMY OF VERTEBRATES.

the sine of inclination, that is, as « 5 to ^ c ; consequently, a
bird with its mngs elevated at any angle to the horizontal plane

37

will descend mth greater velocity than when they are in the
direction of a b. Pigeons elevate their wings in this manner
until they arrive within a foot or two of the ground, when, to
prevent the shock they would otherwise receive, omng to the
velocity acquired during their descent, they suddenly turn their
axis perpendicular, which had previously been parallel, to the
direction of their motion, and by a few rapid strokes of the wing
neutralise their momentum, and thus reach the ground with ease
and safety.'^

The manner of flight varies in different birds : some dart for-
ward by jerks, closing their wings every three or four strokes ;
the Woodpeckers and Wagtails show this kind of undulatory
motion : most birds have an even continuous flight : the Kite and
Albatross sometimes buoy themselves in the air without any per-
ceptible motion of the wings. The best flyers often economise
their forces by availing themselves of the impetus of a few rapid
strokes to scud along with the wings expanded, until the interval
of rest requires to be broken by a fresh eflbrt, — a phase of flight
beautifully defined by an old observer of nature ; —

Mox acre lapsa quieto
Radit iter liquidum, celeres neque commovet alas. — Virgil.

> CCiv. p. 428. The principal data requisite for estimating by dynamics the
amount of the force employed by birds during flight are briefly stated by Mr. Bishop
to be : — ' 1st, the area of the horizontal section of the body of the bird : 2nd, the area
of the wings whilst they are lowered : 3rd, the area of the wings whilst they are
raised: 4th, the velocity with which the bird is driven through the air: 5th, the velo-
city with which the wings are lowered : 6th, the velocity with which the wings are
raised: 7th, the respective durations of the elevation and depression of the wings:
8th, the weight of the whole bird: 9th, the weight of an equal volume of air: 10th,
the resistance of the air due to the figure and velocity of the bird: 11th, the ratio of
the resistance which the air opposes to the wings during their elevation and depres-
sion : 12th, the ratio of the resistance of the air to the time of an elevation of the
wings and to that of a depression.' lb. p. 425.

117

CHAPTER XYI.

NERA OUS SYSTEM OF AVES.

§ 137. Myelenceplialon of Birds.— The myelon, with its nerves,
having led to the developement of protecting arches in the em-
bryo, soon ceases to be coextensive with the neural canal, shrink-
ing from the hind part of it, as the caudal vertebrae begin to be
modified, and leaving there but a filamentary trace of its original
condition : the neurine accumulates in the sacral region, fig. 38, s,
as the pelvic members grow, and the central canal there expands,
ib. t. The myelon becomes more slender in the dorsal region,
and again expands near the base of the neck, in connection with
the nerves of the wings, ib. u, v, iv ; then, resuming its dorsal
dimension, it is continued to the brain, ib. a- e. The expansions,
or at least the pelvic one, present a full transverse ellipse in sec-
tion, the rest of the chord is cylindrical; it consists of white
neurine with grey matter internally originating nerve-roots, and
lining a subcentral canal.

The myelon is divisible into ventral and dorsal tracts accord-
ing to their relative position to the transverse plane of the canal ;
the ventral tract is actually divided by a longitudinal fissure into
symmetrical halves or ' columns,' the fissure extending from the
exterior nearly to the canal from which it is separated by a very
thin commissural tract unitino^ the ventral columns. The dorsal
ones diverge from each other in the sacrum, forming the cavity
above mentioned, called in Ornithotomy ^ sinus rhomboidalis,'
fig. 38, s, t, which is a Ventricular' dilatation of the my clonal
canal. The longitudinal fissure thence continued between the
dorsal columns becomes less conspicuous than the ventral fissure,
and appears to be obliterated in the neck : but the dorsal co-
lumns diverge in the medulla oblongata, as in the sacrum, and
again expose the myelonal canal, which is here called '^fourth
ventricle,' ib. d.

The two expansions of the bird's myelon vary in relative size
according to the different developement and powers of the wings
and legs : the anterior or alar enlargement is greatest in Volito-
res, especially the Swifts and Humming-Birds : the posterior or

118

ANATOJklY OF VERTEBRATES.

^■^^

i -V\^'-j

pehdc one is greatest in most otlier birds,
and especially in the Cursores. The alar
enlargement is due to an accession of
white and grey substance, without dila-
tation of the myelonal canal.

In the brain of a chick at the eighth
day of incubation, fig. 39, the 'fourth
ventricle ' is exposed by divergence of

39

Brain of emhryo Bh"d.

Brain of Lizard, ccxvi.

the dorsal myelonal columns which noAv
have the name of ' posterior pyramids :'
the plate of neurine developed from them
to bridge over the ventricle shows the
same incipient state of the cerebellum, ib.
b, as in the Batrachia : it next expands
at the middle and represents the condi-
tion of the cerebellum in the Lizard, fig.
40 : continuing to grow, the cerebellum,
fig. 41, e, covers, at the sixteenth day of
incubation, the fourth ventricle, and has a
smooth exterior, as in the Crocodile and
Turtle (vol. i. fig. 191). Towards the

Brain of chick at IC days. Id. at 20 days, ccxvi.
MyelenceplialoD, or brain and spinal cloSC of iuCubatioU tllC CCrebellum, fig.

42, c, presses forward toward the cere-

chord, with part of the backbone, of a
bird (Anser)

NERVOUS SYSTEM OF AVES.

119

brum, ib. a, and seems mechanically to pusli aside the optic lobes,
h ; the multiplied grey matter of its superficies is disposed in
transverse folds : small beginnings of lateral lobes are present in
many birds. The white neurine, fig. 45, q, continues to accumulate
beneath the grey, ib. d, and reduces the cavity of the originally
vesicular cerebellum to a fissure, ib, 7i, which retains its primitive
connection with the fourth ventricle, the fioor of which shows the
longitudinal groove called ' calamus scriptorius.' The medulla
oblongata expands, but its ventral surface, fig. 44, d, is not sculp-
tured so as to permit ' anterior pyramids,' ' olivary bodies,' a 'tra-
pezium,' or a ' tuber annulare,' to be defined.

The optic lobes in the embryo, fig. 39, a, are smooth vesicles of
white neurine, in contact with each other, as in RejMia : they are
at first oblong, as in Batrachia ; next acquire a spheroid figure,
as in Lizards, fig. 40, b, and then assume their ornithic character
by diverging laterally toward the lower plane of the brain, figs. 42,
44, Z> : they maintain their smooth exterior, and their ventricle
much reduced in capacity by internal growth of neurine.

The crura cerebri show their first superadditions, forming the
optic thalami, in the eight-days embryo, between a and c, fig. 39,
before expanding into the ' hemispheres,' ib. c. These progres-
sively increase in size until they acquire the relative dimensions
and position shown in fig. 43, a.

They are usually of a cordiform shape with the apex directed
forward : in the Parrot tribe they present a more elongate, de-
pressed oval figure : they are devoid of convolutions ; but a

43

Brain of Sea-gull (Lariis). Upper view, ccxvi.

Brain of Eayle. Base view. ccil.

shallow longitudinal depression marks off, in some birds, a median
from a lateral tract of the upper surface of the hemisphere : in
most this surface is uniformly convex. The hemispheres present
an undulate surface beloAv ; the medial parts being in some birds

120

ANATOMY OF VERTEBRATES.

Dissected brain of a Pigeon.

XXXIV.

produced, so as to cause a concavity transversely between them
and the Lateral borders, as shown in fig. 44. On the lower
part of the side of each hemisphere there is a depression which
corresponds to the ' fissura magna Sylvii,' and affords the sole
indication of a division into lobes. The hemispheres are con-
nected together by means of the round commissure, fig. 45, k.
The mesial surfaces of the hemispheres, which are in contact
mth each other, present stride which diverge
from the commissure. These surfaces are
composed of an extremely thin layer of medul-
lary substance, fig. 45, /, ^, forming the in-
ternal parietes of the ventricle, and extended
outwardly over the corpus striatum, ib. i.
Like its homologue in Rejjtilia and the mam-
malian embryo, it does not present the alter-
nate strioe of grey and white matter, which
suggested its name in Anthropotomy. This
cerebral ganglion is of great relative size in Birds, constituting of
itself almost the entire substance of the hemisphere, projecting
into the ventricle, ib. A, not only from below, but from the ante-
rior and outer sides of the cavity,
and being covered by a smooth
layer or fold of medullary matter,
f, which increases in thickness an-
teriorly. The ventricle does not
extend below the corpus striatum
to form an ' inferior horn,' or
' cornu ammonis.^ A fold of pia
mater enters the bottom of the
cerebral ventricle and lies free in
the cavity : it is highly vascular,
and developes tufts containing plexi-
form loops of capillaries defended
by epithelium, the cells of which are
shoAvn at the marmn of the villi mao^nified in fior. 46. The vessel
forming the plexus choroides penetrates the ventricle beneath the
posterior part of the thin internal wall, and the lateral ventricles
communicate together there, and with the third ventricle. They
are continued anteriorly to the root of the olfactory nerve, which
is itself a continuation of the apex of the hemisphere.

Just above the orifice of communication there is a smooth
flattened projection, rounded externally, which advances into the
ventricle from the internal Avail ; this represents a beginning of

Tuft of the choroid plexus of the braii
Goose. XXXV.

NERVOUS SYSTEM OF AVES. 121

the fornix. The round anterior commissure, k, is prolono-ed on
either side into the substance of the hemispheres.

The optic thalami, ib. I, are of small size, and not united by a
soft commissure : between them is the ca\aty called the third ven-
tricle, ib. m ; and above and behind they give off the peduncles
of the pineal gland. This body does not hang freely suspended
by the pedicles, but seems to form a rounded and thickened
anterior border of the valvula Yieussenii or lamelliform commis-
sure of the optic lobes. It adheres firmly to the confluence of
the great veins situated at the anterior orifice of the aqueduct of
Sylvius : it is usually of a conical or pyriform shape. The valve
which closes the upper part of the passage from the third to the
fourth ventricle, is a thin lamella of great width, in consequence
of the distance at which the optic lobes are separated from one
another. Anteriorly the third ventricle communicates with the
infundibulum, which terminates in a large hypophysis.

Besides the cavities or ventricles above mentioned, there are
also two others situated in the optic lobes, fig. 45, o, or bigeminal
bodies, each of which, when laid open, is seen to be occupied by a
convex body, ib. jj, projecting from the posterior and internal
side of the lobe ; these ventricles communicate with the others in
the aqueduct of Sylvius.

The brain of the Bird differs from that of the Reptile in tho
superior size of the cerebrum and cerebellum, together with the
folding of the latter, which relates probably to the higher locomo-
tive powers of the Bird : it differs from the brain of the Mammal
in the absence or small beginning of the fornix, and of the lateral
lobes of the cerebellum : it differs from the brain of every other
class in the lateral and inferior position of the optic lobes. In a
pigeon weighing eight ounces with and seven ounces mthout the
feathers, or 3360 grains, the myelenceplialon weighs 48 grains,
the weight of the myelon being 1 1 grains, and that of the brain
37 grains. The proportion of the weight of the brain to the
body is much greater in the Humming- Bird : whilst in the huge
Dinornis, the brain does not exceed two inches and a half in
length, and two inches in width. It thus presents a limited range
of size, and much sameness of form and structure in the different
orders of the class of Birds.

§ 138. Nerves of Birds. — The olfactory or first pair, usually
of a simple rounded form, proceed from the small pyriform
rhinencephalon, fig. 44, r, continued from the apex of the hemi-
sphere, and usually somewhat deflected. The nerve runs along
an osseous canal, accompanied by a venous trunk above the

122 ANATOMY OF VERTEBRATES.

orbits, as far as tlie pituitary membrane of the ethmoturbinals,
upon wliicli its filaments are distributed in a radiated manner.
In Apteryx and Dinornis, the rhinencephalon is of large relative
size, and sends off the olfactory nerves by many filaments through
a ^ cribriform plate.'

The optic nerves, fig. 44, a, are in general of remarkable size ;
they arise from the whole of the outer surface of the optic lobes,
and from the thalami, the two origins forming by their union
the ^ radix opticus,' fig. 47, d, which expands into the ' chiasma.'
Here a partial decussation, ib. h, takes place. By removal of the
firmly adherent neurilemma, the optic nerve is seen to be com-

47 48

Chiasma of optic ucrves. Fowl. xxx*. Laminated optic nerve of an Eagle, ecu.

posed of parallel, longitudinal lamellae, the margins of which are
most free on one side, fig. 48, 5.

The third, or oculomotorial nerve, arises behind the hypophysis
from the grey matter that lies here between the crura cerebri :
it escapes, usually, by a distinct hole, fig. 5Q, 3, near the foramen
opticum, and supplies the superior, inferior, and internal musculi
recti, and the obliquus inferior : it also sends off a ciliary branch,
which sometimes forms a ganglion before, sometimes after, joining
the ramus ciliaris trigemini.

The fourth nerve arises from the posterior flattened band,
extending over the ' valvula Yieussenii ' between the back part of
the optic lobes : its course, immediately above the superorbital
branch of the fifth pair, is shown at fig. 6Q, 4*, as far as its termi-
nation in the superior oblique muscle, ib. f\ to which it is, as in
other Vertebrates, exclusively distributed.

The^fth or trigeminal nerve, fig. 49, 5, 6, 7, has two origins ;
the ' portio major,' from the fore part of the base of the crus
cerebelli, the ' portio minor,' from the prepyramidal tract in ad-
vance of the foregoing, which it joins after the reddish gan-
glionic swelling, fig. 49, 3, has been formed. The two origins are
less distinct than in Mammals ; but the larger one is more readily

NERVOUS SYSTEM OF AVES. 123

traceable, towards the myelon, from not being crossed bv a ' tra-
pezium.'

The first or oplitlialmic division, fig. 49, 5, passes out of the
cranium by a canal situated externally to the optic foramen. It
is of large size, and describes in its passage through the orbit a
curve corresponding to the roof of that cavity ; it generally pene-
trates the substance of the facial bones, fig. ^^, 5*, above the
nasal fossa, ib. m. It divides into three branches ; the first or
superior is the smallest and is lost upon the pituitary membrane ;
the second branch is the largest of the three and the longest ;
it is received into an osseous canal, and terminates at the ex-
tremity of the beak in a great number of divisions ; the tldrd
branch of the ophthalmic nerve is entirely
distributed to the skin which covers the
circumference of the external nostrils.

The second division, fig, 49, 6, or supe-
rior maxillary nerve, passes out of the
same foramen as the inferior one, ib. 7 :
it passes forward along the floor of the
orbit, and in this part of its course gives
oflT two filaments, of which one joins the
ramifications of the ophthalmic nerve,
the other ascends, penetrates the sub-
stance of the pterygoid muscles and the
maxillary bone, to be lost on the lateral
parts of the bill. In those Birds, as the re.X^'I^ororS-^r'
Anatidce and other Water-fowl, where

the upper mandible is notched on the edge, each denticulation re-
ceives four or five nervous filaments, and the nerve is propor-
tionally of large size.

The inferior maxillary nerve separates from the superior, and
proceeds obliquely downward, dispensing branches to the ptery-
goid and quadrangular muscles of the jaws ; the trunk proceeds
outward to the lower jaw, where it divides into two branches, an
internal and an external. The internal, which is a continuation
of the trunk, penetrates the maxillary canal, and is continued to
the anterior end of that mandible. In the Anatidce it gives oft^
nerves to the dentations along the edge of the mandible. The
external branch recedes from the internal, perforates thejaAv, and
is distributed on its external surface beneath the tegumentary or
horny substance which sheaths the extremity of the mandible.
It supplies no gustatory branch to the tongue, which is an organ
of prehension, not of taste, in Birds. The non-ganglionic part of

124 ANATOMY OF VERTEBRATES.

the third division of the fifth is traced on the left side of fig. 49, 7,
passing beneath the ganglion. There is no ' otic ' ganglion in
Birds.

The facial nerve, or portio dura, arises immediately anterior to
the acoustic from the prepyramidal tracts, enters the petrosal an-
terior to the acoustic, quits it to pass into the fallopian canal,
sends off the ' chorda tympani ' to the ramus alveolaris inferior of
the trigeminal, and communicates with the sympathetic ; it passes
out behind the tympanic bone (as in Mammals), gives branches
to the digastric and stylohyoid muscles, and combines with the
glossopharyngeal, vagus, hypoglossal, and upper cervical nerves,
to form the plexus supplying the anterior part of the constrictor
colli muscle.

The auditory nerve, or portio mollis, is large, soft, and of a
reddish colour; it is received into a depression on the petrosal,
fig. dQ, 7, whence it penetrates by several small foramina to the
labyrinth.

The roots of the ^ eighth ' nerve penetrate the exoccipital by
two or three foramina, and unite on their emergence to form the
ganglion, from which the glossopharyngeal and the pneumo-
gastric trunks diverge. The glossopharyngeal is large ; it com-
municates more freely with the sympathetic than does the
pneumogastric in the neck ; it sends off a small internal branch in
front of the muscles of the neck ; a small posterior twig which
unites with the pneumogastric, and a large inferior branch to the
anterior part of the neck. The latter is a continuation of the
nerve itself; it descends along the oesophagus and divides into
two principal branches, of which one passes to the cerato-max-
illary muscles, and this branch is remarkably tortuous in the
Woodj)ecker, in order to be accommodated to the extensile motions
of the tongue ; it supplies the upper larynx, and the surfixce of
the tongue, as far as the ti}^. The other branch descends along
the lateral parietes of the oesophagus, and sends off a twig to join
the lingual nerve. The termination of the glossopharyngeal is
expended upon the oesophagus.

Tlie pneumogastric, after communicating with the glossopha-
ryngeal, sympathetic and ninth nerves, passes down the neck,
along with the jugular vein, and closely connected with the spinal
nerves. The right trunk crosses the arch of the aorta, and sends
off the recurrent round that vessel, the left trunk reflects its
recurrent near the origin of the bronchi ; the recurrents supply
the lower larynx and part of the trachea, but are chiefly spent
u]>on the oesophagus. The trunks of the two pneumogastrics

NERVOUS SYSTEM OF AVES. 125

converge ventrad of the oesophagus and unite above the pre-
ventriculus, supplying that part, the gizzard, and ultimately com-
municating with the splanchnic plexus of the sympathetic. In
the Eagle the pneumogastric is recruited by an ^ accessorius ' nerve
arisino' behind the third cervical.

The hypoglossal nerve (9th pair) escapes by one or two pre-
condyloid foramina. It is very slender at its origin ; passes to the
front of the nervus vagus, partly uniting with, as it crosses over,
this nerve, and in that situation it detaches a filament to the hyo-
laryngeal and long tracheal muscles. The trunk of the hyo-
glossal next crosses the glossopharyngeal nerve, passing forward
to sujiply the hyoglossal and lingual muscles.

The spinal nerves arise by motory (anterior or ventral) and
sensory (posterior or dorsal) roots of nearly equal size ; but the
anterior have more numerous filaments. The ganglion on the
posterior root is proportionally large. In the sacral region of
the spine, the anterior and posterior roots escape by distinct fora-
mina, and can be separately divided without laying open the
bony canal, but they are deeply seated and well protected by the
anchylosed processes of the sacrum and the extended iliac bones.

The cervical nerves vary with the number of the vertebras from
ten to twenty-three : each nerve divides ; the anterior branch sup-
plying the muscles and the skin, the posterior branch the muscles
chiefly. Those of the lower cervicals form a plexus, supplying
the scapular muscles, and communicate with the lowest cervical
nerve going to the brachial plexus. Only the last two or three
j)airs, fig. 38, u' v!' , of cervical nerves concur in the formation of
this plexus, which is completed by the first pair or two of dorsal
nerves v. The other dorsal nerves, after giving filaments to the
intercostals and diaphragmatic muscles, pass to the skin at the
sides of the trunk.

The sacral nerves have no other peculiarity than their mode of
passing out of the spinal canal : they form exclusively the plexus
analogous to the lumbar and sacral, fig. 38, iv. The terminal
sjoinal nerves supply the muscles and skin of the cloaca and tail.

The hracliial plexus, formed by the two or three last cervical
and one or two first dorsal nerves, soon becomes blended into a
single fasciculus whence all the nerves of the wing are derived.
The internal cutaneous nerve passes from the axilla along the
inner and back part of the humerus, bends round the inner
(ulnar) side of the elbow joint ; it supplies the skin. The next
branch distributes filaments to the muscles 22, 24, fig. 35 ; sends
off the ^ circumflex ' nerve which supplies the latissimus dorsi,

126 ANATOMY OF VERTEBRATES.

deltoid, and shoulder joint ; and is then continued as the ^ musculo-
spiral,' supplying the brachialis internus and biceps, and, as it
passes behind the antibrachium, the extensors of the pinion;
it also distributes filaments to the skin. The next large branch
from the plexus is the ' median nerve,' which sends off the ^ ex-
ternal cutaneous ' in its course along the biceps, supplying the
skin on the outer or radial side of the wing. The ^ ulnar ' nerve
is the next branch, supplying the ^ ulnaris internus ; ' and the
continuation of the ^median' gives branches to the muscles on
the radius, to those on the pinion, and to the integument.

The nerves of the pelvic limbs are derived from the sacral
plexus. The obturator nerve, formed by the second and third sacral
nerves, passes through the upper part of the foramen ovale, gives
off a branch to join the ' saphenus nerve,' and is distributed to the
muscles around the hip-joint. The femoral nerve passes out of
the pelvis in company with an artery, over the front edge of the
ilium. It divides into three branches, which are dispersed among
the muscles, fig. 35, 4o, 42, and integuments on the anterior and
inner part of the thigh. One of these filaments represents the
' saphenus,' and descends superficially for a considerable way upon
the limb.

The ischiatic nerve is derived from five or six of the nerves
constituting the sacral plexus, on quitting which, even within the
pelvis, it is easily separable into its primary branches. Im-
mediately after it passes through the ischiatic foramen it sends
filaments to the muscles on the outer part of the thigh ; it then
proceeds under the biceps, along the back of the thigh, about the
middle of which it becomes divided into the tibial and the peroneal
nerves.

The posterior tibial nerve, before it arrives in the ham, sepa-
rates into several branches, Avhich pass on each side of the blood-
vessels, and are chiefly distributed to the muscles, fig. 35, 46, 50,
51, on the back of the leg. Two of these branches, however,
are differently disposed of; the one accompanies the posterior
tibial artery down the leg, passes over the internal part of the
pulley, and is lost in small filaments and anastomoses with a
branch of the peroneal nerve on the inner side of the metatarsus ;
the other branch runs down on the peroneal side of the leg, along
the deep-seated flexors of the toes, ib. 52, passes in a sheath
formed for it on the outer edge of the moveable pulley of the heel,
and proceeds under the flexor tendons along the metatarsal bone,
to be distributed to the internal part of the two external toes.

The jjeroneal nerve is directed to the outer part of the leg ; it

NERVOUS SYSTEM OF AVES. 127

dips above tlie gastrocnemii muscles^ and runs tlirongli tlie same
ligamentous pulley that transmits the tendon of the biceps muscle,
ib. 41 ; it then detaches some large filaments to the muscles on
the anterior part of the leg, under which it divides into two
branches, which proceed close together, in company with the
anterior tibial artery, to the fore part of the ankle-joint, at which
place they separate ; one passes superficially over the outer part
of the joint, the other goes first under the transverse ligament
which binds down the tendon of the tibialis anticus muscle on the
tibia, and then over the inner part of the joint, below which it
divides into two branches : the one is distributed to the inner side of
the metatarse, and the tibial side of the back toe, /, and the next
toe ; the other turns toward the centre of the metatarsal bone,
and penetrates the tendon of the tibialis anticus just at its inser-
tion, and then rejoins the branch of the peroneal nerve it accom-
panied down the leg. They continue their course together again
in the anterior furrow of the metatarsal bone ; and at the root of
the toes, separate once more, and proceed to the interspaces of
the three anterior toes, and each divides into two filaments, which
run alono; the sides of the toes to the claw.

§ 139. Sympathetic System, — The superior cervical ganglion is
connected with the glossopharyngeal nerve more closely in some
birds than in others : it communicates by branches with the
portio dura and second di^'ision of the fifth, and supplies the
lacrymal gland : a second branch accompanies the entocarotid,
supplies the harderian gland, and communicates with the first
division of the fifth. ^ The " cervical portion " of the sympathetic
may be compared with that in the Snake in its not having a chord
or prolongation accompanying the trunk of the par vagum ; it,
however, corresponds in some measure also with that of the
Turtle, for in the Swan a branch is continued down the neck
with each carotid artery, and in its course communicates several
times with its fellow.' ^ ' In the Pelican the carotid is a single
trunk dividing into two at the upper part of the neck ; a branch
passes from the superior cervical ganglion with each of these, and
becomes united into one near their bifurcation; it gives off
branches for the supply of the carotid, and to communicate with
the prolongation accompanying the vertebral artery : at the bottom
of the neck it dips down in the median line between the anterior
cervical muscles, and divides into two branches, each joining the
penultimate cervical ganglion.' ^ The sympathetic passes down

' Liv. '' lb. p. 104.

128

ANATOMY OF VEETEBKATES.

50

the cervical vertebrn3 in a canal with the vertebral artery ' re-
sembling the prolongation in the imperfect canal in the Snake.'
(Vol. i. p. 310, fig. 206, 3.) 'Also like the chord sent from the
first thoracic ganglion and placed at the side of the neck in the
Turtle, and that accompanying the vertebral artery in Mam-
malia.' ' The sympathetic adheres to the anterior trunk of each
cervical nerve through a ganglion.' * Having reached the thorax,
the G:anolia are connected with those of the dorsal nerves,
much as in the Turtle. In the Swan and Pelican a large nerve
from the first thoracic ganglion communicates with the pulmonary
branches of the par vagum.' ^ The thoracic trunk of the sympa-
thetic is generally double between each ganglion. The anterior
ones give off an anterior splanchnic nerve or plexus accom-
panying the coeliac artery to the gizzard and liver, communicating
with the pneumogastric ; the posterior splanchnic nerve is inti-
mately combined with the adrenal body, and
with the testis or ovarium. Intestinal branches
accompany those of the mesenteric arteries ;
other branches supply the kidneys, and com-
municate w^ith long branches of the spinal
nerves destined for the cloaca and adjoining
parts, and thus form a plexus corresponding in
some degree with that in Mammalia produced
by the junction of the hypogastric plexus with
branches of two or three of the sacral nerves.
The termination of the sympathetic is formed
by a ' ganglion impar ' near the end of the
^ ' , iiiii'i caudal vertebrae. The abdominal ganglions

^ in small birds lend themselves favourably to

Sympathetic ganglion o* ., t ' £> ^ n i

Greenfinch, magnified, as seen tllC demOUStratlOU 01 tilC StrUCturC 01 tllCSC
under the compressor. „ , , i , • , i

centres oi the sympathetic system, becoming
transparent under pressure, and permitting the nerve-vesicles to
be well distinguished from the nerve-chords : the latter only are
represented in fig. 50, showing the finer filaments, c, that bend
round the periphery of the ganglion, as if by resolution of and
divergence from the main chords entering at a and emerging
at b, b.

§ 140. Organ of Touch in Birds. — The ej)ithelial papillai^
sheathed upon vascular ones of the corium ^ on the sole of the
toes of most Birds relate to mechanical rather than to sensational

104

' XX-. vol. iii. p. 239, preps, nos. 1902-1906.
II). preps. 1400 (Eagle), 1401 (Ostrich).

ORGAN OF TASTE IN BIRDS. 129

ends, giving a closer grasp of the perch or the prey, and a firmer
tread of the hard ground. The digital villi are unusually long in
the Capercailzie ( Tetrax urogallus) enabling it to grasp with
more security the frosted branches of the NorAvegian pine-trees.
The integument of the toes is sparingly supplied with nerves in
all Birds ; but it may be supposed that the more delicately
papillose slender flexible digits of the smaller nidificators guide,
by sensations analogous to touch, in the complex interweavings
of the materials of such beautiful structures as the pensile, domed,
and otherwise adaptively perfected nests fabricated by the Tailor-
birds, and most Cantor es.

Actions indicative of tactile exploration have hitherto been
observed to be performed by the bill, exclusively, in Birds.
Although in most of the class the horny sheath of the bill be
hard, sensitive filaments of the ' fifth' nerve (fig. 53, c) are trace-
able to the papillose extensions of the vascular formative surface
into such sheath. In the Lamellirostrals the substance of the
sheath is softer and its marginal lamellae are more abundantly
supplied by the ^ fifth : ' from the tactile and selective actions of
the bill in those Birds, they are called ' Sifters.' The soft and
slightly expanded end of the long and slender bill of some GrallcR
(Woodcocks, Snipes) is so organised for touch, that it is used as
a probe in soft ground to detect the worms, grubs, and slugs that
constitute their food.

Peculiar productions of integument, devoid of feathers, such as
the ^ cere ' of Birds of Prey, the ' wattles ' of the Cock, and of
species of Philedon, Glaucojns, and other so-called ^ wattle birds,'
the cephalic caruncles of the King Vulture and Turkey, &;c., have
been loosely cited amongst ^ organs of touch.'

§ 141. Organ of Taste. — The gustatory sense is very imper-
fectly enjoyed in Birds, which, having no manducatory organs,
swallow the food almost as soon as seized. The tongue is
organised chiefly to serve as a prehensile instrument, and its
principal modifications will be treated of in Chapter XVII.
It is generally sheathed at the anterior part with horn, and is
destitute of papillae except at its base, fig. 51, o, near the aperture
of the larynx, /; these papillce are not, however, supplied by a
true gustatory nerve, but by filaments of the glossopharyngeal.
No branch of the fifth pair goes to the tongue ; but the mem-
brane of the palate and fauces is so supplied that the sapid
qualities of food may be there appreciated.

The tongue is proportionally largest and most fleshy in the
Parrot tribe, and the food is detained in the mouth longer in

VOL. II. K

130 ANAT01\r5f 0^ VEKTEBRATES.

these than in other Bh'ds. It is triturated and comminuted by
the mandibles, and turned about by the tongue, which here seems
to exercise a gustatory faculty, since indigestible parts, as the
coats of kernels, &c., are rejected. In the Lories the extremity of
the tongue is provided with numerous long and delicate papillae
or filaments projecting forwards.

The marginal epithelial papillie of the tongue of the Toucan,
fig. 51, h, appear to test, in the way of touch, the ripeness or
mellowness of fruit. Similar papilla at the tip of the tongue of
many small birds (Humming-birds, Thrush-tribe, fig. 75, B, Field-
fare) exemplify probably the tactile rather than the gustatory
faculty.

Fauces and tongue of the Toucan (Ramphastos). xx:

§ 142. Organ of Smell, — The close affinity subsisting between
the cold and warm-blooded Ovipara is manifested in the olfactory
organs. The external nostrils are simple perforations, ha\dng no
moveable cartilages or muscles provided for dilating or con-
tracting their apertures, as in Mammalia. The extent of surface
of the pituitary membrane is not increased by any large accessory
cavities, but simply by the projections and folds of the turbinals.
The olfactory nerve passes out of the skull, as a rule, in Birds,
by a single foramen. The Apteryx and Dinornis form the ex-
ceptions.

The external nostrils vary remarkably both in shape and posi-
tion, and serve on that account as zoological characters. They
are placed at the sides of the upper mandible in the majority of
Birds, but in some sjoecies are situated at or above the base of the
bill ; the latter is the case in the Toucans, fig. 53, d ; in the
Apterijx australis they are found at the extremity of the long
upper mandible.

In general they are wide and freely open to facilitate the inha-
lation of air during the rapid motions of the bird, but they are so
narrow in the Herons as scarcely to admit the point of a pin ;
and in some Pelecanidce they are wanting, and the odorous par-
ticles get access to the olfactory organ from the palate.

In the Rasores the nostrils are partially defended by a scale.
In the Corvidce they are protected by a iDunch of stiff feathers

ORGAN OF SMELL IN BIRDS.

131

52

Bill aud nostrils of the Petrel.

directed forward. In the Petrels the nostrils are produced in a
tubular form, parallel to one another for a short distance alono-
the upper part of the mandible, with the ori-
fices turned forwards, fig. 52, a.

The septum narium, fig. 53, e, e, is, in
general, complete, and is partly osseous, partly
cartilaginous. It is perforated in the Swan
just opposite the external nostrils, and in the
Toucan, lower down, ib. b. The surface of
the septum is rugose in this bird, and the pituitary membrane
which covers it is highly vascular. The parietes of each of the
nasal passages give attachment to three turbinal laminae. The
inferior one is a simple fold adhering to the lower and anterior
part of the septum narium ; it is partially ossified in some Ba-
sores. The middle turbinal is the largest : it is of an infundibular
figure, and adheres by its base to the septum and externally to the
side-wall of the nose. It is convoluted with two turns and a half
in the Anserine Birds, but in many birds it is compressed and
forms only one turn and a half. The superior turbinal t, h" ,

53

Section of head, showing vertical nostrils, Toucan (Ramphastos). xx:

fig. 56, generally presents the form of a bell ; it is more or less
ossified at its base, but mostly cartilaginous, and adheres to the
upper part of the prefrontal. It is hollow, and divided into
two compartments, which are prolonged in a tubular form ; the
internal one extends toward the orbit, the external terminates
behind the middle turbinal in a cul-de-sac. The turbinal
supports of the pituitary membrane may be membranous

K 2

132 ANATOMY OF VERTEBRATES.

gristly, or bony, and in different proportions. The latter is
their texture in the Toucan, in which the olfactory organ is
confined to the base of the huge upper mandible, fig. 53, d, e, the
meatus describino- a vertical sigmoid curve. At its commencement
it is cylindrical, then dilates forward to receive the outermost tur-
binal, and bends backward to admit the projection of two ethmo-
turbinals : after which it descends vertically to the palate, e. The
pituitary lining of the meatus is not continued or reflected into
the contiguous pneumatic structure of the bill, a, h.

In most Birds the nasal passages communicate with the palate
and pharynx by two distinct but contiguous apertures : in some,
e. g., the Cormorant and Gannet, the passages unite and terminate
by a single aperture.

The olfactory nerves are distributed to the pituitary mem-
brane of the septum narium, and of the superior and middle, or
ethmo-, turbinals ; the lower turbinals being supplied by the fifth
nerves. The membrane is most vascular and delicate on the ethmo-
turbinals ; and these acquire an unusual size in the Apteryx,
where they are attached to the whole outer part of the prefron-
tals, answering to the ' os planum,' which makes a large convex
projection between and beloAV the orbits. This bird appears
to be guided by the sense of smell to the worms that form its
food, the outer nostrils being at the end of the long probe-shaped
bill. The olfactory nerves are proportionally largest in the
Apteryx, and are sent ofl" in numerous filaments from the rhinen-
cephalon, by a cribriform plate, to the nose. The extinct Dinornis
had a similar developement of the organ of smell. In the Vulture
the olfactory nerve is single on each side, and continued from an
olfactory ganglion, or * rhinencephalon,' along the upper part of
the interorbital space to be distributed upon an upper and middle
turbinal, the latter being the largest. In the Turkey the
olfactory nerve is one-fifth the size of that in the Vulture, and
is ramified on a small middle turbinal, there being no extension of
the pituitary membrane over a superior, or ethmo-turbinal.^ This
result of comparative anatomy, and the observed differences in
the habits and food of the Vulture and Turkey, point to the
greater importance and exercise of the sense of smell in the
carrion-eating raptorial bird. But it has been sought to invalidate
the inference by certain well-known experiments. Mr. Audubon
exposed the skin of a deer, stuffed with hay, and in a few minutes
a Vulture flew towards and alighted near it, attacked the seeming
carcass in the usual way, and tore open the seams of the skin ;

' XXX1-. p. 34.

ORGAN OF HEARING IN BIRDS.

133

when, finding nothing eatable, the bird flew away. Hence the
American ornithologist concludes that the Vulture is led to its
game by sight alone. But the truer deduction may be that
having always received impressions from sight, combined Avith
and confirming those, in some cases the first received, from smell,
the Vulture was unwilling to disbelieve its own eyes, thouo-h the
odour was absent. It may .often have been led by sight to the
carcass of a dying beast, or one dead too soon for any putre-
factive emanations to have escaped, and so it mistook the stuifed
deer for a recently dead one. In a converse experiment, a dead
hog being concealed in a ravine, and covered with briers and
cane, ^ many Vultures were seen from time to time sailing over
the spot where the putrid carcass was hid,' but none of them
attempted to expose it ; whilst several dogs found their way to it,
and devoured the flesh.' ^ The right inference from this experi-
ment is, that the Vultures were attracted by the putrefactive
effluvia; but, having always associated sight with smell, and
having neither the burrowing power of the dog, nor the habit of
hunting exclusively by scent, they were baffled.

§ 143. Organ of Hearing. — The general character of this
organ resembles that in Reptilia, but, as Hunter well remarks,
' there is a neatness and precision in the
structure which is not to be found in the
Tricoilia^'^ The whole of the primitive
cartilaginous acoustic capsule is ossified
and confluent with contiguous elements
of cranial vertebra?, and there is a better
defined and usually deeper fossa or ' mea-
tus ' external to the ear-drum. In most
Birds a fold of integument projects from
the fore part of the meatus ; this is largest
in the Owls, but the ear-drum is not pro-
tected by one so developed as to form a
conspicuous ^ conch' or ^ auricle.' At most,
in some Birds, as the Bustard, fig. 54, d.
Ostrich and Owls, particular feathers are
so developed and arranged around the
meatal margin, as to serve the office of an
external ear : the auricular feathers beino^
raised and directed so as to catch and concentrate the vibrations
of sound that may have excited the bird's attention.

54

Head and auricle of Bustard, with
cervical air-cell, xxxiii-.

' XXXII-. vol. ii. p. 34 ; vol. v. p. 345.

Vol. i. p. 208.

134

ANATOMY OF VERTEBRATES.

The labyrinth or internal ear consists of the * vestibule,' three
semicircular canals, and beginning of the cochlea. The vestibule
is smaller in proportion to the other parts, but is longer than in
Reptilia. The superior semicircular canal, fig. 55, h' , is usually
the largest, as in the Owl ; but it is relatively smaller in most
Cantores : the external canal, z, inosculates at m with the horizon-
tal one k, but the chief communications of the canals are through
the medium of the vestibule. The ends of the canals where the
acoustic nerves enter are expanded into ' ampullge,' ib. /, and the
nerves are supported in exquisitely delicate vascular membranes
lining the canals, and slightly projecting into the ampulla.

The cochlea is represented by an obtuse osseous conical cavity,
fig. 55, ?z, longer than in the Crocodile, very slightly bent, mth the

concavity directed backward. Its
interior is occupied by two small
cylinders of fine cartilage, each a
little tmsted, and united by a
thin membrane at their origin and
termination. They proceed from
the osseous bar, which separates
the two foramina, communicating
respectively, the one, ' foramen
rotundum,' mth the vestibule, the
other, ' foramen ovale,' A\dth the
tympanum. The sulcus, which is
left between the cartilages, is dilated near the point, and accom-
modates the same branch of the auditory nerve, which is sent
to the cochlea in Mammals. This nerve spreads in fine fila-
ments upon the united extremity of the cartilaginous cylinders.
The cavity is divided by the presence of the cartilages into two
'scalae,' the anterior of which communicates with the vestibule
and is not closed; the posterior scala is shorter, and w^ould
communicate with the tympanum by the foramen ovale, Avere it
not closed by a membrane. Besides these parts the cochlea
still contains a trace of the cretaceous substance which forms so
conspicuous a part of the organisation of the internal ear in
Fishes. The Struthious Birds manifest their closer relation to
the Reptilia by having the cochlea smaller in proportion to the
other parts than in the ears of birds of flight.

The cavity of the tympanum has been already described, p. 62 :
besides the communications Avith the air-cells of the surrounding
bone, it is continued by the ' eustachian' tube, fig. 55, e, to the
palate : to the membrane closing the ' foramen ovale' is applied the

Organ of hearing, Owl.

ORGAN OF HEARING IN BIRDS. I35

base of the columelliform stapes : the much larger external aperture
of the tympanic cavity is closed by the ear-drum, e. This is con-
vex outwardly, semitransparent and glistening : the proper ' mem-
brana tympani' is lined by that of the tympanic cavity, which
is continued into the eustachian tube ; and is covered externally
by an epithelial layer, continuous with that of the meatus : the
former is more intimately united with the proper membrane.
In this may be discerned an outer layer, showing more distinctly
a structure of radiating fibres, and one inner, thicker, and less
distinctly fibrous layer.

The margin of the ear-drum is set in a groove of bone, afforded
by or attached to the tympanic anteriorly, the mastoid above, and
the paroccipital behind. One or more points of ossification may
be set up in the thick periphery of the drum, Avhich coalesce
with the above-named bones. The membrane of the vestibule,
passing across the foramen ovale, becomes a little thickened where
it adheres to the margin of the disc of the stapes : the connection
is such as to admit of a sli2:ht movement of the ossicle. From the
disk the bone is continued, of a slender form, like a pedicle, to the
cartilaginous bifurcation, and this is connected by a larger cartilagi-
nous plate, representing the ' malleus,' to the membrana tympani,
at c, fig. 55. To the latter cartilage, as to the ossified and coalesced
incus and malleus of Marsupials, is attached the chief muscle of the
ear-drum, a ' tensor,' fig. 55,f: it arises from a depression in the ba-
sisphenoid, enters the tympanic cavity above the beginning of the
eustachian tube, and by its insertion into and action upon the mal-
leus, tends to push the membrane outward : it is counteracted by
two small cords extended to the inner wall of the tympanum : but
the muscular character of them is doubtful, and the ear-drum re-
sumes its normal state when the tensor ceases to act. The eusta-
chian tube, fig. 55, e, is continued from the lower and back part of
the tympanic cavity, grooves the sides of the basisphenoid, as it
converges toward its fellow, A^th which it unites, in most Birds,
to terminate by a common aperture behind the posterior or palatal
nares.

§ 144. Organ of Sight in Birds. — The avian peculiarities of the
eye chiefly relate to the extraordinary powers of locomotion in
this class, adjusting \dsion to a rapid change of distance in the
objects viewed, and facilitating their distinct perception through
a rare medium.

There is no species of Bird in which the eyes are wanting, or
rudimentary, as occurs in the other A^ertebrate classes.

The eyes of Birds are remarkable for their great size, both as

136

ANATOMY OF VERTEBRATES.

56

compared with the brain and with the entire head, fig. 56, being
analogous, in this respect, to the eyes of some of the flying
insects. Their form is admirably adapted to promote the objects
above named. The anterior segment of the eye is more promi-
nent than in any other class of animals, and is in many Birds

prolonged into a tubular form,
terminated by a very convex cor-
nea, fig. 137, 6? ; the Owl fur-
nishes the best example of the
disproportion between the ante-
rior and posterior divisions of the
globe, the axis of the anterior
portion being twice as great as
that of the other. This gives
room for a greater proportion of
aqueous fluid, and by removing
the crystalline lens from the
retina, causes a greater converg-
ence of the rays of light, by which
the nocturnal bird is enabled to
discern the objects placed near it,
and to see with a weaker light.
The anterior division of the eye
is least convex in the Swimming
Birds. The antero-posterior dia-
meter is to the transverse as 19 to 26 in the Swan, and as 17 to
20 in the Duck.

The sclerotic coat, fig. 57, b, is divisible into three layers.
It is thin, flexible, and somewhat elastic posteriorly, where it
presents a bluish shining appearance, but anteriorly its form is
maintained by a circle of osseous plates or scales, ib. a, fig. 26, 17,
interposed between the exterior and middle layers. These plates
A ary from thirteen to twenty in number, and are situated imme-
diately behind the cornea, with their edges overlapping each
other. They are in general thin, and of an oblong quadrate
figure, becoming elongated from before backward in proportion
as the bird possesses the power of changing the convexity of
the cornea. In the Owls they extend from the cornea over the
long anterior division of the eye to the posterior hemisphere,
which they also contribute to form. The figure of the eye is
thus maintained, notwithstanding its want of sphericity.

The bony plates are capable of a degree of motion upon each
other, which is, however, restrained within certain limits by the

Cerebral nerves, eyes, &c. in situ, of a Goose.

OKGAN OF SIGHT IN BIRDS. 137

attachments of their anterior and posterior edges to the sclerotic
coat ; and by their being bound together by a tough ligamentous
substance, as it were the continuation of the sclerotic between
the edges that overlap each other.

The cornea, fig. 57, c, possesses the same structure as in IMam-
malia, but differs with respect to form. When the posterior part
of the eye is compressed by the muscles, the humours are urged
forward and distend the cornea ; which, at that time, becomes
more prominent than in Mammalia ; and under such circum-
stances, the eye is in a state for perceiving near objects. When
the muscles are relaxed, the contents of the eyeball retire to the
posterior part, and the cornea becomes flatter: this is the con-
dition in which we find the eye of a dead bird, but we can have
no opportunity of perceiving it during life. It is only practised
for the purpose of rendering objects visible that are placed at an
extreme distance. From the well-known effects of form upon
refracting media, it must be presumed, that the cornea is least
convex when a bird which is soaring in the higher regions of the
air, and invisible to us, discerns its prey upon the earth ; its form
mil change as the bird descends A\4th unerring flight to the spot,
as is customary with many of the rapacious tribe.

On reflecting the sclerotica from the choroid,
a grey substance is seen upon the fore part of
the latter, like a ring : it consists of fibres
showing, like those of the iris, the transverse
stride, and which serve to attach the choroid to
the sclerotic plates and contiguous margin of
the cornea. These fibres are regarded by the section of eyebaii, Faico.
anatomist, who first called attention to their xxxiv.

muscular nature in Birds, as helping * to accommodate the eye to
the different distances of objects,' being supposed to act upon
the cornea in a manner analogous to that of the muscles of the
diaphragm upon its tendinous centre.^

The choroid coat is a loosely cellular and highly vascular mem-
brane, devoid of ' tapetum,' and copiously covered or saturated with
a black pigment. Opposite the bony circle the choroid separates
into two layers ; the external layer is the thinnest, and adheres at
first firmly to the sclerotica, after which it is produced freely
inwards to form, or be continuous with, the iris.

The iris, fig. 57, ^, is delicate in its texture, which under the lens
appears composed of a fine network of interlacing fibres, but it is
remarkable for the activity and extent of its movements, which

' XXXIV. p. 170.

138 ANATOMY OF VERTEBRATES.

seem in some Birds to be voluntary. The contraction and dilata-
tion of the pupil, independently of any change in the quantity of
light to which the eye is exposed, is most conspicuous and re-
markable in the Parrot tribe, but it has been observed also in the
Cassowary and other birds. ^

The colour of the iris is subject to many varieties, Avhich fre-
quently display great brilliancy, and afford zoologists distinguish-
ing specific characters of Birds ; although these cannot always be
implicitly relied upon. The breadth of the iris varies in diffe-
rent species, but is greatest in Birds which take their food in the
gloom, e. g.. Owls and Nightjars, in order that the pupil may be
proportionally enlarged to admit as much light as possible to the
retina. The ciliary nerves and vessels run in the form of single
trunks between the choroid and sclerotica, and terminate ante-
riorly in several ring-shaped plexuses for the supply of the iris
and of the muscular circle of the cornea. The pupil is usually
round : in the Goose and Dove it is elongated transversely, and
in the Owls is vertically oval.

The inner layer of the choroid is thicker than the external, and
is disposed in numerous thickly set plicae radiating towards the
anterior part of the crystalline lens, where they terminate in
slightly projecting ciliary pj^ocesses, fig. 57, d, the extremities of
which adhere firmly to the capsule of the crystalline. These
processes are the most numerous, close set, and delicate in the
Owl : they are proportionally larger and looser in the Ostrich.

The chief peculiarity in the eye of the Bird is the marsuplum
or pecten, ib. f, which is a plicated vascular membrane analogous
in strvicture to the choroid, and equally blackened by the pig-
mentum ; situated in the vitreous humovir anterior to the retina,
and extending from the point where the optic nerve penetrates
the eye to a greater or less distance forward, being in many Birds
attached to the posterior j^art of the capsule of the lens. As its
posterior point of attachment is not to the choroid but to the
termination of the optic nerve, this requires to be first described.

When the optic nerve, ib. g, arrives at the sclerotic, it tapers
into a long conical extremity, which glides into a sheath of a
corresponding figure, excavated in the substance of that mem-
brane, and directed downward and obliquely forward. The
central or inner layer of this sheath is split longitudinally, and the
plicated substance of the nerve, fig. 48, passes through this fissure.
A similar but longer fissure exists in the corresponding part of
the choroid : so that the extremity of the optic nerve presents in

• vir. p. 304.

ORGAN OF SIGHT IN BIRDS. 139

the interior of the eye, instead of a round disc, as in Mammalia,
a Avhite narrow streak, from the extremities and sides of which
the retina is continued. Branches of the ophthahiiic artery, dis-
tinct from the vessels of the choroid, and homologous Avith the
arteria centralis retince, enter the eye betAveen the laminae of the
retina, along the whole extent of the oblique slit above mentioned,
and immediately penetrate the folds of the marsupial membrane,
upon which they form delicate ramifications. These vessels are
shown in fig. 58, representing the excised marsupium unfolded
and spread out.

The marsupium is lodged like a wedge in the substance of the
vitreous humour, in a vertical plane, directed obliquely forward.
In those species in which the marsupium is widest, the angle

58

Jliiipfc.

ararsiipium of the eye of a Rook, unfolded, xxvii-.

next the cornea reaches the inferior edge of the capsule of the
crystalline ; but where it is narrow, the whole anterior border is
in contact with the same point. This contact is close in some Birds,
as the Vulture, Parrot, Turkey, Cassowary, Stork, Goose, and
Swan ; but in other Birds the marsupium does not extend further
than two-thirds of the distance from the back part of the eye, and is
attached at its anterior extremity to some of the numerous laminae
of the hyaloid membrane which form the cells for the lodgment
of the vitreous humour. In these cases the marsupium can have
no influence on the movements of the lens, unless it be endowed
with an erectile property, and be so far extended as to push for-
w^ard the lens. There is no muscular structure in the marsupium ;
and its changes of form, if such occur in the living bird, must be
effected by changes in the condition of the vessels of Avhich it is
almost exclusively composed.

The form of the marsupium varies in different Birds ; it is
broader than it is long in the Stork, Heron, Turkey, and Swan ;
and of the contrary dimensions in the Owl, Ostrich, and Casso-
wary. The plica3 of the membrane are perpendicular to the

140 ANATOMY OF VERTEBRATES.

terminal line of the optic nerve ; tliey are of a rounded figure in
most species, but in the Ostrich and Cassowary they are com-
pressed, and so far inclined from the plane of the membrane, that
their convergence towards its extremity gives it a resemblance to
a close-drawn purse. ^ The folds vary in number, being four in
the Cassowary, seven in the Great Horned Owl, eight in the
Maccaw, from ten to twelve in the Duck and Vulture, fifteen in
the Ostrich, sixteen in the Swan and Stork, and still more nu-
merous in the Insessorial Birds, amounting to twenty-eight,
according to Soemmerring, in the Fieldfare.

The exact functions of the marsupial membrane are still in-
volved in obscurity. Its position is such that some of the rays of
light proceeding from objects laterally situated with respect to
the eye must fall upon and be absorbed by it ; and Petit ac-
cordingly supposed that it contributed to render more distinct the
perception of objects placed in front of the eye.

Some physiologists have supposed that this black membrane
was extended toward the centre of the eye, where the luminous
rays are most powerfully concentrated, in order to absorb the
excess of intense light to which Birds are exposed in soaring aloft
against the blazing sun. Others have considered it as the gland
of the \dtreous humour, and that, as this fluid must be rapidly
consumed during the frequent and energetic use made of the
visual organ by Birds, it therefore might require a superadded
vascular structure for its reproduction.

The marsupium may act as an erectile organ, and occupy a
variable space in the vitreous humour : when fully injected, there-
fore, it will tend to push forward the lens, either directly or
through the medium of the vitreous humour, which must be dis-
placed in a degree corresponding to the increased size of the mar-
supium ; the contrary effects will ensue when the vascular action
is diminished. The nocturnal Apteryx, in which the eye is so
small, shows also the exception of the absence of the marsupium.

The retina is continued from the circumference of the base
of the marsupium, and after unfolding its plicte expands into
a smooth layer of medullary matter, which seems to terminate
at the periphery of the corpus ciliare. In the Owls not more
than half the globe of the eye is lined by the retina ; it ceases in
fact where the eye loses the spherical form at the base of the
anterior cylindrical portion.

* The Parisian Academicians, who took their description of this part from the
Ostrich, first applied to it the name o^ Marsnpinm or Bourse, xl'.

ORGAN OF SIGHT IN BIRDS. 141

The humours of the eye no less correspond to the peculiar
vision of the Bird, and the rare medium through which it is
destined to move, than the shape of the globe and the texture of
its coats.

The aqueous humour is extremely abundant, owing to the
extent of the anterior chamber gained by the convexity of the
cornea, and its refractive power must be considerable in the
higher regions of the atmosphere. The membrane inclosing it
can be more readily demonstrated in Birds than in most Mammals,
especially where it adheres to the free edge of the iris. The large
size of the ciliary processes may have the same relation to the
reproduction of the aqueous, as the marsupium is supposed to have
mth reference to the vitreous, humour.

The crystalline lens is remarkable for its flattened form, espe-
cially in the high-soaring Birds of Prey; it is also of a soft
texture, and is without the hard nucleus found in Fishes and
Reptiles. In the Cormorant and other birds which seek their
food in water, the crystalline is of a rounder figure, and this is
peculiarly the case in the nearsighted Apteryx and Owls which
hunt for prey in obscure light. It is inclosed in a distinct
capsule, which adheres very firmly to the depression in the an-
terior part of the vitreous humour ; the capsule is itself lodged
between two layers of the membrana hyaloidea, which, as they
recede from each other to pass — the one in front and the other
behind the lens — leave round its circumference the sacculated
canal of Petit.

The vessels of the lens are derived from those of the marsu-
pium, which, as before observed, are ramifications of the homo-
logue of the arteria centralis retinae : this is not continued as a
simple branch from its origin to the marsupium ; but, imme-
diately before penetrating the coats of the eye, it breaks into
numerous subdivisions, the aggregate of which is greater than the
trunk whence they proceed, and these again unite, forming a
plexus, s, fig. 59, close to the external side of the optic nerve.
The artery of the marsupium proceeds from this plexus, and runs
along the base of the folds, giving off at right angles a branch to
each fold, which in like manner sends off smaller ramuli, fig. 58.
The plexus at the origin of the marsupial artery serves as a
reservoir for supplying the blood required for the occasional full
injection of the marsupium ; and a snnilar but larger plexus, fig.
59, 4, is formed at the origins of the ciliary arteries which supi)Iy
the erectile tissue of the ciliary processes and iris.

The vitreous humour presents few peculiarities worthy of note;

142

ANATOMY OF VERTEBKATES.

59

Muscles of the eye. Goose.

compared with the aqueous humour, it is proportionally less in
quantity than in the eyes of Mammals. The outer capsule formed
by the hyaloid membrane is stronger, and can be more easily
separated from the humour.

The eyeball is moved in Birds by four straight and two ob-
lique muscles. The Recti muscles arise from the circumference
of the optic foramen, and expand, as they pass forward, to be
inserted into the soft middle part of the sclerotic. We have not

been able to trace their insertion dis-
tinctly to the osseous circle ; their apo-
neurosis cannot be reflected forward from
the sclerotica without lacerating that
membrane.

The Obliqui both arise very near to-
gether from the anterior parietes of the
orbit, and go to be inserted, the one into
the upper, the other into the lower part
of the globe of the eye ; the superior
obliquus does not pass through a pulley,
as in Mammalia. All the muscles are
proportionally short in this class, but especially so in the Owls,
in which the eye, from its large size and close adaptation to the
orbit, can enjoy but very little motion. In figs. dQ and 59, a is
the rectus superior or attollens ; h the rectus inferior or deprimens ;
c the rectus externus or abducens ; d the rectus internus or addu-
cens \ e the obliquus superior-, /the obliquus inferior-, g the
quadratus ; h the pyrainidalis.

The accessory parts of the eye in Birds are similar to those of
the higher Reptiles. There are three eyelids, two of which move
vertically, and have a horizontal commissure, while the third,
which is deeper-seated, sweeps over the eyeball horizontally,
from the inner to the outer side of the globe. The vertical, or
upper and lower eyelids, are composed of the common integu-
ment, of a layer of conjunctiva, and between these of a liga-
mentous aponeurosis, which is continued into the orbit, and lines
the whole of that cavity. The lower eyelid is the one which
generally moves in closing the eye in sleep, and it is further
strengthened by means of a smooth oval cartilaginous plate, which
is situated between the ligamentous and conjunctive layers.

The orbicularis muscle is so disposed as by means of this plate
to act more powerfully in raising the lower than in depressing
the upper eyelid. In the latter it is continued immediately along

ORGAN OF SIGHT IN BIEDS. 143

the margin : in the lower eyelid the tarsal cartilage intervenes
between the muscle and the ciliary margin.

The levator jjcilpehrcs superioris arises from the roof of the
orbit, and is inserted near the external angle of the lid. There is
also an express muscle for depressing the lower eyelid, as in the
Crocodile. In the Owls and Nightjar (^Caprimulgus) the eyelids
are closed principally by the depression of the upper one. There
are but few Birds that possess eyelashes; of these the Ostrich is an
example, as also the Hornbills and the Owls, in which they are
arranged in a double series ; but here they are rather to be con-
sidered as feathers with short barbs, than true eyelashes.

The third eyelid, or membrana nictitans, is a thin membrane,
transparent in some Birds, in others of a pearly white colour.

Two muscles are especially provided to eifect its movements,
but are so placed as to cause no obstruction to the admission of
light to the eye during their actions. One of these is called the
quadratus nictitantis, fig. 59, g ; it arises from the sclerotica at the
upper and back part of the globe of the eye, and its fibres slightly
converge as they descend towards the optic nerve, above which
they terminate in a tendinous sheath, having no fixed insertion.
The second muscle, called pyramidalis nictitantis, ib. h, arises from
the lower and nasal side of the eyeball : its fibres converge toward
the upper part of the optic nerve, and terminate in a small round
tendon which glides through the pulley at the free margin of the
quadratus ; thus, A\dnding over the nerve, it passes down to be in-
serted into the lower part of the margin of the third eyelid. By
the simultaneous action of the two muscles, that nictitatino; lid is
drawn outward and obliquely downward over the fore part of the
eyeball. The tendon of the pyramidalis gains the due direction
for that action by winding round the optic nerve, and it is
restrained from pressing upon the nerve by the counteracting
force of the quadratus, which thus augments the power of the
antagonist muscle, while it obviates any inconvenience from
pressure on the optic nerve, which its peculiar disposition in
relation to that part would otherwise occasion. 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 when not in use.

The lacrymal glands are two, as in Reptiles ; but the inner one is
the largest, especially subserving the more frequent movements
of the nictitating membrane : it is called the * harderian gland,'
fig. 56, d', is situated at the inner or nasal can thus, has a lobu-

144 ANATOMY OF VERTEBRATES.

lated exterior, and emits its viscid secretion by a short duct which
opens beneath the third lid. The ' lacrymal gland/ fig. 59, d,
lies at the posterior and external part of the eyeball ; in the
Goose it is of a flattened form, about the size of a pea, and pours
its thinner transparent secretion, by a short Avide duct, upon the
inside of the outer canthus of the eyelids. The naso-lacrymal
conduit commences by two apertures at the nasal canthus, and
terminates below and a little before the middle turbinal. In the
Ostrich there is a glandular prominence at each 'punctum,' ana-
logous to a ' caruncula lacrymalis,' but this structure is not
present as a rule in Birds.

Besides the two glands which serve to lubricate and facilitate
the movements of the eyeball and eyelids, there exists another
gland which from its position in or near the orbit seems to belong
to the lacrymal group ; but its secretion is exclusively employed
upon the pituitary membrane of the nose, and it corresponds
rather to the nasal gland of Serpents. In many water and marsh
Birds the gland in question is lodged in the superorbital fossa,
before described, p. 61 ; but in most Birds it is situated within
the orbit, either beneath the nasal or between it and the maxil-
lary : in the Woodpecker it is found in the subocular air-cell. I
have detected it in one or more species of every order of Birds.
In the Anserines the gland is large, and seems to complete the
upper margin of the orbit, fig. 5Q, k, and is enclosed in a dense
fibrous capsule. It is composed of ramified follicles, with cellular
walls. In the Albatross and Penguin it sends two or three ducts
to the nasal cavity.

145

CHAPTER XVII.

DIGESTIVE SYSTEM OF BIEDS.

The digestive function is most potent and rapid in Birds, in
order to supply the waste occasioned by their extensive, frequent
and energetic motions, and in accordance with the rapidity of
their circulation and their high state of irritability.^

The parts to be considered mth reference to this function are
the rostrum or beak, the tongue, the oesophagus, the stomach
which is always divided into a glandular and muscular portion,
the intestines, and the cloaca: with these are connected the
salivary glands, the proventricular follicles, the liver and pancreas.

§ 145. Beaks of Birds. — The beak consists of an ' upper
mandible,' supported by the maxillary and premaxillary bones,
and of a ^ lower mandible ' forined by the lower jaw. In place
of teeth these bones are provided Avith a sheath of horny fibrous
material, similar to that of which the claws are composed:
this sheath is moulded to the shape of the osseous mandibles,
being formed by a vascular substance covering these parts, and
its margins are frequently provided with horny processes or
laminae secreted by distinct pulps, analogous in this respect to
the whalebone laminae of the Whale. In a foetus of a Perroquet
nearly ready for hatching, the margins of the bill are beset with
white and round tubercles, arranged in a regular order, about
seventeen in the upper jaw, the foremost on the mid-line.^ These
tubercles are not, indeed, implanted in the alveolar border, but
form part of the sheath of the bill. Under each tubercle,
however, there is a gelatinous pulp, like that of a tooth, but
resting on the edge of the jaw-bones, and every pulp is supplied
by vessels and nerves traversing a canal in the substance of the
bone. These tubercles form the first margins of the mandibles,
and their remains are indicated by canals in the horny shcatli
subsequently formed, which contain a softer material, and which
commence from small foramina in the margin of the bone.

' The Cormorant devours, in captivity, six or eight pounds offish daily; what may
be the amount iu its state of wild activity ! 2 xxxvi*.

VOL. II. L

146

ANATOMY OF VERTEBRATES.

The different degrees of hardness and varieties of form of the
beak exercise as much influence upon the nature of Birds as the
number and figure of the teeth do upon that of Mammals.

The beak is hardest in those Birds which tear their prey, as
Eagles and Falcons ; in those which bruise hard seeds and fruits,
as Parrots and Grosbeaks ; and in those which pierce the barks
of trees, as Woodpeckers, in the larger species of which the
beak absolutely acquires the density of ivory. The hardness
of the covering of the beak gradually diminishes in those Birds
which take less solid nourishment, or which swallow their food
entire ; and it changes at last to a soft skin in those which feed
on tender substances, or which have occasion to probe for their
food in muddy or sandy soils, or at the bottom of the water, as
Ducks, Snipes, Woodcocks, &c.

Cceteris paribus, a short beak must be stronger than a long one,
a thick one than a thin one, a solid one than one which is flexible ;
but the general form produces much variety in the application of
the force. A compressed beak T\dth trenchant edges, and a
hooked, sharp-pointed end, is the fit instrument for seizing and
slaying prey, whether birds, beasts, or fishes ; and such ^ aduncate'
beak is seen in the Frigate-bird, Tropic-
bird, Albatross, Petrel, fig. 52, but com-
bined with length in these piscivorous birds.
In the Raptores the beak is shorter and
stronger, and in some genera a tooth-like
process on either side of the upper man-
dible, fig. 60, adds to its destructive
power: hence the Falcons, having this armature, are reckoned
the more ' noble ' or courageous birds of prey.

The Shrike {Lanius) and Yanga, which have their bill similarly
armed, fig. 61, have the cruel disposition of the
Hawk, but take prey proportioned to their small
l^ ^^ size : and the ^ tooth' is confined to the horny sheath,
fig. 61, not developed on the bone. As the beak
becomes straio;hter and conical with the maro^in

60

Beak of Falcon.

Beak of a Shrike.

entire, the bird is less daring in attacks on other
kinds, though occasionally predaceous when large and strong (as the

Baven and Crow, fig. 62) : but most
' conirostrals ' are omnivorous, and
the rest granivorous, as the ' Hard-
billed Passeres ' of Ray. When the
_____ cone is attenuated and leno-thened

Beak Of a Crow. out, iig. 63, it IS adapted to extract

DIGESTIVE SYSTEM OF BIRDS.

147

delicate insects from the recesses of trees and flowers : and the
type ' tenuirostrals ' ( TrocliilidcE) may suck up, also, the sweet
juice of the nectarium.

The Fissirostrals, fig. 64, like the Humming-birds, feed on the

63

Beak of Humming-bird
(Oi-thorhyncus).

Rostrum of the Caprimulgus.

Aving, but as their food consists of volant insects, the form of the beak
is modified accordingly, and is remarkable for its shortness and
the -vvideness of its gape, fig. 64, especially in the typical families.
In these the mode of catching the prey is conformable to their
distinguishing characters ; they receive it in full flight into the
cavity of their mouths, which remain open for that purpose, and
where a viscous exudation within, and a strong fence of * vibrissas '
on the exterior, assist in securing the victim.

A strong, trenchant and pointed, but elongated and straight,
bill serves to cut and pierce, and characterises many Waders
preying upon reptiles, flshes, and animals that offer some resist-
ance : such a beak is found in the Herons and Bitterns. As it
becomes more lengthened and attenuated it is adapted to prey of
a lower grade of life, and to
get at these it is endoAved
A\4th a specially sensitive
apex. In the Ibis and Cur-
lew such a beak is curved
down, fig. 3 : in the Jabiru,
fig. Of 5, it is bent up. Some
trenchant bills are so com-
pressed as to resemble the
blade of a knife ; these offer least resistance in the swift pursuit of
fishes, and are seen in the Awks, Puffins, and Coulternebs, in which

Bill of the Jahiru.

Bill of the Skimmer.

latter the beak may be as deep as it is long. The Skimmer

L 2

148

ANATOMY OF VERTEBRATES.

{Rh?/ncops) has the further peculiarity of an inequality in the length
of the two mandibles, the upper one being the shortest, fig. 66, so
that this sea-bird gets its food, which consists of floating marine
animals, by pushing and tilting them within the action of the
upi^er blade as it swims along.

A sharp-edged beak may be as remarkable for transverse ex-
tension and depression, or horizontal flat-
tening : and such a form serves for cap-
turing fishes and reptiles : it is seen in

(O the Boatbills of South America {Can-
croma), fig. 67, and of Nubia {Balcsni-
ceps).

Of the blunt-edged bills we may first
notice those which are flattened hori-
zontally. When a bill of this description is long and strong.

Bill of the Boatbill.

Bill and pouch of the Pelican.

as in the Pelican, fig. 68, it serves to seize large but feebly
resisting fishes.

When it is long and weak, as in the Spoonbill, which derives
its name from the dilated extremity of the mandibles, it is only

available to seize amid sand, mud,
or water, very small Crustaceans,
Mollusks, &c., fig. 69.

The more or less flattened bills
of Ducks, the more conical ones
of Geese and Swans, and that
of the Flamingo, of which the extremities of the mandibles are
bent downwards abruptly, fig. 70, have all transverse horny
lamina) arranged along their edges, which when the bird has
seized any object in the water, serve, like the whalebone laminae

Bill of the Sroonhill.

DIGESTIVE SYSTEM OF BIRDS.

149

Bill of tlic Flamingo.

of the Whale, to give passage to the superfluous fluid. The
aquatic habits of all these
birds are in harmony with
this structure. But the long-
legged palmiped sifts the sand
of the sea-shore by raking it
up with the bill reversed, as
shown in fio;. 14. In the
Goosanders {Mergiis,^g. 71),
the lateral laminae are de-
veloped into small conical
reflected tooth-like processes,
which serve to hold fast the
fishes on which they feed.

The bills of the Toucans and Hornbills are remarkable for
their enormous size, which is sometimes equal to that of the
whole bird. The substance of the
beak in these cases is extremely
light and delicately cellular ; yet
the osseous portions are adapted
to combine, with great bulk, a
due degree of strength. The
external parietes are extremely
thin, especially in the upper beak : they are elastic, and yield
in a slight degree to moderate pressure, but present consider-
able resistance if the force be increased for the purpose of
crushing the beak : they gain thickness at the points of the man-
dibles.

On making a longitudinal section of the upper mandible,
fig. 53, «, its base is seen to include a conical cavity about two
inches in length and one inch in diameter, with the apex directed
forward. The walls of this cone consist of an osseous network,
intercepting irregular angular spaces, varying in diameter from
half a line to two lines. From the parietes of the cone a net-
work of bony fibres is continued to the outer parietes of the
mandible, the fibres which immediately support the latter being
almost invariably at right angles to the part in which they are
inserted. The whole of the mandible anterior to the cone is
occupied with a similar network, the meshes of which are largest
in the centre of the beak, in consequence of the union which
takes place between different small fibres as they pass from the
cu'cumference inwards. The principle of the cylinder is intro-
duced into this structure : the smallest of the supporting pillars

Bill of the Goosander.

150 ANATOMY OF VERTEBRATES.

are hollow. The structure is the same in the lower mandible,
ib. 7/z, but the fibres composing the network are in general
stronger than those of the upper mandible.

The air is admitted to the interior of the upper mandible from
a cavity, ib. b, situated anterior to the orbit, which communicates
at its posterior part with the air-cell continued into the orbit, and
at its anterior part mth the maxillary cavity. The nasal cavity
is closed at every part except at its external and internal apertures
by the pituitary membrane, and has no communication with the
interior of the mandible.^

The horny sheath of the mandibles in the Hornbills and Toucans
is so thin that it often becomes irregularly notched at the edge
from use. The Hornbills have, besides, upon their enormous
beak, horn-like prominences of the same structure and of different
forms, the use of which is not known.

The Trogons, Touracos, Buccos, &c., exhibit forms of the bill
which are intermediate to that of the large but feeble bill of the
Toucans, and the short, but hard, strong, and broad bill of the
Parrot-tribe, which is also hooked, so as to assist in climbing, like
a third foot, fig. 30.

The short, conical, and vaulted beak of the Rasores, fig. 72,
serves to pick up with due rapidity the vegetable seeds and
grains which constitute their food, as well
as small insects, as ants, &c., with which the
young are frequently nourished. The tooth-
billed pigeon of the Samoan Isles has the
lower mandible deeply cleft into three points
near the top, and the upper mandible hooked,
^ , ,,, . , , the better for seizino; fruit and denudino-

Beak of Gumeu-iuwl. O ^ »

palm-nuts and other strongly coated kinds.
The bills of the small Insessorial or Passerine birds present
every gradation of the conical form, from the broad-based cone of
the Hawfinch to the almost filamentous cone of the Humming-
bird, fig. 63, and each of these forms influences the habits of
the species in the same manner as in the larger birds. The
short and strong-billed Insessores live on seeds and grains ;
those with a long and slender bill on insects or vegetable juices.
If the slender bill be short, flat, and the gape very wide, as
in Swallows, the bird takes the insects while on the wing; if
the bill be elono;ated and endowed with sufficient streno-th,
as in the Hoopoes, it serves to penetrate the soil and pick out

DIGESTIVE SYSTEM OE BIEDS.

151

worms, &c. One kind of Humming-bird, feeding on spiders, lias
the end of the bill finely toothed.

Of all bills, the most extraordinary is that of the Cross-bill, in
which the extremities of the mandibles curve towards opposite
sides and cross each other at a considerable angle — a disposition
which at first sight seems directly opposed to the natural inten-
tion of a bill. With this singular disposition, the Cross-bill,
however, possesses the power of bringing the points of the man-
dibles into contact with each other ; and can pick up the smallest
seeds, and shell or husk larger kinds like other birds. But the
disposition and power of the muscles is such that the bill gains by
its very apparent defect the requisite power for breaking up the
pine-cones and wrenching out the seeds that constitute its usual
food.

§ 146. Tongues of Birds. — The tongue, as has been already
observed, can hardly be considered as an organ of taste in Birds,
since, like the mandibles, it is generally sheathed with horn. It
is principally adapted to fulfil the offices of a prehensile organ in
association with the beak, and it presents almost as many varieties

Ilyoid and upper larynx^
Swan.

of form. The length of the tono^ie
depends chiefly on that of the
glossohyal, fig. 73, 42. In most
birds it is lengthened out by a
cartilage, ib. «', appended to its
extremity. This is remarkable in
the Swan and other Lamellirostres.
The ceratohyals are obsolete. The basihyal, 4i, contracts as it
recedes to support the urohyal, 43, and the hypo- 4G, and cerato-
47, branchials are modified to form the posterior cornua or ^ thyro-
hyals,' which are of moderate length. The tongue supported by
the glossohyal is broad, and furnished Avith a series of retroverted
spines, fig. 75, D. In the Humming-bird the horny sheath of
the glossohyal is divided at its extremity into a pencil of fine
hairs. In the Toucan's tongue, fig. 51, the sheath gives off
from the lateral margins stiff' bristle-like processes which project
forward : this structure is continued to the apex, and the tongue
so provided becomes an instrument for testing the softness and
ripeness of fruit, and the fitness of other objects for food, thereby

152

ANATOMY OF VERTEBRATES.

acting as a kind of antenna or feeler. A similar but less deve-
loped structure is found in the tongue of the frugivorous Touraco.
In the Woodpeckers the apex of the horny sheath, fig. 74, 77,
a, gives off at the sides short pointed processes directed back-
ward, converting it into a barbed instrument for holding fast the

insects which its sharp point
has transfixed, after the
strong beak has dislodged
them from their hidino*
places. The cornua (thyro-
hyals, ib. 46, 47) mnd round
the back of the head, and
converge as they pass for-
ward to be inserted in a
canal generally on the right side of the upper mandible, ib. e.
The tongue of the Flamingo is almost cylindrical, slightly flat-
tened above, and obliquely truncate anteriorly, so as to corre-
spond with the form of the inferior mandible. The pointed

Cranium and tongue of a Woodpecker.

Tongue A. Snipe. B. Fieldfare. C. Kingfisher. D. Goose. CCXL*.

extremity of the truncated part is supported beneath by a small
horny plate. Along the middle of the upper surface there is a
moderately deep and wide longitudinal furrow ; on either side of
which there are from twenty to twenty-five recurved spines, from
one to three lines in length. These spines are arranged in an

DIGESTIVE SYSTEM OF BIRDS. 153

irregular alternate series: the outer ones being the smallest,
which may almost be considered as a distinct row. At the pos-
terior part of the tongue there are two groups of smaller recum-
bent spines directed towards the glottis. The substance of the
tongue is not muscular, but is chiefly composed of an abundant
elastic cellular substance, permeated by an oily fat.^ Of like
nature is the tongue in Anserines : but the retroverted spines are
marginal, fig. 75, D. The tongue of the great Penguin is beset
with horny spines like a hedgehog's skin.

In the Raptores the tongue is of a moderate length, broad,
and somewhat thick, and has a slight division at the tip. In the
Vultures its sides can be voluntarily approximated so as to form
a canal, and its margins are provided mth retroverted spines. In
the Raven it is bifid at the apex : it is more deeply cleft in the
^ Nutcracker.'

In the Struthious Birds, in many of the Waders, and in the
Pelecanidce, the tongue is remarkably short, as it is likewise in
the Kingfisher, fig. 75, c. In the Snipe it is as remarkable for its
length and slenderness, ib. A. In the Fieldfare (^Turdus pilaris)
the sheath is resolved into fine filaments at the apex of the
tongue, ib. b.

In the Parrots the tongue is thick and fleshy, is terminally
tufted in Lories, serves admirably to keep steady the nut or seed
upon which the strength of the mandibles is exerted, and is applied
to the kernel so extracted, as if to ascertain its sapid qualities.

The following are the muscles of the tongue in Birds.

Muscles of tho tongue of the Fieldfare {Tardus pilaris).

1st. The Mijlo-hyoideus: this is a thin layer of fibres attached to
the lower and inner border of the lower jaw, and running trans-
versely to a mesial tendon which separates them, and extends to
the urohyal. It raises the tongue towards the palate.

2nd. The Stj/lo-hyoideus, fig. 76, «, arises from the upper and
back part of the lower jaw, and is inserted into the thyrohyal at

* XXI*.

154 ANATOMY OF VERTEBRATES.

its junction with the basihyal. In some birds it divides into three
or more portions : the iiosterior descends obliquely forward, and
is inserted into the tendinous commissure of the mylohyoideus :
the middle portion is inserted into the urohyal : the anterior fas-
ciculus is inserted into the side of the basihyal above the trans-
verse hyoglossus. The actions of these different portions vary
according to their insertion ; the first and second depress the apex
of the tongue by raising the urohyal, the third raises the tongue
and draws it to one side Avhen it acts singly.

3rd. The Genio-hyoideus, fig. 76, Z> : this arises by two fleshy
bands from the lower and internal edge of the lower jaw ; these
unite, pass backward, and surround the cornua (thyrohyals) ; and
as they draw them forward protrude the tongue from the beak.

4th. The Cerato-hyoideus : this passes from the thyrohyal to
the urohyal, and is therefore subservient to the lateral move-
ments of the tongue.

5th. The Sterno-hyoidei: these are replaced by a slip of
muscle which extends from the anterior surface of the upper
larynx to be attached to the base of the glossohyal.

6th. A small and short muscle, which is single or azygos ; it
passes from the basihyal to the under part of the glossohyal ; it
depresses the tip of the tongue and elevates its base.

7th. A short muscle, fig. 75, c, which arises from the junction
of the basihyal with the urohyal, and is inserted into the thyro-
hyal. ^

All these muscles are remarkably large in the Woodpecker, in
which there is a singular pair of muscles that may be termed
Cerato-traclieales (fig. 77, h). They arise from the trachea
about eight lines from the upper larynx, twist four times spirally
round the trachea, and then pass forward to be inserted into the
base of the thyrohyals. This is the principal retractor of the
singular tongue in this species.

§ 147. Salivary Glands. — The salivary organs, being in general
developed in a degree corresponding to the extent of the changes
which the food undergoes in the mouth, and the length of time
during which it is there detained, are by no means so conspicuous
a part of the digestive system in Birds as in Mammals. Glands
which pour out their secretion upon the food prior to deglutition
are, however, met with in every bird, but vary in number, position,
and complexity of structure.

In some species, as the Crow, they are of the simplest struc-
ture, consisting of a series of unbranched, cone-shaped follicles or
• Dr. Salter proposes the name of ' Cerato-glossal ' for this muscle, ccxl-. p. 1 140.

DIGESTIVE SYSTEM OF BIRDS.

155

77

tubules, opening separately upon the mucous membrane of the
mouth, along the sides of which cavity they are situated. They
pour out a viscid mucus, and
are the only traces of a sali-
vary system met with in this
bird.

In many other birds, and
especially in the Scratching,
Wading, and Smmming Or-
ders, glands of the conglo-
merate structure are found
beneath the lower jaw, an-
swering to the submaxillary
glands of quadrupeds.

In the Goose they occupy
the whole of the anterior part
of the space included by the
rami of the loAver jaw, being
of an elongated form, flat-
tened and closely united to-
gether at the middle line. On
either side of this line the
mucous membrane of the
mouth presents internally a
series of pores, each of which
is the terminal orifice of a
distinct o-land or asc^reffate of
ramified ducts.

A third and liigher form of
salivary gland, in which the
secretion of the conglomerate
mass is conveyed into the
mouth by a single duct, is
found in the Woodpeckers
and some species of the Ka-
pacious Order. In the latter
birds these glands are termed,
from their situation, anterior
palatine : in the Piece they
correspond to the parotid and
sublingual of Quadrupeds.

The sublino'ual o^lands of
the Woodpecker, fig. 77, ?, h, are of extraordinary size, extcndim

Tongue and salivary glands. Woodpecker.

156 ANATOMY OF VERTEBRATES.

from the angle to the symphysis of the lower jaw. The single
ducts of each gland unite just before their termination, which is
a simple orifice at the apex of the mouth.

Besides the preceding, which may be considered as the true
salivary glands, there are numerous accessory follicles in different
parts of the oral apparatus of Birds. In the Waterhen ( Galli-
nula chlorojms) there is a series of coecal glandular tubes along
each side of the tongue : similar elongated follicles are situated
along the margin of the lower jaw, resembling in their parallel
pectinated disposition the branchiae of Fishes. In the Goose the
corresponding follicles are longer and wider, and are situated near
the sides of the tongue. In the Kaven these mucous follicles are
narrower but longer. The glandular structures supplying the
mouth in Birds may be summed up under the following heads :
' folliculi linguales,' ' glanduloe sublinguales,' ^ glandule submaxil-
lares ' {Pici, Raptores, Rasores, Aptenodytes), ^ glandulje anguli
oris ' (Swan, Cantores, Diurnal Raptores) ; * folHculi preglottidei ; '
^ folliculi post-nasales,' i.e., opening behind the posterior nostrils ;
' amygdalae,' or close-set groups of follicles, in two rows, opening
behind the eustachian outlet.

§ 148. Alimentary Canal. — The food, after being imbued with
the secretion of the preceding glands, is poised upon the tongue and
swallowed, partly by means of the pressure of the tongue against
the palate, partly by a sudden upward jerk of the head. The pos-
terior apertures of the nostrils being generally in the form of narrow
fissures are undefended by a soft palate or uvula; and the laryngeal
aperture, which is of a similar form, is in like manner unprovided
mth an epiglottis, but is defended by the retroverted papillae at the
base of the tongue. In many Birds, indeed, as the Albatross and
Coot, there is a small cartilage in the usual place of an epiglottis,
but insufficient to cover more than a very small part of the laryn-
geal aperture.^ The surface of the mouth is rarely smooth above,
commonly provided with retroverted papillae : similar mechanical
helps to the right course of the food occur at or near the fauces,
in addition to those already noted on the tongue. The width of
the mouth in Caprimulgus, and the length and depth due to the
mandibular pouch in the Pelican, are remarkable. The extensi-
bility of the membrane between the rami of the lower jaw admits
of its formation into a bag, fig. 68, a, wliich is calculated to con-
tain ten quarts of water, and serves as a receptacle for fishes,
making in that state a conspicuous appendage to the huge bill ;

* Fur these structures in Birds, see xxxvir. p. 613.

DIGESTIVE SYSTEM OF BIRDS. 157

when empty it can be contracted so as to be hardly visible. By
means of this mechanism a quantity of food can be transported to
the young ; and, as in disgorging the bleeding fishes the parent
presses the bottom of the sac against her breast, this action has
probably given rise to the fable of her wounding herself to nourish
the young with her own blood.

The S^vift presents an analogous dilatation of the faucial mem-
brane at the base of the lower jaw and upper part of the throat :
it is most developed at the period of rearing the young, when it
is generally found distended with insects in the old birds that are
shot while on the "sving. A similar structure obtains in the Rook,
and probably in other Insectivorous Birds. It is notable in the
JSTutcracker ( Caryocatactes) ; which, descending from its favourite
snowy altitudes, may be seen to return with a swelling like an
enormous goitre as big as the head, formed by the gular pouch,
crammed with nuts.'

The oesophagus, H, fig. 94, «, fig. 78, like the neck, is usually
very long in Birds : as it passes do^vn, it generally inclines to-
ward the right side; it is partially covered by the trachea, G^
fig. 94, and connected to the surrounding parts by a loose cellu-
lar tissue. It is wide and dilatable, corresponding to the imper-
fection of the oral instruments as comminutors of the food. In
the rapacious, and especially in the piscivorous Birds, it is of great
capacity, enabling the latter to swallow the fishes entire, and
serving also in many Waders and Swimmers as a temporary re-
pository of food.

When the Cormorant has by accident SAvallowed a large fish,
which sticks in the gullet, it has the power of inflating that part
to its utmost, and while in that state the head and neck are
shaken violently, in order to promote its passage. In the Gannet
the oesophagus is extremely capacious, and, as the skin which
covers it is equally dilatable, five or six herrings may be contained
therein. In both these species it forms one continued canal with
the stomach. In the Flamingo, on the contrary, the diameter of
the gullet does not exceed half an inch, being suited to the

» When writing the article Aves for the ♦ Cyclopedia of Anatomv,' in 1835, I had
not dissected a male Bastard, and introduced the old figure from ' Edwards's Nat, Ilist.
vol. ii. tab. 73 (1747),' fig. 54, with the current story of the sub-gular water-pouch,
Avhich Edwards derived from the anatomist Douglas. In 1848 I had the desired
opportunity and made the preparation, No. 772, q, described in the ' Physiological
Catalogue of the Ilunterian Collection.' The supposed gular pouch is a large cervical
air-cell, fig. 54, a, capable of inflation and singularly swelling out the neck in the
amorous male Bustard. See xxxviii*.

158

ANATOMY OF VERTEBRATES.

smallness of the objects wliicli constitute the food of this spe-

cies.

Besides deglutition, the oesophagus is frequently concerned in
reo-urgitation ; and in the Birds in which this phenomenon occurs,
the muscular coat of the gullet, like that in Ruminants, is well de-
veloped. The Raj)tores, for example, habitually regurgitate the
bones, feathers, and other indigestible parts of their prey, which,
in the language of Falconry, are called ^ castings.' I have ob-
served a Toucan to regurgitate partially digested food, and after
submitting it to a rude kind of mastication by its enormous beak,
ao^ain to swallow it.

The oesophagus possesses an external cellular covering, a mus-
cular coat, an internal vascular tunic, and a cuticular lining. The
muscular coat consists of two layers of fibres ; in the external
stratum they are transverse, fig. 81, a, in the internal longitu-
dinal, ib. h. The mucous coat is generally disposed in longi-
tudinal folds, rarely connected by transverse folds ; still more
rarely villous, as in the Ostrich.^

In those Birds which are omnivorous, as the Toucans and
Hornbills, in the frugivorous and insectivorous Birds, and in
most of the Grallatores, which find their food in tolerable abun-
dance and take it in small quantities without any considerable
intermission, it passes at once to the stomach to be there suc-
cessively digested, and the gullet presents no partial dilatations
to serve as a temporary reservoir or macerating receptacle. But
„g in the larger Raptorial

Birds, as the Eagles and
Vultures, which gorge them-
selves at uncertain intervals
from the carcases of bulky
prey, the oesophagus does not
preserve a uniform width,
but undergoes a lateral di-
latation anterior to the fur-
culum at the lower part of
the neck. This pouch is
termed the ingluvies or
crop, fig. 78, 6.

In those Birds, again, the
food of which is exclusively
of the vegetable kind, as

Digestive canal of an Eagle. graiUS ancl SCeClS, ancl 01

' XX-. vol. i. p. 125, prep. no. 458.

DIGESTIVE SYSTEM OF BIRDS.

159

Digestive canal, Common Fowl.

wliicli consequently a great quantity must be taken to produce
the adequate supply of nutriment, and where the cavity of the
gizzard is very much dimi-
nished by the enormous '
thickness of its muscular
coat, the crop is more de-
veloped, and takes a more ^^^^^r-^ I'l^^^^i
important share in the di-
gestive process. Instead
of a gradual lateral dilata-
tion of the gullet, it as-
sumes the form of a glo-
bular or oval receptacle
aj)pended to that tube, and
rests upon the elastic fascia
which connects the clavi-
cles or two branches of the
furculum together.

In the Common Fowl the crop is of large size and single,
fig. 79, h, but in the Pigeon it is double, consisting of two lateral
oval cavities, fig. 80, h, c.
The dilatation of the
oesophagus to form the
crop is more gradual in the
Ducks than in the Galli-
naceous Birds. The crop
is wantino: in the Swans
and Geese ; but is present
in that modified Anserine,
the Flamingo.

The disposition of the
muscular fibres of the crop
is the same as in the oeso-
phagus, but the mucipar-
ous follicles of the lining
membrane are larger and
more numerous. This dif-
ference is most conspicuous
in the inglu\'ies of the
granivorous Birds, Avhere
it is not merely a tempo-
rary reservoir, but in which
the food is mixed Avith the abundant secretion of the glands, and

Crop of a Pigeon .

IGO ANATOMY OF VERTEBRATES.

becomes softened and macerated, and prepared for the triturating
action of the gizzard and the solvent power of the gastric secretion.

The change Avhich the food undergoes in the crop is well knoAvn
to bird-fanciers. If a Pigeon be allowed to swallow a great
quantity of peas, they will swell to such an extent as almost to
suffocate it.

The time during which the food remains in the crop depends
upon its nature. In a common Fowl animal food will be detained
about eight hours, while half the quantity of vegetable substances
will remain from sixteen to twenty hours. Hunter made many
interesting observations on the crop of Pigeons, which takes on a
secreting function during the breeding season, for the purpose of
supplying the young pigeons in the callow state with a diet suit-
able to their tender condition.^ An abundant secretion of a
milky fluid of an ash-grey colour, which coagulates with acids
and forms curd, is poured out into the crop and mixed with the
macerating grains. This phenomenon is the nearest approach in the
class of Birds to the characteristic mammary function of a. higher
class ; and the analogy of the ^pigeon's milk' to the lacteal secretion
of the Mammalia has not escaped popular notice. In fig. 80, one
side of the crop, h, shows the ordinary structure of the parts, the
other, c, the state of the cavity during the period of rearing the
young. The secretion consists of proteine with oil, but contains
no suo^ar of milk nor fluid caseine.

The canal continued from the ingluvies to the stomach is called
the lower a3Sophagus ; at its commencement it is narrower and
more vascular than that part which precedes the crop, but
gradually dilates into the first or glandular division of the
stomach, which is termed the ' ^voYentviQ.vlu^'' {ventriculus suc-
centuriatus, hulhus glandulosus, echinus, infundibulurn), figs. 78,
79, 80, c.

The proventriculus of the Bird, like the spiral valve of the
Shark, is an alimentary surface packed into the smallest space :
in the latter the membrane is chylific, in the former chymific or
digestive : every follicle is, in fact, a portion of the peptic secret-
ing surface, Avith its gastric tubuli at right angles thereto ; the
surface being moulded to form either a simple or compound
cavity.

In birds with a mde oesophagus, fig. 78, a, the commencement
of the proventriculus is not indicated by any change in the
direction or diameter of the tube, but only by its greater
vascularity, by the difference in the structure of the lining mem-

' XGIV. p. 124,

DIGESTIVE SYSTEM OF BIRDS.

161

brane, and by the stratum of glands which open upon its inner

Part of the pro veutri cuius of
Swau dissected.

surface, and which are its essential characteristic.
Hence it is by some comparative anatomists
regarded as a part of the oesophagus.

The proventriculus varies, however, in
form and mao^nitude in different Birds. In
the Rasores it is larger than the oesopha-
gus, but much smaller than the gizzard. In
Eupliones ^ it forms almost the entire sto-
mach, the gizzard being minute : in Alcedo
opposite proportions prevail. In the Psit-
tacidcB and ArdeidcB (Parrot and Stork
tribe) it is larger than the gizzard, and of a
different form. In the Ostrich the proventriculus is four or five
times larger than the triturating di\dsion of the stomach, being
continued down below the liver,
and then bent up upon itself
towards the right side before it
terminates in the gizzard, which
is placed on the right and anterior
part of this dilatation.

In the majority of Birds the
gastric follicles are simple, having
no internal cells, dilated fundus,
or contracted neck ; but from
their external blind extremity
proceed with an uniform diameter
to their internal orifice. This
form obtains in the zoophagous
and omnivorous Birds. In the
Dove-tribe the follicles are of a
conical shape ; in the Swan they
are tubuliform ; in the Goose and
Turkey they present internal
loculi ; in the Ostrich and Eliea
these loculi are so developed that
each gland forms a racemose
group of follicles, terminating by
a connnon aperture in the pro-
ventriculus.

The subjoined figures show the different forms of the solvent
or proventricular glands in different Birds.

' XXXIX-.

Eagle.

G an net.

Sea-gull.

Pigeon.

Swan.

Goose.

Fowl.

Turkey.

Rhea.

Ostrich.

VOL. II.

/

162 ANATOMY OF VERTEBRATES.

The gastric glands are variously arranged.

Among the Raptores, we find them in the Golden Eagle dis-
posed in the form of a broad compact belt; in the Sparrowhawk
this belt is slightly di\ided into four distinct portions.

In the Insessores the glands are generally arranged in a con-
tinuous zone around the proventriculus ; but in some of the
Si/ndactyli, as the Hornbill, the circle is composed of the blending
together of two large oval groups.

Among the Scansores the Parrots have the gastric glands dis-
posed in a continuous circle, which is at some distance from the
small gizzard. In the Woodpeckers the glands are arranged in a
triangular form, with the apex towards the gizzard. In the Tou-
can they are dispersed over the whole proventriculus, but are
more closely aggregated near the gizzard; the lining membrane of
the cavity is reticulate, and the orifices of the glands are in the
interspaces of the meshes.

Among the Rasores the Pigeon shows its afiinity to the Pas-
serine Birds in having the gastric glands of a simple structure,
and arranged in a zonular form : they are chiefly remarkable for
their large cavity and mde orifice. In the Common Fowl and
Turkey the glands are more complex, and form a complete
circle.

In the Cursores the arrangement of the glands is different in
almost every genus. In the Ostrich they are of an extremely
complicated structure, and are extended in unusual numbers over
an oval space on the left side of the proventriculus, which
reaches from the top to the bottom of the cavity, and is about
four inches broad. The Rhea has the solvent glands aggregated
into a single circular patch, which occupies the posterior side of
the proventricular cavity. In the Emeu the gastric glands are
scattered over the whole inner surface of the proventriculus, and
are of large size ; they terminate towards the gizzard in two
oblique lines. In the Cassowary the glands are dispersed over
the proventriculus with a similar degree of uniformity; but they
are smaller, and their lower boundary is transverse. In the
Apteryx the glands occupy its Avhole circumference, opening in
the meshes of a reticulate surface.^

Among the Grallatores, the Marabou ( Ciconia argald) has the
nearest affinity to the Khea in the structure and disposition of
the gastric glands ; they are each composed of an aggregate of
five or six follicles, terminating in the proventriculus by a com-

GIZZARD OF BIRDS. 163

mon aperture ; and they are disposed in two compact oval masses,
one on the anterior, the other on the jiosterior surface of the
cavity. In the Heron {^Ardea cinereci) the solvent glands are of
more simple structure, and are more dispersed over the proven-
triculus ; but still they are most numerous on the anterior and
posterior surfaces. In the Flamingo the gastric glands are short
and simple follicles, arranged in tAvo large oval groups, which
blend together at their edges.

The Natatores present considerable differences among them-
selves in the disposition of the solvent glands. In the Cormorant
{Plialacrocorax carbo) they are arranged in two circular spots,
the one anterior, and the other posterior ; while in the closely
allied genus Sida, or Gannet, they form a complete belt of
great width, and consequently are extremely numerous. In this
respect the Gannet, or Solan Goose, shows a nearer affinity to
the Pelican.

In the Sea-Gulls the gastric glands form a continuous zone ;
and in the Little Awk (^Alca alle) they are spread over a great
proportional extent of surface, and the form of the digestive
organs is peculiar. The proventriculus is continued from the
oesophagus, -with very gradual enlargement, below the liver, and
is then bent up to the right side, and terminates in the gizzard.
The solvent glands are situated at the anterior or upper part of
the cavity everywhere surrounding it, but lower down they lie
principally upon the posterior surface, and where it is bent
upward toward the right side they are entirely wanting. In the
graminivorous lamellirostral Water-birds, as the Swan, Goose,
&c., the gastric glands have a simple elongated exterior form, but
have an irregular or cellular internal surface : they are closely
arranged so as to form a complete zone.

In general the muscular or pyloric division of the stomach
called 'gizzard' {cjigerium, ventriculus hidhosus), immediately
succeeds the glandular or cardiac division ; but in some Birds, as
the Awk and Parrots, there is an intervening portion without
glands.

The gizzard is situated below or sacrad of the liver, on the left
side of the abdomen, generally resting on the mass of intestines.
In the Owl the aizzard adheres to the membrane covering; the
internal surface of the abdominal muscles ; but in most Birds it
has a more dorsal position.

In all Birds the gizzard forms a more or less lengthened sac,
having at its upper part two apertures ; one of these is of large
size, communicating with the proventriculus, figs. 83, 84, a, the

51 2

164

ANATOMY OF VERTEBRATES.

second is in close proximity with, and to tlie right side of the pre-
ceding, leading to the dnodenum, ib. o; below these apertnres
the cavity extends to form a cu^de-sac, c. At the middle of the

anterior and posterior parts
of the cul-de-sac there is a
tendon, figs. 78, 79, e, from
which the muscular fibres
radiate.

The differences in the
structure of the gizzard
resolve themselves into the
greater or less extent of
the tendons, and the greater
or less thickness of the
muscular coat, and of the
lining membrane.

In the Rajjtores the giz-
zard, fig. 78, d, assumes
the form of a mere mem-
l^ranous canity, in accord-
ance mth the animal and
easily digestible nature of
their food. The muscular
coat is thin ; the fibres prin-
cipally radiate from small
tendons, ib. e, and there are some longitudinal fibres beneath the
radiating or external layer.

In the Rasores and lamelKrostral Natatores it exhibits the
structure to which the term gizzard can be more appropriately
applied, figs. 83, 84, The muscular fibres are distinguished by
their unparalleled density of texture and deep colour, and are
arranged in four masses ; two are of a hemispherical form, and
their closely-packed fibres run transversely to be connected to
very strong anterior and posterior tendons, fig. 84, e ; they con-
stitute the sides of the gizzard, and are termed the digastric
muscles or ' musculi laterales,' fig. 83, di between these, at the
end of the gizzard, are the two smaller and thinner muscles called
' musculi intermedii,' fig. 84, /. There are likewise irregular
bands placed about the circumference of the gizzard.

Fig. 83 shows the relative thickness of the musculi laterales in
the gizzard of a S^Yan, and fig. 84 that of the musculi intermedii
and tendon.

The internal coat of the gizzard, fijr. 84, <?, /i,is extremely liard

Gizzard of a Swan.

GIZZARD OF BIRDS.

165

and thick, and being of a horny nature, it is liable to be increased
by pressure and friction, and as it is most subject to these in-
fluences at the parts of the gizzard opposite the musculi lateraleS;
two callous buttons are there formed, ib. g, g. It is here that
the fibrous structure of the lining membrane can be most plainly

84

Gizzard of a Swan. vii".

seen : and it is worthy of observation that the fibres are not
perpendicular to the j^lane of the muscles, but oblique, and in
opposite directions, on the two sides. Elsewhere the cuticular
lining is disposed in ridges and prominences, figs. 84, S6, h, which
vary in different birds, but are pretty constant in the same species.
In a Petrel {Procellaria glaclalis), tlie lining membrane is dis-
posed in a pavement of small square tubercles, like the gastric
teeth of some Mollusks.

The cavity of the gizzard is so encroached upon by the grinding
apparatus, that it is necessarily very small, the two horny callo-
sities having their internal flat surfaces opposed to one another,
like ^millstones.' A crop is as essential an appendage to this
structure as is the ^ hopper ' to the mill ; it receives the food as it
is swallowed, and supplies it to the gizzard in small successive
quantities as it is wanted.^

Between the stomach of the carnivorous Eagle and that of the
graminivorous Swan there are numerous intermediate structures.

' Thus we find in Parrots, where the gizzartl is remarkably small, that a crop is
present. A like receptacle exists also in the Flamingo, in which the gizzard is small
but stronjr.

166 ANATOMY OF VERTEBRATES.

but it is necessary to observe that the animal or vegetable nature
of the food cannot always be divined from the difterent degrees
of strength in the gizzard. Hardcoated coleopterous insects,
for example, require thicker parietes for their due comminution
than pulpy succulent fruits.

In the subgenus Eaphones, among the Tanagers, the muscular
or pyloric division of the stomach is remarkably small and not
separated from the duodenum by a narrow pylorus.

The parietes of the gizzard, like those of other muscular
cavities, become thickened when stimulated to contract on their
contents mth o;reater force than usual. In the Hunterian col-
lection this fact is well illustrated by preparations of the gizzard
of the Sea-Gull in the natural state, and that of another Sea-Gull
which had been brought to feed on barley. The digastric muscles
in the latter are more than double the thickness of those in the
Sea-Gull which had lived on fish.*

The immediate agents in triturating the food are hard foreign
bodies, as sand, gravel, or pebbles.

Pigeons carry gravel to their young. Gallinaceous Birds grow
lean if deprived of pebbles ; and no wonder, since experiment ^
shows that unless the grains of corn are bruised, and deprived of
their vitality, the gastric juice will not act upon or dissolve them.
The observations and experiments of Hunter have completely
established the truth of Redi's opinion, that the pebbles perform
the vicarious office of grinding teeth.

Hunter inferred from the form of hair-balls occasionally found
in the stomach of Cuckoos,^ that the action of the great lateral
muscles of the gizzard Avas rotatory. Harvey appears to have
first investigated, by means of the ear, as it were in anticipation
of the art of auscultation, the actions wdiich are going on in the
interior of an animal body, in reference to the motions of the
gizzard. He observes (^De Gencratioiie Animalium, in Opera
Omnia, 4to, p. 208), ' Falconibus, ac[uilis, aliisque avibus ex

' XX-. vol. i. p. 149, prep. 522, d, and .523.

2 Grains of barley, inclosed in strong perforated tubes, pass through the alimentary
canal unchanged. Dead meat, similarly introduced into the gizzard, is dissolved.

^ The hairs of caterpillars devoured by this bird are sometimes pressed or stuck
into the horny lining of the gizzard, instead of being collected into a loose ball. They
are then neatly pressed down in a regular spiral direction, like the nap of a hat, and
have often been mistaken for the natural structure of the gizzard. One of these speci-
mens, exibited as such to the Zoological Society, was sent to me for examination, when,
upon placing scjme of the supposed gastric hairs under the microscope, they exhibited
the peculiar complex structure of the hairs of the larva of the Tigei'-moth (Arctia
caja), and the broken surface of the extremity which was stuck into the cuticular
lining was plainly discernible. See Proceedings of Zooi Soc. 1834, p. 9.

INTESTINES OF BIRDS. 167

precla viventibus, si aurem prope admoveris clum ventriculus je-
juniis est, manifestos intus strepitus lapillorum illuc ingestorum,
invicemque collisorum, percipias.' And Hunter observes {Animal
(Economy, 4to, p. 198), ' The extent of motion in grindstones need
not be the tenth of an inch, if their motion is alternate and in
contrary directions. But although the motion of the gizzard is
hardly visible, yet we may be made very sensible of its action by
putting the ear to the sides of a fowl while it is grinding its food,
when the stones can be heard moving upon one another.' Tiede-
mann believed that the muscles of the gizzard were in some degree
voluntary, having observed that when he placed his hand opposite
the gizzard, its motions suddenly stopped.

The pyloric orifice of the gizzard is guarded by a valve in many
Birds, especially in those w^hich swallow the largest stones. This
valve in the Ostrich is formed by a rising of the cuticle divided
into six or seven ridges, which close the pylorus like a grating,
and allow only stones of small size to pass through. In the
Touraco the pylorus projects into the duodenum in a tubular form.
There is a double valve at the pyloric orifice in the Gannet, and
a single large valvular ridge at the same part in the Gigantic
Crane. In this species and some other Waders, as the Heron
and Bittern ; also in the Pelican, and, according to Cuvier, in
the Penguin and Grebe, there is a small but distinct cavity inter-
posed between the gizzard and intestine. The analogous struc-
ture has been described in the Crocodile (vol. i. p. 442, fig.
298, g).

The intestines reach from the stomach to the cloaca ; in relative
length they are much shorter than in the Mammalia. In the
Toucan, for example, the whole intestinal canal scarcely equals
twice the length of the body, including the bill. The canal is
divided into small and large intestines, sometimes by an internal
valve, sometimes by the insertion of a single coecum, but most
generally by those of two cocca, which are always opposite to one
another. In a few instances there is no such distinction. The
small intestines and coeca are longest in the vegetable feeders.
The large intestine is, with one or two exceptions, very short and
straio^ht in all Birds.

The course of the small intestine varies somewhat in the dif-
ferent orders of Birds ; it is always characterised by the elongated
fold or loop made by the duodenum, fig. 85, /, /, which fold re-
ceives the pancreas, ib. q, q, in its concavity.

In the Raptores the intestines are generally disposed as fol-
lows : —

168

ANATOI^IY OF VERTEBRATES.

The duodenum forms a long and broad fold, the lower part of
which is commonly bent or doubled upon itself; the intestine
then passes baclvAvard on the right side of the abdomen, crosses to
the left, and is disposed in deep folds upon the edge of a scolloped

Abdominal viscera of a Pigeon, xxxiv.

mesentery; towards its termination the ileum passes up behind
the stomach and adheres to it, having here but a narrow mesen-
tery ; then passing down the posterior part of the abdomen the
ileum makes another loose fold and ends in the rectum, which is
continued straio-ht to the cloaca.' In the Owls, the last fold of
the ileum is nearly as long as the duodenal fold, and the coeca
adhere to each side of the fold.

In the Diurnal Raptores the intestinal canal is only twice the
length of the body, except in the fish-eating Osprey, in which the
intestines are very narrow, and are to the length of the Bird itself
as eight to one.

In the Cantores the scolloped folds of the small intestine are
narrower and longer than in the Raptores, and the ileum gene-
rally adheres to the duodenal mesentery and pancreas instead of
to the stomach, prior to passing down to form its last fold and to
terminate in the rectum. In the Raven the small intestines are
disposed at their commencement in concentric folds.

Among the Scansores the Cuckoo presents the following dis-

' In fig. 78, tlic intestines are not represented according to their natural arrange-
ment.

INTESTINES OF BIRDS. 169

position of the intestinal canal : after the usual long and narrow
duodenal fold, the ileum ^ makes a fold which is mdened at the end ;
it then forms a close fold upon itself, at the termination of which
the rectum commences. In the MaccaAv the course of the small
intestine is somewhat peculiar : after forming the duodenal fold,
it is disposed in three distinct packets of folds : the intestine,
after forming the first two, passes alternately from one to the
other, describing shorter folds upon each ; it then forms the third
distinct fold, which is a long one, at the termination of which the
ileum adheres closely to the right side of the gizzard, and then
passes backward and dilates into the rectum.

In the Rasores the Dove-tribe have the small intestines dis-
posed in three principal folds ; the first is the duodenal fold, fig.
85,/,/; the second is a long and narrow fold, coiled and doubled
upon itself, with the turns closely connected together, ib. k ; the
third is also a long fold, which is bent or twisted, ib. k'. In the
Common Fowl the duodenum is disposed in a long simple loop ;
the ileum passes toward the left, and is disposed in loose folds on
the right and lower edge of the mesentery ; the ileum before its
termination passes up behind the preceding folds, and is accom-
panied as far as the root of the mesentery by the two coeca, which
there open into the commencement of the large intestine.

The Ostrich presents the most complicated course of the in-
testinal canal in the whole class of Birds. The duodenal fold is
about a foot in length, and the returning part makes a bend upon
itself before it reaches the pylorus ; the intestine then turns down
again behind the duodenal folds and gradually acquires a wider
mesentery. The ileum after a few folds ascends toward the left
side, accompanied by the two long coeca, and becomes again con-
nected with the posterior part of the duodenal mesentery ; beyond
which the co^ca enter the intestine behind the root of the me-
sentery, and the large intestine commences. This part differs
from the rectum in other Birds in its great extent, being nearly
double the length of the small intestines, and being disposed in
folds upon a wide mesentery. It terminates by an oblique val-
vular aperture in a large urinary receptacle. In the Bustard the
rectum is a foot in length, which is the nearest approach to the
Ostrich which the rest of the class make in this respect.

The small intestines in the Grallatores are characterised by
their small diameter and long and narrow folds ; these are some-
times extended parallel to one another, as in the Crane and Coot ;

' There is seldom any part of the small intestine empty so us to merit the name of
jejunum.

170 ANATOMY OF VERTEBRATES.

or folded concentrically in a mass, as in the Curlew and Fla-
mingo. In the latter species the duodenal fold is four inches
in length ; then the small intestines are disposed in twenty-one
elliptical spiral convolutions, eleven descending towards the rectum
and ten returning towards the gizzard in the interspaces of the
former.

Many of the Natatoi^es present a concentric disposition of the
folds of the small intestines similar to the Flamingo.

The arrangement of the muscular fibres of the intestine is the
same as in the oesophagus, the external layer being transverse, the
internal lono;itudinal.

The villi of the lining membrane manifest an analogy with the
covering of the outer skin, being generally much elongated, so as
to present a downy appearance when viewed under water. There
are, however, great varieties in the shape and length of the villi.
In the Emeu they consist of small lamellae of the lining mem-
brane folded like the frill of a shirt. In the Ostrich the lamella)
are thin, long, and numerous. In the Flamingo they are short
and arranged in parallel longitudinal zig-zag lines.

In many Birds a diverticulum is observed in the small in-
testine, which indicates the place of attachment of the pedicle of
the yolk-bag in the embryo, fig. 79, m.. We have found this pro-
cess half an inch in length in the Gallinule, and situated seven-
teen inches from the pylorus : in a Bay Ibis (^Ibis falcinellci)
the vitelline coecum was an inch in length: in a young female
Apteryx it dilated into a sac, about an inch in diameter, with a
yellomsh stratum of the remains of the yolk.^

The Birds in which the cmca coli have been found vv^anting are
comparatively few, though such examples occur in all the orders.
These exceptions are most frequent among the Scansores, in
which the coeca are absent in the Wrynecks, the Toucans, the
Touracos, the Parrot- tribe, and according to Cuvier in the Wood-
peckers.^ In the Insessores the cocca are deficient in the Hornbill
and the Lark. Among the Grallatores, we have found them
Avanting in a Spoonbill. In the Natatores they are absent in the
Cormorant. The Herons, Bitterns, and, occasionally, the Grebes
aiford the rare examples of a single coecum, which is also remark-
ably short.

In the Raptores the diurnal and nocturnal tribes differ re-
markably in the length of the coeca. They are less than half

' xr.

- In the Popinjay (Picus viridis, Linn.) wc have found two small cuica, so closely
adhering to the intestine as easily to be overlooked.

INTESTINES OF BIRDS. 171

an inch in length in the Eagles and Vultures, but are occa-
sionally wanting in the latter. Cuvier states that the coeca are
deficient in the greater part of the Diurnal Kaptores, but we have
observed them in the Halicetus Alhicilla, Aquila Chryscttos, Astur
paluinharius, and Buteo nisus. They seldom exceed the length
above mentioned, fig. 78, g, and in the Secretary Vulture they
form mere tubercles. In the Barn Owl the coeca severally
measure nearly two inches in length, and are dilated at their
blind extremities ; they are proportionally developed in the
larger Strif/idce.

In the Cantores they are invariably very short where present-
Among the Scansorial genera which possess the coeca, these parts
are found to vary in length, measuring in the Cuckoo and Wattle-
bird ( GlaiLcojns), each half an inch ; while in the Scythrops, or
New Holland Toucan, the coeca are each tAvo inches long, and
moderately wide.

In the Rasores the coeca present considerable varieties. In the
Pigeons, fig. 85, ^, they are as short as in the Insessorial order,
and are sometimes wanting altogether as in the Crown-Pigeon.
In the Guan {Penelope cristatci) each coecum is about three
inches in length : while in the Grouse each coecum measures a
yard long, being thus upwards of three times the length of the
entire body. The internal surface of these extraordinary ap-
pendages to the alimentary canal is further increased in the
Grouse by being disposed in eight longitudinal folds, which extend
from their blind extremities to within five inches of their termi-
nation in the rectum. We have always found the coeca in this
species filled with a homogeneous pultaceous matter mthout any
trace of the heather buds, the remains of which are abundant in
the faecal matter contained in the ordinary tract of the intes-
tines.

In the Peacock the coeca measure each about one foot in
length ; in the Partridge about four inches ; in the Common FoavI
and other Pliusicmidce the coeca are each about one-third the
length of the body ; they commence by a narrow pedicle, which
extends about ]ialf their length, and then they begin to dilate into
reservoirs for the chyme, fig. 79, g.

In the Cursores the coeca again present very different degrees
of developement. In the Apteryx the coeca are each five inches
in length. In the Emeu they are narrow and sliort. In the
Cassowary they arc wholly deficient; while in the Ostrich they
are wide, upwards of two feet each in length, and their secreting
and absorbing parietes are further increased by being produced

172 ANATOMY OF VERTEBRATES.

into a spiral valve, analogous to that which exists in the long
coecum of the Hare and Rabbit.

In the Gr alia tores the two coeca are generally short where
present ; they attain their greatest developement in this order in
the Demoiselle, where the length of each coecnm is five inches ;
and they are also large in the Flamingo, where they each mea-
sure nearly four inches, and are dilated at their extremities, pre-
senting with the gizzard, crop, lamellated beak, and webbed feet,
the nearest approach to the Anatidce of the following order.

In the Natatores, the coeca, where they are present, vary in
length according to the nature of the food, being very short in
the fish-eating Penguin, Pelican, Gull, &c., and long in the
Duck, Goose, and other vegetable-feeding LamelVirostres. In
the Crested Grebe {Podiceps cristatus), each coecum measures
3-16ths of an inch in length. In the Canada Goose the coeca
are each nine inches in length, and in the Whitefronted Goose
the same parts measure severally thirteen inches. They have
the same length in the Black Swan. In the Wild Swan the coeca
measure each ten inches in length, while in the tame species they
are each fifteen inches long.

As digestion may be supposed to go on less actively in the
somnolent, night-flying Owls, than in the high- soaring Diurnal
Birds of Prey, an additional complexity of the alimentary canal
for the purpose of retaining the chyme somewhat longer in its
passage, might be expected ; and the enlarged coeca of the Noc-
turnal Raptores afford the requisite adjustment in this case. For,
althouo'h the nature of the food is the same in the Owl ^ as in the
Hawk, yet the differences of habit of life call for corresponding
differences in the mechanism for its assimilation.

In the Rasorial Order, where the nature of the food differs so
widely from that of the Birds of Prey, the principal modification
of the digestive apparatus obtains in the more complex structure
of the crop, proventriculus, and above all the gizzard ; but with
respect to the coeca, as great differences obtain in their develope-
ment as in the Raptores. Now these differences are explicable
on the same principle as has just been applied towards the eluci-
dation of the differences in the size of the coeca in the Raptores,
Where the difference in the locomotive powers is so great in the
Dove-tribe and the common Fowl; where the circulating and

' The indigestible parts of the prey of the Owl do not pass into the intestine, but
are regularly cast or regurgitated from the stomach; the length of the ceeca cannot,
therefore, be accounted for on Macartney's supposition of iheir being receivers of those
parts.

DIGESTIVE SYSTEM OF BIRDS. 173

respiratory systems must be so actively exercised to enable the
Pigeon to take its daily flights and in some species their annual
migrations — a less complicated intestinal canal may naturally be
supposed with such increased energy in the animal and vital
functions to do the business of digestion, than in the more sluggish
and terrestrial vegetable feeders ; and accordingly we find that
the requisite complexity of the intestinal canal is obtained by an
increased developement of the coecal processes in the Gallince,
while in the Columbidce the coeca remain as little developed as in
the Insessores, which they resemble in powers of flight. If we
regard the coeca as excretive organs, their differences in the above
orders may be in like manner explained by their relations to the
locomotive and respiratory functions.

In the Cursores the developement of coeca seems to have re-
ference to the quantity of food, and the ease with which it may
be obtained, according to the geographical position qf the species.
In tlie CassoAvary, which is a native of fertile and tropical islands.
New Guinea, North of Australia, New Britain, &c., vegetable
food of a more easily digestible nature may be selected, and it
need not be detained long, where a fresh supply can be so readily
procured. But in the Ostrich, which dwells amidst arid sands
and barren deserts, every contrivance has been adopted in the
structure of the digestive apparatus to extract the whole of the
nutritious matter of the food which is swallowed.

In the Grallatores, where no material differences of locomotive
powers or means of obtaining food exist, the coeca present in their
developement a direct relation to the nature of the food, and are
most developed in the Gruidce. The same holds good in the
Natatores.

Why the increased extent of intestinal surface in the above
different cases should be chiefly obtained by the elongation of the
coeca, will appear from the following considerations. In conse-
quence of the stones and other foreign bodies Avhich birds swallow,
it is necessary that there should be a free passage for these
through the intestinal canal, Avhich is therefore generally short
and of pretty uniform diameter. In the omnivorous Birds of the
tropics, as the Hornbills, Toucans, Touracos, and Parrots, which
dwell among ever-bearing fruit-trees, the rapid passage of the
food is not inconsistent Avith the extraction of a due supply of
nourishment, but is compensated by the unfailing abundance of
the supply. But AAdiere a greater quantity of the chyle is to be
extracted from the food, and AA^here, from the nature of the latter,
a greater proportion of foreign substances is required for its

174

ANATOMY OF VERTEBRATES.

86

trituration, — wliile the advantages of a short intestinal tract are
obtained, the cliynie is at the same time prevented from being
prematurely expelled by the superaddition of the two coecal bags
which communicate with the intestines by orifices that are too
small to admit pebbles or undigested seeds, but which allow the
chyme to pass in. Here, therefore, it is detained, and chylifica-
tion assisted by the secretion of the coecal parietes, and the due
proportion of nutriment extracted.

The large intestine is seldom more than a tenth part of the
length of the body, and, except in the Ostrich and Bustard, is

continued straio:ht from the coeca
to the cloaca ; it may therefore
be termed the rectum rather than
the colon. It is usually A\dder
than the small intestine, and its
villi are coarser, shorter, and less
numerous. The rectum, fig. 86,
a, terminates by a valvular cir-
cular orifice, h, in a more or less
dilated cavity, which is the re-
mains of the allantois, and now
forms a rudimental urinary blad-
der, c, d. The ureters, h, h, and
eiferent parts of the generative
apparatus,/, g, open into a trans-
verse groove at the lower part of the urinary dilatation ; and be-
yond this is the external cavity which lodges, as in Keptiles,
Marsupials and Monotremes, the anal glands and the exciting
oro^ans of o-eneration. The anal follicles in Birds are lodo'ed in
a conical glandular cavity, k, which communicates with the pos-
terior part of the outer compartment of the cloaca, and has ob-
tained from its discoverer the name of Bursa Fahricii.

§ 149. Liver of Birds. — On the hypothesis of chylification, or
on that of the formation of blood-discs, or on that of the pro-
duction of grape-sugar in relation to the raising of animal heat,
being essential functions of the liver, it might have been expected,
since digestion is so much more active and the blood so much
more abundant and rich, and the temperature so much higher in
Birds than in Reptiles, that the liver Avould be proportionally
larger ; but it is not so. ' Carefully ascertained upon delicate
balances,' the proportionate Aveight of the liver to the body is the
same in a Vulture as in a Tortoise, in an Owl as in a Bull-frog,
in a Curlew as in a Corn-snake, in a Turkey as in an i\lligator.

Cloaca of the Cuiidor. xviit'.

DIGESTIVE ORGANS OF BIRDS.

175

&c.' ' My own observations show the liver to be relatively largest
in the less active aquatic and land birds, smallest in the birds
that fly best and breathe
most : compared in the li-
mits of the class the liver
seems to be developed in-
versely as the lungs and
their appendages, and so
far as it is associated -with
the luno's in eliminatino-
waste elements from the
blood, to have less to do in
that way, as the breathing
organs perform most.

The liver, figs. 85, 87,
m, m, is situated a little above
the middle of the thoracic
abdominal cavity, with its
convex surface towards the
abdominal parietes, and its
concavity turned towards
the subjacent viscera: the
rio^htlobe covers the beo-in-
ning of the duodenal loop,
pancreas, and part of the
small intestines ; the left
lobe covers the proventri-
culus and part of the giz-
zard ; and the apex of the
heart is received between
the upper ends of these
principal lobes. The liver
is, as it were, moulded upon
all these parts, and presents
corresponding depressions
where it comes in contact with them.

It is generally divided into two nearly equal lobes (^Raptor cfi.

Tostcrior view of the liili.-iry ami rancrcatlc duct in the
Horul>iU. VI I- .

^ Numljcr of times the weight of the liver in that of the bod}- :-
Cathartes atratus, 47; Chelonia caretta, 47:
Si/rnium nebulosum, 56 ; liana Catesbiana, 55;
Tantalus locniator, 64; Coluber guttatus, 64:
Meleagris gallopavo, 70; Alligator lucius, 73:
and see other cxanii)les, in ccxlv. p. 113.

176 ANATOMY OF VERTEBRATES.

Stork), which are often separated for a short extent, and con-
nected together by a narrow isthmus of the glandular substance.
In some Birds, however, as in the Pigeon, Cormorant, Swan, and
Goose, there is a third, smaller lobe, situated at the back of the
liver between the lateral lobes, which from its situation appears
analogous to the ^ lobulus Spigelii ' of Mammalia. In the Com-
mon Fowl the left lobe is occasionally cleft from below so deeply
as to form two lobes on that side. In most species the right lobe
exceeds the left in size ; this is remarkably so in the Bustard, in
which the right lobe extends into the pelvis.^ In the Eagle, how-
ever, the left lobe is sometimes the largest. Each lobe is invested
by a double membranous tunic, one embracing it closely, the
other surrounding it loosely, like the pericardium of tlie heart.
They are formed by lamina? of the peritoneum, and by the air-
cells. The two adherent layers are continued from the base of
the liver, one over the anterior, the other over the posterior sur-
face, closely adhering to the proper capsule : the loose layers are
formed by the hepatic air-cell, surrounding each lateral lobe, the
thin border of which is usually free.

The principal ligament of the liver is formed by a large and
strong duplicature of the peritoneum, which divides the abdomen
longitudinally like the thoracic mediastinum in Mammalia. It is
reflected from the linea alba and middle line of the sternum upon
the pericardium, and passes deeply into the interspace of the lobes
of the liver; it is attached to these lobes through their whole
extent, and connects them below to the gizzard on one side, and
to the duodenal fold on the other : the lateral and posterior parts
of the liver are attached to the contiguous air-cells ; and the
whole viscus is thus kept steady in its situation during the rapid
and "violent movements of the bird. The ligament first described
is analogous to the falciform ligament of Mammalia ; and, al-
though there is no free margin enclosing a round ligament, yet
the remains of the umbilical vein may be traced within the dupli-
cature of the membranes forming the septum. As the muscular
septum between the thorax and abdomen is wanting, there is con-
sequently no coronary ligament ; but the numerous membranous
processes which pass from the liver to the surrounding parts
amply compensate for its absence.

The liver is of a lighter colour in Birds of flight than in the
heavier Waterfowl, where it is of a deep livid brown. Each

^ The French Academicians (xl*. 2dc partie, pp. 99-109) saw this in some of their
Bustards : but in the male dissected by me the hepatic lubes were equal, and both
were long.

LIVER OF BIRDS. 177

lobe has its hepatic artery and vena portae. The hepatic arteries
are proportionally small, but the portal veins are of great size,
being formed not only by the veins of the intestinal canal, pan-
creas, and spleen, but also by the inferior emulgent and sacral
veins. The blood, which has circulated in the liver, is returned
to the inferior cava by two venae hepaticse. There are occasionally
some smaller hepatic veins in addition to the two principal ones.
The coats of the portal and hepatic veins appear to be equally
attached to the substance of the liver. A duct arises by two
roots from each lobe, and the biliary secretion is carried out of the
liver by these two and sometimes by three ducts ; one duct always
terminates directly in the intestine, and is an ' hepatic duct,'
fig. 87, n, n\ the other enters the gall-bladder, and is an * cyst-
hepatic duct,' ib. o' ; the cystic bile is conveyed to the duodenum
by a ^cystic duct,' ib. o. Where, as in a few instances, the gall-
bladder does not exist, both hepatic ducts terminate separately in
the duodenum, fig. 85, n, n ; but in no case is there a single
ductus communis choledochus as in Mammalia.

The galUhladder, fig. 87, p, is situated near the mesial edge of
the concave or under side of the right lobe, and is commonly
lodged in a shallow depression of the liver ; but sometimes, as in
the Eagle, Bustard, and Cormorant, only a very small part of the
bao; is attached to the liver. It has no visible muscular tunic :
its inner surface is delicately reticulated.

The gall-bladder is present in all the Raptoi^es, Insessores, and
Natatores. It is wanting in a great proportion of the Scansores,
as in the genus Rhamphastos and in almost all the Psittacidce and
Cuculidce. Among the Rasores the gall-bladder is constantly
deficient in the Columbidce or Dove-tribe alone, in Avhich the
coeca are shorter than in any other vegetable feeder. The gall-
bladder is occasionally absent, according to the French Acade-
micians,^ in the Guinea-fowl ; and they also found it wanting in
two out of six Demoiselles (Anthropoides Virgo). The gall-bladder
is small and sometimes absent in the Bittern : I found it absent in
one out of three Kivis (^Apteryx) : it is always wanting in the
Ostrich, but is present in the Emeu and Cassowary.

The bile, as before observed, passes directly into the gall-
bladder, and not by regurgitation from a ductus choledochus ;
the cyst-hepatic duct arises from the right lobe, and is continued
in some birds alono* that side of the bao^ which is in contact with
the liver, where it penetrates the coats of the cyst and termi-
nates about one-third from the lower or posterior end. In the

' XL*.

VOL. IT. N

178 ANATOMY OF VERTEBRATES.

Hornbill ' I found it passing over the npper end of the bladder to
the anterior or free surface, and the cystic duct continued from
the point where the cyst-hepatic duct opened into the bladder ; so
that the cystic duct had a communication both with the reservoir
and the cyst-hepatic duct; being somewhat analogous to the
ductus communis choledochus ; (fig. 87, where x represents the
orifice by which the bile passes both in and out of the gall-
bladder).

In the Goose the cyst-hepatic duct terminates by a very small
orifice, surrounded by a smooth projection of the inner membrane,
which, aided by the obliquity of the duct, acts as a valve and pre-
vents any regurgitation towards the liver. The cystic duct here
passes abruptly from the posterior extremity of the gall-bladder,
which is not prolonged into a neck. The duct makes a turn
round the end of the bag, and is so closely applied to it, as to
require a careful examination to determine the true place of its
commencement.

The hepatic duct, fig. 87, ji, arises by two branches from the
large lateral lobes of the liver, which unite in the fissure or
Agates' of the gland. Two hepatic ducts have been found in the
Curassow ; but these and the cystic duct terminate separately in
the duodenum. Of the two hepatic ducts in Pigeons, one, the
right and larger, enters the beginning of the duodenum, the other
near its termination. The place of termination of the cystic and
hepatic duct is generally, as shown in fig. 87, pretty close together
at the end of the fold of the duodenum ; but in the Ostrich one of
the hepatic ducts, which is very large and short, terminates in the
commencement of the duodenum about an inch from the pylorus ;
while the other enters with the pancreatic duct at the termination
of the duodenum. Both the cystic and hepatic ducts undergo a
slight thickening in their coats just before their termination. The
passage of the bile-ducts in Birds through the coats of the intes-
tine is oblique, and they terminate upon a valvular prominence of
the linino; membrane of the orut.

§ 150. Pancreas of Birds, — The non-mastication of food in the
mouth is associated with a low condition of the salivary glands ; a
large pancreas is concomitant with gastric mastication, in Birds.
This organ, figs. 85, 87, q, q, consists of two (^Picus, Certhia, Upupa,
Cajirirnulgus, Grus^ Colymhus^^ and sometimes of three ( Oriolus),
distinct portions ; but these are so closely applied together at some
point of their surface as to appear like oae continuous gland, fig.
88. It is of a narrow, elongated, trihedral form, lodged in the inter-

PANCREAS OF BIRDS.

179

space of the duodenal fold, and generally bent upon itself like
duodenum, as in the Hornbill, fig. 87, 5-.
It is there supported by the gastro-
hepatic and gastro-colic omenta.

The structure of the pancreas is
conglomerate, like that of the sali-
vary glands, but the ultimate folli-
cles are differently disposed. In the
salivary glands these are irregularly
branched, while those of the pancreas
in Birds diverge in the same plane
from digitated and pinnatifid groups.
The substance is firmer than in Rep-
tiles, of a pinkish, yellowish, or brown-
ish colour.

The ducts, figs. 85, 87, 88, r, r, formed
by the reiterated union of the efferent
branches from the component follicles
of the pancreas, are in general two in
number, which terminate separately in
close proximity to the hepatic and
cystic ducts, n ; but occasionally there
are three pancreatic ducts, as in the
Fowl, Pigeon, Raven, and Hornbill ;
in which case the third duct commonly
terminates at a distance from the other
two : in the Hornbill it proceeds from
an enlarged lobe of the pancreas at the
end of the duodenal fold, and enters
that part, at /, fig. 87. As a rule,
the pancreatic secretion is the first
poured into the gut, the cystic bile
is the last.

the

Pancreas and duodenum of
Goose, ccxxxi.

N 2

180 ANATOMY OF VERTEBRATES.

CHAPTER XVIIL

ABSORBENT SYSTEM OF BIRDS.

§ 151. The absorbents of Birds, as of Reptiles, differ from those
of Mammals in having fewer valves, which are also less perfect,
being so loose as frequently to permit for a certain extent a
retrograde passage of the injected fluid. The lacteals, lymphatics,
and thoracic ducts have very thin parietes, so as easily to be
ruptured : they are composed of two tunics, of which the internal
is the weakest.

The lymph resembles that of Mammals, but the chyle differs
essentially in its transparency and want of colour. The lacteals
have, however, been observed to contain an opaque white fluid in
a Woodpecker that had been killed after swallomng a quantity
of ants.

With respect to the disposition of the absorbents, they do not
form in Birds two strata, as in Mammals ; at least those only
have been observed which correspond to the deep-seated absorbents
which accompany the large vessels.

The lymphatic glands or ganglions are few in Birds ; the most
constant and conspicuous are those at the anterior part of the chest
or the root of the neck. Small ones have been seen in the axilla
and groin of sea-birds {Aptenodytes). In other parts of the body
the absorbent glands are replaced by plexuses of lymphatic vessels
surrounding the principal bloodvessels.

The absorbents of Birds terminate principally by two thoracic
ducts, one on either side, which enter the right and left jugular
veins by several orifices ; the plexuses of the posterior part of the
body communicate mth the contiguous sacral and renal veins.

The lymphatics of the foot unite to form the vessels which are
found running along the sides of each toe, fig. 89, i. In the
Palmipedes there are anastomosing branches which pass from
the lateral vessel of one toe to that of the adjoining toe, forming
arches in the uniting web, 2. These branches form a small plexus,
.'^, at the anterior part of the digitometatarsal joint, from which
three or four lymphatics are continued. The anterior and in-

ABSOEBENT SYSTEM OF BIRDS.

181

ternal branches, 4, accompany the bloodvessels, and form a net-
work around them ; the posterior and external branches, 5, receive
the lymphatics of the sole

of the foot, then ascend
along the metatarse, and
form at its proximal arti-
culation a close network, 6,
from which the vessels climb
the tibia, forming a plexus,
7, around it as far as the
middle of the leg; from this
proceed two branches, of
which the smaller j)asses
along the anterior part of
the depression between the
tibia and fibula as far as the
knee-joint, where it joins
the other branch which ac-
companies the bloodvessels.
The trunk formed by the
union of the two preceding
branches accompanies the
femoral vessels, forming
plexuses in its course, 8,
which receive tributary ab-
sorbents from the surround-
ing muscles, and a large
branch, 9, corresponding to
the deep-seated femoral ves-
sels.

The iliac trunk, 10, ac-
companies the great femo-
ral vein into the abdomen,
which it enters anterior to
the origin of the pubis ; it
there receives branches from
the lateral parts of the pel-
vis, 11, and afterwards sepa-
rates into two divisions.

The posterior di^^sion re-
ceives some lymphatics from
the anterior lobes of the kidneys, and those of the ovary or testi-
' Erom Lauth's Monograph, Annales dcs Sciences Nat. t. iii, pis. 23 and 25.

Absorbents of a fioose.

182 ANATOMY OE VERTEBKATES.

cles ; it communicates anteriorly "vvith a branch from the absorbents
which surround the great mesenteric artery, and posteriorly with
large vesicular plexuses or receptacles, 12, 13, surrounding the
aorta and its branches, and which receives the lymphatics from
the renal plexus, and those accompanying the arteria sacra
media, 14.

The sacral or pelvic plexiform vesicles of the lymph are two in
number, situated in the posterior region of the body, in the angle
between the tail and the thigh. Each vesicle is little more than
half an inch long and a quarter of an inch broad, and is shaped
somewhat like a kidney-bean in the Goose. ^ They have muscular
coats with striated fibre, distinctly recognisable in those of the
Ostrich, where these ^lymph-hearts' are attached to the con-
tiguous bone. In the Cassowary, Stork, and Goose, they lie free.
The pulsations correspond with the motions of respiration.

The anterior division of the femoral lymphatic trunk, 16, accom-
panies the aorta, upon which it forms a plexus with the branch of
the opposite side, and with the intestinal absorbents, 15. These
vessels commence from a plexiform continuous network situated
between the mucous and muscular coats of the intestine ; they
are larger here than when they quit the intestine to pass upon
the mesentery. They accompany the branches of the superior
mesenteric artery, there being many absorbents for one artery,
which by their anastomoses form plexuses surrounding the blood-
vessels. Before reaching the aorta, the lacteals communicate
with the inferior or posterior division of the femoral trunk, and
mth the absorbents of the ovary or testicles, after which they
pass upon the aorta, 16, 17, where they receive the lymphatics of
the pancreas and duodenum, and terminate by uniting around the
coeliac axis, 18, with the lymphatics of the liver, the proventri-
culus, c, the gizzard, and the spleen, forming a considerable
plexus, from which, according to Lauth,^ it is by no means rare
to see branches passing to terminate in the surrounding veins.

The aortic plexus, 19, which answers to the ' receptaculum
chyli ' of Mammals, gives origin to two thoracic ducts, 20, 20, of
varying calibre, but often, as in the Goose, exceeding a line in
diameter. They are situated at their origin behind the oeso-
phagus, a, and in front of the aorta, b ; they advance forward,
diverging slightly from each other, pass over the lungs, w, w, from
which they receive some lymphatics, and terminate respectively,
after being joined by the lymphatics of the wing, in the jugular

^ XLir, tab. ix. fig. 3. 2 ^li-. p. 381.

ABSORBENT SYSTEM OF BIRDS. 183

vein of the same side. The left thoracic duct, before entering
the vein, receives the trunk of the lymphatics of the left side of
the neck ; the right thoracic duct receives only a branch of those
of the same side.

The lymphatics of the wing follow the course of the brachial
artery, forming a plexus around it, especially at the elbow-joint.
Their principal trunk, to which all the collateral branches are
united about the upper third of the humerus, is here of large size,
but its diameter soon begins to be diminished, and it is very small
at the head of the humerus. When it reaches the parietes of the
chest, it receives two or three large lymphatics from the pectoral
muscles, and a branch which accompanies the brachial plexus.
Soon after a small lymphatic gland is sometimes formed on the
trunk, which lastly unites with the thoracic duct of its own side.

The lymphatics of the head accompany the branches of the
jugular vein, and are readily discerned upon those which are
situated between the rami of the lower jaw. They form, by
uniting with the cervical absorbents, two lateral branches on each
side, which accompany the corresponding jugular vein, being-
situated, one in front, the other behind that vessel. These lym-
phatics communicate together, at the anterior and posterior parts
of the neck, by transverse or oblique branches. They receive in
their progress absorbents from the muscles, and from the peculiar
glands which are seen beneath the skin of the neck. The internal
branch on the left side receives also a considerable absorbent from
the oesophagus. At the lower part of the neck both branches
receive a notable branch which accompanies the carotid arteries,
and a little further on they form on each side a lymphatic gland
situated on the jugular vein. On the right side the trunk of the
cervical lymphatics terminates in the jugular vein, after having
furnished a communicating branch with the thoracic canal of that
side ; on the left side it terminates at once in the corresponding
thoracic duct.

184

ANATOMY OF VERTEBRATES.

CHAPTER XIX.

CIRCULATING SYSTEM OF BIRDS.

§ 152. Blood of Birds. — The blood is hot and of a deep red
colour. The blood-discs are more abundant than in the cold-
blooded Vertebrates, save, perhaps, in some Ophidia : they are
nucleated, elliptic, and flattened in form; averaging in size, in
long diameter -j-^-^th, in short diameter ^gVe^th, of an inch;
with the following observed extremes : — Humming-bird, long
diameter -^-g-g, short diameter xoVo ' Ostrich, long diameter y-gV-g,
short diameter -goVo- Milne-Edwards notes decimally the fol-
lowing range of size in different species of the class : — ^ Long
diameter, maximum, 1*59; minimum, 1*105: short diameter,
maximum, 1*110 ; minimum, 1*158.'^ (Metrical system.)

The blood-discs are largest in the embryo, losing size as the
respiration gains in activity and extent in the progress of the in-
dividual to maturity. The smaller size of the blood-discs of Birds
as compared with those of cold-blooded Ovipara exemplifies the
same inverse ratio of their size to the amount of respiration. The
j)roportion of organic matters contained in the water of the blood
is greater than in the Hcematocrya, as will be seen by comparing
the subjoined Tables with those in vol. i. pp. 463, 464 : —

AVES

Water

Clot

Albumen
and Salts

Anas Boschas (Duck) .....
Ardea cinerea (Heron) ....
Columha livia (Pigeon) ....
Gallus domesticus (Fowl) ...
Corvus Corax (Raven) ....

765

808
797
780
797

150
133
156
157
146

85
59
47
63
56 =

Ardea nycticorax (Night

Heron)
Sijriiium nebulosum (Barred

Owl) ....
Cathartes atratus (Black

Vulture) .

MOIST BLOOD-DISCS

PLASMA

Total
weight

Water

Solid
matter

Total
weight

Water

Solid
matters

315-84
427-36
626-88

236-88
320-52
470-16

78-96
106-84
156-72

684-16
572-64
373-12

63901

519 14
329-01

48-15
•50
44.113

ccxxxix. p. 86.

** CCLXV. p. 64.

' lb. p. 27.

CIRCULATING SYSTEM OF BIRDS.

185

The fibrine in the blood of Birds is soft and very lacerable.
The serum is usually of a light yellow colour, but is golden in
the Cathartes atratus. Dr. Jones notices the strong musky
odour of the blood of this Vulture, like that of the living bird.'

§ 153. Heart of Birds. — This organ consists of two ventricles
and two auricles ; the septum of both being complete.

The form of the heart is always that of a cone, sometimes wide
and short, as in the Ostrich and Crane ; sometimes more elon-
gated, as in the Emeu, fig. 90,
and Vulture; or still more
acute, as in the Curlew and
Common Fowl.

Its situation is more anterior
and mesial than in Mammalia,
and its axis is always parallel
with the axis of the trunk. It
is not contained with the lungs
in an especial cavity, but its
apex is lodged between the
lobes of the liver ; the dia-
phragm, as a rule, not being
so far developed as to separate
the chest from the abdomen.

As the lungs are confined to
the dorsal part of the chest, the
whole of the anterior surface
of the pericardium is exposed

when the sternum of the bird is removed. The pericardium is
thin, but of a firm texture, and adheres by its external surface to
the surrounding air-cells. It is of considerable size, and commonly
prolonged for some way between the lobes of the liver.

The auricles of the heart in Birds have not externally such
free appendices as in Mammals. The right auricle is much
larger than the left ; it is more distinctly divided internally into
a sinus, ib. d, and auricle proper, Z», z, x, than in Mammals, and
these parts are separated by a more complete valvular structure,
but less definitely developed than in the Crocodile.

Three veins terminate in the sinus, there being in Birds always
two precavals, as in Reptiles. The right precaval, ib. a, which
returns the blood from the right wing and right side of the neck,
terminates in the upper and anterior part of the sinus ; the left

Heart of the Emeu.

* CCXLV. p. 16.

186 ANATOMY OF VERTEBEATES.

precaval, ib. b, winds round the posterior part of the left auricle to
open into the lower part of the sinus ; just before its termination
it receives the coronary vein, so that this does not open separately
into the auricle as in most Mammals. The postcaval vein, ib. c,
terminates in the sinus just above the orifice of the left precaval,
and a semilunar valvular fold, ib. h, analogous to that of the
coronary vein in man, is extended forward between these orifices
so as to separate them, and afford a protection to the mouth of
the left precaval, in addition to that which it derives in common
with the other veins from the larger valves at the mouth of the
sinus.

The disposition of the valves between the sinus and auricle
seems more especially destined to prevent regurgitation into the
sinus, when the pulmonary circulation may be impeded. A
strong oblique semilunar muscular fold, ib. g, commences in the
Emeu by a band of muscular fibres running along the upper part
of the auricle, and expanding into a valvular form extends along
the posterior and left side of the sinus, terminating at the lower
part of the fossa ovalis, ib. i. A second semilunar muscular
valve, ib./, of equal size, extends parallel with the preceding
alonar the anterior border of the orifice of the sinus, its lower
extremity being fixed to the smooth floor of the auricle, its upper
extremity being continued into a strong muscular column running
parallel to the one first mentioned across the upper and anterior
part of the auricle, and giving off from its sides the greater part of
the musculi iiectinati. From this structure it results that the more
powerfully the musculi pectinati act in overcoming the obstacle
to the passage of the blood from the auricle to the ventricle, the
closer will the valves be drawn together, and the stronger will be
the resistance made to them by the regurgitation of the blood
from the auricle into the sinus. The valves f and g are homo-
logous with the pair dividing the auricle, 6>, from the sinus, 5, in the
Crocodile's heart (vol. i. fig. 339). The parietes of the auricle
in the interspaces of the muscular fasciculi are thin and trans-
parent, consisting in many parts only of the lining membrane of
the cavity and the reflected layer of the pericardium blended
together. T^q fossa ovalis, fig. 90, i, is a deep depression situated
behind the posterior semilunar valve, which, we may observe, bears
nearly the same relation to the fossa as the annulus ovalis in the
human heart. The membranous septum closing the foramen
ovale is complete and strong, but thin and semitransparent. The
appendix auriculod, ib. x, is the most muscular part of the cavity ;

HEART OF BIRDS.

187

it does not project freely in front of the great vessels arising from
the ventricles, but is tightly tied down to them by the reflected
layer of the pericardium. The auriculo-ventricular orifice is an
oblique slit, fig. 92, k ; a bristle is passed through it in fig. 90.
The manner in Avhich regurgitation by this orifice is prevented is
one of the chief peculiarities in the heart of Birds. The right
ventricle, fig. 91, /«, is a narrow triangular cavity, applied as it
were to the right and anterior
side of the left ventricle, but not
extending to the apex of the
heart. The parietes are of pretty
uniform thickness, except at the
septum ventriculorum, and are
weaker in comparison to those of
the left ventricle than in Mam-
mals. Short fleshy columns ex-
tend from the septum to the
free wall of the ventricle at the
angle of union of these two parts,
leaving deep cells between them ;
a strong column, fig. 92, yn, also
extends from the right side of
the base of the pulmonary artery
to the upper extremity of the
auriculo-ventricular valve ; but
these are the only * columnae
carneaB ' in the right ventricle ;
there being none of a pyramidal form projecting into the cavity,
nor any ' chordie tendinea3.' The principal valve which guards
the auricular aperture is a strong muscular fold, figs. 90, 91,
92, /, nearly as thick as the wall of the ventricle itself, extend-
ing from the fleshy column above mentioned obliquely down-
ward and backward to the angle formed between the septum
and the free wall of the ventricle at the lower and posterior
part of the cavity. The convex edge of this muscular valve
is turned toward the convex projection made by the septum,
and must be forcibly applied to this part during the systole of
the ventricles ; so that, while all reflux into the auricle is pre-
vented, additional impulse is given to the flow of blood through
the pulmonary artery ; the muscidar parietes of the ventricle
being thus complete at every part except at the orifice of the
artery. This valve is strongest in the Diving Birds, weakest in

Ventricles of the heart of a Swan.

188

ANATOMY OF VERTEBRATES.

92

Section of the ventricles. Pelican.

the Struthious, and especially in the Apteryx, in which it is par-
tially membranous and has its margin tied by a few tendons to a
fleshy process from the fixed ventricular wall.

The small muscular column, fig. 92, m, at the upper part of
the auricular orifice is analogous in its position to the single valve
which guards the corresponding orifice in Keptiles; the Cro-
codiles alone present a second muscular valve (vol. i. p. 510, fig.
339, r) homologous Avith the larger valve in Birds.

The right ventricle is remarkable for the smoothness and even-
ness of its inner surface. The
pulmonary artery is pro\dded at
its origin with three semilunar
valves, fig. 92, n. It divides, as
usual, into two branches, fig. 168,
one for each lung; the right
branch passes under the arch of
the aorta.

The aerated blood is returned
from the lungs by two veins
which open into the back part of
the left auricle; a strong semi-
lunar ridge, which is hardly suf-
ficiently produced to be called a valve, divides the cavity of the
auricle in which the veins terminate from the muscular part or
appendix. The fleshy columns are very numerous and compli-
cated in this part of the auricle, which is closely tied down to the
ventricle by the serous layer of the pericardium and dense cellular
tissue.

The left ventricle, figs. 91, 92, o, is an elongated conical cavity,
the parietes of which are three times as thick as those of the
right ventricle, and exhibit strong fleshy columns extending from
the apex towards the base ; two of the largest of these columns
present in the Emeu a short convex eminence towards the auri-
culo- ventricular orifice, fig. 92, r, and give ofl" short thick tendons
to the margin and ventricular surface of two membranous folds,
figs. 91, 92, j9, 5^, which correspond to the 'mitral valve' in Mam-
mals. Of these valves, the one next the aorta, q, corres2:)onds to
the single valve which guards the auricular opening in the heart of
Reptiles, and is most developed in Birds ; the opposite valve is of
much less size. In many Birds the chords tendinete pass from the
valves at once to the parietes of the ventricle, and are not at-
tached to columnas carneas. The surface of the ventricle formed
by the septum is smooth from the orifice of the aorta down to the

HEART OF BIRDS. 189

apex of the heart. The aorta is provided with three semilunar
valves, not -with two only as in Reptiles. The extremities of these
valves are connected to small, firm, and sometimes ossified styles
imbedded in the fibrous coat of the vessels.^

The arrangement of the muscular fibres of the ventricle in
Birds is such that the right ventricle appears to be formed by a
partial secession of the outer from the inner layers of the parietes
of the left ventricle at the anterior and right side of that cavity.
See the transverse section, fig. 92.

§ 154. Arteries of Birds. — The arterial system of Birds
mainly differs from that of Mammals in the follomng points : —
The division of the aorta into three principal branches, almost
immediately at its origin : the course of the arch of the aorta
over the rio^ht instead of the left bronchus to become the descend-
ing aorta : the basilar artery being formed by the entocarotids,
not by the vertebral : the great length of the common carotid,
which is a single median trunk in some birds: and the origin
of the arteries of the posterior extremities, which do not come off
from a single branch, or ^ external iliac,' but from two arteries
which are detached successively from the aorta at a great distance
from each other, and pass from the pelvis by two separate aper-
tures. In these differences the closer affinity of Birds to Reptiles
is shoAvn.

The aortic trunk, fig. 93, i, is so short that it is only brought
into view after the reflections of the pericardium and the adjoining
vessels are detached by dissection. The first branch is to the left
side and, after it is sent off, the trunk afifects to turn over the
auricle before it gives the branch of the right side ; thes^ two
branches pass in a curved manner from the heart towards the
axilla, and may be regarded as two arferice innominatce, fig. 90, t, t.
After these branches are parted with, the arterial trunk, ib. s, fig.
93, 2, is continued over the right bronchus, and, on reaching the
back part of the heart, becomes the ' descending aorta.'

The arteria innominata, fig. 93, 3, first sends off the common
trunk of the carotid and vertebral arteries, ib. 4, which before its
division gives off one or two small branches ; one of these runs
down upon the lungs in company A\4th the par vagum, and ap-
pears to supply branches to the aponeurosis of the lungs, and the
air-cells at the upper part of the tliorax ; the other branch, after
supplying the lymphatic gland of the neck with several small
arteries, ascends upon the side of the oesophagus, to which, and
the inferior larynx, the divisions of the trachea, and to the parts
' Home Clift, in vir. p. 331.

90

ANATOMY OF VERTEBRATES.

and integuments of the side of the neck, its branches are dis-
tributed, anastomosing with the superior oesophageal and tracheal
arteries. Sometimes, in the Duck, the supra-scapular artery,
which is usually divided from the vertebral, is a branch of the
common trunk, as it is also in the Apteryx, where it supplies the
muscles at the back of the base of the neck.

Birds, as a rule, are peculiar in sleeping with their long neck

much bent or twisted, and
this position might be ex-
pected to exercise some
effect on the vessels sub-
ject thereto. Accordingly
we find that the carotid
arteries, ib. 4, fig. 90, u, u,
are frequently of unequal
size ; in the Dabchick the
left is the largest, fig. 93, 2 ;
in an Emeu I found it the
smallest. One or other
carotid may be obliterated,
according, perhaps, as the
bird hal^itually sleeps with
the head under the right or
left wing. In the Apteryx
I found that the left caro-
tid alone passed to the usual
place in the neck, and di-
vided at the third cervical
vertebra to supply the head
in the usual way. In the
Flamingo the rio;ht carotid
was single and bifurcated
at the upper part of the
neck. In the Common
Fowl, each carotid, after
parting from the vertebral artery, ib. 6, proceeds to the middle
of the neck and soon disappears ; becoming covered by the muscles
of the anterior part of the neck, and entering the canal formed
by the hypapophyses, fig. 25, h, within which it lies hidden, and
in close contact with its fellow of the other side, to very near the
head. In the Bittern the two carotids are situated one behind
the other, and adhere so intimately together in this situation that
they seem like a single trunk.

Arteries of the trunk. Grebe, sliv.

ARTERIES OF BIRDS. 191

In the following details of the vascular system, I adopt, with
little modification, the words of Macartney, by whom it was
first and best described in his Article * Birds,' in ^ Rees's Cyclo-
paedia.' The carotid artery emerges from between the muscles
of the neck, at about the third or fourth vertebra from the head
(9); and after giving off the arteries, cutanece colli later ales, fig.
93, 10, 11, to the lateral muscles and integuments of the neck, it
runs along the outer edge of the rectus major anticus to behind
the angle of the jaw, Avhere it divides into its several branches.

An artery {arteria occipitalis) first goes off posteriorly, which
passes a little forward under the thyrohyal, and after sending
some blood to the muscles of the neck, makes a turn backward,
enters the foramen in the transverse process of the second ver-
tebra, and terminates by anastomosing mth the vertebral artery.*

The next branch is the entocarotid ; it passes behind the
muscles of the jaw close to the basioccipital, sends a branch
upward, which penetrates the tympanum ; and another througli
the articulation of the jaw, to unite with the ophthalmic, and con-
tribute to the plexus at the back of the orbit (rete ophtlialmicum
of Barkow). The entocarotid then enters an osseous canal, which
runs along the side of the basisphenoid between the tables of the
bone ; and at the lower and back part of the orbit, the artery
receives a remarkable anastomosing branch of the internal maxil-
lary, which almost equals in size the carotid itself, and these two
vessels produce by their union one which passes almost directly
to the cranium, entering at the deep ' sella turcica.' It forms
within the skull an anastomosis similar to the circle of Willis ; but
the branch which occupies the place of the basilar artery is very
small, and appears to be furnished entirely from the anastomosis
of the carotids, and designed only to supply the medulla oblon-
gata. The branches of the entocarotid are spread in an arbo-
rescent form upon the surfaces of the brain ; some on the outside
and others on the ventricles and the fissure between the two
hemispheres : the tufted termination of the vessels of the choroid
plexus is shown in fig. 46. The orbital plexus formed by the
carotid sends off the inferior palpehral, ethmoidal, lacrymal, and
ophthalmic arteries. The ophthalmic artery forms two remarkable
plexuses at the posterior part of the globe of the eye ; the first,
fig. 59, s, is situated close beside the inner side of the optic nerve,
is formed by an artery answering to the arteria centralis retincB,

' Barkow, xliv., has established the accuracy of this observ^ation of Macartney's
(xLiu-.), having found this singular anastomosis of the occipital with the vertebral
artery in all the birds which he injected.

192 ANATOMY OF VERTEBRATES.

and supplies the marsupial membrane; the second plexus, ib. 4,
is situated more exteriorly, and gives off the ciliary arteries.

After the carotid has sent off the entocarotid, it passes for a
little way downward and forward behind the angle of the jaw, and
divides at once into different branches, corresponding to those of
the ectocarotid in Mammals ; the first of which might be called the
oesophageal or laryngeal artery. This vessel sends a branch to
the muscles upon the thyrohyal, and then turns downward and
divides into two branches, one to the trachea, fig. 93, G i, and the
other to the oesophagus, upon the side of which parts they descend
to near the thorax, forming a series of arches, ib. ii, ii, and ulti-
mately inosculate with the tracheal and oesophageal branches of
the common trunk of the carotid and vertebral arteries.

The external maxillary artery, ib. 12, dips in between the
pterygoid and digastric muscles ; it then passes behind the tym-
panic, and gives twigs upAvard to the muscles of the jaws, and
to the plexus at the back of the orbit: upon emerging from
behind the tympanic, it lies under the zygomatic arch, and sends
an artery upward, which is distributed to the temporal and mas-
seter muscles, and proceeding under the triangular tendon that
comes from the inferior margin of the orbit to the lower jaw, it
divides into two principal branches ; one of these passes along the
side of the upper jaw, gives a branch upward to the fore part of
the orbit which unites with the ophthalmic artery, and is lost at
the top of the head. This branch is very large in birds with
combs, as, in conjunction with the ophthalmic, it furnishes nu-
merous vessels to these vascular parts. The artery then goes on
and supplies branches to the sides of the head before the orbits,
and to the integuments and substance of the upper mandible,
inosculating mth the palatine branches of the internal maxillary
artery. The second portion of the external maxillary proceeds to
the lower jaw, to which, and the lower part of the masseter muscle,
it is distributed. The external maxillary supplies the place of the
temporal, labial, angular, nasal, and mental arteries of mammals.

The laryngeal or j^osterior palatine artery is a little branch of
the ectocarotid, which is sent off posteriorly opposite to the ex-
ternal maxillary artery. Its branches are exhausted upon the
back part of the fauces, the muscles for moving the upper jaw,
and posterior nares.

The lingual or submaxillary artery, ib. 13, passes under the
muscles which connect the hyoid to the lower jaw, and close upon
the back of the membrane of the lower part of the mouth, it sends
a branch to the oesophagus and trachea, supplies the muscles

ARTEKIES OF BIRDS. l98

of the hyoicl, ib. F, the tongue, E, the lower surface of the mouth,
and furnishes the artery which enters the substance of the lower
jaw.

' Just at the origin of the submaxillary artery there is another
little branch of the carotid, which is lost upon the muscles of the
hyoid arch.

' The internal maxillary artery is, as usual, the continuation
of the trunk of the ectocarotid; it runs forward between the
pterygoid muscle and the lining of the mouth, upon the side of
the long muscle for moving the upper jaw, and divides into two
principal branches; one of them proceeds under the tendon of
the long muscle to get upon the palate, where it forms two
branches, of a\ hich one runs along the external side of the palate,
between the membrane and the bone of the mandible to the
extremity of the bill, where it becomes united to the same branch
of the opposite side, as also to the middle artery of the palate.
The other branch lies also superficially under the membrane
which lines the mouth. It passes onward to meet its correspond-
ing vessel of the opposite side, with which it becomes actually
incorporated, and by their union a single artery is generated,
which runs along the middle line of the palate to the end of the
mandible, where it unites mth the lateral branches, as already
mentioned. At the junction of the vessel of each side to form
the middle palatine artery, two branches go off, which are lost upon
the lining of the mouth, and the interior of the organ of smell.

^ The other branch of the internal maxillary artery is reflected
upward toward the orbit, below which it divides and unites again,
forming a triangle, through which the vein passes : at this place
it produces a remarkable plexus of vessels, like the rete mirabile
of the carotid artery of quadrupeds, which is increased by branches
from the ophthalmic and the palatine arteries, and from which the
back part of the organ of smell receives its supply of blood.

^ The internal maxillary artery then runs directly backward
below the orbit, passes between the radiated or fan-shaped muscle
which moves the upper jaw and the pterygoid ; and turning-
inward round the basis of the cranium, becomes incorporated with
the internal carotid artery just as it enters the bony canal which
conducts it to the brain. ^

' The vertebral artery, fig. 93, 6, soon after it parts from the

' Barkow describes the internal maxillary artery as wanting in birds, and its place
being supplied by branches of both the external and internal carotids and the facial
artery, all of which sometimes unite to form the maxillary plexus of vessels, which is
very conspicuous in the Goose and Duck. xliv.
VOL. II. O

194 ANATOMY OF VERTEBEATES.

carotid, sends off a branch backward, Avliich passes over the neck
of the scapula and is lost among the muscles on the posterior part
of the shoulder, inosculating with the articular and other arteries
about the joint : this branch might be called the siqjra-scapular,
ib. 5. In the Duck we have observed it, before it makes the turn
over the scapula, to send an artery upward along the muscles of
the neck. The trunk of the vertebral artery proceeds obliquely
upward, and having entered the foramen in the transverse pro-
cess of the penultimate cervical vertebra, gives off a large branch
downward, which is distributed between the vertebras, and to the
spinal canal, in the manner of the intercostal arteries, with which
it anastomoses upon arriving in the thorax. The remainder of
the vertebral artery is continued upward in the canal formed by
the pleur- and di-apophyses of the cervical vertebrae, diminishing
gradually in consequence of the branches it sends off between each
vertebra to the myelon and the muscles of the neck. Near the
head the artery is found considerably reduced, and within the
uppermost foramen in the transverse processes terminates entirely
by inosculation with the reflected occipital branch of the carotid,
as before noticed.

^ After the common trunk of the carotid and vertebral is detached
from the arteria innominata, this vessel may assume the name of
the subclavian, fig. 93, 14. While passing under the coracoid it
sends off some important branches : the first might be called the
pectoral artery ; it proceeds upward upon the internal surface of
the pectoralis minor muscle, which it supplies, and then dividing
into two branches, one passes over the anterior edge of the
coracoid, and under the pectoralis medius, between which and the
sternum it runs, detaching its branches to the muscle ; the other
sends first along the under side of the coracoid a branch which is
again subdivided and distributed to the outside of the shoulder-
joint and to the deltoid muscle, in which it inosculates with the
articular artery. The vessel then passes between the coracoid and
the furculum, and on a ligament which connects the head of the
coracoid to that of the scapula, and disperses its branches upon
the upper part of the shoulder-joint, forming anastomoses with the
neighbouring arteries.

' The next branch of the subclavian is the humeral artery,
ib. 15; it arises from the upper side of the vessel, and makes a
slight curve to reach its situation on the inside of the arm in order
to disperse its branches in the manner hereafter described.

' The internal mammary artery, fig. 94, 2+, is given off just as
the subclavian leaves the chest. It divides into three branches :

ARTERIES OF BIRDS. 195

one ramifies upon the inner surface of the sternum, another upon
the sternal ribs and the intercostal muscles, and the thu'd runs
along the anterior extremities of the vertebral ribs, supplying the
intercostal muscles, &c.

' The chief peculiarity of the arteries of the superior extre-
mities in birds consists in the great magnitude of the vessels which
supply the pectoral muscles ; these, instead of being inconsider-
able branches of the axillary artery, are the continuations of the
trunk of the subclavian, of which the humeral is only a branch.

' The great pectoral or thoracic artery passes out of the chest
over the first rib and close to the sternum, and immediately
divides into two branches. One of them, fig. 93, 16, ramifies in
the superior part of the pectoralis major, and the other, ib. 17, is
exhausted in the lower part of the muscle, and sends off a branch
analogous to the long thoracic artery of MammaUa.' Fig. 93
shows the distribution of these arteries to the skin after per-
forating the pectoralis muscle.

' The humeral artery, while within the axilla, gives a small
branch backward to the muscles under the scapula, and uj^on
reaching the inside of the arm produces an artery that soon
divides into the articular and the profunda humeri. The articu-
lar artery passes round the head of the humerus, underneath the
extensors ; its branches penetrate the deltoid muscle, and ana-
stomose with the other small arteries around the joint.

' The profunda humeri, as usual, turns under the extensor
muscles to reach the back of the bone, at which place, in birds,
it separates into two branches, of which one descends upon the
inside, and the other upon the outside of the articulation of the
humerus with the radius and ulna, and there inosculate with the
recurrent branches of the arteries of the fore-arm.

' After the humeral artery has sent off the profunda, it descends
along the inner edge of the biceps muscle, detaching some branches
to the neighbouring parts ; upon arri^dng at the fold of the wing,
it divides into two branches ; one of these is analogous to the
ulnar artery, and the other from its position deserves to be called
rather the interosseous than tlie radial artery.

' At the place where the humeral produces the two arteries of
the fore-arm, a small branch is sent off, which is lost upon the
fore-part of the joint, and in anastomoses with the recurrent of
the ulna and profunda humeri.

* The ulnar artery is the principal division of the humeral ; it
proceeds superficially over the muscles which are analogous to the
pronator, sends a large recurrent branch under the flexor ulnaris

o 2

196 ANATOMY OF VERTEBRATES.

to the back of the jomt, upon wliich it ramifies and forms ana-
stomoses with the profunda humeri. The artery then proceeds
along the inner edge of the ulnar muscles, to which it distributes
branches. It is afterwards seen passing over the carpal bone of
the ulnar side, and under the annular ligament, at Avhich place it
sends off some branches which spread upon the joint and inosculate
^dth the similar ones of the interosseous artery. Very soon after
the ulnar artery gets upon the metacarpus, it dips in between the
bones, and reappears u2)on the opposite side, lying under the
roots of the quills, to each of which it sends an artery ; it pre-
serves this situation to the end of the metacarpal bones, where it
passes between the style analogous to the little finger and the
principal or fore-finger, and pursues its course along the edge of
the latter, to the extremity of the wing, supplying each of the
true quills Avith an artery, and sending at each joint of the finger
a cross branch to communicate with the anastomosing branches
on the opposite side.

' The interosseous artery detaches first a branch of some size to
the membrane which is spread in the fold of the wing, upon which
it forms several ramifications, fig. 94, o. After this the artery
dips down behind the flexor muscles to get into the space between
the ulna and radius. It here gives a branch backward to com-
municate ^\ii\\ the others about the joint, and proceeds in the inter-
osseous space as far as the carpal joint, during which course they
become much diminished from o-ivino- off several branches which
are distributed to the integuments and the quills placed upon the
outside of the ulna. The remainder of the interosseous artery is
expended in small branches upon the back of the carpal joint, the
bastard quills, and along the radial edge of the metacarpal and
bones of the fore-finger, Avhere it forms communications Avith the
cross branches of the ulnar artery already mentioned.

^ From this description it Avill be perceived that no artery exists
in birds strictly analogous to the radial ; that there are no i)almar
arches ; and that the size of the interosseous artery, and the
course of the ulnar, along the outside of the metacarpus, are
peculiarities which arise from the necessity of affording a large
supply of blood to the quills during their growth.

' The descending aorta, fig. 93, 19, makes a curve round the
right auricle and right bronchus, in order to get upon the pos-
terior surface of the heart, after which its course is close along the
spine, in which situation it is bound down by cellular substance,
and the strong membrane or aponeurosis, which covers the lungs
on their anterior j)art. The first branches which this vessel

ARTEKIES OF BIRDS. 197

appears to send ofF arc hronchial arteries ; they arise from the
fore part of tlie aorta, just when it arrives upon the spine ; and
having entered the kings, tlieir ramifications accompany those
of the puhnonary arteries. They appear also to send branches
to the spine and the spaces between the ribs.

* The intercostal arteries do not take their origin from the aorta
in numerous and regular branches as in Mammals, but consist
originally of but few vessels, which are multiplied by anasto-
moses with each other, and with the arteries which come out of
the spinal canal. An arterial plexus is thus formed round the
heads of the ribs, from which a vessel is sent to each of the inter-
costal spaces. Many of these branches, besides supplying the
intercostal muscles and ribs, are continued into the muscles upon
the outside of the body and the integuments. The anastomosis
of the intercostal arteries round the ribs is very similar to the
plexus, which is produced by the great sympathetic nerve in the
same situation.

' The aorta produces no branch which deserves the name of
the j)hrenic artery, as birds do not possess that muscular septum
of the body to which the artery of this name is distributed in
other animals.

* The cceliac artery, fig. 93, 20, is a very large single trunk, and
arises from the fore part of the aorta, even higher than the zone
of the gastric glands. It descends obhquely for a short way, and
then ffives off a branch which soon divides into two or three
others that are spread upon the lower part of the oesophagus, and
the side of the zone of the gastric glands, uniting with the other
arteries of the oesophagus above, and extending downwards upon
the posterior side of the ventricle, and anastomosing with the
anterior gastric artery. The trunk of the eoeliac now di\ides into
two very large branches, which from their distribution we have
chosen to call the posterior and the anterior gastric arteries.

' The posterior gastric artery, almost as soon as it is formed,
detaches the splenic artery ; and very soon after it furnishes from
the posterior side of the vessel the right hepatic artery. This
branch proceeds to the right lobe of the liver, which it enters on
the side of the hepatic duct ; after having divided into two or
three minute arteries on its way to the liver, it supplies the
hepatic duct with a branch which accompanies the duct to the
intestine, and is there lost. The posterior gastric artery then
runs down upon the back of the gizzard, and opposite to the
origin of the first intestine it sends off an artery, Avhich proceeds
directly to one of the cocca (in the Fowl), upon which and the

198 ANATOMY OF VERTEBRATES.

side of the next intestine it is expended, inosculating at the end
of the coecum with branches of the mesenteric artery, which are
distributed to the adjoining portion of the small intestine. The
posterior gastric then furnishes a large vessel which runs upon
the gizzard, and divides into two chief branches, which penetrate
the substance of the digastric muscle, in which they are lost.

' The next branch of the posterior gastric artery is the pan-
creatic. It runs between the two pancreatic glands, dispensing
branches to each and to the duodenum. After this the trunk of
the posterior gastric divides into two branches, which furnish
tmgs to the muscular parietes of the ventricle, and run along
the margins of the upper and lower portions of the digastric
muscle, supplying them with numerous twigs, and anastomosing
with the ramifications of the other gastric arteries.

* The anterior gastric artery descends to the angle formed by
the bulbus glandulosus and the gizzard, and there sends off a
small branch which spreads upon the zone of the gastric glands,
and inosculates with the first ramifications of the coeliac, and
immediately afterwards it detaches a large artery, which runs
round the superior margin of the digastric muscle, which it fur-
nishes with many tmgs, and communicates freely with the corre-
sponding branch of the posterior gastric artery.

^ Three small hepatic arteries take their origin from this branch
of the anterior gastric, just as it passes over the highest part of
the margin of the gizzard ; these vessels enter the fissure in the
left lobe of the liver. The anterior gastric artery now proceeds
along the fore part of the gizzard, sending one or two branches
into the muscular substance, and near the tendon it terminates in
two large vessels, one of which is distributed upon the left side of
the digastric muscle, and the other passes a little over the tendon,
and then divides into two arteries, which produce several branches
that disappear in the substance of the gizzard, and betAveen the
digastric muscles and the parietes of the ventricle, anastomosing
with the vessels of the posterior side.

' The superior mesenteric artery, fig. 93, 21, takes its origin
from the fore part of the aorta, a little below the coeliac, and pro-
ceeds for some way without detaching any branches ; after which
it experiences the same kind of division and subdivision that takes
place in Mammalia ; and the numerous arteries which are thus
ultimately produced are spent upon the small intestines. One of
the first and largest branches of the superior mesenteric, however^
is allotted to supply on6 of the coeca, and to establish a communi-
cation with the inferior mesenteric and gastric arteries. This

ARTERIES OF BIRDS. 199

branch, soon after it leaves the trunk of the superior mesenteric,
divides into two. One descends upon the rectum, where it meets
with the inferior mesenteric artery, with which it produces a very
remarkable anastomosis, similar to the mesenteric arch in the
human subject ; this united artery supplies the rectum and origin
of the coeca. The second portion of this branch of the superior
mesenteric runs in the space between the last part of the small
intestine and the coecum of one side, sending numerous branches
to each, and at the end of the ca3cum communicates in a palpable
manner with another branch of the superior mesenteric artery,
which runs upon the adjoining part of the small intestine.

^ A branch, arteria spermatica, fig. 93, 22, arises from the
anterior part of the aorta, just below the lungs ; it is designed
for the nutrition of the organs of generation, and except in the
season for propagation, it is so small as to be discovered with
difficulty ; but when the testicles become enlarged, it is consider-
ably increased in size in the male bird, and much more so in the
female, when the ovary and OAdduct are developed for producing
eggs. It nearly equals the superior mesenteric artery during the
period of laying, in which state we shall describe it. It is a
single artery, like the coeliac and mesenteric, proceeds at a right
angle from the aorta, and soon sends off" a branch, which goes
into the kidney of the left side, to which it gives some twigs, and
afterwards emerging from the kidney, it runs in the membrane of
the o\dduct, upon Avhich it is distributed. After this branch is
detached, the artery projects a little farther forward into the
cavity, and divides into two branches ; one of these goes to the
ovary, in which it ramifies, and furnishes an artery of some size
to each of the cysts containing the ova. The other is distributed
in numerous branches to the membrane and superior parts of the
oviduct, and inosculates with the other arteries of the oviduct.
It deserves to be remarked, that this and all the other arteries
which are furnished to the oviduct have a tortuous or undulating
course, in the same manner as the vessels of the uterus of the
human subject.

' There are no regular emu! gent arteries in birds ; the kidneys
deriving their blood from various sources, which will be pointed
out as they occur.

' The inferior extremity is supplied with two arteries, which
have a separate origin from the aorta. One corresponds to the
femoral, and the other to the ischiadic artery.

' The femoral artery, figs. 93, 94, 23, is a small trunk, which
takes its origin from the side of the aorta, opposite to the notch

200 ANATOMY OF VERTEBRATES.

in the bones of tlie pehds immediately under the last rib. This
notch is formed into a round hole in the recent subject by a liga-
ment which is extended from it to the rib ; and it is through this
hole that the femoral artery makes its exit from the pelvis ; just
before it passes out upon the thigh, it sends off a long branch, 25,
which runs backward the whole length of the margin of the pel-
vis, dispensing arteries to the abdominal muscles on one side, and
the obturator internus on the other. This branch also appears
to supply one to the oviduct. The femoral artery, immediately
after lea\dng the pelvis, separates into two branches ; one goes
upward and outward, ramifying amongst the muscles in that
situation ; the other turns downward, and is distributed to the
flexors of the limb and round the joint, and sends an artery to
the edge of the vastus internus, which can be traced as far as the
knee. The kidneys appear to derive some irregular inconsider-
able branches from the femoral artery while it is within the pehds.

' The ischiadic artery, figs. 89, 93, 26, is the principal trunk of
the lower extremities, exceechng very much in size the femoral.
When it is produced by the aorta, it appears to be the continua-
tion of that trunk ; the remaining part of the aorta becomes so
much and so suddenly diminished, and seems, as it were, to pro-
ceed as a branch from the back part of the vessel.

' The ischiadic artery, wdiile in the pelvis, is concealed by the
kidneys, in which situation it gives a branch from its lower side,
which di\ddes into three others that are distributed to the sub-
stance of the kidneys ; one of these on the left side is continued
out of the kidney to be lost upon the oviduct. The artery leaves
the pelvis by the ischiadic foramen in company with the great
nerve ; while within the foramen it gives a branch obliquely
downward under the biceps to the muscles lying in the pelvis ;
and as it passes over the adductor it sends off another along the
lower edge of that muscle, which is chiefly lost in the semi-mem-
branosus. It then detaches several small branches to the muscles
on the outer and fore part of the thigh, some of which anasto-
mose round the joint -with the branches of the femoral artery.
Just as the ischiadic arrives in the ham, it furnishes a very large
branch downward, which di\ddes into two ; one goes under the gas-
trocnemius, to which and the deep-seated flexors its branches are
distributed as far as the heel : the other is analogous to the
peroneal artery ; it goes to the outside of the leg, supplies the
peroneal muscles posteriorly, and passes along the outer edge of
the flexors of the toes to the heel, above which, and behind the
flexor tendon, it divides, running on each side of the heel, and

ARTERIES OF BIRDS. 201

forming several articular arteries around the joint, and communi-
cating vnth the other branch, and with the anterior tibial, and
the metatarsal branch of the plantar artery.

' The articular arteries go off next from the artery in the ham ;
the two principal ones are deep-seated. One proceeds under the
vastus internus to the external part of the joint ; the other is
large, and situated upon the inside. It forms two vessels : one
is the true articular artery, and spreads upon the ligaments of the
joint ; the other is distributed in the substance of the flexor of
the heel, which is placed upon the inside and fore part of the leg,
and comes out upon the edge of this muscle to be lost in the
integuments.

' The posterior tibial artery, fig. 94, 28, is extremely small ; it
only supplies muscular branches to the internal head of the
gastrocnemius, and some of the flexors of the toes ; it is lost on
the inside of the heel in anastomoses with the peroneal artery,
and other small superficial branches.

' The trunk of the artery of the leg now gets upon the poste-
rior surface of the tibia, and sends off, through the deficiency left
between the tibia and fibula at the superior part, a branch which
is distributed to all the muscles upon the fore part of the leg.
The artery then creeps along the back of the bones for some
way, and passing between them above, where the fibula is anchy-
losed with the tibia, it reappears on the anterior part of the leg
in the situation of the anterior tibial artery ; at this place it
detaches some very small branches, which frequently divide and
unite again, to produce a most singular reticulation or plexus of
vessels, which closely adheres to the trunk of the artery, and is
continued with it as far as the articulation of the tibia with the
metatarsal bone, where it disappears without seeming to answer
any useful design. This plexus resembles in appearance exactly
the division of the arteries of the extremities, which has been
described by Mr. Carlisle in the tardigrade quadrupeds, but
differs from it in this circumstance, that the trunk of the artery
is preserved behind it, without suffering any material diminution
of its size.

' The anterior tibial artery furnishes no branch of any impor-
tance during the time it is proceeding along the fore part of the
leg. It passes under the strong ligament which binds down the
tendons of the anterior muscles of the leg, and over the fore part
of the joint on the inside of the tendon of the tibialis anticus, at
which places it distributes some branches which inosculate Avith
the other arteries round the joint ; it then pursues its course in

202 ANATOMY OF VERTEBRATES.

the groove along the anterior surface of the metatarsal bone,
and covered by the tendon of the flexor digitorum. On coming
near the foot it sends off an artery, which di\ddes, behind the
joint of the internal toe, into two branches; one goes between
the internal and middle toes, ramifies upon both their joints, and
unites with the artery in the sole of the foot ; the other is dis-
tributed between the internal toe, and the pollex or toe which
occupies the place of the great toe ; the main artery now passes
to the sole of the foot through a hole in the metatarsal bone, left
for the purpose, when the original parts of this bone were united
by ossification. In this situation the artery might receive the
name of the plantar. It has scarcely passed through the bone,
when it divides into six branches ; three of these are distributed
to the tendons and ligaments, &c., on the outside of the foot and
the back of the metatarsus, anastomosing -svith the descending
branches of the peroneal artery ; the fourth branch supplies the
pollex, and also sends a branch from the metatarsus. The re-
maining branches are designed for the three principal toes ; one
dips in between the internal and middle toe, unites with the
anterior branch of the metatarsal artery, and is distributed to the
sides of these toes as far as their extremity. The other divides,
between the external and middle toe, into two branches, which
run upon the opposite side of each of these toes to the end.

' When the feet are webbed, the digital arteries send ofl* nu-
merous branches, which, ramifying in the membrane between the
toes, establish a communication with each other. The present
description has been taken from birds which possess three prin-
cipal toes, and the back toe or pollex ; but no material difference
can be expected in those with a greater number of toes.

' After the trunk of the aorta has detached the ischiadic ar-
teries, it is continued along the spine as the arteria sacra media,
fig. 93, 29, sending off small branches answering to lumbar
arteries, one of which ascends upon the rectum, supplies the place
of the inferior mesenteric, ib. so, and unites mth the superior
mesenteric as already mentioned. The aorta separates above the
coccygeal vertebrae into three branches ; two of these (the hypo-
gastric arteries, ib. 31, proceed laterally, and are distributed to
the neighbouring parts, and to the kidneys and oviduct ; the
third branch (the coccygeal artery, ib. 32) descends to the very
point of the tail, upon the muscles and quills of which its branches
are exhausted.

* The arterial system of Birds, besides the distinguishing
characters above mentioned, differs from that of Mammals chiefly

VEINS OF BIRDS.

203

in the frequent anastomoses, which exist more especially amongst
the arteries of the head and tlie viscera. Similar communications
occur between the veins.' '

Besides the remarkable arterial plexuses mentioned in the
general description, as the orbital, the temporal, the spermatic
plexuses, &c., that which Bar-
kow^ has described under the
name of the plexus of the
organ of incubation (^Brutor-
gane) deserves special notice.
It is represented at 17, 18, fig.
93, and is composed of branches
coming from the posterior tho-
racic, abdominal, cutaneous,
and ischiadic arteries, which
ramify beneath the integument
of the abdomen, and form, by
their unions, a rich network
of vessels which becomes truly
extraordinary in the time of
hatching. At this period many
birds pluck off the feathers
from the seat of incubation,
probably thereto impelled by
the o-reat deo-ree of heat caused
by the influx of blood into the
incubating plexus.

§ 155. Veins of Birds. —
The venous blood is returned
to the heart by means of three
trunks ; two of these are j^re-
cavals, fig. 90, «, h, and one
postcaval, ib. c. Each preca-
val, fig. 94, a, is composed of
the jugular and vertebral, and
the veins of the wing.

* The vertebral vein is lodged in the same canal with the verte-
bral artery ; it anastomoses between the vertebras with the veins
of the my clonal membranes. It also freely communicates at the
base of the cranium with the jugular vein, and receives blood
from the muscles of the neck.

' The jugular vein, fig. 94, b, is a single trunk in birds, and

Veins of a Fowl.

204 ANATOMY OF VERTEBRATES.

does not admit of the distinction into external and internal ; it
proceeds snperficially along the side of the neck in company with
the par vagum. The vein of the right side exceeds the other in
size ; it is often twice as large. The jugnlar vein receives several
lateral branches from the muscles and integuments of the neck,
ib. d, the oesophagus, &c. (the veins from the crop joining the
jugular are shown at c) : one of these near the head is much
longer than the rest, ib. e ; it lies deep amongst the muscles, and
appears to communicate with the vertebral vein. There is a
branch of the jugular which goes to the superior larynx amongst
the muscles of the tongue and of the hyoid, and another for the
muscles within the jaws and the integuments in the back of the
mouth ; these might be called the lingual, thyroid, and submaxil-
lary veins, ib. g, h, i.

* The jugular veins form a remarkable communication with
each other immediately below the cranium, by means of a cross
branch, generally of an equal size Avith the trunks themselves.
From each side of the arch thus formed there issues a large
vessel, which is made up of the veins of the external part of the
head; one of these passes round the tympanic, and apparently
penetrates the joint of that bone with the lower jaw ; it appears
in several branches upon the side of the cheek, and contributes
to form a plexus of veins below the posterior part of the orbit,
ib. k, similar to the arterial plexus already described in that
situation. The principal branch of the veins of the head passes
obliquely round the pterygoid bone, and below the orbit di\ddes
into several large vessels, one of which belongs to the back part
of the palate ; another ascends on the orbit, and unites with the
ophthalmic vein ; and a third is distributed to the interior of the
organ of smell, the palate, and the external parts of the upper
and lower jaws. These branches produce plexuses along the
l)ase of the orbit and the external edge of the palate, which
correspond to those of the arteries before described.' ^

The sinuses of the brain are irregular in form, and consist of
flattened canals. The principal ones, besides those upon the
cerebellum, are the superior longitudinal, and one which runs
along the lower edge of each hemisphere of the cerebrum ; there
appears to be also one upon the side of the cerebellum, corre-
sponding to the lateral sinus. All these sinuses communicate
with each other on the back of the cerebellum, and seem to dis-
charge their contents principally into some veins which lie in the

VEINS OF BIKDS. 205

myelonal sheath, and these appear to dispose of their blood
gradually, as they descend in the neck, by means of lateral com-
munication mth the vertebral veins. The superior longitudinal
sinus is continued at its anterior part under the frontal and nasal
bones, and anastomoses with the ophthalmic and nasal veins.
There are other small sinuses in the several duplicatures of the
dura mater.

The veins of the icings, which are derived from the parts within
the chest, the muscles about the scapula, and the pectoral muscles,
accompany jthe arteries of the same parts so regularly that their
course does not require description.

The axillary/ vein, fig. 94, I, lies considerably lower in the axilla
than the artery, but still continues to receive corresponding
branches {m indicates the great pectoral vein). The trunk of
the vein descends in the course of the humeral artery, but more
superficially ; in this situation it may be called the humeral vein,
ib. n. Branches of this vein accompany the articular and
profunda arteries, and at the middle of the humerus a large
branch of the vein enters the bone ; there are also two very
small branches which lie in close contact with the humeral artery,
which they accompany nearly its whole length.

The principal vein of the wing di\ddes into two, opposite to
the joint of the humerus with the fore-arm. One of these
branches, ib. o, belongs to the sides of the radius ; it receives
blood from the muscles and skin on the upper part of the fore-
arm, but its chief vessels lie between the integuments of the fold
of the Aving. The other branch of the humeral vein, ib. p, crosses
the fore-arm, just below the articulation, in company with the
nerve, and running along the inferior edge of the ulna, receives
a branch from between the basis of each quill, is continued along
the ligament which sustains the rest of the quills to the extremity
of the wing, recei\dng many veins of the joints from the opposite
side of the fingers. Besides these large superficial veins of the
fore-arm, there appears to be one, and sometimes two, small
accompanying veins to the ulnar and interosseous arteries, ib. q.

The inferior vena cava, ib. K, before it enters the auricle. A, re-
ceives as usual the hepatic veins, ib. s; these are numerous, and open
into the cava as it passes behind the liver, or more frequently
within the substance of that viscus in the back part.

The trunk of the vena cava is very short in the abdomen ; it
separates into two great branches analogous to the primary iliac
veins, ib. t, opposite to the adrenals ; these turn to each side, and
experience a very singular distribution. On coming near the

206 ANATOMY OF VERTEBRATES.

edge of the pelvis, each of these two veins forms two branches ;
one of which collects the blood of the lower extremity, as here-
after described ; the other passes straight downward imbedded in
the substance of the kidney, and admits the several emulgent
veins, Avhich are very large, and are seen to pass for some way
obliquely in the kidney before their termination. Sometimes the
emulgent veins are double, as in the figure, ib. u. The limb-
vein sends off a descending branch into the renal tissue which,
when arrived at the lower end of the kidney, di\ddes into three
branches ; one receives the blood of the muscles of the tail and
parts adjacent ; another accompanies the ureter to the side of the
rectum, and is distributed about the anus and parts of gene-
ration, answering to the hcEmorrhoidal veins ; the third, ib. v, v,
passes inward to the middle line between the kidneys, and there
unites with the corresponding branch of the opposite side. These
are the branches which have been supposed to carry venous
blood into the kidneys, for the purpose of supplying material
for the urinary secretion. The vessel which is in this manner
produced, ib. z, receives all the blood of the rectum from the anus
to the orio'in of the coeca, anastomosino; below with the branches
of the ha3morrhoidal veins ; and at the upper part of the rectum,
it becomes continuous with the trunk of the veins of the small
intestines, ib. x, forming the most remarkable anastomosis in the
body, both on account of its consequences and the size of the
vessels by which it is effected. By means of this communication,
the blood of the viscera and the external parts of the body flows
almost indifferently into the vena cava and vena port^e, ic ; for
the anastomosing vessels are sufficiently large to admit the ready
passage of a considerable column of blood in proportion to the
whole mass which circulates in the body of the bird ; for instance,
in the Goose the communicating veins of the pelvis are equal in
size to a goose-quill, and in the Ostrich and Cassowary they are
as thick as a finger. Besides their anastomoses the princij^al
visceral veins are remarkable for their large size in the Diving
Birds.

' The anastomosis of the pelvic veins, in being the means of
conveying common venous blood into the liver, goes to prove
that the blood of the vena porta3 does not require any 23eculiar
preparation by circulation in the spleen or other viscera to fit it
for the secretion of bile.

* The vena portce, ib. w, belongs almost exclusively to the
right or principal lobe of the liver. It is formed by three
branches. The splenic vein is the smallest, and is added

VEINS OF BIRDS. 207

to the vena port^e, just as it penetrates the liver on the side of
the hepatic duct. The next is made of two branches ; of wliich
one returns the blood of the posterior gastric artery, and there-
fore may be called the posterior gastric vein ; and the other is
furnished by the pancreas and duodenum, and is the pancreatic
vein. The third and largest branch of the vena portse is the
mesenteric vein, ib. :r, which not only collects the blood from all
the small intestines, but likewise receives the inferior mesenteric,
ib. z, or vein of the rectum, which forms the communication that
has been described with the pelvic veins.

^ The veins of the left lobe of the liver are furnished in the
Goose by those which accompany the anterior gastric artery, and
some branches from the head of the duodenum.

^ The anterior gastric veins produce two small trunks, which
enter at the two extremities of the fissure, in the concave surface
of the left lobe of the liver, as it lies upon the edge of the
gizzard; the veins from the head of the duodenum furnish a
small vessel which passes backward to penetrate the posterior
part of the fissure in the left lobe.

* In the Cock the veins that the left lobe of the liver derives
from the anterior gastric, are more numerous than in the Goose.

' The veins of the zone of gastric glands, and of the lower
portion of the oesophagus, do not contribute to the secretory
vessels of the liver, but proceed to the superior part of that
viscus, to terminate in the vena cava, as does also the umbilical
vein.

* The vein which returns the blood of the inferior extremities
is divided in the pelvis into two branches, which correspond with
the femoral and ischiadic arteries; the one passes through the
ischiadic foramen, and the other through the hole upon the
anterior margin of the pelvis ; but the proportion they bear to
each other in magnitude is the very reverse of what occurs in
the arteries ; for the anterior vein is the principal one, whilst the
other is not a very considerable vessel, and receives its supply of
blood from the muscles at the posterior part of the joint.

' The femoral vein, ib. a a, immediately without the pelvis, gives
branches on both sides, which receive the blood of the extensor
and adductor muscles at their superior part: the trunk passes
obliquely under the accessory muscle of the flexor digitorum, and
over the os femoris, where it lies superficially ; it then mnds
under the adductor muscles, and gets into the ham, h b, where it
receives many muscular branches, and comes into company mth
the artery and nerve. It here divides into the tibial, c c, and

208 ANATOMY OF VERTEBRATES.

peroneal veins. The first is joined by some branches from the
surface of the joint answering to the articular arteries ; it also
receives the anterior tibial vein which accompanies the artery of
the same name. The tibial vein proceeds down the leg along
with the artery on the inside of the deep-seated flexors of the
heel : it turns over the fore part of the articulation of the tibia
with the metatarsal bone, in order to get upon the inner side of the
metatarsus ; above the origin of the pollex, it receives a com-
municating branch from the peroneal vein, and immediately after
two branches from the toes : one of them comes from the inside
of the internal toe ; the other arises from the inside of the exter-
nal and middle toes, unites at the root of the toes in the sole of
the foot, and is joined by a branch from the pollex, before its ter-
mination in the internal vein of the metatarsus.

' The peroneal vein derives its principal branches along with
those of the peroneal artery, from the muscles on the outside of
the leg. The trunk of the vein comes out from the peroneal
muscles, and passes superficially over the joint of the heel, and
along the outside of the metatarsus ; near the pollex, or great
toe, it sends a branch round the back of the leg, to communicate
with the tibial vein ; after which it is continued upon the outside
of the external toe to the extremity, receiving anastomosing
branches from the tibial vein.

' Where the veins run superficially upon the upper and lower
extremities, they seem to supply the place of the branches of the
cephalic, basilic, and the two saplien<B ; but the analogy is lost
upon the upper arm and thigh, these branches forming deep-seated
trunks ; this constitutes the greatest peculiarity,^ as compared
with Man and many Mammals, in the distribution of the veins
in the extremities of Birds.'

209

CHAPTER XX,

RESriKATORY SYSTEM OF BIRDS.

§ 156. Lungs of Birds. Xotwithstanding the extent and ac-
tivity of the respiratory function in Birds, the organs subser-
vient thereto manifest more of the Reptilian than of the Mamma-
lian type of formation.

The lungs are confined, as in the Tortoise, to the back part of
the thoracic-abdominal cavity, being firmly attached to the ribs
and their interspaces ; and, as in the Serpent, they communicate
with large membranous cells which extend into the abdomen and
serve as reservoirs of air. In the Apteryx alone they do not
penetrate the diaphragm.

In those aquatic Birds which are deprived of the power of
flight, as the Penguin, the air-receptacles are confined to the
abdomen ; but in the rest of the class they extend along the sides
of the neck, and, escaping at the chest and pelvis, accompany
the muscles of the extremities. They also
penetrate the medullary cavities and diploe
of the bones, extending in different species
through different proportions of the osseous
system, until in Volitores, even in the Horn-
bill, every bone of the skeleton is per-
meated by air. There is, indeed, no class of
Animals so thoroughly penetrated by the
medium in which they live and move as that
of Birds.

The lungs are two in number, of a length-
ened, flattened, oval shape, fig. 95, extend-
ing along each side of the spine from the
second dorsal vertebra to the kidneys, and
laterally to the junction of the vertebral with
the sternal ribs. They are not suspended
freely, nor divided into lobes, as in Mammals ;
but are confined to the back part of the chest by cellular

VOL. II. p

Kiglit lung of a Goose.

210

ANATOMY OF VERTEBRATES.

membrane, and the pleura is reflected over the sternal surface
only, to which the strong aponeurosis of the diaphragmatic muscles
is attached. They are consequently smooth and even on that
surface, but posteriorly are accurately moulded to the inequalities
of the ribs and intercostal spaces : the bosses varying in number
from four to seven {Apteryx^ or eight (Emeu).

The lungs in general are of a bright red colour, and of a loose
spongy texture. The bronchi, fig. 85, v, fig. 95, «, penetrate
their mesial and anterior surfaces about one-fourth from the upper
extremities, become membranous, dilate, give off branches, which
diverge as they run along the anterior surface; and the trunk

divides into the two which open
^^ at 5, Z>, into the thoracic-ab-

dominal air-receptacles. These
orifices are oblique, and are par-
tially covered by a slight projec-
tion of membrane. Some cartila-
ginous traces are found through
their entire extent.

The pulmonary artery divides,
almost immediately after its ori-
gin, into two branches, one to
each lung; the ramifications of
each artery form plexuses, fig.
96, B, which chiefly compose the
pulmonary tissue : the pulmo-
nary veins leave each lung by a
single trunk, and the two trunks
unite into one before terminating
in the left auricle.
The superficial primary branches

A. Lobule of the lung of a bird represented in ideal ^f f|,p Kvn-nplii -ficr Q'^ n n QPnrI
longitudinal section, cclxviii. ^^ ^'^^ DlOnCUl, Ug. yO, C, C, SCnCl

off deeper-seated secondary ones,
fig. 96, «, «, which maintain a uniform diameter to their c^ecal
terminations : the tertiary bronchi, ib. h, h, distributed penniformly,
also maintain a regular diameter, and open upon a dense laby-
rinth of blood-vessels, ib. B. The mucous ciliated lining of the
bronchi ceases with them ; and the capillaries of the pulmonary
tissue are covered only by a hyaline epithelium, so as to appear
naked. ^ The ultimate pulmonary capillaries do not form a net-
work lining definitely bounded air-cells, but each capillary crosses

' CCLXVIII. p. 277.

KESPIKATORY SYSTEM OF BIRDS.

'211

97

an air-space of its own ; they interlace in every direction, formino-
a cubic mass of capillaries permeated everywhere by air. In
fig. 97, a is the cavity of a bronchial tube, h its lining mem-
brane supporting blood-vessels with large areolae ; c, c, perforations
in the membrane at the orifices of the lobular passages, d,d\ e, e,
are interlobular spaces containing the terminal branches of the
pulmonary vessels supplying the
capillary plexus, /, f, to the
meshes of which the air o-ets ac-
cess by the lobular passages.

§ 157. Air-cells of Birds. —
The thoracic-abdominal cavity is
subdivided and intersected by a

the

thus

The

p OS-

number of

'^

«fe

Section through a broucbial tube, limg of Bird,
magn. XLV.

membranes ;
greater part of the cells
formed are filled with air.
texture of their parietes
sesses considerable firmness in
the larger birds, as the Ostrich
and Cassowary.

The innermost layer of the air-
receptacles can be separated from the outer layer, and is a con-
tinuation of the lining membrane of the bronchial tube ; the outer
layer is a serous membrane, and appears to form the cells by a
series of reflections of what may be regarded as the pleura or
peritoneum.

These large membranous receptacles, into which the extremi-
ties of the bronchial bifurcation and also some of the preceding
branches open, are disposed with suflficient general regularity to
admit of a definite description and nomenclature.

The first or interclavicular air-cell, fig. 98, a, extends from the
anterior part of each lung, forward to the interspace of the fur-
culum, anterior to which it dilates in the Gannet and many other
birds into a large globular receptacle. In the Vultures it is
divided into two lateral receptacles, between which the large crop
is situated. A thin fan-shaped muscle is extended from the
anterior edge of the furculum, over the interclavicular air-cell in
these and some other birds.

The anterior thoracic cell, ib. b, contains the lower larynx and
bronchi, and the great vessels with their primary branches to the
head and wings. It is traversed by numerous membranous septa,
which connect the different vessels together, and maintain them
in their situations. The air passes into the posterior part of this

r 2

212

ANATOMY OF VERTEBEATES.

receptacle by two openings at the anterior part of the lungs. The
deep-seated air-cells of the neck are continued from it anteriorly.
The lateral thoracic cells, ib. d, are continued on each side
from a foramen on the inner edge of the lung, situated just
opposite the base of the heart ; they are covered by the anterior
thoracic air-cell, and from them the air passes into the axil-
lary and suhscajnilar cells, into
those of the wing, and into
the humerus, ib. e. They also
communicate with the cellula
cordis posterior, ib. c, behind

98

the heart and

bronchi, which

into

cell is often subdivided
several small ones.

The cellulce hepaticce are of
much larger size ; they are two
in number, of a pyramidal
figure, with their bases applied
to the lateral thoracic cells, and
their apices reaching to the
pelvis : they cover the lower
portions of the lungs and the
lobes of the liver ; they receive
air from several foramina situ-
ated near and at the external
edo^e of the lunors.

The cellulcB ahdominales com-
mence beneath the cellular he-
patlcte at the inferior extremity
of the lungs, where the longest
branches of the bronchi^e open
freely into them. (A bristle is
passed through one of these
openings in the figure.) They
are distinguished into right Qi)
and left {f) : the former is ge-
nerally the largest receptacle in the body ; it extends from the
last ribs to the anus, and covers the greater part of the small in-
testines, the suprarenal gland, and kidney of the same side. The
left abdominal cell, f, contains the intestines of its own side, and
is attached to the gizzard. In some large Birds, as the Gannet, it
is separated from the right receptacle by a mediastinal membrane,
g, which is continued on from the gizzard to the anus.

Air-receptacles of a Swan.

EESPTEATORY SYSTEM OF BIEDS. 213

Both the abdominal receptacles transmit air to the pelvic cells,
^, li, of their respective sides, and to several small and extremely
delicate cells between and behind the coils of intestine. One of
these is continued round the fold of the duodenum and pancreas
to the gizzard, and has been termed the duodenal cell.

From the inguinal cell are continued the intermuscular cjlutceal
and femoral cells, which surround the head of the femur, and
communicate with that bone by an aperture, /, situated imme-
diately anterior to the great trochanter, except in those Birds in
which the femur retains its medulla.

The cervical air-cells are continued from the laro-e clavicular

o

cell, and form in the Argala and Bustard, fig. 54, a, a singular
appendage or pouch, contained in a loose fold of integument,
which the bird can inflate at pleasure.

In the Pelican and Gannet extensive air-cells are situated
beneath almost the whole of the integument of the body, which is
united to the subjacent muscles only here and there by the septa
of the cells and the vessels and nerves which are supported by the
septa in their passage to the skin. The large pectoral muscles and
those of the thigh present a singular appearance, being, as it were,
cleanly dissected on every side, having the air-cavities above and
beneath them. The axillary vessels and nerves are also seen
passing bare and unsupported by any surrounding substance
through these cavities. Numerous strips of j)anniculus carnosus
pass from various parts of the surface of the muscles to be firmly
attached to the skin ; a beautiful fan-shaped muscle is spread over
the interclavicular or furcular air-cell. The use of these muscles
appears to be to j^roduce a rapid collapse of the superficial air-
cells, and an expulsion of the air, when the bird is about to de-
scend, in order to increase its specific gravity, and enable it to
dart with rapidity upon a living prey.

The air-receptacles of the thoracic-abdominal cavity present
varieties in their relative sizes and modes of attachment in dif-
ferent birds. In the Raptores they are principally attached pos-
teriorly to the ribs, the diaphragmatic aponeurosis covering the
lungs, and to the kidneys; while in the Grallatores they have
anterior attachments to the intestines in many places.

The singular extension of the respiratory into the osseous
system was discovered almost simultaneously by Hunter and
Camper, and ably investigated by them through the whole class
of Birds. The air-cells and lungs can be inflated from the bones,
and Hunter injected the medullary cavities of the bones from the
trachea. If the femur into which the air is admitted be broken.

214 ANATOMY OF VERTEBRATES.

the bird is uuable to raise itself in flight. If the trachea be tied,
and an opening be made into the humerus, the bird will respire
by that opening for a short period, and may be killed by inhaling
noxious gases through it. If an air-bone of a living bird, simi-
larly perforated, be held in water, bubbles will rise from it, and a
motion of the contained air will be exhibited, synchronous with
the motions of inspiration and expiration.

The proportion in which the skeleton is permeated by air
varies in different Birds. In the Alca impenjiis, the Penguins
(^Aptenoch/tes) and the Apteryx, air is not admitted into any of
the bones. The condition of the osseous system, therefore, which
all birds present at the early periods of existence, is here retained
through life.

In the laro'e Struthious Birds, which are remarkable for the
rapidity of their course, the thigh-bones and bones of the pelvis,
the vertebral column, ribs, sternum and scapular arch, the
cranium and lower jaw, have all air admitted into their cavities or
cancellous structure. In the Ostrich the humeri and other
bones of the wings, the tibias and distal bones of the legs, retain
their marrow. INIost Birds of Flight have air admitted to the
humerus : the Woodcock and Snipe are exceptions. The Pigeon
tribe, with the exception of the Crown Pigeon, have no air in the
femur, which retains its marrow. In the Owls also the femur is
flUed wdth marrow ; but in the Diurnal Birds of Prey, as in
almost all other Birds of Flight, the femur is filled with air. In
the Pelican and Gannet the air enters all the bones with the
exception of the phalanges of the toes. In the Hornbill even
these are permeated by air.

Hunter has given the following characters as distinguishing the
bones wdiich receive air. They may be known — ' first, by their
less specific gravity ; secondly, by their retaining little or no oil,
and, consequently, being more easily cleaned, and when cleaned,
appearing much whiter than common bones : thirdly, by having
no marrow, or even any bloody pulpy substance in their cells ;
fourthly, by not being in general so hard and firm as other bones ;
and, fifthly, by the passage that allows the air to enter the
bones.'' Tlie openings by which the air penetrates the bones,
may be readily distinguished in the recent bone, since they are
not filled up by blood-vessels or nerves, but have their external
edges rounded off.

In the dor:ial vertebrae the air-orifices are small, numerous, and
irregular ; situated along the sides of the bodies, and the roots of

' xciv p. 1 78.

RESPIRATORY SYSTEM OF BIRDS. 215

the spinous processes, the air passes into them directly from the
luno's. In the two or three lower cervical vertebrae the air-holes
are in the same situation, but receive the air from the lower
cervical or clavicular air-cells : in the remainder of these vertebras
the air-holes are situated within the canal lodging the vertebral
artery, and communicate with the lateral air-cells of the neck.

The air-holes of the vertebral ribs are situated at the internal
surffice of their vertebral extremities, and appear, like those of
the contiguous vertebra?, to have an immediate communication
with the lungs. The sternal ribs have also internal cavities which
receive air from the lateral thoracic cells by means of orifices
placed at their sternal extremities.

The orifices by which air is admitted to the sternum are nu-
merous, but are principally situated along the mesial line of the
internal surface, opposite the origin of the keel, forming a reticu-
lation at that part ; the largest foramen is near the anterior j)art
of the bone ; some smaller ones occur at the costal margins. All
these orifices communicate with the thoracic air-receptacles.

The scapula is perforated by several holes at the articular ex-
tremity, which admit air into its cancellous structure from the
axillary cell. The coracoid has small air-holes at both extre-
mities ; the largest is situated on its inner surface, where it is con-
nected with the clavicle or furculum. The furculum receives air
principally by a small hole in the inner side of each of its scapular
extremities, which communicates with the clavicular air-cell.

The air-hole of the humerus is of large size, and situated at the
anconal or back part below the head of the bone, in the hollow
of the ulnar or inner tuberosity. It communicates with the
axillary air-cell, and transmits the air to the cavity of the bone
by several cribriform foramina.

The air-holes of the pelvic bones are situated irregularly on tlie
inner surface upon which the kidneys rest, and must therefore
receive air from continuations of the abdominal receptacles around
the kidneys.

A depression at the anterior part of the base of the great
trochanter receives air from the glutteal cell, and transmits it by
several small foramina into the interior of the femur. In tlie
Ostrich, the air-holes are situated at the posterior part of the bone
at both its extremities.

The cavities of the long bones into which air is thus admitted
are proportionally larger than in the corresponding bones of Mam-
malia, and are characterised by small transverse osseous columns
which cross in different directions from side to side, and are more

216 ANATOi\IY OF VERTEBRATES.

numerous near the extremities of the bone ; they abut against and
strengthen, like cross-beams, the parietes of the bone. The
membrane lining these cavities, is not very vascular.

The lower jaw receives its air by an orifice situated upon each
ramus behind the tympanic articulation, from an air-cell which
surrounds the joint. The bones of the cranium and upper jaw
receive air admitted to the tympanic cavity by the Eustachian
tube, not from the nasal passages. With these, however, the
subocular air-cell communicates ; and in the Coot, Water-hen,
Goose, and other water-birds, entozoa (^Monostoma mutahile^ e. g.)
gain access to that air-cell.

The extension from the lungs of continuous air-receptacles
throughout the body is subservient to the function of respiration,
not only by a change in the blood of the pulmonary circulation
effected by the air of the receptacles on its repassage through the
bronchial tubes ; but also, and more especially, by the change
which the blood undergoes in the capillaries of the systemic cir-
culation, which are in contact with the air-receptacles. The free
outlet to the air by the bronchial tubes does not, therefore, afford
an argument against the use of the air-cells as subsidiary respi-
ratory organs, but rather supports that opinion, since the inlet of
atmospheric oxygenated air to be diffused over the body must be
equally free.

A second use may be ascribed to the air-cells as aiding me-
chanically the actions of respiration in Birds. During the act of
inspiration the sternum is depressed, the angle between the
vertebral and sternal ribs made less acute, and the thoracic cavity
proportionally enlarged ; the air then rushes into the lungs and
into the thoracic receptacles, wdiile those of the abdomen become
flaccid : when the sternum is raised or approximated towards the
spine, part of the air is expelled from the lungs and thoracic cells
by the trachea, and j^art driven into the abdominal receptacles,
which are thus alternately enlarged and diminished with those of
the thorax. Hence the luncfs, notwithstandino' their fixed con-
dition, are subject to due compression through the medium of the
contiguous air-receptacles, and are affected equally and regularly
by every motion of the sternum and Y\hs.

A third use, and perhaps the one which is most closely related
to the peculiar exigencies of the bird, is that of rendering the whole
body specifically lighter; this must necessarily follow from the
desiccation of the marrow and other fluids in those spaces which
are occupied by the air-cells, and by the rarefaction of the con-
tained air from the heat of the bod v.

RESPIEATOrvY SYSTEIM OF BIRDS. 217

Agreeably to tliis view of the function of the air-cells, it is
found that the quantity of air admitted into the system is in pro-
portion to the rapidity and continuance of the bird's flight; and,
where it is limited, the air is distributed to those members which
are most employed in locomotion ; thus the air is admitted into
the wino;-bones of the Owl, but not into the femur : while in the
Ostrich the air penetrates the femur, but not the humerus or other
bones of the wing.

A fourth use of the air-receptacles relates to the mechanical
assistance which they afford to the muscles of the wings. This
was suggested by observing that an inflation of the air-cells in a
Gigantic Crane ( Ciconia Ai^gala) was followed by an extension
of the wings, as the air found its way along the brachial and anti-
brachial cells. In large birds, therefore, which, like the Argala,
hover with a sailing motion for a long-continued period in the
upper regions of the air, the muscular exertion of keeping the
wings outstretched will be lessened by the tendency of the dis-
tended air-cells to maintain that condition. It is not meant to
advance this as other than a secondary and probably partial
service of the air-cells. In the same lio-ht mav be reo-arded the
use assigned to them by Hunter, of contributing to sustain the
song of Birds, and to impart to it tone and strength. It is no
aro'ument aa'ainst this function that the air-cells exist in birds
which are not provided with the mechanism necessary to produce
tuneful notes ; since it was not pretended that this was the ex-
clusive and only oflfice of the air-cells.

§ 158. Air-passages in Birds. — The air-passages in Birds com-
mence by a simple superior larynx, from which a long trachea
extends to the anterior aperture of the thorax, where it divides
into the two bronchi, one to each lung. At the place of its divi-
sion there exists, in most birds, a complicated mechanism of bones
and cartilages moved by appropriate muscles, and constituting the
true organ of voice : this part is termed the inferior lan/n.r.

The tendency to ossification, which is exemplified in the bony
condition of the sternal ribs and tendons of the muscles, is again
manifested in the framework of the larynx and the rings of the
trachea, whicli, instead of being cartilaginous, as in Beptiles and
Mammals, are in most birds of a bony texture.

The superior lari/nx, figs. 73, e — li, 99, and 100, is situated be-
hind the root of the tono:ue, and rests upon the urohyal, fig. 73, 43,
to which it is attached by dense cellular texture.

It is composed of several bony and cartilaginous pieces, varying
in number from four to ten. The largest of these pieces constitutes

218

ANATOMY OF VERTEBRATES.

the anterior part of the larynx. It is of an oval or triangular
form, according as its superior termination is more or less pointed,
and answers to the thyroid cartilage, fig. 73, /. The cricoid car-
tilage is represented by three osseous pieces, which are situated at
the posterior and inferior part of the upper larynx ; the middle
one, fig. 73, g, is of an oblong form, and varies in size, being larger
than the lateral ones in the Anatidce, but smaller in the Cantores.
The lateral pieces are connected at one extremity with the thyroid
piece, and at the other to the middle oblong piece above described,
which completes the circle of the laryngeal framework posteriorly :
the first two incomplete tracheal rings, ib. g, g, may represent the
anterior part of the cricoid. The arytenoid bones, ib. A, rest upon
the middle oblong portion of the cricoid, and extend forward,
being connected at their outer edge by means of elastic celhilar
substance to the thyroid, and attached by their anterior extremities

00

upper larynx, Crane, xlviv

Upper larynx. Crane, xlviv

to the urohyal by means of two small ligaments : they form, by
their inner margins, the rima glottidis or laryngeal fissure.

This fissure, fig. 51, i, being thus bounded by inflexible rigid
substances, is only susceptible of having its lateral diameter varied
according to the degrees of separation or approximation to which
the arytenoid bones are subject. These different states are pro-
duced by appropriate muscles, one pair of which may be regarded
as Thgreo-argtenoidei, and the other may be termed Constrictores
glottidis. The former, fig. 99, k, h, arise from the sides and posterior
surface of the thyroid, and are inserted into the whole length of the
inner edge of the arytenoids, which they draw outward, and conse-
quently open the laryngeal fissure. The Constrictores glottidis in
the Gigantic Crane arise from the middle of the internal or posterior
surface of the thyroid, and are inserted into the arytenoids : they
close the laryngeal opening with such accuracy as to supersede the
necessity of an epiglottis. From the simplicity of the structure

RESPIRATORY SYSTEM OF BIRDS. 219

just described, from the situation of the superior larynx with rela-
tion to the rictus or gape of the bill, and from the absence of lips
by which this might be partially or entirely closed, it is plain that
it cannot be considered as influencing the voice, otherwise than by
dividing or articulating the notes after they are formed by the
lower larynx. The superior larynx presents, indeed, but few
varieties in the different species of Birds; and these relate chiefly
to certain tubercles in its anterior, which vary in number, and do
not exist at all in some species, as the Singing Birds ; being chiefly
present in those birds which have a rough unmusical voice. In the
Pelican, the Gigantic Crane, and most of the Rasores, a process
extends backward into the cavity of the upper larynx from the
middle of the posterior surface of the thyroid cartilage, and seems
destined to give additional protection to the air-passage.

The trachea, figs. 93, 94, G, is proportionally longer, in conse-
quence of the length of the neck in Birds, than in any other class
of animals, its length being further increased in many species by
convolutions varying in extent and complexity. A species of
Sloth (Bradypus tridacti/his) among Mammals, and a species of
Crocodile ( Crocodilus acutus) among Keptiles, present an analo-
gous folding of the trachea.

The trachea is composed in Birds of a series of bony, and some-
times, as in the Ostrich, of cartilaginous rings, included between
two membranes. In those cases in which they are of a bony
structure, the ossification is observed to commence at the anterior
part of each ring, and gradually to extend on both sides to the
oj^posite part.

The tracheal rings, w^hether bony or cartilaginous, are, with
the exception of the two uppermost, always complete, and not, as
in most quadrupeds, where the windpipe bears a different relation
to the organ of voice, deficient posteriorly. They differ in shape,
being sometimes more or less compressed. They are generally of
uniform breadth, but in some species are alternately narrower at
certain parts of their circumference and broader at others, and in
these cases the rings are generally closely approximated together,
and, as it were, locked into one another. This structure is most
common in the Grallatorcs, where the rings are broadest alternately
on the right and left sides.

With respect to the diameter of the traclical rings, tliis may
sometimes be pretty uniform throughout, and the trachea will con-
sequently be cylindrical, as in the Cantores, the Grallatorcs which
have a shrill voice, the females of the Natatorci<,w[ii\. most Raptor cs
and Rasores : or the rings may gradually decrease in diameter,

2'20 ANATOMY OF VEIITEBKATES.

forming a conical trachea, as in tlie Turkey, the Heron, the Buz-
zard, the Eagle, the Cormorant, and the Gannet ; or they may be-
come wider by degrees to the middle of the trachea, and afterward
contract again to the inferior larynx ; or lastly, they may experience
sudden dilatations for a short extent of the trachea ; the Golden-eye
{A?ias clangula), the Velvet-duck (A?ias fusca), and the Merganser
{Mergus serrator), present a single enlargement of this kind, in
which the bony rings are entire, and of the same texture as in the
rest of the tube. In the Golden-eye the trachea is four times
larger at the dilatation than at any other part. In the Goosander
{3Iergus merganser^, the trachea presents two sudden dilatations
of a similar structure to that above described. The trachea of the
Emeu ( Dromaius ater^ is also remarkable for a sudden dilatation,
but in this instance the cartilaginous rings do not preserve their
integrity at the dilated part, but are wanting posteriorly, where
the tube is completed by the expanded membranes only.

With regard to the windings of the windpipe, in an Australian
Snipe {Rhynchma australis), the convolutions, which are short,
are external to the chest, between the skin and the fore part of
the pectoral muscles. In the same position lie the long double
coils of the windpipe in the Semipalmate Goose {^Anas semi-
palmatci), and the long single fold in Ortalida Parraqua. In the
Crested Pintado {Numida cristata), the apex of the furculiun
forms a bony cup which receives a loop of the trachea. In the
crestless Guan (^Penelojje Mirail), the Demoiselle {G?'us virgo),
and Stanley Crane ( Grus Stanley anus), the trachea forms a curve
sinking into the upper and fore part of the sternum. In the com-
mon Crane (^Grus cinerea^, and Serass Crane {Grus Antigone), the
keel of the sternum is more deeply hollowed for the lodgment of
more extensive coils of the trachea. In the male wild Swan
(^Cygnus ferus^, the windpipe describes a double vertical coil
within the long and deep keel of the sternum : in Bewick's Swan
( Cygnus Bewickii), the distal part of the coil lies horizontally
within the body of the sternum : the entry and exit of the intra-
sternal coils are shown in fis^. 101.

§ 159. Lower Larynx in Birds. — The main or essential organ
of voice is situated at the bifurcation of the trachea, ib. a, into
the bronchi, ib. b, h ; and herein may be discerned an analogous
relation to convenient stowage, which the jiosition of the mas-
ticatory apparatus shows : for even the muscles of the organs
of voice and the bony drum of the larynx, &c., are brought
beneath the centre of gravity, at the base of the neck, not accu-
mulated at its anterior extremity. In general tlie rings of the

RESPIRATORY SYSTEM OF BIRDS.

221

Tracheal coils and lower larynx, Bewick's Swan, xlviii-

bronchi are incomplete. In the King-Vultnre the entire rings
are continued a little way along the bronchial divisions of the
trachea, without any modifications, external or internal, indicative
of a laryngeal structure. The same may be seen in the Ostrich,
where the bronchi are provided with entire slender rings rapidly
diminishing in size as they approach the lungs : but the terminal
rings of the trachea are thickened and protrude outward, forming
a cavity on each side, the
lining substance of which
projects into the area of the
tube above the commence-
ment of each bronchus.^

In most Birds the bron-
chi, figs. 85, V, 101, h,
are straight, compressed,
and easily lacerable tubes,
strengthened by half-rings
on the outer side, the inner
side being formed by a mem-
brane ('membrana tympani-
formis '). Usually the bronchi rapidly contract as they approach
the lungs.

The muscles of the trachea are the ' sterno-tracheales,' fig. 104,
d, a long pair, arising from the costal processes of the sternum and
converging to ascend along the sides of the windpipe. To these
are sometimes added a second pair from the furculum, called
' cleido-tracheales.' In Cursores and most Rasores the sterno-
tracheales alone are present. In most Raptores and Grallatores, a
muscle, broncho- trachealis, situated on each side of the lower part
of the trachea, descends to be inserted into the first or second
bronchial half-ring : in Alcedo and Caprimulgus it descends to the
third half-ring ; in some of the Owls its insertion is still lower,
and the degree of tension of the tympaniform membrane will be
proportionally varied. In Colopterus crisfatus an azygos muscle
occupies the anterior interspace of the broncho-tracheales.^

In other Yocal Birds there is a double glottis, usually produced
by a bony bar, *pessulus,' ' os transversale,' fig. 102, i, which
traverses the lower end of the trachea from before backward : it
supports a thin membrane which ascends into the tracheal area
and, terminating there by a free concave margin, is called the
' membrana semilunaris,' ib. h. This is most developed in Singing

sx. vol. ii. p. 103 (1834).

- XLIX-.

222

ANATOMY OF VERTEBRATES.

102

Birds^ and, being vibratile, forms an important part of their trilling
vocal apparatus. The air passes on each side the membrana semi-
lunaris and its sustaining bone to and from the bronchi and lungs.
The walls of the loAver larynx are formed by modified rings and
half-rings of the end of the trachea and beginning of the bronchi.
The last ring of the trachea, fig. 103, t,
usually expands as it descends, with its fore
and hind 2:)arts produced, and the lower lateral
borders concave : the extremities of the pes-
sulus, fig. 102, ?, abut against the produced
angles, and expand to be there connected,
also, with the fore and hind terminations of
the first half- ring of the bronchus, fig. 103,
«, strengthening and clamping together the
upper parts of the vocal framework. The
second bronchial half-ring, ib. h, is flattened
and curved with the convexity outward,
like the first, but is more moveable. The
third half-ring, ib. c, is less curved and fur-
ther separated from the second, to the ex-
tremities of which its own are connected by
ligament, and, for the intervening extent,
by membrane ; its inner surface supports
the fibrous chord or fold which forms the outer lip of the glottis of
that side ; it is susceptible of a rotatory movement on its axis, and
is an important agent in the modulation of
the voice. All the above parts, t, «, h, c,
fig. 103, are bony. The bronchial half-
rings and their connecting ligaments and
membranes form the outer convex wall of
the tube : the inner wall is a flat membrane,
stretched like a drum-head, between the
extremities of the half-rings, and attached
above to the cross-bar, and through it to
the semilunar membrane. The outer part
of the lower tracheal and bronchial rings,
being cut away in fig. 102, exposes the
central surface of the 'membrana tympa-
niformis,' g^ with its upper connexions with
the cross-bone /, and the 'membrana semilunaris,' Ji. Part of
the peripheral surface of the tympaniform membrane is seen in
the front view of the lower larynx and bronchi, fig. 104, a, g.
A small appendage to the inner margin of the half-ring, fig.

Side view of cavity of lower
larynx, Raven, yxx-.

103

Lower larynx, Raven, xxx'.

VOCAL ORGAN OF BIRDS.

223

103, b, making a prominence where the external vocal fold is

continued over it, in the starling, thrush, nightingale, &c., has

been called ' arytenoid cartilage,' from its analogy to that of the

upper larynx of Mammals. The proper muscles of the lower

larynx, as seen in the Raven,

are shown in fig. 104, in front ^'^'^

view A, and side view B.

The muscle answering to
the ^ tracheo-lateralis ' in Vo-
litores expands toward the
lower end of the trachea and
divides into two fasciculi
which diverge, the one, f, to
the fore, the other, a, to the
back part of the bronchus, to
be inserted into the corre-
sponding extremities of the
third half-ring, fig. 104, c.
The fasciculus, fig. 104, b,/, is
the * broncho-trachealis anti-
cus : ' the fasciculus, a, is the broncho-trachealis posticus. Beneath
this is a shorter muscle, ib. b, the broncho-trachealis brevis, which
is inserted into the posterior end of the second bronchial half-

A front, B side, view of lower larynx. Raven, xxx*.

The remaining two muscles are enlarged divisions or differen-
tiated fasciculi of the common laryngeal muscle (Kehlkopfmuskel,
Miiller^) of Volitores: the ^ bronchialis posticus,' ib. c, arising
from the lower and lateral border of the last tracheal ring, swells
into a ^ venter,' and contracts as it passes backward to be inserted
into the hinder end of the second half-ring. The ' bronchialis
anticus,' ib. e, is partly covered by the ^ broncho-trachealis anticus,'
and is thick and ventricose : it arises from the last tracheal ring;
and passes forward to its insertion into the fore ends of the first
and second half-rings and into the supplemental (arytenoid) car-
tilage.

All the foregoing muscles tend to tighten the whole or parts of
the tympaniform membrane which is below their points of inser-
tion, and to relax the part above the insertion. They lengthen
the part of the bronchus below or beyond their insertion and
shorten the part above, by approximating to the trachea the half-
rings they are attached to. The chief antagonistic power is the

2:>4 ANATOMY OF VERTEBRATES.

elasticity of the membranes so put on tlie stretch : but there is a
direct 'relaxor' of the tympaniform membrane in the ' sterno-
trachealis/ ib. c?, which, passing from the side of the trachea to the
sternum, shortens the whole bronchus as it draws down the wind-
pipe. This is the most constant of all the muscles affecting the
lower larynx. It is reckoned by Savart as the sixth pair of vocal
muscles, but not by Cuvier, since it is not directly attached to
any part of the lower larynx, and exists in Birds, as, e. g., the
Vulture and Ostrich, in which that larynx is not developed.

The manifold ways and degrees in which the several parts of
the complex vocal organ in Caiitores may be affected, each of the
principal bony half-rings, as one or other end may be pulled, being
made to perform a slight rotatory motion, are incalculable : but
their effects are dehghtfully appreciable by the rapt listener to
the singularly varied kind and quality of notes trilled forth in the
stillness of gloom by the Nightingale.

In many of the Volitores there is a single pair of ' broncho-
tracheales,' and a single pair of short ventricose ' bronchiales.' In
ThamnoiDMlus each sterno-trachealis bifurcates to send a small strip
to the lower larynx, and the rest to the side of the trachea, as
usual. In Furnaria the sterno-trachealis is inserted into the
upper end of a long appendage to the upper bronchial half-ring.
The Parrot tribe have a single glottis bounded by a lateral pair
of vibratile membranes ; each membrane, connecting
105 together, and occupying the interspace between, the

last tracheal and first bronchial half-rings. These
have each one margin concave, with the concavity
turned towards each other, and are moveably joined
too'ether at their fore and hind extremities. These
half-rings expand, and stand out from the end of the
trachea. A narrow muscle, ^ tensor longus glottidis,
fig. 105, a, passes from the side of the trachea to the
upper (tracheal) half-ring ; and, by raising it, makes
tense the elHptical elastic membrane : a broader ' ten-
sor brevis glottidis,' ib. Z>, passes from the lower rings
of the trachea to the same half-ring, diverging to
its extremities : a third narrow muscle passes from the tracheal
to the bronchial half-rings, ib. c, and, by approximating them,
relaxes the membrane occupying the elliptical interspace. These
membranes, projecting on each side into or below the termi-
nation of the air-tube, leave a narrow chink between them,
through which the air passes to and from the lungs ; and when,
in forcible expiration, the membranes are put into a sufficient

Lower laryiix^,
Parrot, xxx".

RESPIRATORY SYSTEM OF BIRDS.

225

state of tension, they vibrate, and the vocal air is driven along
the trachea through the tipper larynx, where some modification
of sound may be made. The tongue of the Parrot is more fleshy

106

Lower larynx : A, right side ; B, left side. Mergus serrator. cccxx.

than in most Birds. These structures, concomitant with the
single glottis and pair of vocal folds in the lower or true larynx,
relate to the faculty, so remarkable 207

in these singular birds, of imitating
human speech.

In the males of the Mergansers
and of most Ducks a certain number
of the terminal rings of the trachea
are welded together and expanded
into an irregular bony case, divided
into two unequal cavities. In the
Mergus serrator , fig. 106, the broad
' pessulus,'/, leaves a passage at its
upper part, h, by Avhich the air from
the right bronchus, y, can pass to and
from the trachea, e : part of the outer
wall of the right laryngeal chamber
is formed by membrane, li : tliis
chamber is extended by the osseous
cavity, g. A similar but somewhat
more complex lower larynx exists in the male Anas clangula.
These modifications relate to the power rather than to the variety
of the voice.

VOL. II. Q

Lower larynx. Mergus Merganser, cccxx.

226

ANATOMY or VERTEBRATES.

CHAPTEK XXI.

URINARY SYSTEM OF BIRDS.

108

,j^^~)0.

§ 160. Kidneys of Birds. — The urinary excretion is early pro-
yided for in the bird : about the third day of incubation a series
of short parallel caecal tubes, fig. 108, c, are developed in the
blastema beneath the vertebral column, and pass transversely to
a longitudinal canal, ib. d, which conveys the excretion to the
cloaca. These are the primordial or transitory kidneys. Behind
them subsequently appear the secondary or persistent kidneys, ib.
«, together with the genital glands, ib. e, and adrenals, ib. f. The
proper ducts of the kidneys, or ureters, ib.
h, soon follow the appearance of the true
renal tissue, and as this proceeds in its de-
velopement, the primordial glands disappear,
or yield up their duct and a remnant of their
tissue to form the epididymis and vas deferens
in the male.

In the mature bird the urinary system
consists of the kidneys, ureters, and a more
or less incomplete urinary receptacle.

As in Reptiles the kidney is distinguished
from that of the Mammal by the homogeneity
of its substance, which is not divided into a
cortical and medullary part, and by the tubuli
uriniferi extending to the surface of the gland
testes of an embryo Bird, mag- thcrc to form bv rcitcratcd unious the ureter,

nifled. Lxxiv. ... . . .

and not terminating m a cavity or pelvis in
the interior of the kidney, from which the ureter commenceSo

The kidneys, fig. 85, x, are two in number, of an elongated
form, commencing immediately below the lungs, and extending
along the sides of the spine as far as the termination of the rectum ;
in which course they are impacted in, and as it were moulded to,
the cavities and depressions of the j)elvis. From this fixed con-
dition it results that they are generally symmetrical in position,
not placed one higher than the other, as in the Mammalia. The
posterior surface of the kidney presents inequalities corresponding

I

m

Kidneys, 'Wolfflan bodies, and

URINAliY SYSTEM OF BIRDS. 227

to the risings and depressions of the pelvis ; the anterior surface is
smoothly convex or flattened ; but rising into a series of promi-
nences which correspond, not to the eminences, but to the cavities
of the bones on which they rest ; their inner or mesial side is
generally pretty regular and straight, but the external edge is
more or less notched. They are relatively larger than in most
Mammals ; resembling in this respect the kidneys of Whales and
of the cold-blooded Ovipara, Avhere there is no perspiration from
the skin.

The kidneys vary in size in different birds, being, for example,
smaller in most of the Grallatores^ as the Bustard and Heron,
where the pehds is short, than in the Rasorial Order, in which it
is of great extent. Where they are short they are in general
more prominent, and this is so remarkable in some Birds, as the
Owls, that in them they resemble somewhat in their superficial
position the kidneys of Mammals.

As might be expected from their relations to the pelvis, the
kidneys in Birds present as many varieties of outward configuration
as there are differences in the part of the skeleton to which they
are moulded. In some Aquatic Birds, as the Grebe (Podiceps) and
the Coot [FuUca), the kidneys are more or less blended together
at their lower extremities, as in most Fishes : in Colymhus the
extent of the union is greater ; in Platalea they have been observed
to be joined by a middle band. In the rest of the class they are
distinct from one another.

The principal lobes are in general three in number : the anterior
or highest one is, in some cases, the largest; while in others,
as the Pelican, the contrary obtains, the lowest division being
most developed in this bird. In the Tern each kidney is divided
by fissures into seven or eight square-shaped lobes : in the Eagle
they each present four divisions ; but in these cases there are not
distinct ureters to each lobe as in the subdivided kidneys of
Mammals. In the Emeu {Dromaius ater) the kidney presents only
two lobes ; the superior or anterior one is the broadest and most
prominent, being of a rounded figure, and constituting one-third of
the whole ; the lower division is flattened, and gradually tapers to
a point. In one specimen I found the left kidney half an inch
longer than the right. In tlie small Cantores the exposed super-
ficies of the kidney is rarely lobular.

Each kidney is invested by its proper capsule, a thin membrane,
which also extends into the substance of the gland, between its
divisions: a layer of peritoneum is reflected over their anterior
surfaces.

Q 2

228 ANATOMY OF VEETEBEATES.

The texture of the kidneys is much more frail than in Mammalia,
readily yielding under the pressure of the finger, to which they
give a granular sensation as their substance is torn asunder.

In colour they resemble the human spleen. Besides being
di\dded into lobes, the surface of the kidneys may be observed to
be composed of innumerable small lobules, separated by continuous
gyrations like the convolutions of the cerebral substance.

The tubuli uriniferi originate from every part of the internal
substance of the lobules, extending to the gyrations, uniting in the
pinnatifid form, and coursing to the margins of the lobules, all the
inflexions of which they follow. The pinnatifid ramification of
the uriniferous tubules is sometimes ' opposite,' sometimes ' alter-
nate,' sometimes the branches are simple, sometimes dichotomously
divided ; but these ramuli appear scarcely smaller than the branches
from which they spring, and never intercommunicate.^ The
uriniferous ducts from the convoluted lobules unite dichotomously,
and ultimately escape by a single duct — the ureter.

The arteries and veins of the kidneys have already been described.
Where the entire stream of the venous blood is not sent to the
lungs, but part is diverted to the arterial system, then also a portion
of the venous blood circulates through the kidneys before it reaches
the heart ; but in Birds, where not only the whole venous current
is sent to the lungs, but mth peculiar energy and frequency, such
vicarious office of removing efiete particles directly from the venous
blood is not required. A certain retention of the oviparous type
in the apparent entry of veins into the lower ends of the kidneys
is shown, but a reniportal vein does not exist : the connection of
the lower veins coming from the kidneys with the ihaco-mesen-
teric is of such a kind that the renal venous blood may flow to
the portal system of the liver when that system and digestion are at
work ; or it may floAV by the upper emulgent veins to the inferior
cava and so to the lungs, when respiration is unusually active.

The ureter, figs. 85, y, 108, h, is continued down along the
anterior surface of the kidney toward the mesial side ; here and
there imbedded in its substance, forming a series of dilatations
corresponding to the principal lobes or enlargements of the gland,
and recei\dng the branches of the tubuli uriniferi as it passes
along. Below the kidney the ureters pass behind the rectum,
becoming connected to, and after a short distance involved in, its
coats; they ultimately terminate upon valvular eminences in a
depression at the lower part of the urinary sac, ib. d ; the terminal
papillas of the ureters are situated with the orifices of the genital

' cxxii. p. 92.

URINARY SYSTEM OF BIRDS.

229

109

Cloaca of the Ostrich.

ducts, in the same segment of the cloaca, which is therefore termed
the urogenital cavity, fig. 109, e.

The space intervening between the urogenital cavity and the
valvular termination of the rectum, ib. c, forms a cavity more or
less developed in different Birds,
but always distinct in the smooth-
ness of its lining membrane from
the rectum, which has a more
vascular and villous internal tu-
nic. The Birds in which this
rudimental urinary bladder pre-
sents the largest capacity are the
Owls, many of the Aquatic Birds,
as the Pelican, Willock, Grebe,
Swan, &c. ; some of the Wading
Order, as the Bittern and Bus-
tard, but more especially the Os-
trich, among the Cursores, in
which the urinary receptacle is
represented as laid open at d, fig.
109.

§ 161. Adrenals of Birds. — The adrenals, d, d, figs. 117, 127, are
small bodies, usually of a bright yelloAv colour, situated on the
mesial or inner side of the superior extremities of the kidneys ;
closely attached to the coats of the contiguous large veins and in
contact with the testes in the male ; and the left one adhering to
the ovary in the female. They vary in shape, being sometimes of
a round, flattened, oval, or irregularly triangular figure. They are
proportionally smaller than in Mammals, being in the Goose each
about the size of a pea. They are sometimes confluent.

They present, like the kidneys, a homogeneous texture through-
out, and do not exhibit^ the alternate strata of different-coloured
substances as in Mammalia. In the Gigantic Crane we found the
texture of the suprarenal glands to be coarsely fibrous ; in the
Hornbill they were granular, similar to the kidney ; in the Pelican
they were of a granular but more pulpy texture.

There is no cavity in the suprarenal glands. The veins which
return the blood from them are of proportionally large size, as in
all the parenchymatous bodies without excretory ducts. The
suprarenal glands have been found to present a slight enlargement
corresponding with the increased developement of the sexual organs.
Their relative size and position to the testes in the male embryo
are shown at/, fig. 108.

230 ANATOMY OF VERTEBRATES.

§ 162. Spleen of Birds. — The spleen, figs. 85, 87, s, s, is com-
paratively of small size in Birds ; it is generally of a round or
oval figure, but sometimes presents an elongated and vermiform
shape, as in the Sea-GuU, or is broad and flat as in the Cormo-
rant. It is situated beneath the liver, on the right side of the
proventriculus. It is, however, somewhat loosely connected to
the surrounding parts, so that its position has been differently
described by different authors. A process of the pancreas com-
monly passes into close contact, and is connected with the spleen
by a continuation of vessels, as in the Hornbill, fig. S7, q, s. The
texture of the spleen is closer in Birds than in Mammals ; but a
minute examination proves that the blood of the splenic artery is
ultimately deposited in cells, from which the splenic veins arise.
These veins in the Swan and some other Lamellirostres form a
network on the exterior surface of the spleen, as in the Chelonian
Reptiles.

In many Birds, as e.g. Vultures, Falcons, the Starling, Magpie,
Heron, Bustard, and in most Aquatic Birds, two small bodies are
found, one on each side of the trachea, very near the lower larynx
and frequently attached to the jugular veins. They may be homo-
logues of the ' thyroid gland.' In addition to these there are two
similar bodies, in the Gannet, attached to the upper part of the
commencement of each bronchus.

§ 163. Peculiar Secretions. — The unctuous fluid mth which Birds
lubricate their feathers is secreted by a gland situated above the
coccyx or uropygium. This gland consists of two lateral moieties
conjoined. As might be expected, it is largest in the birds which
frequent the water. In the Swan it is an inch and a half in length,
and has a central cavity, which serves as a receptacle for the accu-
mulated secretion. Each lateral portion is of a pyriform shape,
and they are conjoined at the apices, which are directed backward,
and are perforated by numerous orifices, encircled in some birds
by a crown of feathers. The longitudinal central cavities present
numerous angular openings, in which there are still smaller ori-
fices of the secerning follicles. These consist of close-set almost
parallel straight tubules, extending to the superficies of the gland,
mthout ramifying or intercommunicating, and preserving an
equable diameter to their blind extremities. The tubules are
longest at the thickest part of the gland, and become shorter and
shorter towards the apex.

The follicles to which is due the peculiar odour of certain birds,
as e. g. the Hoopoe, Muscovy Duck, Black Vulture, &c., are pro-
bably somewhat diffused on parts of the integument.

231

CHAPTER XXII.

TEGUMENTAEY SYSTEM OF BIRDS.

§ 164. Composition of the Tegument. — This is composed, as in
Mammalia and Reptilia, of the corium or derm, the epiderm and
its appendages, and an intermediate layer of unhardened epiderm
with colouring matter, called ' rete mucosum.'

The corium, or true skin, is very thin and lacerable, but vascular.
In some Birds it adheres to the subcutaneous muscles by cellular
tissue, Avhich is frequently the seat of accumulation of dense
yellow fat. In the Penguin the layer of subcutaneous cellular
tissue adheres to the corium, but is separated from the muscles,
and has a smooth internal surface: long vessels, like threads,
connect this layer to the muscles. The skin is moved by muscles
which at the same time raise and ruffle the plumage which it
supports. In most Birds the skin is more or less separated from the
muscles of the trunk by the interposed air-cells ; as in the Batra-
chians it is by the lymph receptacles. It adheres, however, to a
larger proportion of the osseous system than in other classes ; as,
e. g., to the upper and lower jaws, the feet and part of the tibije,
the pinion bones. The corium has extensions beyond the covering
of the body, to form the webs for swimming and the broader folds
at the axilljB and bend of the arm for flight : it developes the
papilla? beneath the toes, the vascular comb and wattles of the
Cock, the caruncle and pendent ornaments of the Turkey, &c.

The rete mucosum rarely contains any colouring matter where
the feathers grow ; at this part the skin is of a pale greyish colour,
or pink, from the colour of the blood which circulates in it. But
in the naked parts of the integument, as the cire, the lore, the
comb, the wattles, the naked parts of the head and neck in some
Birds, and the tarsi and toes, the rete mucosum frequently glows
with the richest crimson, orange, purple, green, black, and a variety
of other tints, of which the planches colorices and the different
zoological monographs of geographical groups and families of Birds
afford numerous examples.^

* Amongst these merit highest mention the works of our countryman Gould on
the Birds of Australia, Europe, Asia, Great Britain, &c.; and his magnificent mono-
graphs on the Humming-Birds, Trogons, and Toucans.

232

ANATOMY OF VERTEBRATES.

110

The epiderm is in some places continued as a simple layer over
the corium, follo\^dng its wrinkles and folds, as around the naked
necks of some Vultures. It is moulded upon the bony mandibles
to form the beak, and in some Birds adheres to osseous pro-
tuberances on the cranium, where it forms a species of horn ; and
it is remarkable that these instances occur chiefly in those orders of
Birds, the Cursores and Rasores, which are most analogous to the
Ruminantia among quadrupeds : the Cassowary and Helmeted
Curassow are examples. The Hornbills are, however, instances
in the Yolitorial, and the Kamichi in the Grallatorial Order. The
cuticle is sometimes developed into spines or spurs, as upon the
wing of the Snake Vulture, Cassowary, Palamedea ; and upon the

leg of many Gallinaceous Birds.
The claws which sheath the
unguial phalanges of the feet
assume various forms adapted to
the habits and manner of life of
the different orders. A remark-
able artificial form is given to the
claw of the middle toe in certain
Birds ; the inner edge being pro-
duced and divided into small
parallel processes like the close-
set teeth of a comb, fig. 110.
These teeth are not reflected or
recurved, as they might be ex-
pected to be, if they had been intended to serve as holders of a
slippery prey, but are either placed at right angles to the claw or
are inclined towards its point. The Common Barn-Owl (Strix
flammea), the Night-jar genus ( Caprimulgus)^ the Heron and
Bittern kind (^ArdeidcB, ^igO' ^Aoi'd examples of this structure ;
and as each species of bird appears to be infested by its peculiar
louse (Nirmus), the solution of the final intention of so singular a
contrivance, which is limited to so few species, and these of such
different habits, may yet be afforded by the entomologist.

With respect to the scales which defend the naked parts of the
legs of birds, they do not differ from those of Reptiles. Their
form and disposition, as has been already observed, have afforded
distinctive characters to the zoologist. In most of the Raptores,
the Psittacidce, the Rasores, the Grallatores, and the Natatores, the
scales are polygonal, small, and disposed in a reticulate form ; the
birds so characterised formed the Retipedes of Scopoli. In the
rest of the class the tarsi are covered anteriorly with unequal

Foot of Night-jar.

PLUMAGE OF BIRDS.

233

111

semi-annular scales, ending on each side in a longitudinal furrow,
and these birds he termed the Scutipedes. In one section of the
Tyramii, Cuv., the scuta surround the tarsi as complete rings.
Where the carneous parts of the muscles are continued low do^vn
upon the legs, as in the Owls, a covering of feathers is co-extended
to preserve their temperature.

§ 165. Ajjpendages of the Tegument, — The Vertebrate classes
have each their characteristic external covering : the cold-blooded
Ovipara are naked, or their external surface is defended only by
hard scales or plates {squamcB and scuta) ; but the warm-blooded
classes require to be invested by an integument better adapted to
maintain the high degree of temperature
peculiar to them : hence quadrupeds are
clothed with fur and hair, and birds with
down and feathers.

Feathers are the most complicated of
all the modifications of the epidermic
system, and are quite peculiar to the class
of Birds. They are proverbially light;
and, as the eloquent Paley well observes,
^ every feather is a mechanical wonder ; '
^ their disposition, all inclined backward,
the down about the stem, the overlapping
of their tips, their different configuration
in different parts, not to mention the
variety of their colours, constitute a vest-
ment for the body so beautiful, and so
appropriate to the life which the animal is
to lead, as that, I think, we should have
had no conception of anything equally
perfect, if we had never seen it, or can
now imagine anything more so.' ^

NotAvithstanding the varieties of size,
consistence, and colour, all feathers are
composed of a quill or barrel, fig. Ill, «,
a shaft, b, b, and a vane or beard, c, c;
the vane consists of barbs, fig. 112, e, and
barbules, ff

The quill (^calamus), by which the fea-
ther is attached to the skin, is larger and shorter than the shaft,
is nearly cylindrical in form and semi-transparent ; it possesses

Lxvi*. p. 234.

234

ANATOMY OF VERTEBRATES.

in an eminent degree the opposite qualities of strength and light-
ness. It terminates below in a more or less obtuse extremity,
which is pierced by an orifice termed the loiver umhilicus, fig. Ill,
e\ a second orifice, leading into the interior of the quill, is
situated at the opposite end, at the point at which the two lateral
series of barbs meet and unite ; this is termed the ujiper umbilicus,
ih.f. The cavity of the quill contains a series of conical cap-
sules fitted one upon the other, and united together by a central
pedicle.

The shaft (scapus) is more or less quadrilateral, and gradually
diminishes in size from the upper umbilicus to its distal extremity.
It is ahvays slightly bent, and the concave side is divided into two
surfaces by a middle longitudinal line continued from the upper um-
bilicus; this is the internal
^ ^ - surface, fig. 112, c. The op-

posite, or external surface,
ib. b, is smooth, and slightly
rounded ; both sides are
covered mth a horny mate-
rial similar to that of which
the quill is formed, and
they inclose a peculiar white
soft elastic substance, called
the j^ith, ib. a.

The barbs (rami) are at-
tached to the sides of the
shaft near the external sur-
face, and consist of laminas,
varying as to thickness, breadth, and length. They are arranged
with their flat sides toward each other, and their margins in the
direction of the external and internal sides of the feather ; conse-
quently they present a considerable resistance to being bent out
of the vane's plane, although readily yielding to any force acting
upon themselves in the line of the stem: (e, e, fig. 112, are the
bases of two barbs of a feather magnified). The barbules (radii,
hamuli), ib. f, f are given off from either side of the thicker
margin of the barbs, and are sometimes similarly barbed them-
selves, as may be seen in the barbules of the great feathers of the
Peacock's tail. In these feathers and in the plumes of the Ostrich,
the barbules are long and loose ; but more commonly they are
short and close-set, and by their form and disposition constitute
the mechanism by which the barbs are united together. The
barbules arising from the upper side of the barb, or that next the

Diagrammatic section of the slaaft aud vane.

I

PLUMAGE OF BIRDS. 235

extremity of tlie feather^ are curved downward or toward the
internal surface of the shaft ; those which arise from the under side
of the barb are curved in the contrary direction : so that the two
adjoining series of hooked barbules lock into one another in a
manner which has been compared to the fastening of a latch of a
door into the catch of the door-post. There is much complicated
variety in the interlocking mechanism here generally explained.

Besides the parts which constitute the perfect feather, there is
an appendage attached to the upper umbilicus, called the accessory
plume {]Ly2)orachis). It is usually a small downy tuft, but varies
both in diiferent species, and even in the feathers of different
parts of the body of the same bird. In the quill-feathers of the
wings and tail, it retains the state of a small tuft of down ; but in
the body-feathers of Hawks, Grouse, Ducks, Gulls, &c., it is to be
found of all sizes, sometimes equal to that of the feather from which
it is produced.

In the Ostrich and Apteryx the feathers have no accessory
plume ; in the Rhea it is represented by a tuft of down ; in the
Emeu it rivals in size and structure the original feather ; and in
the Cassowary, besides the double feather, there is a second ac-
cessory plume, so that the quill supports three distinct shafts and
vanes.

The feathers vary in form in different parts of the bird accord-
ing to their functions, and afford zoological characters for the dis-
tinction of species ; they have, therefore, received in Ornithology
distinct names. The ordinary imbricated feathers which cover the
body are called ^ clothing feathers :' the larger ones for special uses,
' quill-feathers.' Those which surround or cover the external open-
ing of the ear are termed the * auriculars.' Those which lie above
the scapula and humerus are called the ^ scapulars.' The small
feathers which lie in several rows upon the bones of the anti-
brachium are called the * lesser coverts ' {tectrices primce). Those
which line the under or inner side of the wings are the ' under
coverts.' The feathers which lie immediately over the quill-
feathers are the ^ greater coverts ' (tectrices secundcE). The quill-
feathers supported by the wings are the ' remiges,^ or ^rowing-
feathers.' The largest of these remiges, which arise from the bones
of the hand, are termed the ' primaries ' (^primores). Those which
rise from the ulna, towards its distal end, are the ^secondaries'
{secundaricB). Those which are attached to its proximal extremity
are the ^ tertiaries ' {tertiarice). These in some Birds, as the Wood-
cock and Snipe, are so long as to give them the appearance, when
flying, of ha\dng four wings. The quill-feathers which grow

236 ANATOMY OF VERTEBRATES.

from the phalanx representing tlie index, form what is termed the
bastard wing {cilida spuria). Those forming what is called the
* tail ' of the bird, and supported by the coccyx, are the ^ rectrices,^
or steering quills. The overlying feathers are the ' tail-coverts '
{cahjpteria) ; these bear the ornamental ' eyes' and are so developed
in the Peacock as to form what is called the ^ tail ' or * train ' of
that gorgeous bird.

In considering the structures which determine the powers of
flight in different Birds, it is necessary to take into account the
texture, forms, and proportions of the wing-feathers, as well as
the developement of the bones and muscles which support and
move them; as much depends upon the mechanical advantages
resulting from the shape of the expanded wing. When the
primary quill-feathers gradually increase in length as they are
situated nearer the extremity of the pinion, they give rise to the
acuminated form of wing, as in the Swifts and Humming-Birds, in
which the first primary is the longest ; and in the true Falcons,
in which the second primary is the longest. In the Hawks the
wing is of a less advantageous form, in consequence of the fourth
primary being the longest. When the primaries gradually decrease
in length towards the end of the pinion, they give rise to a short
rounded form of mng, such as characterises the Gallinaceous Order;
in which, although the pectoral muscles are immensely developed
in order to counteract the disadvantage resulting from the dispo-
sition of the primaries, yet they are only able, in consequence of
the form of the wing, to carry the bird rapidly forward for a com-
paratively short distance, and that mth an exertion and vibratory
noise well known to every sportsman.

The texture of the quill-feathers has also a material effect on
the powers of flight. In the Falcons each primary quill-feather is
elongated, narrow, and gradually tapers to a point ; the webs are
entire, and the barbs closely and firmly connected together.^ In
the Owls the plumage is loose and soft, filaments from the barbules
extend upon the outer surface of the vane, and one edge of the
primaries is serrated ; so that, while they are debarred from
so swift a flight as the Hawk, they are enabled, by the same
mechanism, to mng their way without noise, and steal unheard
upon their prey.

§ 166. Developement of Feathers. — The first covering of the bird

' Of so much consequence are the quill-feathers to the Falcons, that when any of
them are broken the flight is injured and the falconers find It necessary to repair
them ; for this purpose they are always provided with perfect pinion and tail fea-
thers regularly numbered.

PLUMAGE OF BIRDS.

237

is a partial and temporary one, consisting of fasciculi of long fila-
ments of down, which on their first appearance are enveloped in
a thin sheath, but this soon crumbles away after being exposed to
the atmosphere. The down-fasciculi, which diverge each from a
small quill, are succeeded by the feathers, which they guide as it
were through the skin ; and after the first plumage, at each suc-
ceeding moult, the old feathers serve as the ^gubernacula' to those
which are to follow. It is to be observed that feathers do not grow
equally from every part of a surface of a bird; they are not
developed, for example, at those parts which are subject to friction
from the movements of the wings and legs. They first appear in
clumps upon the parts of the skin which are least affected thereby,
as, e. g., upon the head, along the spine, upon the exterior surface
of the extremities, at the sides of the projecting sternum and of
the abdomen.

113

Young Blaclihirds, showing primary down and growing featlier-clunuis. xx.

In fig. 113, Hunter^ designates them as follows: a, ^cranial
clump ' {jpteryla capitis, Nitzsch) ; h, * posterior cervical ' and
'dorsal clumps ' (/;^. spinalis^ N.) ; d, 'lumbar clumps ' {pt.femorales
seu lumbales, N.); e, 'brachial clumps' (7?^. humerales, N.); /,
' antibrachial,' and g, 'carpal clumps' (7;^. alarum, N.); q,
' femoral clumps ' (7;^. crurales, N.) ; n, the ' anterior cervical,' and
o, ' pectoral clumps ' {pt. colli later ales, N.) ; 7?, ' abdominal clumps '
(^pt. gastrm, N.), &c. Nitzsch^ illustrates the affinities of Birds
by the characters of the ' pterylae,' exhaustively followed out in

LIV.

The matrix, or organ by which the perfect feather is produced,
has the form of an elongated cylindrical cone, and consists of a

' XX, vol. iii. p. 311. ^ Liv.

238

ANATOMY OF VERTEBEATES.

increases in length ,
acquiring a more

114

\ir

m

capsule^ a bulb, and intermediate membranes which mould the
secretion of the bulb into its appropriate form. The matrix is at
first an extremely minute cone, attached by a filamentary process
to a follicle or papilla of the skin ; but it is not a developement of
that part, being of a different structure and adhering to it by a
small part only of its circumference. The matrix j^i'ogressively
its base sinking deeply into the corium, and
extended connection by enlarged vessels and
nerves, while its apex protrudes to a greater or less extent from
the surface of the integument, when the capsule drops off to give
passage to the feather which it incloses, and the formation of which
has, in the meanwhile, been gradually proceeding
from the apex doAvnward. The capsule of the
matrix, «, a, fig. 114, is composed of several
layers, the outermost of which is of the nature
of epiderm; the inner ones are more compact
and pulpy. The sides of the capsule which
correspond to the outer and inner sides of the
grooving feather Avithin are indicated by a white
longitudinal line.

The axis of the capsule is occupied by a me-
dulla or bulb, ib. e, also of a cylindrical form,
and of a soft fibrous texture, adhering by its base
to the parts beneath, and there receiving nume-
rous bloodvessels and a nerve.

Between the medulla and the capsule there are
two parallel membranes, one internal, ib. d ; the
other external, ib. b ; from the latter membrane
a number of close-set parallel laminte extend
obliquely from one of the white longitudinal lines
above mentioned to the other on the opposite side
of the cylinder. The two membranes seem to
be united together by the oblique septa. In the
long and narrow spaces between these septa, the matter of the
vane, ib. c, is deposited and formed into barbs and barbules. The
deposition of the material of the barbs commences at the apex of
the bulb, and the stem is next formed in the following manner.

The external longitudinal line from which the oblique laminae
are continued, receives and moulds on the inner surface of the
external capsule tlie horny covering of the back of the feather,
or that lonoritudinal band to the two sides of which the barbs are
attached ; and on the opposite surface of the internal membrane
are formed the pith or substance of the shaft, and the horny pellicle

IVratrix of a growing
featlier, with the cap-
sule laid open. Li'.

PLUMAGE OF BIRDS.

239

115

116

k

a,

^$X^

which incloses it on the inner surface. The internal lono-itudinal
line has no other use than to establish a solution of continuity
betAveen the extremities of the barbs of one side and those of the
other, which meet at that part, and thus curve round and com-
pletely inclose the formative bulb. In fig. 115, the capsule of the
matrix of a growing feather,
c, has been laid open, and the
nascent barbs, d, d, which sur-
rounded the bulb, have been
unfolded, exposing that part
at «, b. A portion of the
barbs and stem have been
completed and protruded, and
the bulb is beo-inninoc to un-
dergo a process of absorption
at that part, which will here-
after be described. The shaft
and barbs at the apex of the
cylinder are the first parts
which acquire consistence, and
the molecules composing the
remainder are less compactly
aggregated as they are situ-
ated nearer the base of the
matrix. As the gelatinous
medulla increases at the base,
the first-formed shaft and
barbs are protruded through
the extremity of the capsule,
the bulb continuing to furnish
the secretion which is mould-
ed between the two striated
membranes until the entire
feather is completed. If the
striated membrane inclosing
the bulb be attempted to be
reflected from below upward, it will be found to be connected with
a series of membranous cones, a, b, <?, d, e, fig. 116, ranged one
upon the other throughout the whole length of the bulb, and con-
nected together by a tube running through its centre. In this
figure the pulpy matter which occupied the interspaces of the
cones has been removed to show their central connecting tube.
As the developement of the feather advances, the pulpy matter

Growing feather, li*.

Structure of tlic bulb.

240 ANATOMY OF VERTEBRATES.

disappears from the summit of the medulla, aud ouly the mem-
branous funnel-shaped caps remain, Avliioh are }>rotruded from the
theca and the centre of the new-formed barbs, and fall off as these
expand. The theca which incloses the whole is of a firm texture
where the new-moulded barbs are yet pulpy and tender, but it
becomes thinner as tliese acquire consistency, and, lastly, dries and
crumbles away after it has been exposed to the action of the atmo-
sphere. The bulb itself, when examined in a half-formed quill-
feather, is composed of two parts, corresponding to the external and
internal aspects of the feather. The internal part represents a semi-
cylinder or case, inclosing the external part, which is of a conical
form ; the latter extends from the base of the bulb, and gradually
diminishes to a point where the shaft is completed and the barbs
begin to expand. Its office is to deposit the pith within the shaft,
and it is absorbed in proportion as this is effected. The internal
part or case also commences at the base of the bulb, and adheres
closely to the cone, with which, indeed, its substance is continuous ;
it increases in thickness as the cone diminishes, its margins are
beautifully scolloped or crenate, and the crenations are lodged in
the interspaces of the oblique laminae or moulds, and deposit in
them the material of the vane. The horny sides of the shaft are
lodged and formed in the grooves between the external and
internal parts of the bulb, and correspond in degree of formation
to the depths of those grooves ; and being progressively brought
into contact from above downwards, the shaft is thus completed,
leaving the longitudinal line at the internal side. When all the
grooves (wherein are formed the barbs, and the portion of the
shaft which carries them) are filled by the horny matter, and the
barbed part of the feather is finished, this horny matter lastly
expands uniformly around the medulla, and forms the quill of the
feather.

When tlie quill of the feather has acquired the due consistence,
the internal medulla becomes dried up, and is resolved, as before,
into membranous cones arranged one upon the other ; but these
latter never pass out, for the quill, which is now hardened
and closed by the shaft at the extremity opposite to the lower
umbilicus, will not permit their egress ; they remain, therefore,
inclosed, and constitute the liglit dry pith which is found in the
interior of the quill. The last remains of the bulb are seen in the
ligament Avhich passes from the pith through the lower opening of
the quill and attaches it to the skin.

There is a close analogy between the formation of a feather
and that of a tooth ; but a tooth may take years to be perfected,

J'LUMAGE OF BIRDS. 241

and there are but two series produced in one part of the jaw, and
only one in the other, in any warm-blooded animal. Feathers, on
the other hand, are devehjped in the course of some days ; tliey
attain a length of from one to two feet or more in many Birds,
and they are almost all renewed every year, — in some species
even twice a year. It may be conceived, then, how much vital
energy the organisation of lairds must exercise, and how many
dangers must accompany so critical a peric^d as that of the
moult.

The plumage is commonly changed several times before it
attains that state which is regarded as characteristic of the adult
bird. The time rcfj^uired for this varies from one to five years,
and several birds rear a progeny before they acrjuire the plumage
of maturity.

When the male bird assumes a vestment differing in cohmr
from the female, the young birds of both sexes resemble the
latter in their first y)lumage (Blackbird); but when the adult
male and female are of the same colour, llic young have then a
])luniage peculiar to themselves (Swan;. AMicn adult birds as-
sume a plumage during the breeding season decidedly different in
colour from that which they bear in winter, the young birds have
a j>lumage intermediate in the general tone of its colour compared
with the two periodical states of the parent birds, and bearing also
indications of the colours to be afterwards attained at either
])eriod (liuffj. When both males and females are alike in colour,
l)ut species of the genus differ widely in colour, as e. g. the IMack
and White Swans, the young of such species are alike and of an
intermediate hue.

Changes in the appearance of the plumage of birds may be
j)roduced : —

By the feather itself becoming altered in colour ;

Jiy the bird's obtaining a certain nunil)cr of new feathers
without shedding any of the old ones;

By the wearing off of the lengthened lighter-coloured ti])S of
the barbs of the feathers on the body, by which the brighter tints
of the plumage underneath are exposed ;

By an entire or partial moulting, at which old feathers are
throA\Ti off and new ones produced in their places.

The first three of these changes are observed in adult birds at
the approach of the breeding season ; the fourth change is partial
in spring and entire in autumn.

VOL. TI. R

242 ANATOMY OF VERTEBRATES.

CHAPTER XXIII.

GENERATIVE SYSTEM OF BIRDS.

§ 167. Male Organs and Semination. — The few varieties of
structure wliicli the generative organs present in the Class of
Birds, are principally met with in those of the male.

The organs in this sex exhibit all the essential characteristics
of the oviparous type of structure. The testes are situated high
up in the abdomen, whence they never descend into an external
scrotum. The intromittent organ is either double, as in Serpents,
when, however, each penis is extremely small ; or it is single, but
in this case, to whatever extent it may be developed, it is simply
grooved along the upper surface or dorsum for the passage of the
fecundating fluid. As there is no true urethral canal, so neither
are the glands of Cowper or the prostatic glands present.

The testes, figs. 89, x, Wl ,a, a, are two in number ; in form more
or less oval, situated near the upper extremities of the kidneys.
They vary remarkably in colour in different birds ; I have seen
them white in the Peregrine Falcon and Dove ; pale yellow in the
Horn-Owl and Gallinule ; of a brighter yellow in the Magpie,
Bay Ibis, Buff, and Oyster-catcher; of a black colour in the
Chough, Partridge, Heron, Seagull, but whitish toward the
lower end in the last two. They are invested with a strong and
dense ^ albuginean ' tunic, and are fastened or suspended by a fold of
peritoneum. The contorted seminiferous tubules are very slender,
and are separated into packets by delicate and membranous septa,
continued from the inner surface of the tunica albuginea. The
arteries spread in an arborescent form beneath that capsule. The
vas deferens, fig. 117, c, c, is continued from the posterior or
^ dorsal ' and internal or ^ mesial ' part of the gland.

The periodical variations of size which the testicles undergo are
very remarkable in the Class of Birds; and the limited period
during which their function is in activity is compensated by the
frequency and energy with which it is exercised.

The proportional size which the testes acquire at the breeding
season is immense, as may be seen in the subjoined figures of the

MALE ORGANS OF BIRDS.

243

testes of the House-Sparrow, which commences with the glands
as they appear in January, when they are no bigger than pins'
heads, and ends Avith their full developement in April.

It rarely happens that both testes are developed In exactly the
same degree: the left is commonly the largest; but sometimes

118

e

1. January.

2. Middle of February.

3. Beginning of Marcli.

4. Latter end of March.

Urinary and male organs of a Cock.

i. Middle of April.

Testes of the House-Sparrow, xciv.

the right exceeds the left; and I have seen an example, in a
Rook, where it alone had taken on the action of sexual increase,
and had acquired a bulk compensating for the want of develope-
ment in the left testis.

In most Birds, the only appearance of an epididymis, fig. 117, 5,
is a remnant of the primordial kidney, fig. 108, c. This part fre-
quently presents a colour strikingly different from that of the
testes : thus it has been observed in the Bustard and Curassow to
be black ; in the Cassowary, yellow ; and in the Demoiselle {An-
thropoides Virgo) to be of a green colour. In the Ostrich the
epididymis is folded upon itself at the side of the testis.

The vas deferens, fig. 117, c, commonly passes down to the cloaca
by the side of the ureters without undergoing any remarkable con-
volution ; but in the Common Cock it is bent upon itself in short
transverse folds from side to side almost from its commencement ;
the folds gradually but slightly increase as they approacli the

R 2

244

ANATOMY OF VERTEBRATES.

119

cloaca, both in extent and in tlie diameter of the tube composing
them ; and they are so closely compacted, and inclosed by a cover-
ing of peritoneum, as to present
in a longitudinal section the ap-
pearance of a series of cells,
which are capable of retaining,
as in a vesicula seminalis, a
quantity of the seminal secre-
tion. In the Sparrow there is a
dilatation at the end of each
vas deferens, which opens, as in
the Common Cock, on a papilla,
situated in the urogenital divi-
sion of the cloaca anterior to
the insertion of the ureter.

The base of each papilla is
surrounded by a remarkable
plexus of arteries and veins,
M, M, fig. 94, which serve as an
erectile organ during the vene-
real orgasm, when the fossa of the
turgid papilla is everted, and the
semen brought into contact with
the similarly everted orifice of
the oviduct in the female, along
which the spermatozoa pass by
undulatory movements of their
ciliary appendage or ^ tail.'

In some Natatores which co-
pulate in water there is pro-
vision for a more efficient coitus
than by simple contact of evert-
ed cloaca3, and in the Anatidce
a long single penis is developed,
fig. 119. It is essentially a
saccular production of a highly
vascular part of the lining mem-
brane of the cloaca, continued
from the fore-part of that cavity,
ib. a, a ; and in the passive state
is coiled up like a screw by the
elasticity of associated ligamen-
The vascular membrane gives oiF many small

Penis of a Drake, xxvii

tons structure, h, h.

MALE ORGANS OF BIRDS.

245

pointed processes, which, in the Gander, are arranged in transverse
rows on either side the urethral groove, d, and near the extre-
mity of the penis are inclined backward. The elastic band, b, b, has
been cut open lengthwise in the figure given by Home :^ it is
surrounded by cavernous tissue, and terminates in the blind end
of the sac which can be everted. A groove, ib. d, d, commencing
Avidely at the base, follows the spiral turns of the sac to its termi-
nation : the sperm-ducts open upon papillte at the base of this
groove. This form of penis has a muscle by which it can be
everted, protruded, and raised.

The base of the penis in the Ostrich is attached to the fore wall
of the cloaca, the conical body is bent in a recess, out of wliich it
can be drawn and into which it can be returned by muscles. It
consists of two solid fibrous bodies, the fissure between which is
covered by cavernous erectile tissue, bounding the seminal groove ;
but it has no evertible sacciform part : there is a third elastic sub-
stance internal to the cavernous substance which produces the
twisted form.

The Drake's penis is formed after the type of that of Lizards
and Serpents. The Ostrich's penis is like that of the Tortoise
and Crocodile.^

120

121

122

Siiermatozoa of the Cork (Gallus
domestictis) . cccvi.

Sperm-cell with pperniatoa.
Sparrow. Ib.

Sperm-cell with spermatozoa.
Cock. Ib.

The spermatozoa of Birds, like those of Lizards, have

cylindrical body; generally straight or wa^■y,
obtuse anteriorly, and tapering behind into a fihx-
mentary tail of varying length according to tlic
species, fig. 120; but in the Cantor es the body
is tmsted spirally in three to five or more turns,
pointed anteriorly and terminating in a usually
long filamentary tail, fig. 123. The sperm-cell
contains many spermatoa, fig. 121, and in these the
spermatozoa are developed and usually excluded

^ xxvir. and Pbil. Trans. 1802. 2 ^-^^

246

ANATOMY OF VERTEBRATES.

within the common sperm-cell, fig.

124

Earliest stages of tlie formation of the ovarian egg in
the Bird, cccviii.

macula, the ordinary
LCters of the ^ germinal
vesicle.' This is shown, in focus, at C ; the epithelium of the ovisac

122 : here they are agglutinated
together, either in irregular
groups; or, as in the Cantores,
in a regular bundle, with the
spiral bodies at one end and
the tails extending, parallel,
to the other,fig. 123. In both
cases the spermatozoa are set
free by rupture and solution
of the sperm-cell: in the Can-
tores they are then found fas-
ciculate in the ' tubuli testis,'
whilst in other birds they are
irregularly dispersed.

§ 168. Female Organs and
Ovulation of Birds. — The
ovarium of the Bird consists
essentially of the germ-cells,
with the stroma or blastema
modified by their presence,
and the vitelline matter su-
peradded to the germ-cell.
The formative processes are
most clearly traceable in the
smaller sinoino:-birds. In fio;.
124, A, the small clusters of
granules indicate the begin-
ning of the ova in the
ovarian stroma : in larger
clusters a clear point ap-
pears, which in the largest
assumes the character of a
germ-cell surrounded with
opaque minute granules. The
almost contemporaneous for-
mation of the ^ ovisac'
(Barry) soon manifests itself
by its lining of epithelial
cells, ib. B, at which period
the germ-cell manifests, by
its
characters of the ^ germinal

FEMALE OKGANS OE BIRDS. 247

is shown in focus at d : in E, ov is the ovisac mth its epithelial
lining, v the granular yolk surrounding, ^ the germinal vesicle
or developed * germ-cell.' F is part of an ovule of -^-^ of an inch
in diameter, highly magnified: v, minutely granular or primitive
yolk-substance; ^, germinal vesicle ; 2-, ' thick consolidated mem-
branous layer which formed a vesicular covering for the primitive
ovule, and which corresponds to the zona pellucida of the mam-
miferous ovum.' ^

In G and H, Prof. Allen Thomson gives diagrammatic figures
of the earliest stages of formation of the ovarian ovum in a Black-
bird : figs. I and K ' are intended to illustrate, diagrammatically,
the view, that after the disappearance of the zona, and the for-
mation of the larger granular yolk-cells, the outer layer of the
cells of this substance forms the permanent vitelline membrane of
the bird's egg ; vd, * remains of minutely granular yolk, forming
the vitelline disc round the germinal vesicle ; s^, large corpuscles
of the yolk ; vrrif outer layer of the cells of the same, on which
the vitelline membrane is afterwards formed.' ^

The germinal vesicle, with the firmer primitive vitelline granules
(J germ-yolk,' K, vd), moves from the centre to the periphery of
the ovum, which then begins to expand by the addition of the
softer ^ food-yolk,' ib. sff : this seems to be due to cells throAvn off
by, and to fluid exuding from, the inner surface of the ovisac, ov,
the cells greatly and rapidly increasing in number and acquiring
the characteristic yellow or orange colour of the yolk in birds.

At the earlier stages of the developement of the ova the ovarium
appears as a flattened solid, granular body, attached by a fold of
peritoneum, or of air-cell, to the bodies of the middle dorsal
vertebras, fig. 125, a.

At first, the right and left ovaria are similar in size, fig. 127, c:
but the symmetry is soon disturbed by concentration of de-
velopement in the left ovarium (fig. 125, a), the right one, «',
remaining stationary and ultimately, in most birds, disappearing.

The enlaro-ement of the ovarian ovum is now due to the accu-
mulation of the yellow or ^food ' yolk, with concomitant distension
of the membrana vitelli and of the ovarian capsule, or ' calyx,'
fig. 126, a, d, which maintains its connection Avith the rest of the
ovarium by a contracted base or pedicle.

The calyx consists of two membranes, united together by lax
tissue and blood-vessels : these ramify as in fig. 126, c, converging
toward a white transverse line or band across the most prominent

' cccviir. p. 76. ^ lb.

248

ANATOMY OF VERTEBRATES.

part of the calyx, wliere tlie vessels become suddenly so minute,
as to seem to be wanting: fig. 128, c. This part, called the
^stigma,' begins to appear when the ova have attained, in the
Common Fowl, the diameter of an inch: it increases in breadth, and
the membranes there become thinned, as the ovum acquires its

Female organs, Fowl, at non-breediug season,

Relation of the ova to tlie ovary in Birds, ccct:

full size ; when they readily yield and are rent by the compressing
force of the infundibular opening of the oviduct, fig. 128, e, where-
upon the ovum slips out of the calyx into the efferent passage.

The empty calyx collapses, as at h, b, fig. 126, and d, fig. 128,
rapidly shrinks, and is ultimately absorbed.

In birds that have few young at a brood, as the Apteryx,^

' XI. vol. iii. 1'. 310, 1)1.36.

FEMALE ORGANS OF BIRDS.

249

127

Eagle, Dove, &c., the number of enlarged ovarian ova or * yolks'
is correspondingly small ; but in tlie more prolific species, as the
Common Fowl, fig. 126, A, they are more numerous. The number
of young produced may be, by this means, in some degree in-
ferred, if the female of a rare species happen to be killed during
the breeding season.

In the diagrammatic section of a full-sized ovarian ovum, B, fig.
126, o is the outstretched ovarian capsule and stroma forming the
^ calyx,' p its peduncular connection with the rest of the ovarium ;
c is the common position of the germ-cell and discoid germ-yolk ;
ov, the two layers of the ovisac into which the blood-vessels
penetrate ; vm, the vitelline membrane. This membrane is
sufficiently strong and ductile to permit the ovarian ovum being
compressed into an elliptical form to
facilitate its passage through the con-
tracted part of the oviduct. Certain
changes now occur in the ovarian
ovum, and much addition is made to
it; but, before entering upon these,
the canal through which it passes and
in which the egg is completed must be
described.

In the female embryo the basis or
stroma of the ovarium, fig. 127, c, ap-
pears in a similar relation to the pri-
mordial kidneys (ib. b), as the testis
in the male. At the period when the
permanent kidneys, ib. a, have sent
the ureters, ib. e, to the cloaca, the
oviducts, g, have been developed as
prolongations from that part, and, to a
certain point of developement, they are
of equal size and length. Subse-
quently the left oviduct alone proceeds to grow ; the right is
stationary, or shrivels : occasionally it may be discerned as a
rudiment in the mature bird, but usually all trace of it has dis-
appeared. The left oviduct expands above or at its free end into
the infundibular orifice, fig. 125, b, where its parietes are very thin ;
as it descends, these increase in thickness, and the efferent tube
gradually acquires the texture and form of an intestine. Like
this, it is attached to and supported by a duplicature of peritoneum
called the mesometrium, but which also includes muscular fibres,
to be presently described.

Kidneys, 'Wolfflan bodies, ovaries, and
oviducts of a foetal bird, at a period
wlien botli oviducts are still of nearly
equal size. Magnified, lxxiv.

250

ANATOMY OF VEETEBRATES.

128

The o\'iduct in the quiescent state is generally straight, but at
the period of sexual excitement it is augmented in length as well
as capacity, and describes three principal convolutions before
reaching the cloaca, fig. 128, n. The lining membrane presents a
different character in different parts of the oviduct ; at the infundi-
bulum, ib. e, the surface is longitudinally rugous : lower down the
lining membrane begins to be disposed in oblique ridges, ib. g,
beset with follicular glands: at the more contracted part, or

' isthmus,' they become longitudinal
and subside : in the terminal dilata-
tion, ib. k, the lining membrane is
beset with large flattened villi, con-
tainino- the follicles concerned in the
secretion of the shell. The whole
oviduct is lined by vibratile epithe-
lium. The shell-forming part has
been termed the ' uterus,' but the
ovum is never developed in it. The
rest of the canal, /, which, by the same
loose analogy, is termed ' vagina,'
opens into the urogenital segment
of the cloaca, anterior to the orifice
of the left ureter, and its termination,
figs. 86, 109, y*, is provided with a
sphincter.

The mesometry, fig. 128, 7?z, differs
most from the mesentery when the
female organs are in full sexual
action. It presents at that period
a muscular structure, but the fibres
are not striated. It is divided into two parts, one superior, the
other inferior. The inferior mesometry has its point of attach-
ment at the lower part of the uterine portion of the oviduct, and
forms a somewhat dense and cruciform plexus of muscular fibres
radiating from that part. The transverse fasciculi are spread out
on either side and around the uterus. The lower fasciculus sur-
rounds the vagina more laxly, and contributes to the expulsion of
the ovum. The upper fasciculus spreads out like a fan upon the
oviduct from its insertion into the uterine portion to the com-
mencement of the infundibulum.

The superior mesometry commences by a firm elastic ligament,
which is attached to the root of the penultimate rib of the left-
side, whence the muscular fibres are continued to the upper part of

Female organs, Fowl, at breeding season.

XXXIV.

EGGS OF BIRDS.

251

129

the oviduct, upon which they form a delicate muscular tunic,
whose fibres embrace the oviduct for the most part in the trans-
verse or circular direction, except at the infundibular aperture,
where they affect the longitudinal direction, which enables them to
dilate that orifice. Longitudinal muscular fibres begin again to
be distinctly seen in the uterine portion of the oviduct, whence
they are continued along the so-called vagina. An internal stratum
of circular fibres is also situated immediately behind the calcifying
membrane of the * uterus.' In the vas-ina the circular fibres are con-
centrated at its termination to form the sphincter above mentioned.

The 'clitoris' of the Ostrich is continued from the anterior
margin of the preputial cavity of the cloaca, and is grooved like
the penis of the male : it is furnished mth corresponding muscles.
A smaller clitoris exists in those birds of which the males have a
well-developed intromittent organ.

§ 169. Fecundation iri Birds,
and Structure of the laid Egg.
— In coitu spermatozoa enter
the cloaca and penetrate the
o\dduct, ascending to the ova-
rium. The germinal vesicle,
on the reception of the ovum
by the OAiduct, is no longer
visible, as such. A discoid
acroTeo^ate of cells constitutes
an opaque white circular spot
on the part of the periphery
of the yolk to which the germ-
cell and germ-yolk had passed,
and this was known to the

. structure of the cicatricula in a laid Fowl's egg. cccviii

older embryologists as the

' cicatricula.' It consists of a central clearer and of a peripheral
denser portion, fig. 129, B : beneath the clear centre is a group
of minute opaque granules called ' nucleus cicatricula3.' In the
diagrammatic figure A, a is the vitelline membrane ; d the clear
tract leading from the ' nucleus,' c, to the centre of the yolk,
— the trace of the excentric course of the germ-cell : b, b, are the
minute granules forming the denser part of the cicatricula ; e, e,
are the larger yolk corpuscles. The ' nucleus cicatricula^,' c, is
the ' germ-mass,' the result of the same series of spontaneous
divisions of the impregnated germ-cell, as affected the entire yolk
in the Batrachian (vol. i. fig. 452) ; to which the ovum of the Bird
offers the opposite condition in the preponderance of the ' food-

252

ANATOMY OF VERTEBRATES,

yolk' over the ^germ-yolk.' In fig. 129, B is an enlarged view
of the cicatricula as seen from above on the surface of the yolk
in an impregnated egg : the dark central space is the ' transparent
area ' surrounded by the ^ opaque area,' and by one or two de-
licate * halones.' C is the cicatricula of an unfecundated laid
eo-o" : instead of the central transparent area a number of rather
irregular transparent spots are seen.

The yolk forms an ellipsoid mass, somewhat flattened on the
cicatricular surface, and consists of the external coloured part,
fig. 130, B, d, in concentric layers indicative of successive deposit,
and of a central lighter-coloured part, ib. c, about one-fourth of

Fowl's egg and irtructurc of tlie yolk as exhibited by a section, cccviii.

the diameter of the whole. The margins of yolk-layers, inter-
rupted by the ^ cicatricula' and its canal, may form the ' halones.'
The yolk-layers, dj d, usually show some diversity of tint.

The ripe ovarian ovum, having passed into the oviduct, is
propelled by the peristaltic action of that tube in a rotatory course
to the ' uterus.' The contact of the membrana vitelli stimulates
the exudation of the product of the lining membrane in a denser
state than usual, which forms a kind of accessory tunic, and
is continued, thread-like, from near each pole of the ellipsoid,
usually a little toward that half which is opposite the one sup-
porting the cicatricula: these filaments, fig. 130, A, c, are the
* chalazai,' and the layer of dense albumen from which they
are continued is called the '^ membrana chalazifera.' During
the passage of the egg and its acquisition of successive deposits
of the ordinary albuminous secretion, the chalazoe become twisted
in opposite directions, fig. 131, B, and ultimately the one next
the small end of the egg contracts some adhesion to the membrane
linin.o: the shell there. In fig. 131, A shows the ovum from the

EGGS OF BIRDS.

253

131

upper part of the oviduct, with the coating of dense albumen
continued into the chalazoe; B, the outstretched chalaza3 from
opposite sides of the yolk, showing the opposite turns of the
spiral; c, an egg from above the middle of the oviduct, mth the
first layers of soft albumen deposited upon the chalaziferous
membrane and chalaza3.

The albumen is rapidly added in the more glandular and vas-
cular part of the oviduct, by
the ridsfes of follicles which
correspond in direction with
the spiral course of the egg ;
and, when it has arrived at
the narrower part of the
o\dduct called the isthmus,
denser layers of albumen are
again excreted, forming the
' membrana putaminis,' fig.
130, A, d. So inclosed, and
having acquired its ovate
form with the small end to-
ward the cloaca, the egg
passes into the ' uterine ' or
shell-forming dilatation, fig.
128, k.

Artificial coagulation of
the albumen or ' white ' of
an eo;2: enables one to de-
monstrate its disposition in
spirally deposited layers.
It is at the latter stage of
the eofo^'s formation that the
spiral structure of the cha-
lazae becomes apparent. The
time of the passage of the
ecro- from the infundibulum
to the uterus, in the Com-
mon Fowl, is from four to
six hours. Here it may remain from twelve to twenty hours. On
entering the ' uterus,' a thickish white fluid exudes from the inner
surface of the cavity and condenses on the ^ membrana putaminis,'
forming thereon a cellular matrix in which soon appear particles
of calcareous matter, which from the shape they assume in the
interstices of the matrix appear to be crystalline.

stages of egg in oviduct, cccriii.

254

ANATOMY OF VERTEBRATES.

132

(/f^^^^'^Y)^

^r/^ffe-^^^^-

Allen Thomson has given the annexed illustration, fig. 132, of
the structure of the lining membrane of the shell and of the
proper shell-membrane. a shows the ' lining membrane of the
shell ; a, thick matter or felty portion ; b, thin shred of the torn
margin, showing the peculiar fibrous tissue of which the various
layers are composed ; b, outermost layer of the same, which is
incorporated with the shell ; some of the angular corpuscles of

the shell lying upon the fi-
brous substance and firmly
united with it. C, small
portion of the calcareous
shell, which has been steep-
ed in dilute hydrochloric
acid, showing the remains
of opaque calcareous sub-
stance in the centre : here
and there clear oval cells
seen, as at «, «.' ^

The colour of the egg-
shell depends on pigmental
matter secreted by particu-
lar follicles of the villous
membrane of the * uterus ; '
and either incorporated uni-
formly with the outermost
layer of the shell, as in the
Thrush: or deposited in
cells more or less dispersed
or aggregated in patches.
The shell consists in great
part of carbonate of lime,
with a little carbonate of
magnesia and phosphate of
lime and magnesia.

The appearance to the
unaided eye of pores on
the surface of the shell is
due to the impressions of the villi of the formative membrane :
the permeability of the shell by the atmosphere depends on a
more minutely porous texture. The first effect of this per-
meability is penetration of air between the layers of the lining
membrane as the contents of the egg condense by cold and eva-

' CCCVIIT. p. 63.

>

t^rzM

^m

Structure of the shell and shell-membrane in the Fowl's
egg. cccviu.

EGGS OF BIRDS. 255

poration after it is laid. The air accumulates between layers
of the ^ membrana putaminis' at the great end of the egg, fig. 130,
A,/; and in increased quantity as the other contents become
condensed into the tissues of the chick, when it is averred to
contain rather more oxygen than in ordinary atmospheric air.
Such is the complex structure of the egg of a bird prior to its
becoming subject to the influence of incubation.

It diflfers from the egg of the cold-blooded, non-incubating
Ovipara, in the presence of the chalazas and of the air-chamber,
in the firmer and more complex structure of the shell, and in the
greater proportion of albumen : in all which differences may be
discerned a prospective adaptation to the business of hatching.

The cicatricula, or germ, is on the uppermost part of the
floating yolk, the thinner part of which, occupying the nuclear
tract, fig. 130, B, c, makes that half of it the lightest. Pressure
of the upfloated germ against the shell-wall is moderated by the
weight of the denser albumen forming the chalazse, ib. a, c ; and
their usual attachments, a little below the axis of the yolk, help
also to make the cicatricular half the lightest and uppermost.
Under ordinary circumstances rotation of the egg takes place on
its long axis, and, if a fresh egg be so turned round, ^ the cica-
tricula will keep its position upwards for one turn or a little
more, and then, by the twisting of the chalaz^, the yolk is carried
completely round, and balances itself again with the cicatricula
uppermost in its new position.'^ The main function of the
chalazge is to keep the yolk more steady in the albumen, and to
moderate the effects of any \iolent movement or rotation of the
egg. The domed form of the hard shell enables it to bear the
superincumbent weight of the brooding mother. How these
modifications of the oviparous egg in anticipatory relation to the
needs and conditions of incubation can be brought about by
^ selective ' or other operations of an unintelligent nature is not
conceivable by me.

Birds differ in the number of eggs which they lay at one
breeding season, in the relative size, in the shape, colour, sur-
face, and thickness of the shell of the laid eggs. The Frigate
Bird, Albatross, Penguin, Fulmar, Petrel, Awks, and some other
sea-birds that brood on bare rocks, severally lay and hatch but
one egg at a season : the Skua Gulls (Lestris) have two eggs ;
the Common Gulls (^Larus) three eggs ; the Lamellirostres and
most GallincB hatch many eggs at a brood.

The Cuckoo has the smallest egg in proportion to its size, the
' cccvin. p. 65.

256 ANATOMY OF VERTEBRATES.

Apteryx the largest: in this species it weighs 14 J oz. ; the entire
bird 60 oz. ; so that the egg is nearly equal to one-fourth of the
parent. The hugest known egg of a bird is that of the extinct
j^'pyornis of Madagascar. The following are comparative ad-
measurements of this ^^^ and that of an Ostrich : —

Length of majoi- axis

„ „ minor axis

Greater circumference

Smaller circumference

^p

yornis.

Struthio.

In.

Lines.

In.

Lines.

12

3

5

10

9

4

5

0

34

2

17

10

29

2

16

6

The contents of the ^gg of the iEpyornis are computed to equal
those of 6 Ostriches' eggs, and 148 hen's eggs.

The eggs of most Owls, of some Penguins ( Spheniscus), of the
King-fishers {Alcedo, Halcyoii), of the Plantain-eaters (Muso-
phaya), and Bee-eaters {Merops), are those that have, or nearly
approach to, the spherical shape : those that furthest depart from it,
or have the longest shape, are the eggs of the IMegapode and Al-
batross. The oval, or ovate, is the common form in birds (fig. 130,
and vol. i. p. 599, fig. 420, c) : the eggs with the narrowest small
end, ib. D, are those of the Plovers, Snipes, Sand-pipers and allied
Waders, which usually lay four eggs, packed in the smallest
compass by the meeting of the small end of each in the centre.
The egg of the Chinese Jacana {Parra sinensis) is like a top in
shape. The eggs of Grebes, Cormorants, Pelicans, are elliptic.
The shell of the Emeu's and Ostrich's egg has a rough exterior :
that of the Gangas {Pterocles) has a glossy smoothness. The
shell of the egg of the Ostrich, Emeu, and Cassowary is rela-
tively thicker than that of the Apteryx, Mound-bird, and Dinornis.

§ 170. Accessory Generative Structures and External Sexual
Characters. — The exception to the rule of incubation is given by
the Megapodial birds of the Australasian Islands. A huge mound
of decaying vegetable matter is raised: the eggs are deposited
vertically in a circle at a certain depth, near the summit, and
the chick is developed with the aid of the heat of fermentation.
The large size of the egg relates to affording a supply of material
sufficing for an unusually advanced state of developement of the
chick at exclusion ; whereby it has strength to force its way to the
surface of the hatching-mound, with wings and feathers sufficiently
developed to enable it to take a short flight to the nearest branch
of an overshadowing tree.^

A steady continuous temperature of about 100° Fahr. is the

' Lvi'. and LViir.

EGGS OF BIRDS.

257

requisite condition of successful incubation : the heat of the sun
alternatino' with the cokl of nio-ht would hatch no bird's es^sc- The
Ostrich deposits about fifteen eggs in a hollow of the sand : the
male bird incubates, and the young are excluded in from fifty to
sixty days. The following are the periods of incubation in some
birds of the different orders of the class ; the female sitting where
not otherwise stated : —

Species
American Ostrich
Mooruk .
Emeu
Puffin
Guillemot

Hooded Merganser .
Sheldrake
Muddy Wildrake
Summer Duck
Mandarin Duck
Sandwich Island Goose
Cereopsis Goose
Black Swan
White Stork .
Heron
Dotterel .
Capercailzie
Californian Quail
Purple Kaleege
Impeyan Pheasant .
Crown Pigeon .
Ringdove
Cuckoo .

Belted Kin_
Martin
Skylark .
Chatfinch
Wren .
Bullfinch .
Starling .
Kaven
Golden Eagle

fish(

No. of days
(Ehca americana') male . . . . .35
(Casuarius Bennettii) male . . . .48
{Dromaius Novce HollayuUce) male . . 54

(Fratercula arctica) 30

{Uria troile) 30

{Mergus cucuUaius) . . . . .31

{Tadonia vulpanser) . . . . .30

(Casarca ruiila~) 30

(^Aix sponsa) ....... 30

{Aix galericulafn) ...... 30

{Bernicla sandvicensis') . . . . .31

(Cereopsis Novce HoUandice) . . .35

{Ci/gniis atratus) ...... 35

(Ciconia alba) , . . . . .31

{Ardca cinerea) 28

(Charadrius morinellus) ..... 20

(Telrao urogalhis) . . . . . .28

(Calllpepla califomica') . . . . .21

{Gallophasis Horsjieldii) . . . .24

(Lophop/iorus Impeyaynis) . . . .28

(Goura corotiata) . . . . . .28

(Cohimha paluml)a) . . . . .16

{Cucuhis canorus) by Hcdgc-Sparrow or otiicr

Passerines 14

(Alcedu alcyon) .16

(Hirundo urbica) . . . .• . .13

(Alanda arvensis) . . . . , .15

(Fringilla ca^Iebs) . , . . . .13

(Troglodytes vulgaris) . . . . .10

(Pyrrhula vulgaris) . . . . .15

(Sturnus vulgaris) . . . . .16

{Corvus corax) 20

(Aquila chrysaetos) . . . . .30

Most birds nidify, i.e. prepare a receptacle foi* the eggs, to
aggregate them in a space that may be covered by the incuba-
ting body (sand-hole of Ostrich), or superadd materials to keep in
the warmth. The most complex ' nests ' are made by birds of
the singing order : and of these the pendent nests of the AYcaver-
Birds {PloceidcB) are, perhaps, the most perfect and remarkable
examples of nidification. Not only does the female construct licr
nest for incubation ; but the male makes his, in the form of a bec-

VOL. II. s

258 ANATOISIY OF VERTEBRATES.

hive, open at the bottom, which is crossed by a perch of strong
woven material, upon which he sits, sheltered from the tropical
sun or storm by the dome above, which is suspended to a branch
near that to which is attached the nest of the female, whom he
solaces durinej her confinement with his sono;.

Certain conirostral Cantores still practise in the undisturbed
wilds of Australia the formation of marriage-bowers distinct from
the later-formed nesting-place.^ The Satin Bower-Bird {Ptilono-
rhynchus holosericeus), and the Pink-necked Bowser-Bird (CA/«-
mydera maculata), are remarkable for their construction on the
ground of avenues, over-arched by long twigs or grass-stems, the
entry and exit of which are adorned by pearly shells, bright-
coloured feathers, bleached bones, and other decorative materials,
which are brought in profusion by the male, and variously ar-
ranged to attract, as it would seem, the female by the show of a
handsome establishment. For receiving and incubating her eggs
the female builds a nest, like that of the Magpie, in the conceal-
ment of a tree.^

Most birds, on reaching maturity, show external sexual cha-
racters. In Diurnal Raptores the female is larger than the male ;
in Gallinacece and most other polygamous birds, she is less. In
this suborder the male is most conspicuous by the richness and
beauty of his colours ; and a difference in this respect is the most
common sexual character in birds, with the frequent addition of a
peculiar size and shape of certain feathers, especially at the
breeding season, wdien, e.g., the male of Machetes pugnax becomes
the ' Kuff,' the female the ' Reeve.' There is a sexual difference
in the length of the beak in the Hook-billed Parrots (Nestor),
in the Apteryx, and in the singular genus of Humming-Bird
{Androdon, Gould), in w^hich the end of the longer bill of the
male is dentated. The comb and w^attles of the Cock exemj^jlify
sexual characters of certain cutaneous appendages : his spur
and that of other Gallince and PhasianidcB, including Meleagris,
is a w^eapon of combat, analogous to the horns of Mammalian
Herbivores.

Swifts, Swallows, Doves, Crows, King-fishers, Parrots, and
the majority of the Waders are examples of birds in which the
sexes are alike.

' Lvii. and i.viii.

2 It is possible that the old propensity of the Magpie, Jackdaw, and some others of
our Conirostrals, to which the Australian Bower-Birds are allied, to pilfer glittering
objects, may be the remnant of a similar instinct which the increase of human popula-
tion has scared out of them : the conditions of cultivation reducing the birds to the
constructions which are essential to the continuance of the species.

259

CHAPTER XXIY.

DEVELOPEMENT OF BIRDS.

§ 171. The heat-force being converted into movements of the
parts of the germ thereto subjected, the expansion of tlie pellucid
area, fig. 133, a, is the first sign of such change : in tliis area ap-
pears the embryonal trace, in
the form of the parallel lines
called 'plica3 primitlva?,' which
diverge to form the cepha-
lic dilatations. Concurrently
with the appearance of the
myelencephalous columns, ib.
^;,p, the blood-lakes expand in
the surrounding halones, and
\ tracts, ib. /i, A, along which
pass colourless blood-parti-
cles, extend from below the
cephalic expansion, Z*, to the
peripheral sinuses : as the pro-
to-vertebrai, ib. v, v, begin to
appear at the sides of the my-
elon, the red colour is ac-
quired by the blood, and the heart is made more manifest, by its
movements, as the * punctum saliens,' ib. c. A distinct membrane,
' serous layer,' ib. s, s, is formed upon the germ and Ijlastoderm : ^
the cephalic end of the embryo rises from the surface of the
blastoderm, and then cur^'ing doAvn, sinks into it, forming ibr
itself a kind of hood of the serous layer : it is reflected at b, to
show the fossa, /". This hood gradually extends from the margin
of the fossa over the body, and, meeting a similar fold formed
by the i)rojecting and incurved tail, closes over the germ on the
upper side, 'making a circumscribed cavity which is the amnios,''^
fig. 134, a. The progress of differentiation of layers of the blasto-
derm has gone on beneath: in fig. 183, the ' serous layer' b is

I Chu-k tliirty-fifth

XX. vol. Y. p. XX. Ib. 1)1. Ixix. fig. 7.
s 2

2 Ib. p. XX.

260

ANATOMY OF VERTEBRATES.

partially reflected from the ^ vascular ' and ' mucous layers.' ^ The
mucous layer is concerned in the formation of the intestinal
canal ; and beyond this part, which is at first an open groove, the
mucous layer expands over the yolk, which it ultimately incloses,
the margins of the ^ vitellicle ' so formed, fig. 134, c, contracting
and uniting at the side opposite to the embryo at a sort of ^ ci-
catrix, to which the last part of the slime adheres.' ^ The vitellicle
is richly vascular, and the surface next the yolk is augmented by
ruga3, the yolk in contact with which becomes more liquid, and
loses its coagulability.

At about the fortieth hour in the Common Fowl the limbs begin
to bud forth, and a vesicle to protrude from near the anal end of

the intestine which, rapidly
expanding, fig. 1 34, 6, spreads
over the embryo, acquiring
a close adhesion to the am-
nios, ib. a, but remaining
distinct from the -vdtellicle,
ib. e, c, over which it spreads,
finally inclosing the albu-
men, and interposing itself
between the latter and the
lining membrane of the shell.
Bloodvessels called ' umbili-
cal,'fig. 134, i, are coextend-
' called " allantois," from its con-
But that it '^ answers other important purposes,
must appear e\ddent from its extent being far beyond what would
answer that purpose. I conceive that the side of the bag which
surrounds and is in contact with the albumen, acts as the chorion
or placenta, for it must be by this surface that the albumen is
absorbed and the chick supported. The external part of the bag,
which comes in contact T\dth the shell, I conceive to act as lungs,
for it is the only part that comes in contact with the air : and on
opening an egg with the chick pretty far advanced I find that the
blood in the veins is scarlet, while it is of the Modena colour in
the arteries of the bag.'"* SchAvann's experiments show that the
developement of the chick may go on without oxygen to the
fifteenth hour, and that the life of the germ is not destroyed till be-
tween the twenty-fourth and thirtieth hour, but that the presence
of oxygen is essential to further developement.'^ As the embryo

Membranes of the Chick third day. LV.

ed with this bag, which Hunter

>3

tammg virme.

' The mucous layer,/, is shown reflected from the vascular area, g.

2 XX. vol. V. p. xxi. ^ XX. p. xxiv. * Ib. ^ lxix*.

DEVELOPEMENT OF BIRDS. 261

grows it turns upon its left side, exhibiting a profile view ; it then
indents the yolk, and finally almost divides it into two portions.

The formation of the digestive tube and glands closely follows
the course described in Vol. I. pp. 604, 605, 606.

The embryo of the bird is that which best admits the observa-
tion of the commencement of the developement of the organ of
hearing by a superficial depression of the cephalic blastema, fig.
135, f, to meet the process from the epencephalon, ib. e, which
forms the acoustic nerve. The lining of the depression becomes,
on the closure of the slit, the proper tunic of the labyrinth.^

The vesicle of the labyrinth, f, swells into four dilatations, of
which three are * ampullar,' and the fourth ^ cochlear : ' the am-
pullar dilatations extend into very slender
canals, at first almost in the same plane, by
which they are brought into mutual com-
munication : as the canals expand and elon-
gate, they assume their characteristic relative
positions as external, superior, posterior : the
hinder end of the external canal being ex-
tended beneath the posterior canaL The
cochlear dilatation curves as it elongates : an
inner layer becomes distinct from the common Fore part of embryo chick

, , p ^-1 i- 1 • second day.

membrane, and lorms the acoustic lamma.

As in the developement of the eye, the production of the nerve-
process from the cerebral centre is the first step, the infolding of
the superficial blastema to meet the nerve is the next : the so-
called ^ cutaneous follicle' becomes a circumscribed sac or vesicle,
in which the changes and developements next proceed, converting
the vesicle into ^ acoustic labyrinth' or * eyeball.' In each case
neural elements of two vertebrae become modified to lodge and
protect the sense-organs, forming respectively the recesses called
*otocrane' and ''orbit,' the one between the occipital and parietal
vertebrae, the other between the frontal and nasal vertebra?. The
part of the outer blastemal layer of the head which sinks to meet
the process from the mesencephalic dilatation, rapidly changes its
follicular into a vesicular state : the vesicle elongates, bending
round the cell-mass in which the crystalline lens is formed (as in
the Fish, Voh I. fig. 423), and by the meeting of the two ends, the
' choroid fissure,' at the lower part of the eyeball, figs. 134, 135,
results. The mesencephalic process, or * optic nerve,' expands at

* In XX. pi. Ixx. fig. 3, embryo of the Goose at the thirtieth hour of incubation, the
open state of the acoustic sac is erroneously described as ' meatus: ' 1)ut the sac be-
comes closed, and the tympanum and its passage are later developements.

262

ANATOMY OF VERTEBRATES.

136

the back part of the circuhir sac, and, in the course of its muta-
tion into eyeball, lines its posterior part with the layer called
retina, interrupted only by the cicatrix of the inferior and rapidly
blended ends of the primitive eye-sac. The transparent layer
covering the fore-part of that sac and the inclosed lens is meta-
morphosed into cornea. Other layers of the sac are differentiated
into choroid, ciliary processes, iris ; and a fold of the vascular
layer protrudes through the choroid fissure as a persistent struc-
ture in birds, in which the ^ pecten ' significantly marks a curious
step in the developement of the eye in all Vertebrates. Of the
appendages of the eye the membrana nictitans, fig. 137, «, is
the first to appear, the lower lid and then the upper lid follow.
It is a mistake to speak of the labyrinth or eyeball as being-
formed by the integument, or beginning as ^ cutaneous follicles,'

for the structures of the skin are not
differentiated when they first appear ;
a layer of cellular or primitive blastemal
tissue represents the integument, and a
greater number of cells is aggregated at
the points which tend inward to meet
the productions from the nervous centres.
After the essential oro-ans of sense are
established, then is the skin developed
and modified more or less for their pro-
tection, forming the outer ear and the
eyelids : but both passages are closed by
transparent membranes, as ' ear-drum '
and ^ cornea.' Only in the case of the
olfactory organ does the primitive de-
pression, fig. 135, r, retain its outlet,
and in the bird and other air-breathers,
it also communicates with the air-pas-
sage : ha\dng the tegument superadded
and modified, in most, as external nostril
and nose.

As in the Lizard and Snake (Vol. I.
fig. 444), so in the Bird, the four verte-
bral segments constituting the head arc
shown by the embryological characters
and course of formation of the ^ maxil-
lary' arch, figs. 135, 136, a, the '^man-
dibular arch,' ib. Z», the ' hyoidean arch,'
ib. c, and the scapular arch, ib. d. The transitory branchial arte-

Primitive blood-vesrels of embryo
Bird second day. lv.

DEVELOPEMENT OF BIRDS. 2G3

ries, fig. 136, from tlie aortic bulb traverse the tissue between the
hyoidean and scapular arches.

The channels which return the blood from the vitellicle are
the ^ transverse ' and ^ longitudinal vitelline ' veins : the first are
so called because these trunks pass to the embryo at right angles
to its axis ; they are the largest returning channels : the longitu-
dinal veins run parallel with the axis of the embryo and are of
smaller size. The right anterior longitudinal vein, fig. 136, j^,
becomes the right precaval and receives the remains of the
right transverse vitelline vein, ib. s, as the right vena azygos.
The left anterior longitudinal ^-itelline vein, ib. p, is also per-
sistent as the left precaval, and enters in the mature bird, as in the
•embryo, the posterior or lower (sacral) part of the auricle. The
left transverse vitelline vein, ib. r, is also subsequently reduced,
by receiving only the vertebral veins of that side, t, to the con-
dition of a so-called ^ azygos vein.' The main trunk of the post-
caval is the result of the returning channels from the abdominal
viscera and the hind-limbs, at a later stage of developement.
There is but one principal posterior longitudinal vitelline vein,
ib. q, Avhich anastomoses with the left transverse vein as it enters
the embryo : the homotype of the right side appears as one of
the ordinary small tributaries of the right transverse vein.

The auricle which by the dilatation of the left side, ib. u,
appears to be double, receives the venous blood at its right
di\dsion. The left one, subsequently receiving the veins from the
lungs, is ultimately separated from the left precaval and right
auricle to which that vein is conducted and restricted.

The ventricular part of the heart, ib. v, at the second day of
incubation, is in the form of a bent tube, curving from behind
downw^ard, forward, to the right and upward, continued insensibly
into the part representing the ^ aortic bulb,' ib. f, in which the
septum first appears, ultimately dividing the ventricle into two.

At this stage the piers of the maxillary arch, ib. a, appear as
buds from beneath the eyeballs ; the naso-premaxillary process,
ib. /, is above their interspace ; the piers of the mandibular arch,
ib. h, b, and those of the hyoidean arch, ib. c, c, folloAv in close suc-
cession. The blastemal base of the scapular arch, ib. d, d, slightly
projects at the sides of the ' fovea cardiaca : ' the piers, now separate,
ultimately meet in front of the heart, and accompany it in its
retrograde course. The mesencephalon, ib. in, is the largest
segment of the brain, in connection with the eyeballs, «, o.

When the heart has assumed its form, as such, distinct from
the great trunks rising from it, the arteries from the base of the

2G4 ANATOMY OF VERTEBRATES.

Yentricle appear, during the foetal circulation of the chick, to be
two : that to the right bifurcates, one division supplying the head
and wings, the other winds over the right bronchus : that to the
left also bifurcates : its left division arches over the left bronchus
and anastomoses vnth. the right arch a little below and behind the
apex of the heart : its right division arches over the back of the
heart, bending rather to the right, and anastomoses with the right
aortic arch, just above the other ' ductus arteriosus.' Each of
these divisions of the left primary arterial trunk sends off a branch
to its corresponding lung, and as the lung expands, and especially
begins to act as such, toward the close of incubation, the blood is
diverted into the pulmonary vessels, and the channels below them
shrink and disappear. The left primary artery is retained as the
trunk of the pulmonaries, and, through the changes in the interior
of the ventricle, this arises exclusively from the ventricle answer-
ing to the ' right ' in Mammals, whilst the retained aorta rises from
the ' left ' ventricle. It arches, however, over the right bronchus.
There is no left aorta in birds distinct (as in fig. 335, A, Vol. I.
p. 509) from the trunk (ib.^:*) which gives oiFthe artery to the left
lung : only one arterial trunk arises from the right ventricle
instead of two.

The air-cells begin at the lower point of the lungs, like a small
hydatid, and extend further and further into the abdomen, before
the kidneys : they are at first full of a fluid; as they extend, they
are, as it were, squeezed among the intestines and at last fill with
them the whole abdomen. Soon after other air-cells are forming.
The lungs are, at first, free, as in Reptiles, but afterwards begin
to be attached to the ribs and spine. In the female embryo we

first ' observe two oviducts, one on each

^^^"^ side' (as in fig. 127, ^); but '^before

hatching the right seems to decay.' ^

' There are two kinds of down on the

chick, one long, which comes first, about

two or three days before hatching; a

second, or fine, down forms at the roots

of the other.' ^ The little horny knob

at the end of the beak, fig. 137, b, with

which it breaks the shell when arrived

Head of Gosling. Lv. ^t fuU tiuic, is also gradually forming

into a more regular and determinate

p;oiiit, the progress of which is seen from the first figure to the

* AX. vol. V. p. XXV i.

DEVELOPEMENT OF BIRDS. 265

sixth.' ^ As the contents of the egg become condensed by em-
bryonal developement, the air-cavity, fig. 130,/, expands. ^ The
chick some time before birth has a kind of mixed action of life,
for it breathes, and we can hear it pip and chirp in the egg ; and
Ave find the adult circulation throuo-h and out of the heart is
formed before birth : yet it is receiving its nourishment from the
remaining slime.' ^

The ' slime ' or albumen is reduced to the small mass adhering
to the cicatrix of the vitellicle, and with this and its yolk little
decreased in bulk, it is taken into the abdomen, Avhere it serves to
nourish the chick in the first feeble days of its free life : the pedicle
of the vitellicle communicates with a loop of the small intestine.
The allantois is left, lining the shell : the urachus is obliterated.
The anus has a dorsal position near the hind end of the trunk in
the nestlings, fig. 113, A.

The degree of developement under wliich the young bird quits
the egg differs in different groups of the class. It is naked ^r
covered with down only, and is dependent on the parents for
shelter and support, in the orders Raptoees, Scansores, Yoli-
TORES, Cantores, in the Rasorial suborder Gemitores (Doves,
p. 9) ; in the Grallatorial Cidtrirostres (Herons, &c. p. 9) ; in the
Natatorial LongijiennatcB (Gulls, &c. p. 9), and TotijialmatcR
(Pelicans, &c. p. 9). The young bird is excluded well clothed
and able to run or swim about and provide food for itself in the
suborder Gallinace^, in the Cursores, in the Natatorial
BrevipennatcB (Penguins, Awks, &c.) and Lamellirostres (Duck,
Goose, &c.), and in all the Grallatores save the Cultrirostral
group or part of it. Of these ' precocious ' birds {Prcecocesymo&t
are polygamous, and the females hatch many young ; whereas in
the * nursing ' groups {Altrices) the species are monogamous, and
have few young. ^

' Three of the figures here referred to by Hunter arc engraved in xx. vol. v. pi.
Ixxvi. figs. 16, 17, 18. 2 iij, p, xxvii. ^ vir. p. 265.

26G

ANATOMY OF VERTEBRATES.

CHAPTER XXV.

CHARACTERS AND TRIMARY GROUPS OF THE CLASS
MAMMALIA.

§ 172
guished

138

. Class Characters. — Mammals are outwardly distin-
by a covering of hair, entire or partial, and (with two ex-
ceptions) by teats, fig. 138, «, h, whence the
name of the class. ^ All possess mammary
glands and suckle the young : the embryo or
foetus is developed in the womb. The male
has a penis, and impregnation is preceded
by intromission. The lungs, fig. 139, Ig,
minutely cellular throughout, are sus-
pended freely in a thoracic cavity separated
by a musculo-tendinous partition or ' dia-
phragm,' ib. d, from the abdomen.

Mammals, like Birds, have a heart, ib.
h, composed of two ventricles and two auricles, and have warm
blood : they breathe quickly ; but inspiration is performed chiefly

New-born foetus and teats, Kan-
garoo {Macropus major).

139

ZV.^

Ideal section of a Mammalian animal.

by the agency of the diaphragm ; and the inspired air acts only
on the capillaries of the pulmonary circulation.

' Mamma, a teat. The Monotrcmes have mammary glands without teats. The
fcctal Cctacea show tufts of hair on the muzzle.

CHARACTERS OF MAMMALIA.

267

140

The blood-discs are smaller than in Reptiles, and, save in the
Camel-tribe, are circular. The right auriculo-ventricular valve
is membranous, at least never entirely fleshy ; and the aorta bends
over the left bronchial tube. The abdominal aorta terminates by
dividing beyond the kidneys into the iliac arteries, from which
spring both the femoral and ischiadic branches : if continued
beyond, it is as a caudal or sacro-median artery.

The kidneys, ib. k, are relatively smaller and present a more
compact figure than in the other Vertebrate classes ; their paren-
chyme is divided into a cortical and medullary portion, and the
secreting tubuli terminate in a dilatation of the excretory duct,
called the pelvis. They derive their secretion exclusively from
the arterial system. Their veins, commencing by minute capil-
laries in the renal parenchyme, terminate generally by a single
trunk on each side in the
abdominal vena cava : they
never anastomose with the
intestinal veins.

The liver, ib. /, is gene-
rally divided into a greater
number of lobes than in
Birds. The portal system
is formed by veins derived
exclusively from the spleen
and chylopoietic viscera.
The cystic duct, wdien it
exists, always joins the he-
patic, and does not enter
the duodenum separately.
The pancreatic duct is com-
monly single.

The mouth is closed by
soft flexible muscular lips :
the upper jaw is composed

of palatine, fig. 140, 20, maxillary, 21, and premaxillary, 22, bones,
and is fixed ; the lower jaw consists of two rami, formed each by
one bony piece, ib. 30-32, and articulated by a convex or flat con-
dyle, ib. 29, to the squamosal, ib. 27, not to the tympanic, ib. 28.

The jaws of Mammals, with few exceptions, are provided with
teeth. These are limited to the premaxillary, maxillary, and
mandibular bones, and are there arranged in a single row ; they
are lodged in sockets, not anchyloscd with the substance of the
jaw. Only in the present class are teeth implanted by two or more

Skull of Mammal, Deer.

268

ANATOMY OF VEIlTEBliATES.

fangs : when tliey are of limited growth, and usually molars : ever-
groAving teeth require the base to be kept open for the persistent
pulp. Some Mammals are ' monophyodont/ ^ or have but one set
of teeth: the majority are ^ diphyodont/ ^ or have two sets: none
have more. The tongue is large, fleshy, mth the apex more or
less free. The posterior nares are protected by a soft palate, and
the larynx by an epiglottis, fig. 139, ep : the rings of the trachea
are generally cartilaginous and incomplete behind : there is no
inferior larynx. The oesophagus, ib. cc, is continued without

partial dilatations to the
^"^^ stomach, ib. g, which va-

ries in its structure accord-
ing to the nature of the
food, or the quantity of
nutriment to be extracted
therefrom.

The vertebral bodies,
fig. 141, c, are ossified
from three centres, and
present for a longer or
shorter period of life a
discoid epiphysis at each
extremity. They are ar-
ticulated by concentric li-
gaments with interposed
glairy fluid, fig. 199, form-
ing what are called the
intervertebral substances ; the articulating surfaces are generally
flattened, but, in the neck of certain Ungulates, they are con-
cave behind and convex in front. The cervical vertebrae, in all
Mammals save two, are seven in number, neither more nor less.
The atlas is articulated by concave zygapophyses to two convex
condyles, which are developed from the neurapophyses (exocci-
pitals) of the last cranial vertebra.

The scapula is generally an expanded plate of bone ; the cora-
coid, with two (monotrematous) exceptions, appears as a small
process of the scapula. The sternum is usually narrow, and con-
sists of a simple longitudinal series of bones : the sternal ribs are
generally cartilaginous. The centrums of two cranial vertebras
(basisphenoid and prcsphenoid) preserve their distinctness to a
late period of growth, in the species where they ultimately
coalesce.

' jji.6vos, once;

Mammalian vertebra, lumbar of Wlaale.

(pvu, I generate; oZovs, tooth.

- Sfs, twice; <pvu>, and ohovs.

CHARACTERS OF MAMMALIA.

269

The brain has a cerebellum mth large lateral lobes, fig. 142, d,
and the grey superficies much folded; the commissural fibres
form, as they cross the under surface of the epencephalon, a defined
tract or prominence called ^ pons Varolii,' fig. 143, p. The optic

142 143

Upper surface of brain, Dasyure. lxxv

Under surface of brain, Porcupine.

lobes, fig. 142, e, are medial in position and divided by a transverse
furrow. The cerebral lobes, ib. h, are not only united by a round

145

Lycnccphalous brain, Woniljat {riiascolomys fusca). Lxx-

Corpu.a callosum, brain of Beaver, lxx*.

commissure, but by a * lyra ' and hippocampal commissure, fig.
144, m ; from which is developed, in the majority of the class.

270

ANATOMY OF VERTEBRATES.

as in fig. 142, tlie cerebellum, d, olfactory lobes

146

a ' corpus callosum ' or great commissure, fig. 145, /. The rliinen-
ceplialon, fig. 142, a, is in contact with the prosencephalon,
Z», and sends off numerous olfactory nerves which perforate a
^ cribriform ' plate of the prefrontal.

§ 173. Mammalian Subclasses. — The primary subdivisions of
the present class are characterised by conditiolis of the brain.'

When the hemisj^heres are connected by the ^ round commis-
sure ' and ' hippocampal commissure' only, fig. 144, m, this cerebral
condition is associated with the absence of a vascular chorion or
placenta, and wdth prematurely born young, compared Avith the
rest of the class (fig. 138 show^s the natural size of the new-born
Kangaroo of the largest species).

The cerebral hemispheres are usually without folds, and leave,

a, and part of
the optic lobes, c, exposed. The sub-
class so characterised is called Lyen-
CEPHALA.2 Mammals of this low^ type
existed as far back, in time, as the
oolitic and triassic periods, and are
the oldest known.^

The next stage of complexity in the
Mammalian brain is w here the * corpus
callosum,' fig. 145, Z, is present; but
connects hemispheres as little ad-
vanced in relative bulk or outward
character as in the preceding sub-
class ; the

146, e, or with folds
members of the group, not more nu-
merous or complex than in the larger
Lyencephala. The hemispheres, ib.
e, leave the cerebellum, e, d, and part
of the olfactory lobes, /, exposed.
The subclass so characterised is called Lissencephala.'^ In the
species with this condition of brain the testes remain in the
abdomen, or are protruded into a temporary scrotum only at the
breeding period, to be again retracted : in most there is a common
external urogenital aperture : there are two precaval veins. The
squamosal in most, and the tympanic in many, retain their primi-
tive condition as distinct bones. The orbits have not an entire

surface being smooth, fig.
in the largest

Tppcr surf;ice of brain, Agouti.

T.XVIII-. and lxiv.
xvjr. p. 338.

- Xvoo, I loose ; iyKefaAos, brain. Lxx*
■• AicraSs, siDOOtli ; eyiii(pa\os, brain.

SUBCLASSES OF MAMMALIA.

271

rim of bone. Besides these general cliaracters of affinity to Birds
and Reptiles, there are other striking indications of the same low
position in particnlar orders or genera of the subclass. Such,
e.g., are the cloaca, convoluted trachea, supernumerary cervical
vertebrae and their floating ribs, in the Three-toed Sloth ; the irrita-
bility of the muscular fibre, and persistence of contractile power
in the Sloths and some other Bruta ; the long, slender, beak-hke
edentulous jaws and gizzard of the Anteaters ; the imbricated
scales of the equally edentulous Pangolins, Avhich have both
gizzard and gastric glands like the proventricular ones in Birds ;
the dermal bony armour of the Armadillos like that of loricated
Saurians ; the quills of the Porcupine and Hedgehog ; the pro-
ventriculus of the Dormouse and Beaver; the prevalence of
disproportionate developement of the hind-limbs in the Rodentia ;
coupled, in the Jerboa, with confluence of the three chief meta-
tarsals into one bone, as in Birds ; the keeled sterniun and wings

147

Upper surface

Brain of Lemur (Stenops tardigradns). LXix-

of the Bats ; the aptitude of the Cheiroptera, Insectivora, and
certain Rodentia to fall, like Reptiles, into a state of torpidity,
associated Avith a corresponding faculty of the heart to circulate
carbonised or black blood: — these, and the like indications of
co-affinity with the Lyencephala to the Oviparous air-breathing
Yertebrata, concur with the cerebral character in demonstrating
the low position of the Lissencepliala in the Mammalian class.

The third leadino^ modification of the Mammalian brain is such
an increase in the relative size of the cerebrum, fig. 147, Z>, that
it extends over half or more of the cerebellum, and of the
olfactory lobes. The surface of the hemispheres may be smooth,
or with few and simple folds, in the smallest species ; but, as
a rule, it is disposed in many gyri or convolutions, fig. 148,

anato:my of vektebrates.

whence the name Gyrencephala,' proposed for this third sub-
class of Mammalia.

In this subclass, there are no such marks of affinity to the
Oviparous Vertebrates as have been instanced in the preceding.
The testes are concealed, in adaptation to aquatic life, in Cetacea ;
but, in the rest of the subclass, with the exception of the Ele-
phant, they pass out of the abdomen, and the Gyrencephalous

quadrupeds, as a general rule,
1-^8 have a scrotum. The vulva

is externally distinct from the
anus. With the exception,
again, of the Elephant, the
blood from the head and ante-
rior limbs is returned to the
right auricle by a single pre-
caval trunk. The Mamma-
lian modification of the Ver-
tebrate type attains its high-
est physical perfections in
the Gyrencephala, as mani-
fested by the bulk of some,
by the destructive mastery of
others, by the address and
agility of a third order. And,
through the superior psycho-
logical faculties — an adaptive
intelligence predominating over blind instinct — which are asso-
ciated with the higher deve-
lopement of the brain, the
Gyrencephala supply those
species which have ever
formed the most cherished
companions and ser\itors,
and the most valuable sour-
ces of wealth and power, to
Mankind.

In Man the brain presents

an ascensive step in deve-

lopement, higher and more

strongly marked than that ])y

whicli the preceding subclass was distinguished from the one below

it. Although in the highest Gyrencephala the cerebrum, figs. 148,

' yvpdw, I wind about; iyn^cpuXos, braiii. lxiv.

Upper surface of the brain of the Orang-cetaii.
(After Sandifort.)

149

Vertical section of the brain of tlie Orang-oetan.
(After W. Vrulik.) Half uat. size.

MAMMALIAN SUBCLASSES. 273

149, Z>, may extend over the cerebellum^ d, in Man not only do the
cerebral hemispheres, fig. 14 9, b, overlap the olfactory lobes and cere-
bellum, d, but they extend in advance of the one, and further back
than the other. Their posterior developement is so marked, that
anatomists have assigned to that part the character of a third
lobe ; it is peculiar, with its proportionally developed posterior
ventricular horn and ^ hippocampus minor,' to the genus Homo}
Concomitantly with the correspondingly developed anterior lobes
of the cerebrum, the ventricle is, in like manner, produced into a

' Kuhl in Ateles Belzebuth,^ Tiedemann in the Macacque'' and Orang,<= Vrolik in
the Chimpanzee,*^ and myself in the Gorilla,® have severally shown all the homologous
parts of the human cerebral organ to exist, under modified forms and low grades of
developement, in Quadrumana.

Kuhl rightly characterises the homologue of the posterior cornu, which he found
in a platyn-hine monkey, ' Anfang des hintern, dritten Horns dcs Seitenventri-
cels ' {op. cit. p. 70) — ' the beginning of the posterior or third horn of the lateral
ventricle.' Tiedemann, with equal accuracy, defines the answerable part in thecatar-
rhine quadrumana, as, ' Scrobiculus parvus loco cornu posterioris ' (pp. cit. p. 14). In
regard to the posterior cornu in the brain of the Orang he is silent as to any ' hippo-
campus minor.' It exists, however, in the condition described by Vrolik, in that Ape
and in the Chimpanzee, as ' une eminence que nous croyons avoir le droit de nommer
indice de pes hippocampi minor' ( Versl. en Mededeel. der Kon. Akad. 1862, p. xiii.)
These ' beginnings ' and ' indications' of structures which reach their full developement
in Man in no way afi^ect the value of the latter as zoological characters. In propound-
ing them as such to the Linna^an Society in 1857, I forbore to encumber my memoir
with reference to facts known to all who possessed the elements of Comparative Ana-
tomy. Tiedemann's definition was the accepted one : — ' Pedes hippocampi minores
vel ungues, vel calcaria avis, quce a postcriore corporis callosi tanquam processus duo
medullares proficiscuntur, inque fundo cornu posterioris plicas graciles et retroflexas
formant, in cerebro Simiarum desunt ; nee in ccrebro aliorum a me examinatorura
mammalium occurrunt ; Homini ergo proprii sunt.' (lb. p. 51.) In like manner
Cuvier had characterised the species of his order Quadrumana as having, ' Pouce
libre et opposable au lieu du grand orteil.' And he rightly affirms : ' L'homme est
le seul animal vraiment bimane et bipcde.' (Begne Animal, i. p. 70.) To adduce
beginnings of structures in one group which reach their full developement in another,
as invalidating their zoological application in such higher group, is puerile ; to repro-
duce the facts of such incipient and indicatory structures as new discoveries is ridicu-
lous ; to represent the statement of the zoological character of a higher group as a
denial of the existence of homologous parts in a lower one is disgraceful. Mr. Flower
was not the first to see in the hippocampal commissui-e the beginning of the corpus
callosum : the homologues of 'cornu posterius ' and of 'hippocampus minor' were
known in the Orang before Prof. Rolleston : and the homologies of the bones of the
hind foot in mammals had been determined before Prof. Huxley propounded them to
show that the hind thumb of the Ape was a great toe, and that Man was not the only-
animal who possessed two hands and two feet.

" Beitrjige zur Zoologie und vergleichenden Anatomic, 4to, 1820, zweite Abthei-
lung, p. 70, tab. vii. ^ Icones cerebri Simiarum, fol. 1821, p. 14, fig. iii. 2.

" Trevimnns, Zeitschrift fiir Pliysiologic, Bd. ii. s. 25, Taf. iv. '> Nieuwe Ver-

handlungen der erste Klasse vom het Koningl. Nederhvndsche Institut. Amsterdam,
1849. « Fullcrian Lectures, Royal Institution (March 18, 1861), reported, with

copies of diagrams, in 'Athenaeum,' March 23rd, 1861, p. 395.
VOL. II. T

274

ANATOMY OF VERTEBKATES.

hornlike form, in advance of the ' corpus striatum.' The super-
ficial grey matter of the cerebrum, through the number and depth
of the convolutions, attains its maximum of extent in Man.

Peculiar mental powers are associated with this highest form of
brain, and their consequences strikingly illustrate the value of
the cerebral character ; according to my estimate of which, I am
led to regard the genus Homo as not merely a representative of
a distinct order, but of a distinct subclass of the Mammalia, for
which I have proposed the name of ^ Archencephala.' ^

150

Vertical section of tlie adult human brain. (After Arnold.) Half natural size.

With this preliminary definition of the organic characters,
which guide to a conception of the natural primary groups of the
class Mammalia, 1 next proceed to define those of secondary im-
portance, or the subdivisions of the foregoing subclasses.

§ 174. Characters of Orders. — In the Lyencephalous Mammalia
some have the optic lobes less definitely divided into ' corpora
quadrigemina ' than others. Those Avith the more simple optic
lobes are ' edentulous ' or without calcified teeth, are devoid of
external ears, scrotum, nipples, and oviducal fimbria? ; they are

^PX'w, I overrule ; fy-^ecpa^os, brain.

MAMMALIAN ORDERS.

275

151

uterine ovum, dissected, Ornitho-
rliynclius. Lxxvir.

true ^testlconda/ and are ovoviviparous, fig. 151: they have a
coracoid bone extending from the scapula to the sternum, and
also an epicoracoid and episternum, as
in Lizards ; they are unguiculate and
pentadactyle,^ with a supplementary
tarsal bone supporting a perforated spur
in the male. The order so character-
ised is called * Monotremata/ in refer-
ence to the single excretory and gene-
rative outlet, which, however, is not
peculiar to them among Mammalia. The
Monotremes are insectivorous, and are
limited to Australia and Tasmania ;
where they are represented by the Pla-
typus or Duck-Mole ( Orjiithorhynchus),
and by the Spiny Anteater (^Echidna).

The Marsupialia are Mammals distinguished by a peculiar
pouch or duplicature of the abdominal integument, which in the
males is everted, forming a i^endulous bag
containing the testes, and in the females is
inverted, forming a hidden pouch containing
the nipples and usually sheltering the young
for a certain period after their birth : they
have the marsupial bones, fig. 152, m, in
common with the Monotremes ; a much-varied
dentition, especially as regards the number of
incisors, but usually including four true mo-
lars ; and never more than three premolars : the
angle of the lower jaw is more or less inverted.

With the exception of one genus, DidelpJiys,
which is American, all the known existing
Marsupials are Melanesian, i. e. belong to
Australia, Tasmania, New Guinea, and some
adjacent isles. The grazing and browsing
Kangaroos are rarely seen abroad in full day-
light, save in dark rainy weather,
the Marsupialia are nocturnal. Zoological
wanderers in Australia, Aiewing its plains and scanning its scrubs
by broad daylight, are struck by the seeming absence of mam-
malian life ; but during the brief twilight and dawn, or by the
light of the moon, numerous forms are seen to emerge from tlieir
hiding-places and illustrate the variety of marsupial life Avith
which many parts of the continent abound. We may associate

r 2

Most of ^^"-'^^''^ ^^^^ marsupial boues,
Kangaroo. Lxxv.

276

ANATOMY OF VERTEBRATES

153

with their low position in the mammalian scale the prevalent
habit amongst the Marsupialia of limiting the exercise of the
faculties of active life to the period when they are shielded by
the obscurity of night.

The Lissencephala or smooth-brained Placentals form a group,

equivalent to the Lyencephala or
Implacentals, and include the fol-
lowing orders, Rodentia, Insecti-
vora, Cheiroptera^ and Bruta. The
RoDENTiA are characterised by
two large and long curved incisors
in each jaw, fig. 153, z, separated by
a wide interval from the molars ;
and these teeth are so constructed, and the jaw is so articulated,
as to serve in the reduction of the food to small particles by

154

Skull of a Rodent (Jerhoa).

Pteromys Volucella.

acts of rapid and continued gnawing, whence the name of the
order. The orbits, ib. o, are not separated from the tem-
poral fossas. The testes pass periodically from the abdomen

MAMMALIAN ORDERS.

277

into a temporary scrotum, and are associated with prostatic and
vesicular glands. The placenta is commonly discoid, but is some-
times a circular mass (Cavy), or flattened and divided into three
or more lobes (Lepus). The Beaver and Capybara are now the
giants of the order, which chiefly consists of small, numerous,
prolific and diversified unguiculate genera, subsisting wholly or
in part on vegetable food.' Certain squirrels achieve short
flights by means of expansions of skin between the fore and hind
limbs, fig. 154. Some Lemmings perform remarkable migrations,
the impulse to which, unchecked by dangers or any surmountable
obstacles, seems to be mechanical. Many Rodents build very
artificial nests, and a few manifest their constructive instinct in
association. In these inferior psychical manifestations we are
reminded of Birds. Many
Kodents hibernate like Hep- ^^^

tiles. They are distributed
over all continents. They
have not been found in older
deposits than eocene tertiary.
The transition from the
Marsupials to the Rodents

is made by the Wombats;

and the transition from the

Marsu^oials is made, by an

equally easy step, through

the smaller Opossums to the

Insectivora. This term is

given to the order of small

smooth-brained Mammals, the

molar teeth of which are

bristled with cusps, fig. 150,

m, j9, and are associated with

canines and incisors : they are

unguiculate, plantigrade, and

pentadactyle, and they have complete clavicles. The testes pass

periodically from the abdomen into a temporary scrotum, and are

associated with large prostatic and vesicular glands : like most

other Lissencephala, the Insectivora have a discoid or cup-shaped

placenta. Their place and office in South America and Australia

are fulfilled by Marsupialia; but true Insectivora exist in all tlie*

other continents.

Dentition of a Shrew {Sorex). Magnified.

278

ANATOMY OF VERTEBRATES.

The order Cheiroptera, with the exception of the modifica-
tion of their digits for supporting the wide webs that serve as
mngs, fig. 156, repeat the chief characters of the Insectivora ; but
a few of the larger species are frugivorous and have corresponding
modifications of the teeth and stomach. The mamm?e are pectoral
in position, and the penis is pendulous, in all Cheiroptera.

The most remarkable examples of periodically torpid Mam-
mals are to be found in the terrestrial and volant Insectivora.
The frugivorous Bats differ much in dentition from the true
Cheiroptera, and would seem to conduct, through the Colugos
or Flying Lemurs, directly to the Quadrumanous order. The

156

Skeleton of a Bat (Pteropus).

Cheiroptera are cosmopolitan. They have not been found in
older deposits than eocene tertiary.

The order Bruta {Edentata of Cuvier) includes two genera
which are devoid of teeth, figs. 157 and 158 ; the rest possess those
organs, which, however, have no true enamel, are never displaced by
a second series, and are very rarely implanted in the premaxillary
bones. All the species have very long and strong claws. The
ischium as well as the ilium unites with the sacrum ; the orbit is
not divided from the temporal fossa. Besides the illustration of
affinity to the oviparous Yertebrata which the Three-toed Sloths
afford by the supernumerary cervical vertebras supporting false
ribs and by the convolution of the windpipe in the thorax, it may

MAMMALIAN ORDERS.

279

be remarked that the unusual number — three and twenty pairs

of ribs, forming a very long dorsal, with a short lumbar, region of
the spine in the Two-toed Sloth, recalls a lacertine structure.
The same tendency to an inferior type is shown by the abdominal

157

Skull of Anteater {Myrmecophaga).

testes, the single cloacal outlet, the low cerebral developement in
all Bruta, by the bony scutes of the Armadillos and the horny
scales of the Pangolins, fig. 158; by the absence of medullary
canals in the long bones in the Sloths, and by the great tenacity
of life and long-enduring irritability of the muscular fibre, in both
the Sloths and Anteaters.

The order Bruta is but scantily represented at the present
period. One genus, Manis or Pangolin, is common to Asia and
Africa; the Orycteropus is peculiar to South Africa; the rest of
the order, consisting of the genera Myrmecophaga, or true Ant-
eaters, Dasypus or Armadillos, and Bradyjms or Sloths, are con-
fined to South America. The earliest known fossil of this order
is of miocene ao-e. ^

[58

Skeleton of Scaly Anteater (Manis). lxxiii\

In proceeding to consider the subdivisions of the Gyrencephala,
we seem at first to descend in the scale in meeting with a group
of animals in that subclass, having the shape and life of Fishes ;
but a high grade of mammalian organisation is masked beneath
this form. The Gyrencephala are primarily subdivided, accord-

» CLi. t, V. pt. 1, p. 193.

280

ANATOMY or VERTEBKATES.

159

Skeleton of Right Wliale (BaUenav)iisUcetHS}.

LXV.

ing^ to modifications of the loco-
motive organs, into three series ;
viz. Mutilata, Ungulata, and Un-
guiculata, the maimed, the hoofed,
and the clawed series ; and these
are of higher value than the or-
dinal divisions of the Lissence-
phala; just as those orders are of
higher value than the representa-
tive families of the Marsupials.

The Mutilata, or maimed
Mammals with folded brain, are
so called because their hind-limbs
seem, as it were, to have been
amputated, fig. 159, G6 ; they pos-
sess only the pectoral pair of
limbs, and these in the form of
fins, ib. 54 : the hind end of the
trunk expands into a broad, hori-
zontally flattened, tegumentary
caudal fin. They have large
brains with many and deep con-
volutions, are naked, and have
neither neck, scrotum, nor ex-
ternal ears. Like the wingless
group among Birds, the present
includes species allied to, or de-
rived from, different types.

The first order, called Ceta-
CEA, in this division are either
edentulous, fig. 159, or monophy-
odont: the latter have teeth of one
kind and usually of conical shape :
the pectoral digits, ib. iii., may
have more than three phalanges.
They are testiconda and have no
' vesiculse seminales.' The mam-
mae are pudendal ; the placenta
is diffused ; the external nostrils
— siuo-le or double — are on the
top of the head, and called spi-
racles or 'blow-holes.' They, for
the most part, range the ocean ;

MAMMALIAN ORDERS.

281

tliough with certain geographical limits as respects species. They
feed on fishes or marine animals. Some undoubted Cetacean
fossils are of eocene age : and there are indications of the order
in the upper oolitic period.^

161

Deutitiou of Dugoug (Halicore). V.

The second Mutilate order, called Sirenia, have teeth of differ-
ent kinds, incisors, i, fig. 160, which are preceded by milk-teeth,
d i, and molars, m, with flattened or
ridged crowns, adapted for vegetable
food. No digit has phalanges in
excess of the mammalian number,
three. The nostrils are two, situated
at the upper part of the snout ; the
lips are beset with stiff bristles ; the
mamma3 are pectoral; the testes are
abdominal, but are associated with
vesiculae seminales. The Sirenia
exist near coasts or ascend large
rivers ; browsing on fuci, water

plants, or the grass of the shore. The oldest known Sirenian is
of miocene age. There is much in the organisation of this order
that indicates its affinity to members of the succeeding division.

In the Ungulata the four limbs are present, but that portion of
the toe which touches the ground is incased in a hoof, figs. 162
and 163, which blunts its sensibility and deprives the foot of
prehensile power. With the limbs restricted to support and

Molars of lower jaw, African Elci>haiit.

' XV11I-. pp. XV. 520.

282

ANATOMY OF VEKTEBRATES.

locomotion, the Ungulata have no clavicles ; the fore-leg is prone :
the molar teeth are massive, with inflected folds of enamel: they
feed on vegetables.

A remarkable order, most of the members of which have passed
away, is characterised by two incisors in the form of long tusks ;
in one genus {Dinotlieriurn) projecting from the under jaw, in
another genus {Eleplias) from the upper jaw, fig. 162, i, and
in some of the species of a third genus (^Mastodon) from both
jaws. There are no canines; the molars are few, large, and

162

Skeleton of Elephant (Elephas Indiais)

transversely ridged, fig. 161, the ridges sometimes few, some-
times mammillate, often numerous and with every intermediate
gradation. The nose is prolonged into a cylindrical trunk,
flexible in all directions, highly sensitive, and terminated by a
prehensile appendage like a finger, fig. 162, 7i : on this organ is
founded the name Proboscidia given to the order. The feet
are pentadactylc, but the digits are outwardly indicated only by
divisions of the hoof; the testes are abdominal ; the placenta is
annular ; ' the mamma? are pectoral.

' Besides the annular placenta there is a subcircular villous patch at each pole of

MAIVBIALIAN ORDERS.

283

Pcrissodactjie hoofed limb
Hind leg, Rliiaoceros.

The present order rests with the Ungulata mainly upon its
hoofs : the dentition and some other particulars of the organisa-
tion of the Elephant, indicate an affinity to the Rodentia : the
abdominal testes, the two precavals and exposed cerebellum, are
characters of the inferior subclasses : but the cerebrum, concomi-
tantly with the bulk of the mammal, is large and well convoluted,
and the psychical qualities correspond. The
earliest known evidences of Proboscidian Un- 1^3

gulates are from miocene strata.

The typical Ungulate quadrupeds are di-
vided, according to the odd or even number of
the toes, into Perissodactyla and Artio-
DACTYLA.^ In the former the hoofs may be
one (Horse) or three {Rhinoceros, fig. 163):
in the latter the hoofs may be two (Giraffe),
or four (^Hippoijotamus), or two functional and
two rudimental (most Kuminants, fig. 164).

In the Perissodactyle Ungulata — odd-toed
in regard to the hind-foot in all, and with the
fore-foot unsymmetrically tetradactyle in the Tapir — the dorso-
lumbar vertebrse, fig. 165, C, D, differ in number in different species,
but are never fewer than twenty-two ; the femur has a third
trochanter, ib. 65 ; and the medullary artery
penetrates the back-part of its shaft. The
fore-part of the astragalus is divided into two
very unequal facets. The os magnum and the
digitus medius which it supports are large, in
some disproportionately so, and the digit is
symmetrical : the same applies to the ectocu-
neiform and the digit which it supports in the
hind-foot. If the species be horned, the horn
is single : or, if there be two, they are placed
on the median line of the head, one behind the
other, each being thus an odd horn. The nasals
expand posteriorly.^ There is a well-developed post-tympanic pro-
cess which is separated by the true mastoid from the paroccipital
in the Horse, but unites with the lower part of the paroccipital
in the Tapir, and seems to take the place of the mastoid in the
Rhinoceros and Hyrax. The hinder half, or a larger proportion

164

Artiodactyle hoofed limb ;
Hind leg, Antelope.

the chorionic bag, by which it derived additional attachment to the uterus, in the
Elephant. Lxiir. p. 347, ph xvi.

' JFrom Trepto-troSoKTi/Aos, qui digitos habct imparcs numero ; and &pTios, par,
MktvAos, digitus. - LXXi. p. 398.

284

ANxVTOMY OF VERTEBRATES.

of the palatines enters into the formation of the jDOsterior nares, the
oblique aperture of which commences in advance either of the last
molar, or, as in most, of the penultimate one. The pterygoid
process has a broad and thick base, and is j)erforated lengthwise
by the ectocarotid. The crown of from one to three of the hinder
premolars is as complex as those of the molars : ^ that of the last
lower milk-molar is commonly bilobed. To these osteological and

165

Perissodactyle skeleton {Rhinoceros Indicus). Lxxiii

dental characters may be added some important modifications of
internal structure, as, e.g., the simple form of the stomach and the
capacious and sacculated caecum, which equally evince the mutual
affinities of the Perissodactyle hoofed quadrupeds, and their claims
to be regarded as a natural group of the Ung2data. The placenta
is replaced by a diffused vascular villosity of the chorion in all the
recent genera of this order, excepting the little Hyrax, in which
there is a localised annular placenta, wdth decidua, as in the
Elephant. But the diffused placenta occurs in some genera of
the next group, showing the inapplicability of that character to
exact classification. The oldest known Perissodactyles are from
the lowest tertiary strata. Many extinct genera, e.g. Coryphodon,
Plioloplius, Lophiodon, Tapir other ium, PalcEotherium, Ancitherium,
Hijjparion, Acerotlieriiim, Elasmotlierium, &c., have been dis-
covered, which once linked together the now broken series of

' Some early tertiary extinct forms (Pliolophus, Coryphodon, Lophiodon') oifcred
exceptions to this rule.

MAMMALIAN ORDERS.

285

Perissoclactyles, represented by the existing genera Rhinoceros,
Hyrax, Tapir us, and Equus.

In the even-toed or * artiodactyle ' Ungulates, the dorso-lumbar
vertebrae are the same in number, as a general rule, in all the
species, being nineteen, fig. 166, d, l. The vertebral formulae of
the Artiodactyle skeletons show that the difference in the number
of the so-called dorsal and lumbar vertebra? does not affect the

166

Artiii(l;ictylc skeleton i^Ccrvus ^[cgacr,|■os^. xviir

number of the entire dorso-lumbar series : thus, the Indian Wild
Boar has d. 13, Z. 6 = 19; the Domestic Hog and the Peccai-i
have d. 14,1 5 = 19; the Hippopotamus has d. 15, /. 4 = 19 ; the
Gnu and Aurochs have d. 14, /. 5 = 19 ; the Ox and most of tlie
true Euminants have d 13, Z. 6 = 19; the aberrant Ruminants
have c?. 12, /. 7 = 19. The natural character and affinities of the
Artiodactyle group are further illustrated by the absence of the
third trochanter in the femur, ib. 65, and by the place of perfora-

286 ANATOMY OF VERTEBRATES.

tion of the medullary artery at the fore and upper part of the
shaft, as in the Hippopotamus, the Hog, and most of the Rumi-
nants. The fore part of the astragalus is divided into two
equal or sub-equal facets : the os magnum does not exceed, or
is less than the unciforme, in the carpus; and the ectocunei-
form is less, or not larger, than the cuboid, in the tarsus. The
dio'it answering to the third in the pentadactyle foot is unsymme-
trical, and forms, with that ansAvering to the fourth, a symmetrical
pair. If the species be horned, the horns form one pair or two
pairs ; they are never developed singly, of symmetrical form, from
the median line. The post-tympanic does not project downward
distinctly from the mastoid, nor supersede it, in any Artiodactyle ;
and the paroccipital always exceeds both those processes in length.
The bony palate extends further back than in the Perissodactyles ; ^
the hinder aperture of the nasal passages is more vertical and
commences posterior to the last molar tooth. The base of the
pterygoid process is not perforated by the ectocarotid artery.
The croA\^s of the premolars are smaller and less complex than
those of the true molars, usually representing half of such croAvn.
The last milk-molar is trilobed.

To these osteological and dental characters may be added some
modifications of internal structure, as, e.g., the complex form of
the stomach in the Hippopotamus, Peccari, and Euminants ; the
comparatively small and simple cascum and the spirally folded
colon in all Artiodactyles. The placenta is diffused in the
Camel-tribe, Chevrotains,^ and Non-ruminants ; is cotyledonal in
the true Ruminants. The oldest known Artiodactyles were non-
ruminants, and from eocene beds. Many of the extinct genera,
e. g. Cheer opotamus, Anthracotherium, Hyopotamus, Entelodon,
Dichodon, Merycopotamus, Xipliodon, Diclwbujie, A?ioplotherium,
Microtherium, &c., linked together the now broken series of
Artiodactyles, represented by the existing genera, Hipjwjmtamus,
Sus, Dicotyles, Camelus, Auchenia, Mosclms, Camelopardalis,
Cervus, Antelope, Ovis, and Bos.

A well-marked, and at the present day very extensive subor-
dinate group of the Artiodactyles, is called Ruminantia, in refer-
ence to the second mastication to which the food is subject after
having been swallowed ; the act of rumination requiring a pecu-
liarly complicated form of stomach. The Ruminants have the
^ cloven foot,' i.e. two hoofed digits on each foot forming a sym-
metrical pair, as by the cleavage of a single hoof; in most species
two small supplementary hoofed toes are added, fig. 166, sp.
• Lxxr. p. 399. ^ CCXXXY1-. vol. ii. p. 135j and Lxxir.

MAMMALIAN ORDERS.

287

167

The metacarpals of the two functional toes coalesce to form a single

' cannon-bone,' fig. 166, 57, as do the corresponding metatarsals,

ib. 69. The Camel-tribe have

the upper incisors reduced to a

single pair ; in the rest of the

Ruminants the upper incisors

are replaced by a callous pad,

figs. 167, 168. The lower ca-
nines, fig. 168, c, are contiguous,
and, save in the Camel-tribe,
similar, to the six lower inci-
sors, ^ forming part of the same ^^^^^^^^, ^^^^^^ ^.^^^^^
terminal series of eight teeth,

between which and the molar series there is a wide interval. The
true molars have their grinding surface marked by two double
crescents, the convexity of which is turned inward in the upper,
^g. 168, *, and outward in the under jaw, fig. 169, *.

168

ir.9

Raiuinant dentition, Sheep.

Many fossil Artiodactyles, with similar molars {Dicliodon,
Microtherium, Sic), appear to have differed from the existing
Ruminants chiefly by retaining structures which in them are
transitory and embryonic, as, e.g., upper incisors and canines,
first premolars, and separate metacarpal and metatarsal bones;
these are among the lost links that once connected more intimately
the Ruminants with the Hog and Hippopotamus.

The third division of the GyrenccpJuila enjoy a higlier degree

288

ANATOMY OF VERTEBRATES.

of the sense of touch through the greater number and mobility
of the digits, and the smaller extent to which they are covered
by horny matter. This substance forms a single plate, in the
shape of a claw or nail, which is applied chiefly to one of the
surfaces of the extremity of the digit, leaving the other, usually
the lower, surface possessed of its tactile faculty, fig. 170; whence
the name Unguiculata, which, in the present classification, is re-
stricted to this group. All the species are ' diphyodont,' and the
teeth have a simple investment of enamel.

170

17

Unguiculate limb, Lion.

Carnivorous dentition, Bear.

The first order, Carnivoea, includes the beasts of prey, pro-
perly so called. With the exception of a few Seals, the incisors.

^g, 171, z, are o^q in number; the canines, ib.

■i i_p

always

longer than the other teeth, and usually exhibiting a full and
perfect developement as lethal weapons ; the molars, ib. p, m,
graduate from a trenchant to a tuberculate form, in proportion as

172

173

\ J

rimiigrade foot : Hind limbs. Seal. Bones of do.

the diet deviates from one strictly of flesh to one of a more mis-
cellaneous kind. The clavicle is rudimental or absent ; the inner-
most digit is often stunted or absent; there are no vesiculte
seminales ; the teats are abdominal ; the placenta is zonular. The
Carnivora are divided, according to modifications of the limbs,
into ^ pinnigrades,' ^ plantigrades,' and ' digitigrades.' In the

MAMMALIAN ORDERS.

289

Pinnigrades (Walrus, Seal-tribe) both fore and hind feet are short,
and expanded into broad, webbed paddles for swimming, fig. 173,
the hinder ones being fettered by continuation of integument to
the tail, fig. 172. In the Plantigrades (Bear-tribe) the whole or
nearly the whole of the hind foot, fig. 174, forms a sole, and rests

174

c b

riantigrade foot, hind limbj Bear.

on the ground. In the Dlgitigrades (Cat-tribe, Dog-tribe, &c.) only
the toes touch the ground, the heel, cZ, being much raised, fig. 175.

It has been usual to place the 175

Plantigrades at the head of the '^W

Carnivora, apparently because ^mV' r":;^

the higher order, Quadrumana, is ^^ ^%\ llrV\

plantigrade ; but the affinities of c^^ \V r v

the Bear, as evidenced by inter- ^^^ \*^ /'

nal structure, e. g. the renal and M\\ \ # // ^

genital organs, are closer to the ^IM^^) f

Seal-tribe ; the broader and flat- tt ^Pir '

ter pentadactyle foot of the planti- <? - "flEi^r^''

grade is nearer in form to the ^ m^^r^^ ^

flipper of the Seal than is the H ) }J\)

more perfect digitigrade, retrac- m I --f-y *

tile-clawed, long and narrow hind ^.^^^ 11 I I 'i '^

foot of the feline quadruped, /^^^^^-■^ii k I \

which is the highest and most \W^^^j^\^f\^'^mA\

typical of the Carnivora. The '"V \Qr' 'ffj^i '1/

oldest known species of the order ""' "^^'^fc^ ^^^^

are of eocene tertiary date. v^-' ^ \,

/. . 1 • 1 • Digitigrade foot, liind limb. Lion.

The next perfection which is
superinduced upon the unguiculate limb is such a modification

VOL. II. u

2ryO

ANATOMY OF VERTEBRATES.

in the size, shape, position, and direction of the innermost
digit, that it can be opposed, as a thumb, to the other digits,
thus constitutinor what is termed a ' hand.' Those Uno;uiculates
which have both fore and hind limbs so modified, or at least
the hind limbs, figs. 176, 180, form the order Quadrumana.
The incisors are commonly 2^, and the molars ^, broad and
tuberculate; they have perfect clavicles, an os penis, pectoral

176

177

PelTic limb, Ape.

Dentition of Woolly Lemur.

mammre, vesicular and prostatic glands, a simple or slightly bifid
uterus, and a discoid, sometimes double, placenta. The Quadru-
mana have a well-marked threefold geographical as well as
structural division. The Strepsirhines are those with curved or
twisted terminal nostrils, with much-modified incisors, commonly
1^ ; premolars ~, Lichanotus, fig. 177, or ^^ in number, and

178

179

Platyrhine dentition (Celus).

Catarhiue dentition {Fupio).

molars with sharp tubercles ; the second digit of the hind limb
has a claw. This group includes the Galagos, Pottos, Loris,
Aye- Ayes, Indris, and the true Lemurs ; the three latter genera
being restricted to Madagascar, whence the group diverges in one

MAMMALIAN ORDERS.

291

180

direction to the continent of Africa, in the other to the Indian
Archipelago. The Platyrhines are Quadrumana with the nostrils
simple, subterminal, and wide apart ; premolars 3^3 in number, the
molars with blunt tubercles,
fig. 178 ; the thumbs of the
fore-hands not opposable, or
wanting ; the tail in most pre-
hensile ; they are peculiar to
South America. The Cata-
rhines have the nostrils oblique
and approximated below, and
opening above and behind the
muzzle : the premolars are ^
in number, fig. 179; the
thumb of the forehand is op-
posable. They are restricted
to the Old World, and, save
a single species on the rock
of Gibraltar, to Africa and
Asia. The hio-hest oro-anised
family of Catarhines is tail-
less, and offers in the Gorilla,
or, as some contend, the Sia-
mang, fig. 180, the nearest
approach to the human type.

In all the tailless Apes the
pelvic limbs are short, and,
like the longer pectoral ones,
are organised for grasping.
The pelvis is long and nar-
row; the spine shows one
curve, and articulates mth
the hinder part of the skull.
There is a sexual distinction
in the teeth, the canines being
lono; and laniariform in the
males. All Quadrumana are
clothed with hair. The oldest
known species of the Qua-
drumanous order are of mio-
cene date.

The structural modifica-
tions in the genus Homo, — sole representative of the Archencephak.

u 2

Quadrumauous skeleton, Siamang {Ilyluhates
syndactylus) .

292 ANATOMY OF VERTEBKATES.

— more especially those of the pelvic limbs, by which the erect
stature and bipedal gait are maintained, — are such as to claim for
Man, on merely external zoological characters, ordinal distinction,
at least. The consequences of the liberation of one pair of limbs
from all service in station and progression, due to the extreme
modification of the other pair for the exclusive discharge of those
functions, are greater, and involve a superior number and quality
of powers, than those resulting from the change of an ungulate into
an unguiculate condition of limb : and they demand, therefore, an
equivalent value in a zoological system. But, as I have elsewhere
argued, Man's psychological powers, in association with his extra-
ordinarily developed brain, entitle the group which he represents to
rank with the primary divisions of the class Mammalia founded on
cerebral characters. In this subclass Man forms but one genus.
Homo, and that genus but one order, called Bimana, on account
of the opposable thumb being restricted to the
^^^ upper pair of limbs. In every Ape the pelvic

limb is terminated by a ^ hand,' fig. 176 ; in every
Man by a * foot,' fig. 181.^ In Bimana the testes
are scrotal; their serous sac does not communi-
cate with the abdomen ; they are associated with
vesicular and prostatic glands. The penis is
pendulous, without bone, and the prepuce has a
fnisnum. The mammai are pectoral. The placenta
is a single, subcircular, cellulo-vascular, discoid
body.

Pelvic limi., Man. Man is uakcd, and is the sole terrestrial Mam-

mal in that predicament: of the partial growths
of hair, the chief protects the head, and is distinctive of sex.

' The fact of the homologous bones being determinable in the pelvic limb, as in
other parts of the skeleton, of Mammals, does not make the grasping organ of the
Ape, fig. 176 the less a 'hand,' nor does it prove the lacerating organ of the Lion,
fig. 175, to be no 'paw,' nor the swimming organ of the Seal, fig. 172, to be no ' fin.'
Prof Huxley, however, by pointing out those homologies between Man and the Ape,
under colour of a new element in the question, probably persuaded the ' working
men ' for whom, as ' Government Professor ' in the School of Science, he selected such
subject of instruction, that it was an important argument in favour of their Ape-origin,
So speciously indeed was this old elementary fact in zootomy set fortli, that the pro-
pounder succeeded in deceiving some non-anatomical authors into a belief that he
had really made a discovery. See Crawfurd, 'Antiquity of Man,' 8vo. 1863 :
* Prof. Huxley has very satisfactorily shown that the designation of " quadrumane,"
or four-handed, is incorrectly applied to the family of monkeys. Their feet are real
feet, ahhough prehensile ones ; but the upper limbs are true hands,' &c., p. 18 ; also
Lyell, ' Antiquity of Man,' 8vo. 1863, p. 476 et seq.: whom I would refer to Cuvier,
' Leyons d'Anatomie Comparee,' 8vo. 1805, torn. i. p. 376, ' Des os du coude-pied.'

MAMMALIAN ORDERS.

293

The dentition of the genus Homo is reduced to thirty-two teeth
by the suppression of the outer incisor and the first two premolars
of the typical series on each side of both jaws, the dental

formula being:-

2-2'

C.

2—2
P' 2—2'

m. g = 32,

The teeth are of equal length, show no sexual distinctions, and
there is no break in the series ; they are subservient in ^lan not
only to alimentation, but to beauty and to speech, fig. 182.

The human foot is broad, plantigrade, with the sole, not in-
verted as in Quadrumanai but applied flat to the ground ; the

182

Bimanous dentition (.Homo).

leg, fig. 183, 66, bears vertically on the foot ; the heel, 68, is ex-
panded beneath ; the toes are short, but with the innermost, z,
longer and much larger than the rest, forming a ' hallux ' or great
toe, which is placed on the same line with, and cannot be opposed to,
the other toes : the pelvis, 62, 63, is short, broad, and ^mle, keep-
ing well apart the thighs ; and the neck of the femur is long, and
forms an open angle Avith the shaft, 65, increasing the basis of
support for the trunk. The whole vertebral column, with its
slight alternate curves, and the well-poised, short, but capacious
subglobular skull, are in like harmony with the requirements of

294

ANATOMY OF VERTEBRATES.

the erect position.

183

Bimanous skeleton (.Homo).

The widely-separated shoulders, with broad
scapula and complete
clavicles, 58, give a fa-
vourable position to the
upper limbs, now libera-
ted from the service of
locomotion, with complex
joints for rotatory as well
as flexile movements, and
terminated by a hand of
matchless perfection of
structure the fit instru-
ment for executing the
behests of a rational intel-
ligence and a free will.
Hereby, though naked,
Man can clothe himself,
and rival all native vest-
ments in warmth and
beauty ; though defence-
less, Man can arm him-
self with every variety of
weapon, and become the
most terribly destructive
of animals. Thus he ful-
fils his destiny as the
master of this earth, and
of the lower Creation.

The system of Cuvier
beino^ still in use in some
estimable works, and the
one according to which
groups of Mammals are
most commonly referred
to in physiological and
paleontological proposi-
tions, an outline thereof,
as applied to that class,
is here appended, with
a similar outline of the
classification adopted in
the present work.

MAMMALIAN ORDERS.

295

fcJD
O

a

fcX)-

15 '5

CU fcC a sii

fcJD

M O

tc

Vi cc '^ S IS '-^ ti5

rS

i J 3-2-b-^

^ S '^^ ss t^

f^S^S^^c^c:^^ ^ ci; O eg t3;o

H ^ OS

296

ANATOMY OE VERTEBRATES.

I :::::::::::::::::::::::: ig ::: :^ J

I -11:1 lO i i lis Jl s^llll i bl-l H| lils^

M C

Hi
<

w

u
P5

<
V

tJO

a

297

CHAPTER XXVI.

OSSEOUS SYSTEM OF MAMMALIA.

§ 175. General Characters of the Skeleton. — The osseous tissue
and the bone-cells characteristic of it in the higher members of the
Mammalian class are shown in Vol. I. p. 23, figs. 14, 15. In the
Lyencephala ( Ornithorhynchus, Echidna, Kangaroo, Kat, Beaver,
Sloth, Hedgehog, Moley the Haversian canals resemble those of
Birds in their smaller relative size, as do the bone-cells in the
number and peculiar branchings of their canaliculi, compared
with higher Mammalia\ in these the radiated disposition of the
canaliculi, concomitantly with the shorter and wider form of the
cells, becomes more marked, as shown in fig. 14, Vol. I. In
the larger Cetacea the bone-cells have a larger size and less
regular shape, and send off long branching canaliculi.^ The
osseous tissue in Mammals is less dense and compact than in
Birds: the long bones have medullary cavities, as a rule, re-
latively larger than in Rejjtilia, smaller and with thicker walls
than the homologous pneumatic cavities in Birds. In the Cetacea
and the Sloths, recent and extinct, the long, like the other, bones
are solid, the central tissue being cancellous : in the Sirenia the
bone of the thick ribs is dense and compact throughout: the
hardest bone in the present class is that which is accordingly
termed * petrosal,' especially in the Whale- tribe, in which its
specific gravity reaches 2*433, that of ivory being 1*744.

The proportion of the Mammalian skeleton which is pneumatic
is noticed in Vol. I. p. 25. The vertebral bodies and the limb-
bones have the articular surfaces, in the grooving state, supported
on distinct plates, called ' epiphyses,' Avhich usually coalesce with
the rest of the bone, at maturity. Examples of the exoskeleton
are seen in the Armadillos and their huge extinct congeners the
Glyptodons: small detached bony nodules were also developed
in parts of the thick tegument of the Megatherioids.^ The
lacrymal is properly a mucous scale-bone. The bone of the heart

' ccxciii. pis. xi. and xii. ^ lb. p. 151. ^ Burmcistcr, MS.

298

ANATOMY OF VERTEBRATES.

1S4

1^

Mammalian type

vertebra, from the

thorax.

185

in large Ruminants is referable to the ^ splauclmoskeleton ; ' the
ossified tendons in some small Musk-Deer to the
^ scleroskeleton.'

In the Mammalian class the centrum, figs. 141,
184, <?, coalesces -with the neural arch, ib. w,
throughout the vertebra3 of the trunk. In the
seven anterior vertebra?, fig. 185, i-7, the pleur-
apophyses are short and commonly coalesce with
the centrum and diapophysis, circumscribing the
lateral foramina for the ' vertebral ' arteries. In
the Monotremes they retain, as in Reptiles, their
individuality, fig. 186, a. In Cetacea the inter-
space between the cer\dcal par- and di-apophyses
is not always closed by bone. Occasionally the pleurapophyses

of the seventh, fig. 185, A,
h, and, more rarely, also of
the sixth, «, vertebrae, mani-
fest their rib-like nature by
increase of length, and free-
dom of articulation, even in
Man; but these segments
are not completed by the
liaemapophyses and haemal
spine. This resumption of
type takes place in the eighth
vertebra, ib. c, d\ and the
dorsal series of vertebras here
begins, as a rule, in Mam-
mals. The most marked ex-
ception occurs in the Ai
(^Bradi/pus tridactylus) ; and
supporting the pleurapophyses,
a, h, be regarded as homologous
with the first two dorsals in other
Mammals, the exception is so far
saved : but the presence of short
pleurapophyses in all the cer-
vical vertebrae and their occa-
sional developement in the last
two, as in fig. 185, A, support the
recognition of the tenth verte-
bra in the Three-toed Sloth, ib. b,
10, c, d, as the first dorsal. The

cervical vertebn-e, Ornithorliyncl.us. plcUrapOphySCS of thc dorsal VCr-

Cervical vertebrae, A Man, B Sloth.

if the vertebra, fig. 185, B, 8, 9,

186

OSSEOUS SYSTEM OF MAMMALIA.

299

187

tebrse, figs. 184, and 186, j)l, are subject to slight displacement,
and their articulations, like those of the neurapophyses in the
Bird's sacrum, extend over the interspace between their own and
a contiguous centrum. The hajmapophyses, ib. h, are rarely
ossified : the exceptions occur in the lowest subclasses (Duck-
Mole, Armadillo, Sloth) : in the Monotremes a portion of cartilage
intervenes between the pleur- and hiem-
apophyses. Some of the posterior htemapo-
physes have no haemal spine, but terminate
freely, fig. 187, 7, or in connection with
each other. The segments typically com-
pleted, as in fig. 184, are called ' vertebra3
with true ribs,' those not so completed '^ ver-
tebras with false ribs,' in Anthropotomy.
The haemal spine of each thoracic seg-
ment is separately developed. They
commonly remain distinct, fig. 187, 9, 9,
forming a chain of ossicles, answering in
number to those anterior dorsal segments
which they complete : they coalesce with
each other in some Mammals, and form
collectively the ^sternum.' Only in Mono-
tremes is there an episternum, figs. 186,
h, c, 187, 9, z, or haemal spine of a cervical
segment, to which the clavicles articulate.
As the dorsal vertebrae recede in position
the pleurapophyses become shorter, return
to their proper segment, and usually be-
come appended to its diapophysis. When
it becomes confluent therewith, or replaces that process, the
' dorsal ' series ends and the ' lumbar ' one,
figs.166,/, 183, 1-5, begins. These vertebrae
are commonly more numerous in Mammals
than in Eeptiles. Their haemapophyses —
the abdominal ribs of Reptiles — are re-
presented by the ' intersectiones tendineae
musculi recti,' &c., the lowest pair are par-
tially ossified as ' marsujoial bones,' fig. 187,
6, in Lyencepliala. In the Mutilata the
^ sacrum ' is defined by the reappearance of
the ossified h^emapophyses, fig. 159,63, of
a segment at the end of the trunk. In
Cetacea it is suspended beneath its segment, as in Fishes, and
may support some rudiment of a pelvic or ventral fin, ib. 65, 66,

Hseraapopliyses .ind spines of
truuk, Mammal.

Type of pelvic and caudal segment,
Mammal.

300 ANATOMY OF VERTEBRATES.

In Sirenia, the htemapophyses, fig. 188, h, 3, are connected by
pleurapophyses, ib. j^U 2, completing the h?emal arch with the dia-
pophyses d, i ; and the Batrachian condition of pelvis (Vol. I. p. 48,
p. 163, fig. 101, d) is resumed. In the rest of the class two or
more segments following the lumbar series become, like those
in the head, the seat of modifications by anchylosis of the cen-
trums, flattening and broadening with an expanse of the neural
canal: and with these modifications is associated great develope-
ment of the hajmal arches of two of those segments, fig. 187,
4 and 5, which, therefore, have got special names, as ^ ischium,'
ib. 4, and ^ pubis,' ib. 5. These are, however, connected with
their respective segments by a concomitant expanse of the single
pleurapophysial element, fig. 188, j)l, which, so modified, has the
name of 'ilium,' and in some Lyencephala (Sloths, Megatherioids,
Armadillos) resembles that bone in Birds, by the number of sacral
seorments with which it articulates or coalesces.

The caudal segments in Mammals are characterised by the
abrupt cessation of the pleurapophysial developement forming the
ilium, by the retention of the riblet, or beginning of the pleura-
pophysis, anchylosed, as a diapophysis, fig. 188, d, and by the
approximation of the ha3mapophyses, ib. h, 3, to the under surface
of the centrum, c, as at A, 4, the divergent bases articulating there-
with, and the apices converging to unite with, or develope, a haemal
spine, ib. 5. The wider pelvic ha3mal canal encompassed terminal
parts of the generative and intestinal canals ; the narrower caudal
one has only to defend the main blood-vessels of the tail. The
terminal caudal vertebrae are progressively reduced in size and
complexity, and vary greatly in number : anchylosis is an excep-
tion (^Dasypus, e.g.) in this region.

§ 176. General Characters of the Skull. — Pursuing the survey
of the Mammalian modifications of the Vertebrate archetype as
they appear in the segments of the skeleton forming the skull,
with the light of the stage of developement manifested in an
immature Mammal when a certain growth has proceeded from the
several points of ossification established in the primordial mem-
branous and cartilaginous basis, we find that the neural arch of
the occipital vertebra, fig. 189, Ni, i, 2, and 3, agrees with that of
the Bird and Crocodile in the connation of the diapophysis, 4,
with the neurapophysis, 2 ; but the process, called ' paroccipital,'
now descends from the lower part of the arch, and, in many
Mammals, is of great length. An articular condyle is developed
from each neurapophysis, 2, which articulates with the concave
anterior zygapophysis of the atlas, and is the homotype of the

OSSEOUS SYSTEM OF MAMMALIA.

301

posterior zygapophysis in the trunk-vertebrte. The centrum, i,
is reduced to a compressed plate, and its hinder articular surface
is not more developed than is the front one of the centrum of the
atlas, with which it is connected by ligament. The expanse of

Side view of cranial vertebne and appendages, Hog.

the occipital spine, 3, has been governed by the superior develope-
ment of the cerebellum in the Mammalian class.

The haemal arch of the occipital vertebra is here represented,
like those of the cervical vertebrae, by the pleurapophysial elements
only ; but these are developed into broad triangular plates with
outstanding processes: that called ' spine,' 5i, is exogenous; but
that called ' coracoid ' is developed from an independent osseous
centre, which is a rudiment of the haemapophysis, coalesces with
the pleurapophysis, and, in the present class, only attains its nor-
mal proportions, completing the arch at figs. 186, d, 187, 2, with the
haemal spine, ib. 9, in the Monotremes. The diverging appendage
(fore-limb, 53-57) of this arch, though retaining the general fea-
tures of its primitive radiated form, has been the seat of great de-
velopement and much modification and adjustment of its difterent
subdivisions in relation to the locomotive office it is now called
upon to perform.

AVith the exception of this excess of developement of the
appendage, the defective developement and displacement of the
haemal arch, and the coalescence of the diapophyses in the
neural arch, there are few points of resemblance which are not
sufficiently salient between the segment represented by the bones,
Nr, 1 , 2, and 3, in the INIammal, and that so marked in the Fish, Vol. I.

302 ANATOMY OF VERTEBRATES.

fig. 81. And, if the interpretation of the more normal or archetypal
condition of this segment in the lower Vertebrate animal, fig.
101, A, Vol. I., be accepted, so also must be the explanation here
given of the nature of the modifications of the special homologues
of the constituents of the occipital segment by which that arche-
type is masked in the Mammal. A single nerve supplies the
appendage, 53-57, in Protojjterus ; subsequent developement of that
appendage in higher forms presses more nerves from other centres
into its service ; these do not originate the complex conditions
calling for them. And if the simple limb, fig. 101, A, 53-57, be
the special homologue of the complex one, fig. 189, 53-57, neither
the number of nerves, of vessels, or of terminal rays can afiect
the conclusions deducible from fig. 101, as to its general nature
in relation to the Vertebrate archetype.

In the second segment of the skull, Nii, the centrum, 5, is long
distinct from both i and 9; and the haemal arch (hyoid bone)
retains its natural connection with the rest of the segment, and
by means of a more complete developement of the pleurapophyses,
38, than in any of the inferior air-breathing Vertebrates. In the
Hog, as in other Mammals, may be separated, without artificial
division of any compound bone, the entire parietal segment, but
with it is brought away the petrified capsule of the acoustic organ
and the anchylosed distal piece, 27, of the maxillary appendage,
which more or less conceals the typical character of the neural
arch of the parietal vertebra in every Mammal : least so, however,
in the Monotremes and Ruminants. The neurapophyses, 6, of the
parietal vertebrae have coalesced with the centrum, 5, but retain
much of the proportions they present in the cold-blooded classes ;
for the mesencephalic segment of the brain is, in fact, but little
more developed in the Mammal : they are notched in the present
example, but are perforated in the Sheep, by the larger divisions
of the trigeminal, and they send down an exogenous process,
which articulates and sometimes coalesces with the appendage, 2 1,
of the palato-maxillary arch, and with the pleurapophysis, 20, of
the same arch. The neural spine, 7, always developed from a
pair of centres in Mammals, often vastly expanded, and sometimes
complicated with a third, intercalary or interparietal osseous piece,
in subserviency to the large size of the prosencephalon, is occa-
sionally uplifted and removed from the neurapophyses by the
interposed squamous expansion of the bone, 27 ; but this, which
reminds one of the occasional separation of the neural arch from
the centrum of the atlas in Fishes, is a rare modification in the
Mammalian class. The diapophysis, 8, always commences as an

OSSEOUS SYSTEM OF MAMMALIA. 303

autogenous element by a distinct centre of ossification ; in most
Mammals it speedily coalesces with the petrosal, but not in the
Babyroussa,^ e.g. : it usually coalesces with the squamosal, 27, as in
the Hog ; but retains its distinctness in the Echidna; its apophysial
character is usually well-marked, and it is known as the * mastoid
process ' in Anthropotomy. In most Mammals the pleurapophysis,
38, retains its primitive independency and rib-like form, with usually
the ^ head ' and * tubercle ; ' but by reason of its arrested growth it
has been called ^ styloid ' bone or process. Sometimes it is sepa-
rated from the short hasmapophysis, 40, by a long ligamentous
tract, sometimes is immediately articulated with it, or by an inter-
vening piece. The haemal spine, 4i, is usually small, and always
single. The rudiments of hypobranchial elements, 46, are retained
as diverging appendages of the parieto-hasmal arch in all Mam-
mals, and have received the special names of ' posterior cornua,'
or ^ thyrohyals,' from their subservient relationship to the larynx.
In the frontal segment, Nm, the centrum, 9, and neurapophyses, 10,
very early coalesce. Two separate osseous centres mark out the
body, and each neurapophysis has its distinct centre, the optic fora-
mina, op, being first surrounded by the course of the ossification
from these points. The superior developement of the neurapophy-
sial plates, 10, as compared with those of the parietal vertebra, 6, in
most Mammals, harmonises with the greater developement of the
prosencephalon ; but the chief bulk of this segment is protected
by the expanded spines of the frontal, 11, and parietal, 7, vertebra,
and the intercalated squamosal, 27. This appendicular piece not
only fulfils some of the functions of the proper cranial neurapo-
physes, but, likemse, the normal office of the frontal pleurapo23hysis,
28, in the support, viz., of the distal elements of the htemal
arch, 29-32, which now articulate directly with 27, in place of 28,
as in all oviparous Vetebrates. The true pleurapophysis of the
frontal vertebra, 23, is almost restricted in the Mammalian class to
functions in subserviency to the organ of hearing ; is sometimes,
as in the Hog, swollen into a large bulla ossea, like the parapo-
physes and pleurapophyses of the cervical vertebras of Cohitis ; is
sometimes produced into a long auditory tube, and somethnes
reduced to the ring supporting the tympanic membrane. Yet,
under all these changes, since its special homology is demonstrable
with 28 in the Bird, fig. 26, Turtle, fig. 91, Vol. I., and Crocodile,
fig. 92, Vol. I., as well as with the teleologically compound bone,
28, a, h, c, d, in the Fish, fig. 81, Vol. I., so likemse must its general

^ XLiv. p. 556, no. 3338, in which the petrosal is instructively distinct from all the
surrounding vertebral elements composing the otocrane.

304 ANATOMY OF VEKTEBEATES.

homology be equally recognised. The frontal haimapophysis,
fig. 189, 29, and the corresponding half of the haemal spine, ib. 32,
are connate on each side in all Mammals. The arch, as in other
air-breathing Vertebrates, has no diverging appendage.

The nasal segment, Niv, is chiefly complicated by the confluence
of parts of the enormously developed olfactory capsules, 18, and
its typical character is further masked by the compression and
mutual coalescence of the neurapophyses, 14. The centrum is
usually much elongated, as at 13, and soon coalesces with both
neurapophyses, u, and with the nasal capsules, 18. The neural
spine, 15, is bifid. The pleurapophysis, 20, or proximal element
of the h^mal arch of the nasal vertebra has its real character and
import almost concealed by the excessive developement of the
second element of the arch, 21, which resumes in Mammals all
those extensive collateral connections which it presented in the
Crocodile ; and to which are sometimes added attachments to the
expanded spine of the frontal vertebra, as w^ell as to that of its
own segment. The pleurapophysis, however, besides its normal
attachment to its centrum, 13, sends up a process to the orbit, in
order to effect a junction with its neurapophysis. The haemal
spine, 22, is developed in two moieties, which never coalesce
together, although, in the higher Apes, and at a very early
period in Man, each half coalesces with the hasmapophysis, and
repeats the simple homogeneous character of the corresponding
elements of the succeeding (mandibular) arch.

The appendicular element, 24, which diverges from the pleura-
pophysis, 20, contributes to fix and strengthen the palato-maxillary
arch by attaching it to the descending process of the parietal
centrum, 6 : with which, in most Mammals, it ultimately coalesces.
The other elements of the diverging member of the arch corre-
spond in number and in the point of their divergence with those
in Birds, Chelonians, and Crocodiles. They are two in number,
succeeding each other, and both become seats of that expansive
developement which is followed by the multiplication of the points
of connection ; thus the proximal piece, 26, ' malar bone,' is con-
nected in the Hog not only with the ha^mapophysis, 21, from
which it diverges, but likewise with the muco-dermal bone,
called ' lacrymal,' 73. The distal piece of the appendage, 2:,
expands as it diverges, and fixes the naso-htemal arch not only to
the frontal pleurapophysis, 28, and parietal parapophysis, 8, but
also to the frontal, parietal, and, sometimes, occipital neurapo-
physes and spines : it also aflbrds, in the Hog, as in other Mam-
mals, an articular surface to the frontal ha3mapophysis, 29.

OSSEOUS SYSTEM OF MAMMALIA.

305

190

The steps by which the bony capsule of the otic organ is
finally differentiated and individualised in Mammals are instruc-
tive examples of that character of advance in organisation. The
ex- and par-occipitals which contribute a partial bony support to
the back part of the gristly cap-
sule in Fishes and Reptiles, and
coalesce with that fully ossified
capsule in Birds, remain distinct
from the petrosal in all Mammals.
The alisphenoid, which contri-
butes a partial bony support to
the fore part of the gristly otic
capsule in H^ematocrya, and co-
alesces with the same part of the
bony capsule in Birds, has like-
wise permanently liberated itself
therefrom in Mammals. The
mastoid, which contributes a bony
support to the outer part of the
otic capsule in cold-blooded Ver-
tebrates, and is extensively con-
fluent with the same part of the
ossified capsule in Birds, retains
such confluence in some Mam-
mals, but instructively manifests
its primitive independency in
others. In the Cetacea, where
the mastoid and paroccipital are
distinct from the petrosal, this
capsule coalesces with the tym-
panic, which, having lost its man-
dibular function, is fixed and
contracts anchylosis with the pe-
trosal. The Babyroussa exempli-
fies the essential individuality of
the acoustic capsule, the petrosal
not only being ossified from its
own centre, but remaining dis-
tinct from every bone of the oto-
crane.^

§ 177. General Characters of the Limhs. — The diverging append-
age of the occipital vertebra is never absent in Mammals, and

Bones of fore-limb, Horse.

XLiv. p. 556, nos. 3388, 3345.

VOL. II.

306

ANATOMY OF VERTEBRATES.

offers its most simple condition in the Horse, fig. 190. It is essen-
tially, as in Protopterus, a jointed ray, but every part is adap-
tively modified for special ends and reciprocal adjustment and
interplay ; in the monodactyle Mammal it is, in fact, the result of
simplification from a more complex ancestral condition of limb, in
reference to the application of that limb to a more vigorous kind
of locomotion. Viewing the framework of such limb, here, in
merely its archetypal relations, we remark that the supporting
arch is incomplete, as in most Mammals ; the pleurapophysis, a, h,
is expanded into a ' scapula,' with its coalesced h^emapophysis as a
' coracoid ' process, ib. k. The first segment of the appendage is
modified as ' humerus,' a ; the second segment as ' radius,' o, with
which has coalesced the process s, u, developed in most Mammals
' ulna.' In the blastema between the second and third ray have

as

been formed a cluster of ossicles called 'carpal,' ic, z,2,3; the
third segment, 4, 5, is a metacarpal, and with it are connected two

Oning.

Atcles. Hyajua. Megathere. Sloth.

styliform appendages, 6, 7 ; the abortive remnants of other me-
tacarpals. Next follow the three terminal shorter segments of
the limb-ray called 'phalanges,' 13, u, 15 ; the whole forming the
* digit' which answers to the middle finger, iii, in the pentadac-
tyle foot of beast and in the hand of man. Gradational stej)s to this
perfect condition of ' hand ' are selected from the Mammals with
claws, in fig. 191. In the Unau or Two-toed Sloth {^Bradypus
didactylus), the digits which are functionally developed answer to
the second, ii, and third, iii, in Man; the fourth, iv, and first, i,
are represented by styliform beginnings of their metacarpals.
Tlie carpal ossicles include one, s, t, answering to the separate
scaphoid, s, and trapezium, t, in Man, a ' lunare,' /, and ' cunei-
form,' c, a ' trapezoides,' r/, supporting the metacarpal of the second

OSSEOUS SYSTEM OF MAMMALIA. 307

digit ; a ' magnum/ m, supporting that of tlie middle digit, and
an ' unciforme,' u, limited to the rudiment of iv.

In the huge extinct congener of the Sloths (^Megatheriuni), the
fourth, IV, as well as the third and second digits are developed,
as in the Bradyjnis tridactylus, for the support of claws. There
is a metacarpal of the fifth digit, supporting stunted rudiments of
the first, 1, and second, 2, phalanges; the first digit is still repre-
sented by a like rudiment of its metacar2:)al, i. The carpal
ossicles include, as in Sloths, a ^ scapho-trapezium,' s, t, with a
well-marked ^ pisiforme,' p, and a larger ^ unciforme,' u. In the
HycEna the fifth digit, v, is functionally developed : the first, i,
retains the rudimental state. The scaphoid and lunare, s, /, have
here coalesced : the trapezium, t, is distinct, but very small : the
unciforme supports, as usual, the metacarpals of the fourth, iv,
and fifth, v, digits. In the Spider-Monkey {Ateles), the meta-
carpal representative of the first digit, i, is longer : the scaphoid,
s, is distinct, and the ' intermediilm,' /, is a dismemberment
thereof, answering to e, fig. 173, Yol. I.

In the Orang the carpus also has the dismembered sca-
phoid, s, or ' intermedium,' /. The inner digit, i, is short and
feeble, but with the usual mammalian number of two pha-
langes. In the hand of Man, this digit, which is the last to
be completed in that class, attains its highest functional deve-
lopement : it is articulated in such a way and at such an angle
as to be opposable to any of the joints of any of the other digits.
Of these the third, ill, which is the most constant in the class, is
the longest. The carpus con-
sists of eight bones in two
rows ; the first including the
undivided * scaphoides,' s, ' lu-
nare,' /, ' cuneiforme,' c, '• pisi-
forme,'/?; the second including
' trapezium,' t, ' trapezoides,'
d, * magnum,' ???, ^ unciforme,'

U. These names, SUG:2:ested Pelv-lc arch and appendage, i}ateHrtJy//6(ue«(ts.

. LXV.

by the shapes and proportions

of the carpal bones in the human skeleton, become arbitrary signs

of their homoloo'ues in lower animals.

The appendage of the pelvic arch may be wholly Avanting, as
in Sirenia and most Cetacea, or represented by a two-jointed ray,
as in the Right Whale, fig. 192, and fig. 159, 65, 66 ; articulated to
two elements, 63 and 64, of the pelvic arch, which, as in Fishes^
are loosely suspended in the flesh.

308

ANATOMY OF VERTEBKATES.

The successive gradational steps by Avliich the pentadactyle
condition of the limb or appendage is attained are selected from
the aeries of hoofed Mammals in fig. 193.

The pelvic limb, fig. 195, shows the same monodactyle sim-
plicity as the pectoral one, in the Horse. The ossicles developed
in the connective substance between the second and third prin-
cipal segments of the long-jointed ray, are the ' astragalus,' a,
' calcaneum,' cl, ' naviculare,' 5, ' mesocuneiforme,' cm, ' ectocunei-
forme,' ce, ' cuboides,' h. The metacarpal supporting the three
joints or 'phalanges' of the digit articulates chiefly with the ecto-
cuneiform, e, which accords in size. The largely developed digit,
or continuation of the main limb-ray, fig. 193, answers to the third,
III, of the pentadactyle foot. At its base are rudiments of the
metatarsals of the second, ii, and fourth, iv, digits. In the Ox
the naviculare, ib. s, is connate with the ' cuboides,' h : and, as this
supports one-half of the single metatarsal, such half is held to be
the developed homologue of the rudimental fourth metatarsal
in the Horse : whilst the half supported by the ' ectocuneiforme,'
ce^ in the Ox, is held to answer to the metatarsal of the developed
digit. III, in the Horse.

Elephant. Hippopotamus. Rhinoceros.

Embryology here lends partial proof to this view : the so-called
' cannon-bone ' being developed from a single centre and epi-
physes in the Horse, and from a pair of shafts or centres and
epiphyses in the Ox : it accordingly supports a pair of toes,
which answer to the third, iii, and fourth, iv, in the penta-
dactyle foot. The Camel and Giraffe have not rudiments of
any other toes : in the Ox such rudiments of the distal parts of

OSSEOUS SYSTEM OF MAMMALIA.

309

the second, ii, and fifth, v, digits are appended to the coalesced
metatarsals of the functional pair of toes, in and iv.

In the miocene fossil Horse (^Hipparion,^g. 194) a similar pair
of ^ spurious ' hoofs, ii, iv, dangled behind the main toe, in, com-
pleting the digits, ii and iv, indicated by the ' splint-bones ' or
proximal parts of the metatarsals in the modern Horse, fig. 193,
II, IV, but stunted in growth. In the eocene Palceotherium
these digits were nearly equal in size to the middle one. The
Rhinoceros at the present day preserves these proportions of the
toes, II, III, IV, but with shorter and more massive proportions of
the whole foot. Accordingly, in fig. 193, it will be seen that the
* mesocuneiforme,' cm, and ' cuboides,' b, have a larger propor-
tional size than in the Horse ; but the structure of the tarsus is
essentially the same : the cuboid, b, articulates directly with the
calcaneum, cl\ the naviculare, &, intervenes between
the two cuneiform bones and the astragalus, a. The
aflinity of these ' perissodactyles ' is obvious, and the
closer links of affiliation are supplied by the extinct
forms above cited. In like manner we find the affinity
of the Ox and Hippopotamus illustrated in the struc-
ture of the hind-foot, the Hog holding a similar inter-
mediate step in the developement of the toes, iv and
V. In the tarsus the cuboid, b, and naviculare, s, show
the same near equality of size, but they are distinct
bones in the Hippopotamus as in all Artiodactyles
except the restricted or horned Ruminants : a mesocu-
neiforme, cm, now supports the metatarsal of the toe,
II, that of the fifth, v, articulates with the cuboid.
In the Elephant the innermost digit, i, is present — the
last to appear in the ungulate as in the unguiculate
series, and the tarsal group shows the completeness
which it manifests in Man. The human anatomist will
recognise the astragalus, a, calcaneum, cl, naviculare, s, extended
transversely and presenting articular facets to the three ' cunei-
form ' bones, * internal,' * middle,' and ' external,' which for con-
venience of definition I have called ' entocuneiform,' ci, * meso-
cuneiform,' cm, ' ectocuneiform,' ce ; the ' cuboides,' b, supports as
usual the metatarsals of the fourth and fifth toes. The toe, i, has
a short metatarsal and some bony representative of a phalanx
imbedded in the innermost part of the hoof: the other toes have
the normal complement of phalanges, which, in Mammalia, do
not exceed (save in Cetacea) three in number, nor two in the
innermost digit, I, in both pectoral and pelvic limbs.

Foot of extinct

Horse

iHippurian).

310

ANATOMY OF VERTEBRATES.

The ' serial homology ' of the parts of the respective arches of
these limbs is illustrated in Vol. I. p. 188. In the limbs them-
selves, or appendages of the arches, the femur, fig. 195, a, answers
to, or is the homotype of, the humerus, fig. 190, a\ the tibia, fig.
195, u, is the homotype of the radius, fig. 190, o\ the fibula, fig.
195, 1, 2, of the ulna, s, u: the tarsus repeats the carpus, the
metatarsus the metacarpus, and the three phalanges, as respec-
tively named ' proximal,' ' middle,' and ' distal ' or ' ungual.' In
the tarsus it will be seen that the cuboid, in the ' Elephant,' fig.
193, ^, supports the two outer metatarsals, as does the unciforme
the two outer metacarpals, in the Orang and Man, fig. 191, u:

the ectocuneiform in the tarsus, ce, and

195

the

m

the

carpus.

771, re-

sj)ectively support the middle digit, iii :
the mesocuneiforme, mc, holds the
same ^ serial ' relation to .the trape-
zoides, fZ, and the ' entocuneiform,' ec,
to the ^ trapezium,' t. The bone of the
carpus, fig. 191, 5, in Man articulates
with the three innermost carpals of the
second row ; and, in the Orang, but
in a divided state, s and s', leaves a
larger share of the v\a'ist-joint with the
radius to the bone Z, and in the same
degree tends to repeat in the carpus
the position and connections of the bone
s in the tarsus : so I infer that the
carpal scaphoid and tarsal naviculare
are homotypes : the carpal lunare, fig.
191, I, answers to the tarsal astragalus,
and the carpal cuneiforme and pisi-
forme to the tarsal calcaneum, in which
bone the lever-process forming the
'heel' more immediately repeats the
pisiforme, which also in many quadru-
peds, fig. 191, j9. Hyaena, makes a 'heel-
like ' projection in the carpus.

§ 178. Special Homologies. — As that
which is engendered by a Mammal is
mammalian from its beginning, each
step of its building up has the finish-
ing of the Mammal for its end, and
shows it the more as it nears the goal. The developemental phe-

Boncs of liind-limh, Horse

OSSEOUS SYSTEM OF MAMMALIA. 311

nomena of the head neither supersede nor can supply the better
evidences of homology afforded by relative position and connec-
tions any more than do those of the foot. The cannon-bone of
the ox is developed from three terminal and two middle centres
of ossification ; but embryology does not show which of these
signify bones distinct in other Mammals : it is neither here nor
elsewhere the criterion of homoloixy- Iii the foreo-oinoc account
of the Mammalian modifications of the Vertebrate skeleton, the
general and serial homologies are given, as determined in my
work on the Vertebrate Archetype. But as a few of the special
homologies of cranial bones are still unaccepted by fellow-labourers
in this field of anatomy, I offer the follomng remarks in excuse
for the retention of my opinions on such moot-points.

To rightly determine the cranial bones in Mammals, as in
Birds, we must pass to their investigation from the previously
determined bones in the skull of an inferior Vertebrate. Thus,
placing the skull of a young Ostrich or Apteryx, showing the
sutures, by the side of that of the Ioav, bird-like Monotreme
{Echidna,^g. 197), we find that the transversely extended, medially
notched occipital condyle, in the Bird, fig. 27, has become bisected
or divided into two in the Mammal, fig. 202 ; each moiety being
developed wholly (^jEchicbia) or in great part (some Cetacea) from
the exoccipital, 2. The basioccipital either wants, or developes
only the lower end of, the divisions of the occipital condyle. The
exoccipital, in most Mammals, sends ofFa ^paroccipital ' process, 4, as
in Birds. The basi-, ex-(2), and super-(3)occipitals coalesce into one
bone, but rarely are fused, as in Birds, with the sense-capsule and
segment in advance. The basisphenoid, fig. 202, 5, differs from that
of the Bird, figs. 27, 32, in not being coossified with the presphenoid,
9 : laterally it contributes to form part of the otocrane and tym-
panum, in advance of which it articulates with the alisphenoid, figs.
196, 197, 6. In the Echidna a bone, fig. 197, 8, coossified with or
anchylosed to the outside of the petrosal, expands beyond it to arti-
culate with the ex-(2) and super-(3)occipitals, with the parietals, 7,
and the alisphenoids, 6. This bone, in many other Mammals, deve-
lopes a ' mastoid ' process, as in Birds : it is developed, as in them,
in and from the lateral cranio-cartilage enveloping the otic capsule :
it is plainly the homologue of 8 in the Bird, fig. 196. Between 8 and
6 in Echidna there is a vacuity in the bony .skull. The parietal, 7,
is relatively larger, the frontal, ii, is smaller, than in the Bird.
The nasal, 15, is simply elongate, in Echidna as in Rhea, : it does
not bifurcate anteriorly by sending down a maxillary prong or pro-
cess as in the Ostrich, fig. 196, 15, and most Birds : but it is longer

312

ANATOMY OF VERTEBRATES.

and articulated, or is united, throughout its length, with its fellow
in the Mammal. The premaxillary, 22, is correlatively shorter in
the Mammal, not medially confluent nor sending off a nasal process
from the symphysis, as in the Bird. The maxillary, 21, is larger,
and the nasal process, of which the beginning is shown in
Struthio, is a broad and high plate in Echidna and most other
Mammals. The hind part of the maxillary unites with a malar,

196

Skull of Ostrich.

fig. 197, 26, styliform in Echidna and some Bruta, as it is in Birds,
fig. 196, 26. The bone, 27, articulates with 26, but expands in
Echidna, as in Chelonians, as it extends backward, and applies

Skull of Ecliidna.

itself, in most Mammals, to close the gap in the side-wall of the
cranium left between 8 and 6, before articulating with the tym-
panic, 28 : it also developes the articular surface for the mandible,
29-32. This is one of the marked modifications of the squa-
mosal in the Mammalian class. The retroduced part or append-
age of the upper jaw again affords the joint to the lower jaw, as in
the Plagiostomous Fishes : but the common pedicle, 28, is reduced

OSSEOUS SYSTEM OF MAMMALIA. 313

in the Mammal mainly to the support of the ear-drmn, the accessory
function with which it is charged wholly or in part in all air-
breathing Vertebrates.

Remove 27 and 28 from the cranium of the Bird and Monotreme,
as in figs. 196 and 197, and the homology of the remaining cranial
bones, especially of 2, 3, 8, 6, is unmistakable. The mastoid, 8,
in both Bird and Monotreme, is developed from cartilage ; arti-
culates posteriorly with 2, 3, superiorly with 7, anteriorly with 6 ;
coossifies internally with the petrosal, and gives attachment
inferiorly to the bone, 28, which supports wholly or in part the
^ membrana tympani.' The squamosal, 27, is a backward prolon-
gation of the bar, 2fi, attaching the upper jaw to the tympanic; it
is developed in the embryonal scaffolding external to the proper
cranial cartilage ; it articulates posteriorly Avith the tympanic,
28. It forms no part of the outer wall of the cranium in Birds,
and is equally excluded from that cavity in Cetacea, fig. 198, in
most Ruminants, fig. 140,
and in many Rodents : the
supplementary function
of completing such cra-
nial wall is peculiarly
mammalian, and does not ^^JLc '-i^ '^
supersede the share taken ^^%X^J^-1
in such lateral wall by ^^ ^'

* Section of cranium, Porpoise.

8 and 6, ni all Verte-

brates. Moreover, 27 constitutes the hinder and major part of
the zygomatic arch in both Birds and Mammals, as in most Rep-
tiles ; with such homologically unimportant modifications of shape
as are exemplified in the Turtle and Crocodile (Vol. I. figs. 91
and 95, 27), and in the figures 26, 140, 196, 197, 27, of the present
Volume.

The bony pedicle wdiich suspends the mandible to tlie side-
processes of the cranium, is that which is marked 28 in the Fish
(Vol. I. figs. 81, 84), the Serpent(figs. 96, 97), the Tortoise (figs. 91
and 92), and the Crocodile (figs. 93, 95). As those side-processes
are homotypes of the transverse processes (par- di-apophyses) of the
trunk-vertebrge, so 28 bears the same serial relation to the ' pleura-
pophyses,' the mandibular rami completing ' hajmapophysially ' the
inferior or haemal arch of the cranial segment. This vertebral
character is shown in tlie developement of the Vertebrate skull :
the simple rib-like cartilage formed in the second (counting back-
ward) of the embryonal, ' visceral,' or haemal arches, manifests
always its upper or ' pleurapophysial ' and its lower or ' hajmapo-

314 ANATOMT OF VERTEBRATES.

physial ' portions : and these are more equal in length in Birds and
Hoimatocrya than in Mammals ; for the embryo of a highly modi-
fied and advanced class early shows the characters of its class,
which become deceptive when exclusively used as a light to
general vertebral homologies. The true guide to the homology
of 2S is its articular connections to one or more cranial diapo-
I)hyses: in Fishes and Crocodiles, e.g., to the post-frontal and
mastoid, in Lizards and Snakes to the mastoid, in Birds to the
mastoid and paroccipital, in Mammals to the mastoid. The con-
nection witli the squamosal is later and supplementary in the
Vertebrate series.

The tympanic pedicle undergoes various and extreme modifi-
cations in relation to the functions, as various, allotted to the
second ha3mal arch (counting backward) in the head. In Fishes,
much of the mechanical part of the respiratory functions is performed
by the ' tympano-mandibular ' arch : hence the length, subdivision,
and resultant elasticity of the suspensory piers or pedicles. In
air-breathing HcBmatocrya the branchial duty ceases; but a special
organ of sense, claiming more direct relation Avith the air, presses
the tympanic pedicle into a service unknown to it in the water-
breathers. In Chelonia, fig. 91 (Yol. I.), the tympanic, 28, is
developed to form a frame for the ear-drum, and it contributes
more or less of that frame in Crocodiles, Lizards, and Birds : it
has least concern with the tympanum in Serpents ; and, as these
are exclusively air-breathers, 28 is restricted to its function of
suspending the mandible, and retains most of its simple rib-like
form as it descends from the lengthened diapophysis, 8, fig. 97
(Vol. I.) to the dentigerous hajmapophysis, si. The proximal arti-
cular end of the tympanic may have a double condyle, as in some
Fishes and Birds, a single condyle, as in Lizards and Serpents, or a
sutural margin for fixed junction, as in Chelonia, fig. 91, 28, and
Crocodilia, fig. 95, 28. Such is its mode of articulation in all Mam-
mals, in which class it manifests its extreme simplicity of function
and reduction of size. To the ear-drum, which it sustains, is
articulated, in Birds, a columelliform ^ stapes,' by the intermedium
of a cartilage ; and in Monotremes and Marsupials, fig. 197, f/, by
the intermedium of a bone, c. This ossicle in higher Mammals is
divided into ^ incus ' and ' malleus,' Avhich, like the columelliform
* stapes' in Birds and Reptiles, is developed, as in fig. 444, B, e
(Vol. I.), in connection with, but not like the tympanic (r/) and
mandible in and from, the peripliery of the primary ' visceral '
or haemal cartilaginous arch, called, from its discoverer, ^ Meckel's
cartilage.'

Skeleton of the Ornltliorhyiiclius.

LXXXI-.

316 ANATOMY OF VERTEBRATES.

Having premised so much in reference to tlie Mammalian
skeleton generally or typically, its main modifications as exem-
plified in the several orders of the class, will next be noticed.

§179. — Skeleton of Monotremata. — A. Vertebral Column. — The
principal osteological characters of this order are: — The extension
of the ' coracoid,' fig. 199, 52, o, as in Birds and Lizards, from the
scapula, 51, to the sternum, 5, and anchylosing at full growth with
the scapula, as at G, fig. 199 ; the epicoracoid, ib. n, as in Lizards ;
the marsupial bones, ib. x, x ; the supplementary tarsal bone,
ib. d, supj)orting the perforated spur, e, in the male ; the long
persistence of distinct pleurapophyses, j)l, in the vertebra dentata.
Both the genera have twenty-six ' true vertebrae,' of which
^^Q seven are cervical ; but the Ornithorhynchus

has seventeen and the Echidna sixteen dor-
sals, the lumbar vertebrie being three in the
latter, and reduced to the lacertian number
two in the Ornithorhynchus.

The intervertebral substance is dense and
fibrous at its periphery, fig. 200, a, but the
fluid central part, h, fills a more definite
cavity in the Echidna than in higher Mam-
mals. '
Lumbar rertei.ras, inter- Jn thc dorsal vcrtebrffi thc ucrvcs perforate

A-ertebral cavities, Efliidua. '■

the neurapophyses ; but escape, as usual, at
their intervals in the cervical and lumbar regions. The dorso-
lumbar neural spines are short and subequal, fig. 201. The
ribs of the first six dorsals have ossified sternal portions which
articulate with the sternum ; in the succeeding vertebrae to the
fifteenth the sternal portions are cartilaginous, expanded, and
overlap each other, fig. 199 ; the last two pairs of ribs termi-
nate freely. Most of the vertebral ribs articulate over the in-
terspace of their own and the antecedent centrum ; a small
tubercle defines the neck of the rib, save in the last four ; but,
save in the first and second, does not articulate with the dia-
pophysis. The first dorsal pleurapophysis is broad, the others
are cylindrical and slender ; cartilage is interposed between the
bony pleur- and hajm-apophyses of the anterior dorsal vertebra,
as in the Crocodile. The sternum consists of four bones in
Ornithorhynchus, and of five in Echidna, The first, fig. 199, s,
is an unusually expanded ' manubrium,' receives the hasmapo-
physes of the first and second ribs, and supports a large T-shaped

' 1.XXTX-. p. 375.

SKELETON OF MONOTREMATA.

317

episternum, ib. t. The sacrum consists of two vertebras in
Ornithorhynchus, and of three in Echidna.

There are thirteen caudal vertebrae in the Echidna, fig. 201.
The first is the largest, with broad transverse processes, the rest
progressively diminishing, and reduced, in the six last, to the

201

^-^5^>^S:~

^'^N.^

Skeleton of Echidna. Lxxrii.

central element. The Ornithorhynchus, fig. 199, has twenty-one
caudal vertebrae, of w^hich all but the last two have transverse
processes, and the first eleven have also spinous and articular
processes. The pleurapophysial parts of the transverse processes
are distinguishable in half-grown animals. The transverse pro-
cesses are broad and depressed ; they gradually increase in length
to the tenth caudal, then as gradually diminish to the twentieth ;
their extremities are expanded, and, from the fifth backward, are
thickened and tuberculate. The spinous processes progressively
diminish in height from the first caudal. Hypapophyses are
developed from the bodies of the third to the nineteenth caudal
vertebra inclusive ; but there are no hiemapophyses articulated to
the vertebral interspaces, as in many Marsupials. In the Echidna
hypapophyses are absent ; but rudiments of hnemapophyses are
connected with the interspaces of one or tAvo of the middle ver-
tebrae of the tail. The caudal vertebrae in the Ornithorhynchus
are of nearly the same length to the tAvo last ; they progressively
diminish in vertical diameter as they recede from the trunk, and
are chiefly remarkable for their breadth and flatness ; resembling
in this respect the caudal vertebra? of the Beaver and of the
Cetacea ; the horizontally extended tail having a similar relation

318

ANATOMY OF VERTEBRATES.

to the frequent need which an aquatic animal with hot blood and
a quick resj^iration of air has to ascend rapidly to the surface of
the water.

The cervical vertebra?, fig. 186, have short and broad centrums
confluent with neurapophyses ; the former developing a par- the
latter a di-apophysis : the pleurapophysis,7>/, is short and broad, and
circumscribes the ' vertebrarterial ' canal by junction with both the
transverse processes : which joints in the last five cervicals are
obliterated earlier in Ornithorliynchus than in Echidna. In the
latter not any of the cervicals have zygapophyses save the atlas.
The true centrum of this vertebra supports a great part of its neural
arch, and long continues distinct from that of the axis : it has a long
' odontoid ' process. The lower part of the ring of the atlas sends
off" in Oniithorhynchus a pair of long divergent hypapophyses.

B. Skull. — The skull in both genera of Monotremata is long
and low, but characterised by a relatively larger cranium in pro-
portion to the face than in most Marsupials. The parietes of
the exjDanded cerebral cavity are rounded, and their outer surface

smooth. These characters

202

Base view of partially disarticulated cranial
segments. Echidna. Lxxix'.

lower part of each condyle, 2, 2 :

IS

are most conspicuous in the
Echidna, in which the jaws are
slender, elongated, and gradu-
ally diminish forward to an ob-
tuse point, so that the whole
skull resembles the half of a
pear split lengthwise. The facial
angle of the Echidna is 36°, that
of the Ornithorliynchus 20°,
being almost the lowest in the
mammiferous class. The cra-
nial bones and their constituent
pieces continue longer distinct
in the Echidna than in the Or-
nithorliynchus, in which they
ultimately coalesce to a degree
resembling that in Birds.

In the Echidna the basiocci-
pital, fig. 202, 1, is flat and
hexagonal, with the hind-border
notched to complete below the
laro-e vertical ^ foramen mao;-
num,' and contributing to the
these are large and formed chiefly

SKELETON OF MONOTREMATA. 319

by the exoccipitals,fig. 203, 2,2, which are separated above the fora-
men magnum by a notch, ck^sed by membrane, in the recent state.
The superoccipital, ib. 3, is a transversely oblong quadrilateral
plate, articulated by ' harmonia,' not only with the exoccipitals,
but Avith the large mastoids, 8, and anteriorly with the parietals,
fig. 197, 7. The basisphenoid, fig. 202, 5, supports laterally a
pair of alisphenoids, fig. 197, 6, w^hich are notched posteriorly by
the trigeminal nerves, and expand as they rise to articulate mth
the parietals, 7, the mastoid, 8, and anteriorly with the orbito-
sphenoid and frontal, 1 1 . The mastoid, 8, is chiefly conspicuous by
its great size, in the Echidna, and the share Avhich it takes, con-
jointly with the petrosal, in the formation of the lateral, lower and
posterior parts of the cranial cavity : in this character it retains
much of its ornithic condition, fig. 196, s. The small vacuity,
left in the Monotreme, between the mastoid and alisphenoid, is
closed by the application thereto of the posteriorly expanded squa-
mosal, fig. 197, 27. The pre- 203
sphenoid, fig. 202, 9, is con-
nate with orbitosphenoids, fig.
197, 10, pierced by the small
optic nerves : the frontals, 1 1 ,
expand as they rise, but with-
out developing superorbital
ridges, and meet at a toothless
suture along the middle of the
narrow forehead. The vomer

, f, , 1 • n Occiput of Echitlua. lxxix'.

and preirontals are chieny

remarkable for their connection with enormous and obscurincr tur-
binals, supporting an olfactory organ of vast extent. The anterior
part of the frontals is largely overlapped by the bases of the nasal
bones, which encroach upon the interorbital space. These, fig.
197, 15, receive the upper edge of the maxillary into a groove at
their outer margin, and articulate anteriorly with the premaxil-
laries, ib. 22, which meet above the nasal canal in front of the nasal
bones for an extent of about three lines, and thus exclusively
form the boundary of the single, oval, and terminal external
nostril. The lower or palatal process of the premaxillary
extends backward in the form of a long and slender pointed
process which is wedged into a fissure of the maxillary. The
incisive fissure is narrow and extends from the premaxillary
symphysis some way between the palatine plates of the maxil-
laries. The palatines, fig. 202, 20, arc long and entire Avliere
they form the hinder half of the roof of the mouth, diverging

320

ANATOMY OF VERTEBRATES.

posteriorly to form the narrow median nasal opening. The
roof is continued by the pterygoids, ib. 24 and 16^, which articu-
late, as in many Birds, with the tympanic, e, 28, and the basi-
sphenoid, 5. Another mark of ornithic affinity is the confluence
of the malar and squamosal, fig. 197, 27 : unless the slender pro-
cess of the maxillary, ib. 26, may represent the malar. The
tympanic cavity is excavated in the petromastoid and partly
closed by the slender tympanic, fig. 202, 28, e, which sends for-
ward a short homologue of the orbital process of that of the
bird: about three-fourths of the ear-drum are attached to the
tympanic, and one-fourth to the mastoid : the plane of the drum
is nearly horizontal and looks downward. The ' stapes ' is colu-
melliform, fig. 197, d\ one crus of the incus anchyloses with the
reduced tympanic at 0 ; the other is confluent with the malleus, c.
The lower jaw consists in the Echidna, fig. 197, 29-32, of two
long and slender styliform rami without a symphysial joint, but
loosely connected together at their anterior extremities. An
angular process, so, divides the horizontal from the ascending

204

Skull of Ornithorhynchus, half natural size. Lxxxi'.

ramus, which rises at an open angle and terminates in a small
oblong convex condyle, 29. A short obtuse coronoid process, 3i,
extends from the upper part of the horizontal ramus as far in
advance of the angle as the condyle is behind it. The rest of
the ramus is rounded like a rib, and diminishes to the anterior
extremity. The dental canal commences below the coronoid pro-
cess and divides in its progress, one branch terminating near the

SKELETON OF MONOTREMATA .

321

middle of the smooth alveolar border, the other close to the end
of the ramus. In no mammiferous ammal does the lower jaw
bear so small a proportion to the skull or to the rest of the
skeleton as in the Echidna.

In the Ornithorhynchus the lower jaw, fig. 204, E, is much
more developed. Each ramus commences posteriorly by a large
convex condyle. The ascending ramus is nearly horizontal,
flattened below, and continued upward in the form of a low
vertical compressed plate, on each side of which there is a deep
fossa. The ascending is continued by a gentle curve into the
horizontal ramus, and the angle of the jaw is very feebly in-
dicated. The horizontal ramus suddenly expands and sends off
above in the same transverse line two short obtuse processes, both
of which might be termed ^ coronoid ; ' this structure is peculiar
to the Ornithorhynchus. The innermost process, c, although
the largest, is the superadded structure, as it affords insertion to
the internal pterygoid. The socket, d, e, for the horny grinder,
is shalloAv ; its floor is perforated by several large foramina. The
dental canal divides ; one branch opens by a wide elliptical fora-
men on the outside of the ramus immediately anterior to the
alveolus, the other terminates at the lower part of the end of the
ramus. The rami of the jaw converge and are united at a sym-
physis of more than half an inch in length ; there they become
expanded and flattened, then again disunite, and are continued
forward as two spatulate processes, b, which diverge from each
other to their broad rounded terminations,
and are situated just behind the inflected
extremities of the similarly separated pre-
maxillaries, ib. A, and fig. 205, 22. On the
outer sides of the upper surface of the
broad symphysis are the long and narrow
sockets of the two anterior trenchant horny
teeth. The Monotremes diflfer from the
Marsupials in the absence of the inflected
process developed from the angle of the
lower jaw.

The exoccipitals, fig. 205, 2, h, and
superoccipital, ib. 3, are separate in the
skull of the young Ornithorhynchus liere
figured of the natural size. The mastoid,
ib. e, e, contribvites to part of the occi-
pital surface, and advances anteriorly to the small cranial expan-
sion of the squamosal at /. This expansion does not exceed

VOL. II. Y

205

Skull of young Ornithorliynchus,
iiat. size.

322 ANATOMY OF VERTEBRATES.

in size the glenoid process, which it meets at a right angle, and
from the union of which the zygomatic process is continued for-
ward to join the malar process of the maxillary : there is no dis-
tinct malar bone. The parietal, ib. 7, is long and large, undivided
by a sagittal suture, from the place of which a bony falx is
developed internally, fig. 204, b. The frontals are small, and in
fig. 205, h, h, retain the frontal suture. The nasals, ib. 7i, n, are
long and large : they contribute to the rim of the orbit, and form
the posterior half of the large bony nostril, p. The maxillary, ib.
m, 2£iQv sending off a process which curves over the antorbital
foramen, extends forward, diverging from the nasal to form the
angular fissure which receives the premaxillary, o, 22. Each of
these bends inward at the anterior extremity, but is separated
by a wide space. There is a small prenasal ossicle at p, fig. 205,
and Z>, fig. 204, a. The vomer forms a bony vertical septum
dividing the nasal cavity from the presphenoid forward. The
palatine plate of the maxillary, fig. 204, a, 21, is pierced by large
oblique canals for the transmission of palatine branches of the
trigeminal nerve. The bony palate is continued backward entire
between the large shallow alveoli, ^, h, of the upper horny molars
to the posterior nostrils, i, which resemble those of the Crocodile
in their backward position. The sutures defining the palatines
and pterygoids are soon effaced.

The Ornithorhynchus differs from the Echidna in the large
vacuities behind and in front of the tympanic cavity, the one
representing the combined jugular and precondyloid foramen, the
other the foramen ovale. The notch above the foramen magnum,
fig. 204, c, is better defined ; as is also the orbit.

There is a small lacrymal foramen at the anterior and inner
part of the orbit in both the genera of Monotremes ; a little
loAver down is the commencement of the antorbital canal. This
canal branches in the Echidna, and terminates on the outer side
of the maxillary bone by a succession of small foramina ; but in
the Ornithorhynchus, Avhere it transmits a much larger sensi-
tive nerve, it divides into three canals, of which one emerges
beneath the uncinated process of the maxillary above mentioned ;
a second descends and opens upon the palate ; and the third
passes forward into the substance of the facial fork, and termi-
nates by a large foramen at the outside of the premaxillary bone.

On the exterior of the cranium the ridj^es indicatino^ the extent
of the temporal muscles are clearly developed in the Ornitho-
rhynchus, and correspond with the stronger zygomata and the
more complete apparatus for mastication in this Monotreme.

SKELETON OF MONOTREMATA. 323

Four linear impressions upon the upper surface of the skull
diverge from the middle of the lambdoidal ridge, and terminate
at the temporal ridges.

The interior of the skull oflPers many unusual modifications.
The sella turcica is elongated and narrow in both Monotremes ;
it is bounded by two very distinct lateral walls in the Echidna.
The posterior clinoid processes are chiefly remarkable for their
height in the Ornithorhynchus. The semicircular canals stand
out in high relief in this species, as in Birds. In the Echidna
the olfactory capsule encroaches upon the anterior part of the
cranial cavity in the form of a large convex protuberance, and a
very extensive cribriform plate is developed. In the Ornitho-
rhynchus the olfactory tract is comparatively small in the form of
a depression, and the nerve escapes by a single foramen in the
prefrontal : this is likewise an interesting mark of affinity to the
Bird and Reptile. But the most remarkable feature in the interior
of the skull of the Ornithorhynchus is the bony falx, fig. 204, b.
This is not present in the Echidna. The tentorium is mem-
branous in both Monotremes.

C. Bones of the Limbs. — The scapulcB, fig. 199, G and 51, are
compressed curved plates, vertical in position, like the other
pleurapophyses : they have coalesced with their hajmapophyses,
the coracoids, 52 and G, o, which articulate below to the expanded
ha3mal spine, called ^ episternum,' t, and also with the succeeding
spine, called ' manubrium,' s, or first bone of the true sternum.
A dismemberment of the coracoid, n, extends its attachments also
to the elongated T-shaped episternum.

The whole scapula is broader, thicker, and less curved in the
Echidna, fig. 201, 5i, than in the Ornithorhynchus. In both
Monotremes, the posterior margin or costa is concave, most so in
the Ornithorhynchus, and in both it is turned toward the trunk,
so that the subscapular surface looks obliquely forward and
inward. The articular surface is divided into two facets : the
one, internal and flat, articulates with the coracoid ; the other,
external, is slightly concave, and contributes, with a similar but
narrower concave surface of the coracoid, to form the glenoid
cavity for the humerus.

The coracoid, fig. 199, G, o, and 52, early coalesces with the
scapula in the Ornithorhynchus ; it maintains its independent
condition to a later period in the Echidna. In both it is a strong,
subcompressed, subelongate bone, expanded at both ends : one of
these is articulated and anchylosed with the scapula, as above
described ; the other is joined to the anterior and external facet

Y 2

324 ANATOMY- OF VERTEBRATES.

of the manubrium stferni. The posterior margin of the coracoid
is concave and free; thfe'an^rior- margin is straight and articu-
lated with a narrower ' epicoracoid ' in the Echidna than in the
Ornithorhynchus.

The clavicles, fig. 199, m, m, are two curved styles, extending
from the acromion along the transverse bar of the episternum, t.
The humerus, ib. 53, is remarkable for its shortness and breadth,
especially of its two extremities. There is a small sesamoid os-
sicle, above the internal tuberosity, answering to the ' os humero-
capsulare ' in the shoulder-joint of Birds (p. 67). The proximal
expansion terminates by a broad thick convex border, the middle
part of which is developed into the articular head, which is so
adapted to the glenoid cavity, that the bone is maintained in a
horizontal position, and the distal expansion is nearly vertical.
The deltoid and pectoral crests are strongly developed ; both
condyles are remarkably produced, especially the internal one,
which is perforated, fig. 199, H, a. The distal articular surface
scarcely occupies a fourth part of that broad termination of the
humerus: it presents, in the Echidna, fig. 201, 5.3, a convex
tubercle, which is broadest in front for the articulation of the
radius, narrow behind for that of the ulna. The articular sur-
faces of both antibrachial bones are concave : so that the elbow-
joint admits freely of flexion and extension, abduction and adduc-
'tion, but is restricted in the movement of rotation.

The radius, fig. 199, 5 4, and ulna, ib. 55, are in contact and
pretty firmly connected together through nearly their whole ex-
tent; the interosseous space being reduced to a slight fissure.
The ulna is chiefly remarkable for the olecranon, fig. 199, I, u,
which is bent forward upon the humerus, and transversely ex-
panded at its extremity, especially in the Ornithorhynchus, in
which the lower or inner angle of the expanded extremity is con-
siderably produced. The shaft of the ulna is compressed, and
increases in breadth, in the Echidna, as it approaches the broad
carpus. In the Ornithorhynchus it is bent like the italic f, is
more cylindrical, and more suddenly expanded at the distal end.
The radius offers little worthy of notice, except that in the Orni-
thorhynchus it is flattened next the ulna, and so applied to that
bone as to prevent altogether a rotation of the hand upon the
ulna. In the Echidna the distal articular surface of the ulna,
fig. 207, n, presents two convex trochlege separated by a median
concavity ; that of the radius, ib. r, oflPers a reverse condition ;
here two concavities are divided by a median convex ridge : all
the four facets at the carpal joint of the antibrachium are in the

SKELETON€6WTlMOlf^W|f^E*5«|A. 325

; NEwyqefc ' . J.

same transverse line. Th4'^^,ypraaial .ii^l^^jfities receive the two
articular convexities of tlie broifai^^^^j^^ffiiar bone, fig. 206, « ;
the two convex trochleas of the ulna play upon two concavities,
one-half of each of w^hich is contributed by the cuneiform, ib. h,
and pisiform, c. This complicated joint limits the movement of
the hand upon the fore-arm to flexion and extension.

Notwithstanding the confluence of the scaphoid with the lunar
bone in the carpus of the Echidna, as in that of the Marsupials
and Carnivora, it includes eight ossicles, a small sesamoid bone,
^g. 206, X, being developed in the tendon of the flexor carpi
radialis, and articulated with the scapholunar bone, a, and
radius. The distal series of the carpus includes the four nor-

206

207

Bones and claws of the fore-foot. Echidna, anconal aspect.

Bones of the fore-foot.
Echidna, palmar aspect.

mal bones, the trapezium, ib. d, supporting the innermost digit
or pollex, the trapezoides, e, the index, the os magnum, f, which
is almost the smallest, sustaining the medius, and the unci-
forme, g, the two outer digits : in the Ornithorhynchus the os
magnum contributes a greater share to the articulation w4th the
rino;-fino:er.

In the Echidna all the bones of the fore-extremity are rela-
tively larger and stronger than in the Ornithorhynchus, but this
diiFerence is especially remarkable in the metacarpals and two
first rows of phalanges, fig. 206, h, i, k, which are singularly
short, broad, and thick. The palm is strengthened by two large
sesamoids developed in the flexor tendons; these are sometimes

326

ANATOMY OF VERTEBRATES.

confluent, fig. 207, /. The number of phalanges in both Mono-
tremes is the same as in other Mammals, viz. two to the thumb
and three to each of the fingers. This is not the case in any-
Saurian, and the retention of the Mammalian type at the peri-
pheral segment of the limb, with the singular deviation from it
at the central supporting arch, is not one of the least remarkable
points in the osteology of the Monotremes.

There is a sesamoid bone at the palmar aspect of each of the
distal articulations of the phalanges in the Echidna, fig. 207, m,
and at all the digital articulations in the Ornithorhynchus, fig.
199, H, d. The ungual phalanges are long, depressed, nearly
straight, of great strength in the Echidna, in which each of them
is perforated at the palmar aspect, fig. 207.

The pelvis of the Monotremes bears a resemblance to that of
Reptiles in the length of time during which the three components

of each os innominatum remain
^^® distinct, especially in the Echid-

na ; and in the great develope-
ment of the ilio-pectineal spine,
which equals in size that of the
Tortoise, in the Ornithorhyn-
chus : the pelvis of the Echidna
resembles that of Birds in the
perforation of the acetabulum,
fig. 208,^ ; but the pelvis in both
Monotremes chiefly resembles
that of the higher Lyencephala
in the presence of the marsupial
bones, ib. e, fig. 199, x.

The ilium, figs. 199, 208, 62,
is a short, strong, trihedral bone,
"\vith the upper extremity ex-
panded and everted in the Ornithorhynchus : the ischium, ib. 63,
has its tuberosity prolonged backward in an obtusely-pointed
form: t\iQ pubis in the same animal, besides having the spinous
process directed forward, gives off' a second smaller process, which
projects outward; this process is present, but less developed, in
the Echidna, fig. 208, 64. The pubis and ischium contribute an
equal share to the formation of the foramen obturatorium, ib. h,
and to the symphysis, d, which closes the pelvis below.

The marsupial hones, fig. 199, x, x, 208, e, are relatively larger
and stronger in the Monotremes than in the ordinary Marsupialia,
the Koala excepted ; their base extends along the anterior margin

Internal view of pelvis, Echidna.

SKELETON OF MONOTREMATA.

327

of the pubis from the symphysis outward to that of the spinous
process : they are relatively longer in the Echidna than in the
Ornithorhynchus ; they always remain moveably articulated with
the brim of the pelvis.

The femur, fig. 199, 65, is short, broad, and flattened ; its head
rises, like that of the humerus, from the middle of a broad ex-
panded proximal end, having on each side a strong process, the
outer one representing the great, the inner one the small, tro-
chanter. In the Echidna a projecting ridge extends from the
great or outer trochanter beyond the middle of the bone ; the
whole of the inner part of the shaft is bounded by a trenchant
edge ; both outer and inner margins of the bone are trenchant in
the Ornithorhynchus. The distal end of the femur is expanded
transversely, but compressed from before backward. The rotular
trochlea is flat transversely, convex vertically, in the Echidna ; it
is hardly definable when the cartilage is separated from the bone ;
but the patella itself is well developed, and ossified in both
Monotremes, fig. 199, />.

The tibia, ib. 66, is straight in the Echidna, but bent, with the
convexity next the fibula, in the Ornithorhynchus ; its cristoe are
slightly marked.

209

The fibula is slightly bent
in the Echidna, fig. 201, 67,
but is straight in the Orni-
thorhynchus, fig. 199, 67 ; in
both Monotremes it is longer
than the tibia by the extent
of a process, ib. v, which
rises upward beyond the
proximal articulation of the
fibula, and strongly expresses
the homotypal relation of
this bone with the ulna:
this process reaches halfway
up the back of the femur in
the Ornithorhynchus, and,
like the olecranon, is greatly
expanded at its termination.

The tarsus, figs. 209, 210,
consists of a naviculare, a,
astragalus, b, a calcaneum, c,
three cuneiform bones, d, e, f, and a cuboid, g, in the Echidna ;
but the cuboid in the Ornithorhynchus is divided into two bones.

Bones and claws of tlie liind-foot, rotular aspect,
Echidna.

3-28

ANATOMY OF VERTEBRATES.

210

as in some Keptiles, one for the fourth and the other for the fifth
metatarsals. In both Monotremes there is a sesamoid bone, fig.
209, *, placed at the interspace between the astragalus and the
naviculare; a second supernumerary bone, ib. **, is articulated
to the posterior part of the astragalus, and supports the per-
forated spur Avhich characterises the male, sex, fig. 199, K, d, e.
The calcaneum of the Ornithorhynchus, cl, terminates by sending
outward a short obtuse tuberosity ; in the Echidna this part is
more slender, and is singularly directed inward and forward
nearly in a line with the digits, fig. 210, c.

The astragalus in the Ornithorhynchus presents a double
trochlea above for the tibia and fibula, and a depression on its
inner side, which receives the incurved mal-
leolus of the tibia, almost as in the Sloths.
The toes have the same number of bones
as in other Mammals ; their size and form
are more alike in the two Monotrematous
genera than those of the fingers : the un-
gual phalanges, like the claws they support,
are more curved than those on the fore-foot,
but like them they are perforated on their
inner and concave side, fig. 210.

§180. Skeleton of Mar supialia. — A. Ver-
tehral Column. — The number of ' true ' ver-
tebra3 is the same in all the Marsiqnalia,
viz. 20 ; that of the dorsal and lumbar series
varying according to the number of long
and free ribs, e. g. c? 12 Z 7 in Petaurists,
^15 Z 4 in Wombats, ^13 Z 0 in other genera ;
the cervicals are seven in all.
In the Koala the length of the spine of the first dorsal hardly
exceeds that of the last cervical, but in all other Marsupials the
difference is considerable, the first dorsal spine being much longer ;
those of the remaining dorsal vertebras progressively diminish in
length and increase in breadth and thickness. They slope toward
the centre of motion, which is shown by the verticality of its
spine : this, in the Perameles, is at the eleventh dorsal vertebra,
in Potoroos and Kangaroos, fig. 211, at the ninth -twelfth, in the
Petaurists at the thirteenth vertebra. In the Phalangers, Koala,
and Wombat, the flexibility of the spine is much diminished, and
the centre of motion is not defined by the convergence of the
spinous process toward a single vertebra, but they all incline
slightly backward, fig. 212.

Bones of hind-foot, plantar
aspect, Echidna setosa.

SKELETON OF MARSUPIALIA.

329

The metapophyses Avhicli begin to increase in length in the
three posterior dorsal vertebrae, attain a great size in the lum-
bar vertebrae, and are locked 'into the interspace between the
anapophyses and post-zygapophyses. The diapbphyses of the
lumbar vertebras progressively increase in length as the ver-
tebras approach the sacrum ; they are most developed in the
Wombat, where they are

directed obliquely forward. 211

In the Kangaroos, Potoroos, /; . \

and .Perameles, they are
curved forward and ob-
liquely downward. The
length of these and of the
metapophyses is relatively
least in the Petaturists,
Phalangers, and Opossums.
In the Wombat the meta-
pophysis rises suddenly from
the outside of the prezyga-
pophysis of the twelfth dor-
sal, increases in length to

Kangaroo.

the second lumbar, diminishes by degrees to the second sacral,
and is rudimental in the following sacral and caudal verte-
brae. A rudiment of the anapophysis is first discernible on the
eleventh dorsal : the process gradually increases to the last dorsal,
diminishes in the lumbar, and disappears in the last of that series.
The diapophysis, moreover, is not suppressed on the last dorsal
vertebra. The serial homology of the transverse processes of
the lumbar vertebra is here manifested in the most unequivocal
way ; both metapophyses and anapophyses coexist with diapo-
physes in the last four dorsal and the first three lumbar vertebra3.
Whether, therefore, the metapophysis or the anapophysis be the
part called ' tubercle ' by some Anthropotomists, neither of them
is, in the lumbar vertebrae, .the process named * transverse ' in
the thoracic vertebras : that process, to which the name ' diapo-
physis ' is restricted in the present work, is continued distinctly
into the lumbar region, and is there lengthened out by a super-

330

ANATOMY OF VERTEBRATES.

added ^ pleurapophysis,' which is ossified from a distinct centre in
the Wombat.

The free or thoracic ribs consist of bony pleurapophyses and
gristly hgemapophyses, acquiring bone-earth only in aged Mar-
supials : in the Wombat the six anterior pairs articulate directly
with the sternum, in the nine following the haemapophyses are
attached to one another. The pressure which the trunk of the
Wombat must occasionally have to resist in its burrowing work
may be the condition of the unusual number of bony arches of the
trunk. In the Kangaroo seven anterior pairs of ribs join the
sternum ; several of the posterior pairs terminate freely, fig. 211.

212

The sternum consists of a longitudinal series of four bones in
the Wombat, of five in the Petaurist, and of six in most other
Marsupials. The first, or ' manubrium,' is the largest ; in many
a longitudinal crest is developed from the middle of its outer
surface, which in Wombats and Phalangers is produced, and gives
attachment to the clavicles. The first pair of ribs abut upon the
anterior angles of the triangular manubrium of the Wombats, but
in Dasyures, Opossums, Petaurists, and Kangaroos, the manubrium
is compressed and elongated, and the clavicles join the produced
anterior end. The haemapophyses articulate at the interspaces
of the succeeding sternebers, the last of which supports a broad
iiat ' xiphoid ' cartilage.

The number of vertebrae succeeding the lumbar which are
anchylosed together in the sacral region of the spine, amounts in

SKELETON OF MARSUPIALIA.

331

213

the Wombat to seven, fig. 213 ; but if we regard those vertebrae
only as sacral which join the ossa innominata, then there are but
four. In the Phalangers there are generally two such sacral
vertebra3, but in the Phalangista Cookii the last lumbar assumes
the character of the sacral vertebras both by anchylosis and partial
junction with the ossa innominata.

In the Kangaroos and Potoroos the impetus of the powerful
hinder extremities is transferred to two anchylosed vertebrae. In
the Perameles there is only a
single sacral vertebra, the spine
of which is shorter and thicker
than those of the lumbar verte-
brae, and is turned in the con-
trary direction, viz. backward.

In the Myrmecobius there are
four sacral vertebra by anchy-
losis, two of which join the ilia.
In Mange's Dasyure, two sacral
vertebrae are anchylosed, but it
is to the expanded transverse pro-
cesses of the anterior one only
that the ossa innominata are
joined. The same kind of union
exists in the Viverrine Dasyure,
but three vertebrae are anchy-
losed together in this species. In
the Phalangers and Petaurists

there are two sacral vertebras. In Petaurus macrurus three are
anchylosed together, though only two join the ilium. In the Wom-
bat, fig. 213, the transverse processes of the numerous anchylosed
vertebra are remarkable for their leno^th and flatness : those of the
first four are directed outward and are confluent at their extremi-
ties ; the remaining ones are turned in a slight degree backward,
coalesce, and very nearly reach the tuberosities of the ischia:
behind these they gradually diminish in size and disappear in
the three last caudal vertebrae. The transition from the sacral
to the caudal vertebrae is here very obscure. If we limit the
sacral to the three or four which join the ilium, then there
remain twelve vertebra? for the tail. The spinal canal is com-
plete in all but the last three, which consist only of the body.
There are no haemal spines, and as only the six posterior ver-
tebrae, which progressively diminish in length, extend beyond
the posterior aperture of the pelvis, the tail is scarcely visible

Pelvis of the "Wombat.

332 ANATOMY OF VERTEBRATES.

in the living animal. In the Koala, fig. 227, the tail is also
very short. In the Ch^ropus it seems to be wanting. In one
species of Perameles I find eighteen caudal vertebra ; in another
twenty-three. In two species of Potoroo there are twenty-
four caudal vertebra, but the relative length of the tail differs
in these by one third, in consequence of the different length
of the bodies of the vertebra. In Hypsiprymnus ursinus there
are more than twenty-six caudal vertebrae. In the Great Kan-
garoo there are twenty-two caudal vertebrae. In Bennett's Kan-
garoo there are twenty-four caudal vertebrae, which are remark-
able for their size and strength. In the Phalangista vulpina,
there are twenty-one caudal vertebrae. In the Petaurus ma-
crurus I find twenty-eight caudal vertebrae, while in the Pet.
sciureus there are but twenty ; the bodies of the middle caudal
vertebrae in both these species are remarkably long and slender.
The Myrmecobius has twenty-three caudal vertebrae : in Didelpliys
cancrivora there are thirty-one ; in the Virginian Opossum there
are twenty-two caudal vertebrae. In the latter species the spinal
canal is continued along the first six; beyond these the neural
spines cease to be developed, and the body gives off, above, only
the two anterior and two posterior zygapophyses which are rudi-
mental, and no longer subservient to the mutual articulation of
the vertebrae. The transverse processes are single on the first
five caudal vertebrae, and are nearly the breadth of the body,
but diminish in length from the second caudal, in which vertebrae
they are generally the longest. In the other vertebrae a short
obtuse process is developed at both extremities of the body on
either side, so that the dilated articular surfaces of the posterior
caudal vertebrae present a quadrate figure.

In most of the Marsupials which have a long tail, this ap-
pendage is subject to pressure on some part of the under surface.
In the Kangaroo, fig. 211, this must obviously take place to a
considerable degree when the tail is used as a fifth extremity, to
aid in supporting or propelling the body. In the Potoroos and
Bandicoots the tail also transmits to the ground part of the super-
incumbent pressure of the body by its under surface, when the
animal is erect, but it is not used as a crutch in locomotion as
in the Kangaroos. In the Phalangers and Opossums the tail is
prehensile, and the vessels situated at the under surface are liable
to compression when the animal hangs suspended by the tail.
To protect these vessels, therefore, as well as to afford additional
attachment to the muscles which execute the various movements
for which the tail is adapted in the above-mentioned Marsupials/

SKELETON OF MAKSUPIALIA.

214

V-shaped bones, or haemal arches, are developed, of various forms
and sizes, and are placed beneath the articulations of the vertebrae,
a situation which is analogous to that of the neural arches in the
sacral region of the spine in Birds, and in the dorsal region of
the spine in the Chelonian Reptiles. The two crura of the
hfemal arch embrace and defend the bloodvessels, and the spinous
process continued from their point of union presents a variety of
forms in different genera. In Cook's Phalanger the hasmapo-
physes commence between the second and third caudal
vertebrae, increase in length to the fourth, and then
progressively diminish to the end of the tail ; the
penultimate and antepenultimate presenting a per-
manent separation of the lateral moieties, and an
absence of the spine, fig. 214. In the Great Kan-
garoo the spine of the first haemal arch only is simple
and elongated, the extremities of the others are ex-
panded, and in some jut out into four obtuse pro-
cesses, two at the sides, and two at the anterior and
posterior surfaces.

The cervical vertebrie, seven in number in all Mar-
supials, show usually to the last the circumscription of
the vertebrarterial foramen by confluence of a short
pleurapophysis, fig. 216, pi, with di- and met-apophy-
ses : but I have seen the pleurapophyses still unan-
chylosed in a full-grown Perameles. In Dasyures,
Opossums, Phalangers, and Perameles, the seventh
cervical has the diapophysis only : in the Kangaroos
both atlas and dentata may have the transverse pro-
cess merely grooved by the vertebral arteries : in the
Koala and Wombat the atlas presents only the per-
foration on each side of the superior arch. In the
Perameles and some other Marsupials, the neurapo-
physes of the atlas, fig. 216, n, are distinct from the '^caSf^
hypapophysis, fig. 215, h, as well as from their proper PhTSfr.
centrum, the odontoid, fig. 216, c a. In the Koala
and Wombat the hypapophysis remains cartilaginous, and the
lower part of the vertebral ring is completed, in the
skeleton, by dried gristly substance, fig. 216. In the
Petaurists, Kangaroos, and Potoroos, the atlas is
completed below by an extension of ossification from
the neur apophyses into the cartilaginous hypapophy-
sis, simulating the body, and the ring of the vertebra is for a long
time interrupted by a longitudinal fissure in the middle line, the

215

Atlas of Pera-
meles lagotis.

334

ANATOMY OF VERTEBRATES.

216

breadth of which clmiinishes with age. In all the Marsupials the
spine of the dentata is well developed both in the vertical and longi-
tudinal directions, but most so in the Virginian and Crab-eating
Opossums, fig. 217, where it increases in thickness posteriorly;
in these species also the third, fourth, and fifth cervical vertebrae

have their spines remarkably long and
thick, but progressively diminishing
from the third, fig. 218, which equals
in height and thickness, but not in
longitudinal extent, the spine of the
dentata. These spines are four-sided,
and being closely impacted together,
one behind another, must add greatly
to the strength, while they diminish
the mobility, of this part of the spine.
The structure of the transverse pro-
cesses of the cervical A^ertebrje, fig.
218, d, is also adapted to the strength-
ening and fixation of this part of the
vertebral column : they are expanded nearly in the axis of the
spine, but so that the posterior part of one transverse process

overlaps the anterior part of

Atlas, axis, and third cen'ical vertebra,
Koala.

217

218

Vertebra dentata,
Didelphys Virginicma.

Third cervical vertebra,
Didelphys Virginiana.

the succeeding. This struc-
ture is exhibited in a slighter
degree in the cervical verte-
brae of the Dasyures, Pha-
langers, and Great Kangaroo.
In the Petaurists, Potoroos,
Wombat, and Koala, the di-
rection and simpler form of the
transverse processes allow of
greater freedom of lateral mo-
tion. In the Koala and Wombat a short obtuse process is given
oif from the under part of the transverse process of the sixth
cervical vertebrae. In the Potoroos, Kangaroos, Petaurists, Pha-
langers. Opossums, and Dasyures, this process is remarkably
expanded in the direction of the axis of the spine. In the Bandi-
coots corresponding processes are observed, progressively increasing
in size, on the fourth, fifth, and sixth cervical vertebra?.

B. Skull — The form of the skull varies much in different
Marsupials, but it may be said, in general terms, to resemble an
elongated cone, being terminated by a vertical plane surface
behind, and in most of the species converging toward a point

SKELETON OF MARSUPIALIA. 3:^5

anteriorly : it is also generally more depressed or flattened than
in the placental Mammalia. The skull is also remarkable in all
the Marsupial genera for the small proportion which is devoted
to the protection of the brain, and for the great expansion of the
nasal ca\dty immediately anterior to the cranial cavity.

In the stronger carnivorous Marsupials the exterior of the cra-
nium is characterised by bony ridges and muscular impressions,
but in the smaller herbivorous and insectivorous species, as the
Petaurists, Potoroos, and Myrmecohius, the cranium presents a
smooth convex surface as in Birds, corresponding with the smooth
unconvoluted surface of the simple brain contained within, fig.
219.

The breadth of the skull in relation to its length is greatest in
the Wombat,^ Ursine Dasyure,^ and Petaurists, in which it equals
three-fourths of the length, and is least in the Perameles lagotis,
in which it is less than one-half.

The occipital region, which is generally plane, and vertical in
position, forms a right angle with the upper surface of the skull,
from which it is separated by an occipital or lambdoidal crista.
This crista is least developed in the Myrmecobius, Petaurists,
and Kan2;aroos, and most so in the

. /-x • 219

Thylacine and larger Opossums, m
which, as also in the Koala, the
crest curves slightly backward, and
thus changes the occipital plane
into a concavity for the firm im-
plantation of the strong muscles p,,.... ,.,,«.»., .magnified.
from the neck and back.

The upper surface of the skull presents great diversity of
character, which relates to the different developement of the
temporal muscles, and the varieties of dentition in the different
genera.

The extinct Nototherium offers the singular exception of an
expansion of the facial part of the skull, vertically and trans-
versely, from the orbits to the terminal muzzle.^

In the Wombat the coronal surface offers an almost flattened
tract bounded by two slightly elevated temporal ridges, which
are upwards of an inch apart posteriorly, and slightly diverge as
they extend forward to the anterior part of the orbit. In the
skull of the Virginian Opossum the sides of the cranium meet
above at an acute angle, and send upward from the line of their

> As 15 to 20. 2 As 10 to U.

^ Lxxxiir. p. 170, pi. vii.

336 ANATOMY OF VERTEBRATES.

union a remarkably elevated sagittal crest, which, in mature
skulls, is jDroportionally more developed than in any of the pla-
cental Carnivora, not even excepting the strong-jawed Hyjena.
The Thylacine and Dasyures, especially the Ursine Dasyure, ex-
hibit the sagittal crest in a somewhat less degree of developement.
It is again smaller, but yet well marked, in the Koala and Pera-
meles. The temporal ridges meet at the lambdoidal suture in the
larger Phalangistce and in the Hypsiprymni, but the size of the
muscle in these does not require the developement of a bony crest.
In the Kangaroo, the temporal ridges, which are very slightly
raised, are separated by an interspace of the third of an inch.
They are separated for a proportionally greater extent in the
Petaurists, especially Petaurus flaviventer ; and in the smooth
and convex upper surface of the skull of Petaurus sciureus, Pet
pigmceus, Myrmecobius, the impressions of the feeble temporal
muscles almost cease to be discernible.

The zygomatic arches are, however, complete in these as in all
the other genera ; they are usually, indeed, strongly developed ;
but their variations do not indicate the nature of the food so
clearly, or correspond with the differences of animal and vegetable
diet in the same degree, as in the placental Mammalia. And
this is not surprising when we recollect that no Marsupial ani-
mal is devoid of incisors in the upper jaw, like the ordinary
Ruminants of the placental series : accordingly the more com-
plete dental system with which the herbivorous Kangaroos,
Potoroos, Phalangers, &c., are provided, and which appears to be
in relation to the scantier pasturage and the dry and rigid cha-
racter of the herbage or foliage on which they browse, requires a
stronger apparatus of bone and muscle for the action of the jaws,
and especially for the working of the terminal teeth. There are,
however, well-marked differences in this part of the Marsupial
skull ; and the weakest zygomatic arches are those of the Insecti-
vorous Perameles and Acrobates, in which structure we may
discern a correspondence with the Edentate Anteaters of the
placental series. Still the difference in the developement of the
zygomata is greatly in favour of the Marsupial Insectivora.

The Hypsiprymni come next in the order of developement of
the zygomatic arches ; which again are proportionally much
stronger in the true Kangaroos. The length of the zygomata in
relation to the entire skull is greatest in the Koala and Wombat.
In the former animal they are remarkable for their depth and
straight and parallel course, as well as for their longitudinal ex-
tent, fig. 221. In the Wombat, fig. 220, they have a considerable

SKELETON OF MAKSUPIALIA. 337

curve outward, so as greatly to dimmish the resemblance which
otherwise exists in the form of the skull between this Marsupial
and the Herbivorous Kodentia of the placental series, as, e. g.,
the Viscaccia.

In the carnivorous Marsupials the outward sweep of the zygo-
matic arch, Avhich is greatest in the Thylacine and Ursine
Dasyure, is also accompanied by a slight curve upward, but this
curvature is chiefly expressed by the concavity of the lower
margin of the zygoma, and is by no means so well marked as in
the placental Carnivora. It is remarkable that this upward cur-
vature is greater in the slender zygomata of the Perameles than
in the stronger zygomata of the Dasyures and Opossiuns. In
the Koala and Phalangers there is also a slight tendency to the
upward curvature ; in the Wombat the outwardly expanded arch
is horizontal. In the Kangaroo the lower margin of the zygoma
describes a slightly undulating curve, the middle part of which is
convex downward.

In many of the Marsupials, as the Kangaroo, the Koala, some
of the Phalangers, Petaurists, and Opossums, the superior margin
of the zygoma begins immediately to rise above the posterior
origin of the arch. In the Wombat an external ridge of bone
commences at the middle of the lower margin of the zygoma, and
gradually extends outward as it advances forward, and being
joined by the upper margin of the zygoma, forms the lower
boundary of the orbit, and ultimately curves downward in front
of the antorbital foramen, below which it bifurcates and is lost.
This ridge results, as it were, from the flattening of the anterior
part of the zygoma, which thus forms a smooth and slightly con-
cave horizontal platform for the eye to rest upon.

The same structure obtains, but in a" slighter degree, in the
Koala. In the Kangaroo the anterior and inferior part of the
zygoma is extended downward in the form of a conical process,
Avhich reaches below the level of the grinding-teeth ; it is de-
veloped from the maxillary. A much shorter and more obtuse
process is observable in the corresponding situation in the Pha-
langers and Opossums.

The relative length of the facial part of the skull anterior to
the zygomatic arches varies remarkably in the different Marsupial
genera. In the Wombat it is as six to nineteen ; in the Koala as
five to fourteen ; in the Petaurus sciureus and Petaurus Bennettii
it forms about one-fourth of the entire skull ; in the Phalangers
about one-third ; in the carnivorous Dasyures and Opossums more
than one-third; in the Thylacine nearly one-half; in Perameles^

VOL. II. z

338 ANATOMY OF VERTEBRATES.

Macropus, and Hi/psiprymniis murinus, the length of the skull
anterior to the orbit is equal to the remaining posterior part ; but
in a species from Van Dieman's Land {^Hypsiprymiius myosurus,
Ogiib.), the facial part of the skull anterior to the orbit exceeds
that of the remainder, and the arboreal Hypsiprymni from New
Guinea present a still greater length of muzzle. In most Mar-
supials the skull gradually converges toward the anterior ex-
tremity ; the convergence is more sudden in the Petaurists,
especially Pet. Bennettii\ but in the Perarneles lagotis the skull
is remarkable for the sudden narrowing of the face anterior to
the orbits, and the prolongation of the attenuated snout, pre-
serving the same diameter for upwards of an inch before it finally
tapers to the extremity of the nose. In- the Koala the corre-
sponding part of the skull is as remarkable for its shortness as
it is in the Per. lagotis for its length, but it is bounded laterally
by parallel lines through its whole extent. In nearly all the
Marsupials two long parapophyses project do"svnward from the
inferior angles of the occipital region. These processes are
longest in the Kangaroos and Koala ; in the Wombat they
coexist with the true mastoids, which are of larger size, fig.
220, 8. In the Opossums and Dasyures the paroccipitals are
short and obtuse ; in Acrohates they cease to exist, but they are
present in the larger Petaurists.

The elements of the occipital neural arch remain longer dis-
tinct in IMarsupials than in most other Mammals. In the skull
of a half-grown Thylacine the basioccipital has coalesced mth
the exoccipitals, which almost meet above the foramen magnum.
The lateral sinus impresses the fore part of each exoccipital, and
then sinks into a canal which communicates or opens into the
precondyloid canal : from this another canal extends forward
through the side of the basioccipital. The superoccipital has
coalesced with the parietals and interparietal. The basisj)henoid
has coalesced mth the alisphenoids and the presphenoid, but
not with the pterygoids : it has no ' sella ' nor clinoid processes :
it is perforated by the entocarotid at its back and outer angle :
the canals converge forward and slightly upward, and terminate
above the middle of the basisphenoid. The alisphenoids have
the foramen ovale near their posterior borders : the foramen
rotundum is a longer canal. The posterior angles of the ali-
sphenoid expand into tympanic bullae: pterapophyses are sent
oif in advance which join both pterygoids and palatines. The
parietals have coalesced with each other, with the frontal, mth
the interparietal, and the superoccipital. The orbitosphenoids

SKELETON OF MARSUPIALIA. 339

are very small ; their coalesced bases arch backward over the
optic nerves and presphenoidal prolongation of the basisphenoid,
as in the bird, and their under part is grooved (not perforated) by
the optic nerves, which escape by the fissura lacera anterior.

The nasal portion of the coalesced frontals is more expanded
than the cerebral one : the frontal sinuses extend to the coronal
suture and raise the outer far above the vitreous table : in this
table the frontal and coronal sutures remain, but they are obli-
terated in the outer table. The vomer is carinate below. The
nasals are distinct from each other and from the frontals : they
are grooved externally for the premaxillaries. The petromastoid,
tympanic, and temporal bones continue permanently separate,
though confluent ossification proceeds to blend the occipital,
parietal, and frontal into one bone. The petrosal is small, its
tentorial ridge or angle is sharp, and its cerebellar fossa very
deep, though small : a branch of the lateral sinus perforates the
petromastoid and the adjoining part of the temporal to open
behind the root of the zygoma : the mastoid part is compressed
and abuts against the outer side of the base of the paroccipital.
The tympanic is a simple scoop-shaped bone, or half-cylinder, cut
obliquely. The palatine process of the premaxillary is very
deeply notched, and is excavated behind the outer incisor.

In the skull of the mature Wombat, fig. 220, the exoccipitals
were still unanchylosed ; the left is figured separate at 3.

In the skull of a Perameles nasuta the exoccipitals are sepa-
rated by an interspace, so that a fissure is continued from the
upper part of the foramen magnum to the superoccipital element.
The same structure may be observed in the Great Kangaroo, and
it is very remarkable in the young skulls of this species. In the
Wombat the corresponding fissure is very wide, and the lower
margin of the superoccipital is notched, so that the shape of the
foramen magnum somewhat resembles that of the trefoil leaf.
In the Opossum, the exoccipitals meet above and complete
the foramen magnum. The petrosal and mastoid are commonly
confluent. So loose is the connection of the tympanic, that
without due care it is liable to be lost in preparing the skulls
of the Marsupials. In the Kangaroo and Wombat, it forms a
complete bony tube, fig. 220, 28, and in the Potoroo the bony
circle is incomplete at the upper part ; in the Perameles and
Dasyures the tympanic bone forms a semicircle, the posterior
part being deficient, and the tympanic membrane being there
attached to the mastoid, as in Birds. In the Dasyures, Petaurists,
Perameles, Potoroos, and Koala, fig. 221, c, there is a large bulla

z 2

340

ANATOMY OF VERTEBRATES.

220

ossea for increasing the extent of the auditory cavity, formed by
the expansion of the base of the sphenoid. In Acrohates and Pera-

meles lagotis, there is also an
external dilatation of the
petrosal, fig. 222, 16, which
thus forms a second and
smaller bulla on each side,
behind the large bulla ossea
formed by the alisphenoid, h.
In other Marsupials the pe-
trous bone is of small size,
generally limited to the
office of protecting the parts
of the internal ear, and
sometimes, as in the Koala,
is barely visible at the ex-
terior of the base of the
skull. The mastoid portion
appears in the occipital re-
gion of the skull of the

Koala, fig. 221, 8, between
the exoccipital and squa-
mous j)ortion of the tempo-
ral. In the Wombat the
mastoid sends outward the
strong compressed process,
fig. 220, 8, which terminates
the lateral boundaries of the
occipital plane of the cra-
nium ; but this process is
entirely due to the exocci-
pitals in the Koala, fig. 221,
4, and other Marsupials.
The auditory chamber of the ear is augmented in the Phalan-
gers, the Koala, the Kangaroos, and Potoroo, by a continuation
of air-cells into the base or origin of the zygomatic process ; but
the extent of the bony air-chambers communicating with the
tympanum is proportionally greatest in the Flying Opossums,
where, besides the sphenoid bulla, the mastoid and the Avhole of
the zygomatic process of the squamosal are expanded to form air-
cells with very thin and smooth Avails, fig. 219.

The direction of the bony canal of the organ of hearing corre-
sponds with the habits of the species. The meatus is directed

Phascolomys.

SKELETON OF MAESUPIALIA. 341

outward and a little forward in the carnivorous Dasyures ; out-
^v ard and a little backward in the Perameles and Phalangers ;
outward, backward, and upward in the Kangaroos, and directly
outward in the Petaurists and Wombat ; but the differences of
direction are but slightly marked in these timid vegetarians.

The squamosal generally reaches half-way from the root of the
zygoma to the sagittal ridge or suture ; it is most developed in
the Wombat, in which its superior margin describes a remarkably
straight line. The zygomatic process is generally compressed
and much extended in the vertical direction in the Opossum,
Dasyure, Phalanger, Koala, fig. 221, 27, and Kangaroo. In the
Wombat it curves outward from the side of the head in the form
of a compressed and almost horizontal plate, fig. 220, 27 ; it is
then suddenly twisted into the vertical position, to be received
into the notch of the malar portion of the arch, ib. 26. In Macro-
pus the back part of the zygoma is perforated by a pneumatic
foramen which receives air from the tympanum.

The cavity corresponding to the sphenoidal bulla ossea in other
Marsupials is in this species excavated in the lower part of the
squamosal at the inner side of the articular surface for the lower
jaw. This articular surface, situated at the base of the zygomatic
process, presents in the marsupial as in the placental Mammalia
various forms, each manifesting a physiological relation to the
structure of the teeth and adapted to the required movement of
the jaws in the various genera. In the herbivorous Kangaroo
the glenoid ca\dty forms a broad and slightly convex surface, as
in the Ruminants, aflPording freedom of rotation to the lower jaw
in every direction. In the Phalangers and Potoroos the articular
surface is quite plane. In the Perameles it is slightly convex
from side to side, and concave from behind forward. In the
Wombat it is formed by a narrow convex ridge considerably ex-
tended, and slightly concave, in the transverse direction. This
ridge is not bounded by any descending process posteriorly, so
that the jaw is left free for the movements of protraction and re-
traction. In the Koala the glenoid cavity is a transversely oblong
depression with a slight convex rising at the bottom, indicating
rotatory movements of the jaw. In the carnivorous Dasyures
it forms a concavity still more elongated transversely, less deep
than in the placental Carnivora, but adapted, as in them, to a
ginglymoid motion of the lower jaw. In all the genera, save in
the Wombat, retraction of the lower jaw is opposed by a de-
scending process of the temporal bone immediately anterior to the
meatus auditorius and tympanic bone.

342

ANATOMY OF VERTEBRATES.

Phascolarctos.

The glenoid cavity presents a cliaractenstic structure in most
of the Marsupialia in not being exclusively formed by the squa-
mosal. With the exception of the Petaurists, the malar bone
forms the outer part of the articular surface for the lower jaw,
and in the Thylacinus, Dasyurus Maugei, Dasyurus ursinus,
Perameles, Hyj)si])rymniis, and Macropus, the alisphenoid forms
the inner boundary of the same surface. In the Kangaroo,
Dasyures, Koala, and Wombat, the alisphenoid articulates mth
the parietal, but by a very small portion in the two latter species :

in the Perameles and Po-

221

toroos the alisphenoid does
not reach the parietal.

In \hQ parietals,fLg. 221,
7, the sagittal suture is ob-
literated in those species
in which a bony crista is
developed in the corre-
sponding place. They pre-
sent a singularly flattened
form in the Wombat, in an
aged skull of which, and
in a similar one in the
Kangaroo, I observe a like obliteration of the suture. In the
Kangaroo, Potoroo, Petaurus, Phalanger, and Myrmecobius,
there is a triangular interparietal bone. The corresponding bone
I find in three pieces in the skull of a Wombat.

The frontals, ib. ii, are chiefly remarkable for their anterior
expansion and the great share which they take in the formation
of the nasal cavity. In the Thylacine the part of the cranium
occupied by the frontal sinuses exceeds in breadth the cerebral
cavity, from which it is divided by a constriction. The coronal
suture presents in most of the Marsupials an irregular angular
course, forming a notch in the frontals on each side which receives
a corresponding triangular process of each parietal bone. A
process corresponding to the posterior frontal augments the bony
boundary of the orbit in the Thylacine, the Ursine Dasyure, and
in a slighter degree in the Virginian Opossum ; it is relatively
most developed in the skull of the Myrmecobius fasciatus, where
the orbit is large; but the bony boundary of the orbit is not
complete in any Marsupial. In the Myrmecobius there is a deep
notch at the middle of the superorbital ridge. A corresponding
but shallower notch is present in the skull of Petaurus sciureus.
I have found the frontal suture obliterated in old specimens of

SKELETON OF MAESUPIALIA. 343

the Tliylacine, the Virginian Opossum, Cook's Phalanger, the
taguanoid, and yellow-bellied Petaurists ; but the frontal suture
exists in Petaurus sciureus, Acrohates, and other Marsupials.
The interorbital space is concave in the Phalangers and in the
Petaurus taguanoides, but is quite flat in the other Petaurists.

The lacrymals vary in their relative size in different Marsupials.
In the Koala, fig. 221, 73, they extend uj^on the face about a line
beyond the anterior boundary of the orbit, and at this part they
present a groove mth one large and two or three small perfora-
tions. In the Wombat their extent upon the face is slightly
increased ; it is proportionally greater in the Kangaroos, Potoroos,
Phalangers, and Petaurists, in which this part of the lacrymal
bone presents two perforations close to the orbit. In the Thyla-
cine, besides the two external holes there is a large perforation
within the orbital margin. This carnivorous Marsupial, as com-
pared with the Wolf, presents a greater extent of the facial
portion of the lacrymal bone, and thus indicates its inferior type.
In the Myrmecobius the lacrymal bone exhibits its greatest rela-
tive developement. The extraorbital lacrymal foramen is a good
marsupial character : it is present in the Thi/lacoleo, where it is
single, as in Dasyurus ursinus.

The molars, figs. 220 and 221, 26, are very strong and of great
extent in almost all the Marsupialia. They are least developed
in Acrohates, fig. 219, Myrmecobius, and Perameles lagotis. In
the latter, fig. 222, the malar bone presents a singular form, being
bifurcate at both extremities : the processus zygomoticus maxillcB
superioris is wedged into the cleft of the anterior fork ; the cor-
responding process of the squamosal fills up the posterior notch.
The anterior bifurcation of the malar bone is not present in the
Marsupials generally : the external malo-maxillary suture forms
an oblique and almost straight line in the Wombat, Phalanr^er,
Opossum, Dasyures, and Kangaroo. Omng to the inferior deve-
lopement of the zygomatic process of the superior maxillary in
the Wombat, the malar bone is not suspended in the zygomatic
arch as in the Rodentia. It is also of relatively much larger size
and of a prismatic form, arising from the developement of the
oblique external ridge above described. In the Kano-aroos,
Potoroos, Great Petaurus, and Phalangers, it is traversed exter-
nally by a ridge showing the attachment of the masseter, of
which muscle the extent of origin is augmented by the descending
zygomatic process of the maxillary ; this is most developed in
the gigantic fossil Nototherc and Diprotodf^ii.

The nasal bones vary in their form and relative size in the

344 ANATO^NIY OF VERTEBRATES.

different genera ; they are longest and narrowest in the Perameles,
shortest and broadest in the Koala, fig. 221, i^ Their most cha-
racteristic strncture is the expansion of their upper and posterior
extremity, which is well marked in the Wombat, Myrmecobius,
Petaurists, Phalangers, Opossums, and Dasyures. In the Po-
toroos the anterior extremities of the nasal bones converge to
a point which projects beyond the premaxillaries. In the Perameles
lagotis the bony case of the nasal passage is further increased
by the presence of two small rostral bones, resulting, as in the
Hog, from ossification of the nasal cartilage.

The premaxillaries always contain teeth, and the ratio of the
developement of these bones corresponds mth the bulk of the
dental apparatus which they support. They are consequently
largest in the Wombat, where they extend far upon the side of
the face and are articulated to a considerable proportion of the
nasals, but do not, as in Rodentia, reach the frontal or divide the
maxillary bone from the nasal. They present a somewhat lower
degree of developement in the Koala, fig. 221, 22, but both in
this species and in the Wombat they bulge outward, and thus
remarkably increase the transverse diameter of the osseous cavity
of the nose. In Hypsiprymnus and Macropus the incisive palatal
foramina are chiefly in the premaxillaries, but a small proportion
of their bony circumference is due to the anterior extremity of
the palatal process of the maxillary : the same structure obtains
in the Wombat, Koala, and Opossums. In the Dasyures and
Phalangers a greater proportion of the posterior boundary of the
incisive foramina is formed by the maxillaries ; in the Petaurists
they are entirely surrounded by the maxillary bones, while in the
Perameles they are, on the contrary, entirely included in the
maxillaries. They always present the form of two longitudinal
fissures, fig. 222, a.

The maxillary, fig. 221, 21, in the Koala and Wombat sends
upward a long, narrow, irregular nasal process, which joins the
frontal and nasal bones, separating them from the premaxillaries.
The antorbital foramen does not present any marked variety of
size, which is generally moderate. It is much closer to the orbit in
the carnivorous Marsupialia than in the corresponding placental
quadrupeds. It is relatively largest in the Ursine Dasyure. It
presents the form of a vertical oblique fissure in the Wombat. I
have observed it double in the Kangaroo. In this and some
other herbivorous Marsupials the malar process of the maxillary
sends down a process for increasing the poAver and size of the
masseter muscle.

SKELETON OF MARSUPIALIA. 345

In Phalangista Cookii, in Petaurus Jiaviventer, and Petauriis
sciureus, in Macropus major, and some other Great Kangaroos,
the bony palate is of great extent and presents a smooth surface,
concave in every direction toward the mouth ; it is pierced by
the two posterior palatine foramina at the anterior external angles
of the palatine bones, either Avithin or close to the transverse
palato-maxillary sutures. Behind these foramina, in the Kan-
garoo, there are a few small irregular perforations. The bony
palate is similarly entire in the Hypsipryrnnus ursinus. In
Macropus Bennettii there are four orifices at the posterior part of
the bony palate. The two anterior ones are situated upon the
palato-maxillary suture, and are of an ovate form with the small
end forward. The two posterior foramina are of a less regular
form and smaller size. In the Brush Kangaroo {JSIacropus Brunii,
Cuv.) the posterior palatal foramina present the form of two large
fissures placed obliquely and converging posteriorly. They en-
croach upon the posterior borders of the maxillary plate. Anterior
to these vacancies there are two smaller foramina, and posterior
to them are one or two similar foramina.

In the Potoroos, Wombat, and Koala, the posterior palatal
openings are large and oval, and situated entirely in the palatal
bones. In Hyps, setosus they extend as far forward as the inter-
space between the first and second true molars ; in Hyps, murinus
they reach to that between the second and third true molars :
posterior and external to these large vacuities there are two small
perforations. In the Phalaugers, with the exception of Ph.
Cookii, the palatal openings are proportionally larger ; they ex-
tend into the palatal process of the maxillaries, and the thin
bridge of bone which divides the openings in the Potoroo, &c., is
w^anting ; the two perforations at the posterior external angles of
the palatine bones are also present. In the Virginian Opossum
the bony palate presents eight distinct perforations, besides the
incisive foramina; the palatal processes of the palatine bone
extend as far forward in the median line as the third molars : a
long and narrow fissure extends for an equal distance (three lines)
into the palatal processes both of the palatines and maxillaries :
behind these fissures and nearer the median line are two smaller
oblong fissures ; external and a little posterior to these are two
similar fissures, situated in the palato-maxillary suture ; lastly,
there are two round perforations close to the posterior margin of
the bony palate.

In the Ursine Dasyure a large transversely oblong aperture is
situated at the posterior part of the palatal processes of the

346

axato:my of verteeeates.

maxillarv bones, and encroaches a little upon the palatines. In
Mange's Dasyure there are two large ovate apertures crossing

the palato-maxillarv sutures se-
parated from each other by a
broad plate of bone : posterior to
these are two apertures of sunilar
size and form, which, being situ-
ated nearer the mesial line, are
divided bv a narrower osseous
bridge ; each posterior external
angle of the bony palate is also
perforated by an oval aperture.
In the Yiverrine Dasyure the
two vacancies which cross the
])alato-maxillary suture are in the
form of longitudinal fissures, cor-
responding to the fourth and fifth
grinders : the posterior margin of
the bony palate has four small
apertiu'es on the same transverse
line.

Since the defective condition
of this ])art of the cranium is one
of the characteristics of the skull
of the Bird, it might be ex-
pected that some approximation
would be made to that structure
in the animals which form the
transition between the Placental
and Oviparous Vertebrates. We
have already noticed the large vacuities which occur in the bony
palate of nearly all the Marsupials : but this imperfectly ossified
condition is most remarkable in the Perameles lagotis, in which,
fig. 222, the bony roof of the mouth is perforated by a wide oval
space extending from the second premolars to the penultimate
molars, exposing to view the vomer and the convolutions of the
inferior spongy bones in the nasal cavity. The pterygoids, fig.
220, 24, long maintain their individuality ; and repeat the connec-
tions they present in Birds.

The parietes of the cranial cavity are remarkable for their
thickness in some of the ^larsupial genera. In the Wombat the
two tables of the parietal bones are separated posteriorly for the
extent of more than half an inch, the interspace being filled with

Perameles lagotis.

SKELETON OF ^LVKSUPIALIA. 347

a coarse cellular diploe ; the frontal bones are about two and a
half lines thick. In the Ursine Dasyure the cranial bones have
a similar texture and relative thickness. In the Koala the tex-
ture of the cranial bones is denser, and their thickness varies from
two lines to half a line. In the Kangaroo the thickness varies
considerably in different parts of the skull, but the j^arietes are
generally so thin as to be diaphanous, which is the case with the
smaller ^Marsupials, as the Potoroos and Petaurists. The union
of the body of the second with that of the third cranial vertebra
takes place in the marsupial as in the placental Mammalia at the
sella turcica, which is overarched by the backward extension of
the orbitosphenoids. The optic foramina and the fissura3 lacera3
anteriores are all blended together, so that a wide opening leads
outward from each side of the sella. Immediately posterior and
external to this opening are the foramina rotunda, from each of
which in the Kangaroo a remarkable groove leads to the fossa
Gasseriana at the commencement of the foramen ovale ; the same
groove is indicated in a slight degree in the Dasyures and Pha-
langers, but is almost obsolete in the Wombat and Koala. The
entocarotid canals pierce the basisphenoid, as in Birds, and ter-
minate in the cranial cavity very close together behind the sella
turcica, which is not bounded by a posterior clinoid process. The
sphenoidal bulla, which forms the chief part of the tympanic
cavity in the Perameles lagofis, forms a large convex protuberance
on each side of the floor of the cranial cavity in that species.
The petrosal in the Kangaroo, Koala, and Phalangers, is im-
pressed above the meatus auditorius by a deep, smooth, round
pit, which lodges the lateral appendage of the cerebellum, as in
Birds. The corresponding pit is shallower in the Dasyuri, and
is almost obsolete in the AVombat. The middle and posterior
fissurae lacer^e have the usual relative position, but the latter are
small. The condyles are each perforated anteriorly by two fora-
mina in most of the Marsupials, the Thylacinus forming the ex-
ception and showing only one. The foramen magnum is of great
size in relation to the capacity of the cranium ; the aspect of its
plane is backAvard and slightly do^^Tiward. A venous canal leads
from the lateral sinus between the upper part of the petrosal and
the squamosal, and perforates the latter behind or above the root
of the zygoma.

In the Kangaroo and Phalanger a thin ridge of bone extends
for tlie distance of one or two lines into the periphery of the
tentorial process of the dura mater, and two sharp spines are sent
down into it from the upper part of the cranium in the Phalan-

348 ANATOMY OF VERTEBRATES.

gista vulpina. The tentorium is supported by a thick ridge of
bone in the Thylacine ; but it is not completely ossified in any of
the Marsupials : in some species, indeed, as the Dasyures, the
Koala, and the Wombat, the bony crista above described does not
exist. There is no ossification of the falciform ligament as in the
Ornithorhynchus.

The rhinencephalic division of the cranial cavity is well defined
from the prosencephalic one. It is relatively smallest in the Koala.
In all Marsupials it is bounded anteriorly by the cribriform plate,
wliich is converted into an osseous reticulation by the number
and size of the olfactory apertures. The cavity of the nose,
from its great size and the complication of the turbinal bones,
forms an important part of the skull. It is divided by a complete
bony septum to within one-fourth of the anterior aperture ; the
anterior margin of the septum is slightly concave in the Koala ;
describes a slight convex line in the Wombat, Kangaroo, and
Phalanger, and a sigmoid flexure in the Dasyure. A longitudinal
ridge projects doAvnward from the inside of each of the nasal
bones, and is continued posteriorly into the superior turbinal;
this bone extends into the dilated space anterior to the cranial
cavity, which corresponds with the frontal sinnses. The convo-
lutions of the middle turbinal are extended chiefly in the axis of
tlie skull ; the processes of the anterior turbinal are arranged
obliquely from below npward and forward. The nasal cavity
communicates freely with large maxillary sinuses, and finally
terminates by wide apertures behind the bony palate. In the
skull the nasal cavity communicates with the mouth, as before
mentioned, by means of the various large vacuities in the palatal
processes.

In the carnivorous Marsupials, as the Thylacine, the lower
maxillary bone resembles in general form that of the correspond-
ing species in the placental series, as the Dog : a similar transverse
condyle is placed low down near the angle of the jaw, on a level
mth the series of molar teeth ; a broad and strong coronoid pro-
cess rises high above the condyle, and is slightly curved back-
ward ; there is the same well-marked depression on the exterior
of the ascending ramus for the firm implantation of the temporal
muscle, and the loAver boundary of this depression is formed by a
strong ridge extended downward and forward from the outside of
the condyle. But in the Dog and other placental Carnivora (some
Seals excepted), a process, representing the angle of the jaw,
extends directly backward from the middle of the above ridge,
which process gives precision and force to the articulation of the

SKELETON OF MAESUPIALIA. 349

jaw, and increases the power by which the masseter acts upon the
jaw. Now, although the same curved ridge of bone bounds the
lower part of the external muscular depression of the ascending
ramus in all the INIarsupials, it does not in any of them send
backward, or in any other direction, a process corresponding to
that just described in the Dog. The angle of the jaw itself,
in the Marsupials, is as if it were bent inward in the form of
a process, encroaching in various shapes and various degrees of
developement in the different genera upon the interspace of the
rami of the lower jaw. On looking directly upon the lower
margin of the jaw, we see, therefore, in place of the margin of
a vertical plate of bone, a more or less flattened triangular sur-
face extended between the external ridge, and the internal pro-
cess or inflected angle. In the Opossums the internal angular
process is triangular and trihedral, directed inward, with the
point slightly curved upward, and more produced in the small
than in the large species. In the Dasyures it has a similar form,
but the apex is extended into an obtuse process. In the Thy-
lacine the base of the inverted angle is proportionally more
extended, and a similar structure is presented by the fossil Phas-
colothere. In the Perameles the angle of the jaw forms a still
longer process ; it is of a flattened form extended
obliquely inward and backward and slightly curved ^"^
upward. It presents a triangular, slightly incurved,
and pointed form in the Petaurists, in which it is longest
and weakest in the pigmy species {^Acrohates, Desm.).
It is shorter and stronger in the Myrmecobius, fig.
223, a. In the Potoroos and Phalangers the process
is broad with the apex slightly developed ; it is bent
inward and bounds the loAver part of a wide and
deep depression in the inside of the ascending ramus.
In the Great Kano-aroo the internal marcrin of this
process is turned upward, so as to augment the depth
of the internal depression above mentioned. The in-
ternal angular process arrives at its maximum of de-
velopement in the Wombat, fig. 220, «, and the breadth L.nvorjaw,
of the base of the ascending ramus very nearly equals
the height of the same part. In the Koala the size of the process
in question is also considerable, but it is compressed, and directed
backward with the obtuse apex only bending inward, so that the
characteristic flattening of the base of the ascending ramus is least
marked in this species. There is no depression on the inner side of
the ramus of the jaw in the Koala, but its smooth surface is simply

350 ANATOMY OF VERTEBRATES.

pierced near its middle by the dental nerve and artery. The
surface of the external muscular depression bounded below by a
broad angular ridge, as above described, is entire in the Dasyures,
Opossums, Bandicoots, Petaurists, and Phalangers; but in the
Wombat the outer surface of the ascending ramus is directly
perforated by a round aperture immediately posterior to the com-
mencement of the dental canal : ^ the corresponding aperture is
of laro-er size in the Kangaroo. But in the Potoroos both the
external and internal depressions of the ascending ramus lead
to wide canals, or continuations of the wide depressions vvdiich
pass forward into the substance of the horizontal ramus, and soon
uniting into one passage, leave a vacant space in the intervening
bony septum.

In the Thylacine, Ursine Dasyure, and the allied fossil carni-
vores called Phascolothere, Thylacoleo, and Plagiaulax,^ the con-
dyle of the lower jaw is placed low down, on a level mth the
molar series : it is raised a little above that level in the smaller
Dasyures and Opossums, and ascends in proportion to the vege-
table diet of the species.

In all those Marsupials which have few or very small incisors
the horizontal rami of the jaw converge toward a point at the
symphysis. The angle of convergence is most open in the
Wombat, in which the symphysis is longest. The suture be-
comes obliterated in aged individuals. In other Marsupials, the
rami of the lower jaw are less firmly united at the symphysis ;
they permit independent movements of the right and left in-
cisors in the Kangaroos : and in the Opossum, both the rami
of the lower jaw and all the bones of the face are remarkable
for the loose nature of their connections.

C. Bones of the Limhs. — The scapula varies in form in the
different Marsupials. In the Petaurists it is a scalene triangle,
vdth the glenoid cavity at the convergence of the two longest
sides. In the Wombat, fig. 212, 5 1, it presents an oblong qua-
drate figure, the neck being produced from the lower half of
the anterior margin, and the outer surface being traversed diago-
nally by the spine, which in this species gradually rises to a full
inch above the plane of the scapula, and terminates in a long
narrow compressed acromion arching over the neck to reach the
clavicle.

In the Koala (fig. 224), the superior costa does not run parallel

' A bristle is represented passing through this aperture in fig. 220.
2 xvir.pp. 341, 353, figs. 113, 119, 173.

SKELETON OF MARSUPIALIA. 351

with the inferior, a, d, but recedes from it as it advances forward,
and then passes down, forming an obtuse angle, c, and with a gentle
concave curvature, to the neck of the scapula ; a small process ex-
tends from the middle of this curvature.
In the Potoroo, the upper costa is at first ^-"^

parallel with the lower, but this parallel
part is much shorter ; the remainder de-
scribes a sigmoid flexure as it approaches
the neck of the scapula. In the Great Kan-
garoo, the Perameles, Phalangers, Opos-
sums, and Dasyures, the whole upper costa
of the scapula describes a sigmoid curve,
the convex posterior position of which varies
as to its degree and extent. The sub-
scapular surface is remarkable in the Pera-
meles for its flatness, but presents a shal- scapuia of Koaia.
low groove near the inferior costa. In
most other Marsupials it is more or less convex or undulating.

In the Kangaroos, fig. 211, the supraspinal fossa is of less ex-
tent than the space below the spine, and the spine is inclined
upward. In the Perameles and Dasyures the proportions of the
supra- and infra-spinal surfaces are reversed, and the whole spine
is bent downward over the infraspinal surface. In the Potoroos
and Phalangers the acromion is bent downward so as to pre-
sent a flattened surface to the observer ; in the Potoroos and
Opossums this appearance is produced by a true expansion of the
acromion. In the Perameles the coracoid process is merely re-
presented by a slight production of the superior part of the
glenoid cavity. In the Kangaroo and Potoroo it forms a protu-
berance on the upper part of the head of the scapula. In the
other Marsupials it assumes the character of a distinct process
from the same part, and attains its greatest developement in the
Wombat and Koala, in the latter of which it is forcibly curved
downward and inward, fig. 224, o.

The clavicles are present in all the Marsupials, with the ex-
ception of the genus Perameles and probably also the Chceropus.
In the claviculate Marsupials they are relatively strongest and
longest in the burrowing Wombat, weakest and shortest in the
Great Kangaroo. In the latter they are simply curved with the
convexity forward, and measure only two inches m length. In
the Wombat they are upwards of three inches in length, and
have a double curvature ; they are expanded and obliquely trun-
cate at the sternal extremity, where the articular surface presents

3.')2 ANATOMY OF VERTEBRATES,

a remarkably deep notch ; they become compressed as they ap-
proach the acromion, to which they are attached by an extended
narrow articular surface.

In the Koala the clavicles are also very strong, but more com-
pressed than in the Wombat, bent outward in their Avhole extent,
and the convex margin formed, not by a continuous curve, but
by three almost straight lines, with intervening angles ; progres-
sively diminishing in extent to the outermost line which forms
the articular surface mth the acromion. In the Myrmecobius
the clavicles are subcompressed and more curved at the acromial
than at the sternal end. In most of the other Marsupials the
clavicle is a simple compressed elongated bone, with one general
outward curvature.

The humerus in most Dasyures resembles that of the Dog-tribe
in the imperforate condition of the inner condyle, but differs in
the more marked developement of the muscular ridges, especially
of that which extends upward from the outer condyle for the origin
of the great supinator muscle. This ridge is terminated abruptly
by the smooth tract for the passage of the musculo-spiral nerve.

In all the other genera of Marsupials that I have examined the
internal condyle of the humerus is perforated. But in some
species of Petaurus, as Petaurus sciureus, the foramen is repre-
sented by a deep notch ; and in the Phalangista CooMi, both
foramen and notch are wanting, i The ridge above the external
condyle is much developed in the Petaurus macruriis and sciureus,
and notched at its upper part, but this notch does not exist in
Pet. taguanoides. I find similar differences in the developement
of the supinator, or outer ridge, in the genus Perameles ; in the
Per. lag Otis it is bounded above by a groove ; in Per. Gunnii it is
less developed and less defined. In the Kangaroos, Potoroos,
Wombat, and Koala (fig. 225), the outer condyloid ridge ex-
tends in the form of a hooked process above the groove of the
radial nerve. In all these, and especially in the Wombat, the
deltoid process of the humerus, fig. 212, 53, is strongly developed ;
it is continued from the external tuberosity down the upper half
of the humerus ; except in the Petaurists, where, from the greater
relative length of the humerus, it is limited to the upper third.
The interspace of the condyles is occasionally perforated, as in
the Perameles lagotis and Wombat. The articular surfaces at
both extremities of the humerus have the usual form ; but it may

^ In the other species of Phala7igista, and in the Petaurus taguanoides and macrurns,
the internal condyle of the humerus is perforated. In a Thyjacine I found it per-
forated ; and in one Ursine Dasyure in the left humerus, but not in the right.

SKELETON OF MARSUPIALIA.

353

Humerus of the
Koala.

be observed in some Marsupials, as the Koala, that at the distal
articulation the external convexity for the radius has a greater
relative extent than usual, and the ulnar concavity
is less deep.

The bones of the fore-arm are always distinct and
well developed, and their adaptation to pronation
and supination is complete. The prehensile faculty
and unguiculate structure of the anterior extre-
mities appear to have been indispensable to ani-
mals where various manipulations were required in
the economy of the marsupial pouch. When,
therefore, such an animal is destined like the rumi-
nant to range the wilderness in quest of pasturage,
the requisite powers of the anterior members are
retained and secured to it, as has been already
observed, by an enormous developement of the
hinder extremities, to which the function of loco-
motion is restricted.

We find, therefore, that the bones of the fore-
arm of the Kangaroo differ little from those of the
burrowing Wombat, the climbing Koala, or the carnivorous
Dasyure, save in relative size. They present the greatest propor-
tional strength in the Wombat, and the greatest proportional
length and slenderness in the Petaurists or Flying Opossums,
in which the radius and ulna are in close contact throuo^h a grreat
portion of their extent, and thus lend a firmer support to the
outstretched dermal parachute. They are also long and slender
in the Koala. In general the radius and ulna run nearly parallel,
and the interosseous space is very trifling. It is mdest in the
Potoroos. The olecranon is well developed in all the Marsupials.
In the Virginian Opossum and Petaurists we find it more bent
forward upon the rest of the ulna, than in the other Marsupials.
In the Wombat, where the acromion is the strongest, and rises an
inch and a half above the articular cavity of the ulna, it is ex-
tended in the axis of the bone. The distal end of the radius in
this animal is articulated to a bone representing the os scaphoides
and OS lunare.

The ulna, which in the same animal converges toward a point
at its distal end, has that point received in a dej)ression formed by
the cuneiform and pisiform bones ; these are bound together by
strong ligaments, and the pisiform then extends downward and
backward for two-thirds of an inch. The second row of the
carpus consists of five bones. The trapezium supports the inner

VOL. II. A A

354 ANATOMY OF VERTEBRATES,

digit, and has a small sesamoid bone articulated to its radial
surface. The trapezoides is articulated to the index digit, and is
wedged between the scapholunar bone and os magnum ; this
forms an oblique articular surface for the middle digit ; but the
largest of the second series of carpal bones is the cuneiform, which
sends downward an obtuse rounded process, and receives the
articular surface of the fifth, and the outer half of that of the
fourth digit, the remainder of which abuts against the oblique
proximal extremity of the middle metatarsal bone. The five
metacarpal bones are all thick and short, but chiefly so the
outermost. The innermost digit, or pollex, has two phalanges,
the remainder three ; the ungual phalanx of all the digits is
conical, curved, convex above, expanded at the base, and simple
at the opposite extremity. In the Perameles the ungual phalanx
of the three middle dimts of the hand, and of the two outer dio-its
of the foot, are split at the extremity by a longitudinal fissure
commencing at the upper part of the base. This structure, which
characterises the ungual phalanges in the placental Anteaters,
has not been hitherto met with in other Marsupial genera.^ The
terminal phalanges of the Koala are large, much compressed
and curved ; the concave articular surface is not situated, as
in the Cats, on the lower part of the proximal end, but, as
in the Sloths, at the upper. The claws which they support are
long.

In the Great Kangaroo the first row of the carpus is composed,
as in the Wombat, of three bones, but the apex of the ulna
rotates in a ca^dty formed exclusively by the cuneiforme. There
are four bones in the second row ; of which the unciform is by far
the largest, and supports a part of the middle, as well as the two
outer digits. In the Potoroos I find but three bones in the distal
series of the carpus, the trapezoides being wanting, and its place
in one species being occupied by the proximal end of the second
metacarpal bone, which articulates with the os magnum. In the
Perameles there are four bones in the second carpal row, although
the hand is less perfect in this than in any other Marsupial
genus, Chceropus excepted, the three middle toes only being fully
developed. In the Petaurus the carpus is chiefly remarkable for
the length of the pisiforme.

It would be tedious to dwell on the minor diflerences observable
in the bony structure of the hand in other Marsupials. I shall
therefore only observe that though the inner digit is not situated

' It would be instructive to examine tlie skeleton of the rare Chceropus, with
reference to this structure.

SKELETON OF MARSUPIALIA. 355

like a thumb, all the fingers enjoy lateral motion, and that
those at the outer can be opposed to those at the inner side so
as to grasp an object and perform, in a secondary degree, the
function of a hand. In the Koala the two inner dimts are more
decidedly opposed to the three outer ones than in any other
climbing Marsupial. But some of the Phalangers, as the Ph.
Cookii and Ph. gliriformis of Bell, present in a slighter degree
the same disposition of the fingers, by which two out of the five
have the opposable properties of a thumb. I have observed a
similar disposition of the digits in the act of climbing in the
Dormouse, and it probably is not uncommon in other placental
Mammalia of similar habits and which have long, slender, and
freely moveable fingers. As a permanent disposition of the digits,
the opposition of three to two is most conspicuous in the prehensile
extremities of the Chameleon.

The pelvis, figs. 152, 226, 227, in the mature Marsupials is
composed of the os sacrum, the two ossa innominata, and the
characteristic supplemental bones, attached to the pubis, called
by Tyson the ossa marsupialia or Janitores Marsupii, m.

We seek in vain for any relationship between the size of the
pelvis and that of the new-born young, the minuteness of which
is so characteristic of the present tribe of animals. The diameters
both of the area and apertures of the pehdc canal are always con-
siderable, but more especially so in those Marsupialia which have
the hinder extremities disproportionately large ; as also in the
Wombat, where the pehis is remarkable for its width. The
pelvis is relatively smallest in the Petaurists ; but even here the
diameter of the outlet is at least six times that of the head of the
new-born young. The anterior bony arches formed by the ossa
pubis and the ischia are always complete, and the interspace
between these arches is divided, as in other Mammalia, into the
two obturator foramina by an osseous bridge continued from the
pubis to the ischium on each side of the symphysis.

In the Kangaroos, Potoroos, Phalangers, and Opossums, the
ilia offer an elongated prismatic form. They are straight in the
Opossum, but gently curved outward in the other Marsupial
genera. In the Dasyures there is a longitudinal groove Avidening
upward in place of the angle at the middle of the exterior sur-
face of the ilium. The ilia in the Petaurists are simply compressed,
with an almost trenchant anterior margin. They are broader and
flatter in the Perameles, and their plane is turned outward. But
the most remarkable form of the ilia is seen in the Wombat, in which
they are considerably bent outward at their anterior extremity,

A A 2

356

ANATOMY OF VERTEBRATES.

226

fig. 226, 62. In the Kangaroos and Potoroos the eye is arrested
by a strong process given off from near the middle of the ilio-
pubic ridge, and this process may be ob-
served less developed in the other Mar-
supialia. The tuberosity of the ischia
inclines outward in a very slight degree
in the Dasyures, Oj^ossums, Phalangers,
Petaurists, and Perameles, in a greater
degree in the Kangaroos and Potoroos,
and gives off a distinct and strong obtuse
process in the Wombat, fig. 226, 63, which
not only extends outward but is curved
forward. In the Potoroos the symphy-
sis of the ischia, or the lower part of
what is commonly called the symphysis
pubis, is produced anteriorly. The length
of this symphysis, and the straight line
formed by the lower margin of the ischia,
is a characteristic structure of the pehds
in most of the Marsupials.

The marsupial bones, figs. 226,227, 7n,
are elongated, flattened, and more or less
curved, expanded at the proximal extre-
mity, which sometimes, as in the Wombat,

Right OB innominatuni and marsupial ^g articulatcd tO thc pubis bv tWO polutS I

boue. Wombat. , .

they are relatively straightest and most
slender in the Perameles ; shortest in the Myrmecobius, where they
do not exceed half an inch in length ; longest, flattest, broadest, and
most curved in the Koala, where they nearly equal the iliac bones
in size. They are always so long that the cremaster muscle winds
round them in its passage to the testicle or mammary gland, and
the uses of these bones mil be described in treating of that
muscle. Homologically they are the last pair of lumbar hsema-
pophyses advanced, as in many Reptiles, from the sclerous to the
osseous states : teleologically they belong to the category of the
trochlear ossicles, commonly called sesamoid, and are developed in
the tendon of the external oblique which forms the mesial pillar
of the abdominal ring, as the patella is developed in the tendon of
the rectus femoris. I cannot, however, participate in the opinion
of Laurent and De Blainville,* that the marsupial bones are super-
added to the abdominal muscles to aid in an unusually energetic

' 'Bulletin des Sciences Medicales' of Ferussac, 1827, No. 77, p. 112, and the
' Annales d'Anat. et de Fhysiologie,' 1839, p. 240.*

SKELETON OF MAKSUPIALIA.

S57

227

Pelvis and marsupial bones of the Koala.

compression required to expel the uterine foetus. It is not in the
females of those animals which give birth to the smallest young
that we should expect to find
auxiliary parts for increasing
the power of the muscles en-
gaged in parturition. The
bones in question are, more-
over, equally developed in both
sexes : and they are so situated
and attached that they add to
the power of the muscles which
wind round them, and not of
those implanted in them. They
are not, however, merely sub-
servient to add force to the
action of the * cremasteres,' but
give origin to a great propor-
tion of the so-called ' pvrami-
dales.' 1

The osteogenesis of the mar-
supial pelvis derives some ex-
trinsic interest from the not yet forgotten speculations which have
been broached regarding the homologies of the marsupial bones.
These have been conjectured to exist in many of the placental Mam-
malia, with a certain latitude of altered place and form, disguised,
e.g., as the bone of the penis in the Carnivora, or appearing as
the supplemental ossicles of the acetabulum, which exist in the
young of many of the Rodentia. In the os innominatum of the
immature Potoroo the curved prismatic ilium contributes to form,
by the outer part of its base, the upper or anterior third of the
acetabulum ; the rest of the circumference of this cavity is com-
pleted by the ischium and pubis, excepting a small part of the
under or mesial margin, which is formed by a distinct ossicle or
epiphysis of the ilium («, fig. 152), answering to that described
by Geoifroy St. Hilaire as the rudimental marsupial bone in the
Rabbit. Now here there is a coexisting marsupial bone : but
besides the five separate bones just mentioned, there is a sixth
distinct triangular ossicle, which is wedged into the posterior
interspace of the ischiopubic symphysis. The circumference of
the acetabulum is always interrupted by a deep notch opposite
the obturator foramen, which is traversed by a ligamentous bridge,

' Sec the absti-act of a paper on the anatomy of tlie Dasyiirus, Proc. Zoo). Soc.
January, 1835.

358 ANATOMY OF VERTEBRATES.

and gives passage to the vessels of the Harderian gland lodged in
the wide and deep acetabular fossa.

The femur is a straight, or nearly straight, long, cylindrical
bone, having a hemispherical head supported on a very short
neck, especially in the Petaurists, and situated here almost in the
axis of the shaft, above and between the two trochanters, which
are nearly of equal size. In the Kangaroos and Potoroos the
head of the thigh-bone is turned more inward, and the outer or
greater trochanter rises above it. In other Marsupials the great
trochanter is less developed. In most of the species a strong
rid2:e is continued downward to within a short distance from the
trochanter, and this ridge is so produced at the lower part in the
Wombat as almost to merit the name of a third trochanter. In the
Wombat and Koala there is no depression for a ligamentum teres.
The shaft of the bone presents no linea aspera.

The canal for the nutrient artery commences at the upper third
and posterior part of the bone in the Koala, and extends down-
ward, contrarimse to that in most other marsupial and placental
Mammalia.

At the distal extremity of the femur the external condyle is
the largest, the internal rather the longest. The intermediate
anterior groove for the patella is well marked in the Perameles,
where the patella is fully developed, but is broad and very shallow
in the Phalangers and Dasyures, where the tendon of the rectus
muscle is merely thickened or offers only a few irregular specks
of ossification ; and the corresponding surface in the Petaurists,
Wombat, and Koala is almost plane from side to side ; in these
Marsupials and in the Myrmecobius the patella is wanting. I
find a distinct but small bony patella in the Macropus Bennettii.
There is a sesamoid bone above and behind the external condyle
of the femur in the Myrmecobius and some other Marsupials.

In the knee-joint, besides the two crucial ligaments continued
from the posterior angles or cresses of the semilunar cartilages —
one to the outer side of the inner condyle, the other to the inter-
space of the condyles — there is a strong ligament which passes
from the anterior part of the tibial protuberance backward to
the inner side of the fibular condyle, and a second continued from
the same point along the outer margin of the outer semilunar
cartilage to the head of the tibia.

The tihia, fig. 228, 66, presents the usual disposition of the arti-
cular surface for the condyles of the femur, but in some genera,
as the Wombat and Koala, the outer articular surface is con-
tinuous with that of the head of the fibula. In the Kangaroos

SKELETON OF MARSUPIALIA. 359

and Potoroos the anterior part of the head is much produced,
and in the young animal its ossification commences by a centre
distinct from the ordinary proximal epiphysis of the bone. A
strong ridge is continued down from this protuberance for about
one-sixth the length of the tibia. In the Koala a strong tube-
rosity projects from the anterior part of the tibia at the junction
of the upper with the middle third. In this species and in the
Wombat, as also in the Opossums, Dasyures, Phalangers, and
Petaurists, the shaft of the tibia is somewhat compressed and
twisted; but in the Kangaroos, Potoroos, and Perameles the
tibia is prismatic above and sub-cylindrical below. The internal
malleolus is very slightly produced in any Marsupial, but most so
in the Wombat.

The^/ibida, ib. 67, is complete, and forms the external malleolus
in all the Marsupials. In one species of Hijpsijjrijmnus and in one
species of Perameles (P. lagotis) it is firmly united to the lower
part of the tibia, though the line of separation be manifest exter-
nally. In a second species of each of the above genera it is in
close contact wdth the corresponding part of the tibia, but can be
easily separated from that bone. In the Great Kangaroo the
fibula is also a distinct bone throughout, but it is remarkably
thinned and concave at its lower half, so as to be adapted
to the convexity of the tibia, with which it is in close attach-
ment. In each of these genera, therefore, in which locomotion
is principally performed by the hinder extremities, we perceive
that their osseous structure is so modified as to insure a due de-
gree of fixity and strength ; while in the other Marsupial genera,
as Phascolarctos, Phascolomys, Plialangista, Petaurus, Didel2)hys,
and Dasyurus, the tibia and fibula are so loosely connected toge-
ther and with the tarsus, that the foot enjoys a movement of rota-
tion analogous to the pronation and supination of the hand. This
property is especially advantageous in the Petaurists, Phalangers,
Opossums, and Koala, because in these the inner toe is so placed
and organised as to perform the oflfice of an opposable thumb,
whence these Marsupials have been termed Pedimana, or foot-
handed (fig. 228).

It is to this prehensile power that the modifications of the fibula
chiefly relate. In the Wombat, fig. 212, 67, Koala, Petaurists, and
Phalangers, it expands to nearly an equal size with the tibia, 66, at
the distal extremity, and takes a large share in the formation of the
tarsal joint ; but the articular surface is slightly convex, while
that of the tibia is slightly concave. The proximal extremity of
the fibula is also much enlarged, but compressed and obliquely

360

ANATOMY OF VERTEBRATES.

truncated, and giving off two tuberosities from its exterior surface ;
to the superior of these a large sesamoid bone, fig. 228, c?', is ar-
ticulated ; a similar sesamoid ' fabella ' is attached to the upper end
of the fibula in a Dasyurus macrurus and Petaurus taguanoides.
M. Temminck figures it in the Didelphys ursina and Didelphys

Philander. This sesamoid and the ex-
panded process to which it is attached
form the homotype of the olecranon,
fig. 212, 55; and the correspondence
of the fibula with the ulna is very
remarkably maintained in the Pet.
taguanoides, in which the proximal
articular surface of the fibula is divi-
ded into two facets, one playing upon
the outer condyle of the femur, the
other concave, vertical, and receiving
an adapted convexity on the outer
side of the head of the tibia, which
rotates thereupon like the radius in
the lesser sigmoid cavity of the ulna.
In the scansorial and gradatorial
Marsupials the bones of the hinder
and fore extremities are of nearly
equal length, but in the saltatory
species the disproportion in the de-
velopement of the bones of the hind
leg is very great, especially in the
Kangaroos and Potoroos, fig. 211.
However, in those singular species
of Hypsiprymnus which inhabit New
Guinea and take refuge in trees, the
organisation of the Kangaroo is mo-
dified and adapted so as to make
climbing a possible and easy action.
The fore and hind legs are here more equally developed, and the
claws on the two larger toes of the hind feet are curved instead of
straight. In a skeleton of one of these scansorial Potoroos, the
Hypsiprymnus ursinus, in the Museum at Leyden, in which the
humerus is three inches and a half long, the femur does not quite
equal five inches in length : the ulna is nearly four inches, the
fibula nearly five inches in length. The fibula is also less firmly
connected with the tibia than in the Great Kangaroo.

The following is the structure of the tarsus in the Wombat
The astragalus, a, is connected as usual

Bones of the leg and foot, Phalcmgista.

and Phalanger,

fig. 228.

SKELETON OF MARSUPIALIA. 361

with the tibia, fibula, calcaneum, c, and na\dculare, n. The upper
articular surface for the tibia is as usual concavo-convex, the in-
ternal surface for the inner malleolus flattened and at rio-ht anofles
with the preceding, but the outer articular surface presents a tri-
angular flattened form, and instead of being bent down parallel
with the inner articular surface, slopes away at a very open angle
from the upper surface, and receives the articular surface of the
fibula, 67, so as to sustain its vertical pressure. A small propor-
tion of the outer part of the inferior surface of the astragalus
rests upon the calcaneum : a greater part of the superincumbent
pressure is transmitted by a transversely extended convex anterior
surface to the naviculare, n, and cuneiform bones, i, e. This
form of the astragalus is also characteristic of the Koala, Petau-
rists, Dasyures, and the Pedimanous Marsupials generally. In
the Kangaroos, Potoroos, and Perameles which have the pedes
saltatorii, the fibular articular surface of the astragalus is bent
down as usual at nearly right angles with the upper tibial surface.

The calcaneum in the Wombat presents a ridge on the outer
surface which serves to sustain the pressure of the external mal-
leolus, which is not articulated to the side of the astragalus. The
internal surface which joins the astragalus is continuous with
the anterior slightly concave surface Avhich articulates with the
cuboides. The posterior part of the bone is compressed, it pro-
jects backward for nearly an inch, and is slightly bent down-
ward and inward. This part is relatively shorter in the Koala,
Phalangers, Opossums, and Petaurists, but it is as strongly de-
veloped in the Dasyuri as in the Wombat. The anterior part of
the calcaneum of the Phalangers is shown at c, fig. 228.

In the Dasyurus macrurus a small sesamoid bone is wedged
in between the astragalus, tibia, and fibula at the back part of
the ankle-joint. In the Petaurus tac/uanoides there is a supple-
mental tarsal bone wedged in between the naviculare and cuboides
on the plantar surface.

The homotypy of the carpal and tarsal bones is very clearly
illustrated in the Phalanger. The lunare and scaphoid of the
hand correspond with the astragalus and naviculare of the foot,
transferring the pressure of the focile majus upon the three
innermost bones of the second series. The long, backward-
projecting pisiform bone of the wrist closely resembles the pos-
terior process of the os calcis ; the articular portion or body of
the OS calcis corresponds with the cuneiforme of the carpus ; the
large carpal unciform represents the tarsal cuboides, and performs
the same function, supporting the two outer digits ; the three
cuneiform bones of the foot are obvious homotypes of the trape-

362 ANATOMY OF VERTEBRATES.

zium, trajjezoides, and os magnum. The entocuneiform bone is the
largest of the three in the Wombat^ although it supports the
smallest of the toes. It is of course more developed in the Pedi-
manous Marsupials, where it supports a large and opposable thumb.

In the Wombat the metatarsals progressively increase in length
and breadth from the innermost to the fourth ; the fifth or outer-
most metatarsal is somewhat shorter but twice as thick, and it
sends oiF a strong obtuse process from the outside of its proximal
end. A corresponding process exists in the Phalangers, fig. 228.
The innermost metatarsal of the Wombat, fig. 212, i, supports only
a single phalanx ; the rest are succeeded by three phalanges each,
progressively increasing in thickness to the outermost ; the ungual
phalanges are elongated, gently curved downward, and gradually
diminish to a point.

In the Myrmecobius the tibial or innermost toe is represented
by a short rudimental metatarsal bone concealed under the skin.
In the Dasyures the innermost toe has two phalanges, but it is the
most slender and does not exceed in length the metatarsal bone of
the second toe. In the Petaurists it is rather shorter than the
other digits, but is the strongest, and in Petaurus taguanoides the
terminal phalanx is flattened and expanded ; the toes are set wide
apart in this genus. In the Opossums and Phalangers the inner-
most metatarsal bone is directed inward apart from the rest, and
together with the first phalanx is broad and flat. The second
phalanx in the Opossums supports a claw, but in the Phalangers
is short, transverse, unarmed, singularly expanded in Ph. CooMi,
but almost obsolete in Ph. ursina (fig. 228, i). In all the preced-
ing genera there are two small sesamoid bones on the under side
of the joints of the toes, both in the fore and hind feet.

The commencement of a degeneration of the foot which is
peculiar to Marsupial animals may be discerned in the Petaurists,
in the slender condition of the second and third toes, as compared
with the fourth and fifth. In the Phalangers this diminution of
size of the second and third toes, counting from the hallux, is
more marked. They are, also, both of the same length and have
no individual motion, being united together in the same sheath of
integument as far as the ungual phalanges, whence the name of
Phalangista applied to this genus (fig. 228, 2 and s).

In the saltatorial genera of Marsupials the degradation of the
corresponding toes is extreme ; but though reduced to almost fila-
mentary slenderness they retain the usual number of phalanges,
and the terminal one of each is armed \Ai\\ a claw. These claws
being the only parts of the rudimental digits which project freely

SKELETON OF MAESUPIALIA. 363

beyond the integument, they look like little appendages at the
inner side of the foot for the purpose of scratching the skin and
dressing the fur, to which offices they are exclusively designed.
The removal of the innermost toe, corresponding mth our great
toe and the hallux of the Pedimana, commences in the Perameles.
In one species I find the metatarsal bone of this toe supports only
a single rudimental phalanx which reaches to the end of the next
metatarsal bone, and the internal cuneiform bone is elongated.
In another species the internal toe is as long as the abortive
second and third toes, and has two phalanges, the last of which is
divided by the longitudinal fissure characteristic of the ungual
phalanges in this genus. In the Perameles lagotis the innermost
toe is represented by a rudimentary metatarsal bone, about one-
third the length of the adjoining metatarsal.

In the Poephagous Marsupials no rudiment of the innermost
toe exists. The power of the foot is concentrated in all these
genera on the fourth and fifth or two outer toes, but especially
the fourth, which, in the Great Kangaroo, is upwards of a foot in
length, including the metatarsal bone and the claw. This for-
midable weapon resembles an elongated hoof, but is three-sided
and sharp-pointed like a bayonet, and with it the Kangaroo stabs
and rips open the abdomen of its assailant: with the anterior
extremities it will hold a powerful dog firmly during the at-
tack, and firmly supporting itself behind upon its powerful tail,
deliver its thrusts Avith the whole force of the hinder extremities.
The cuboid bone which supports the two outer metatarsals is
proportionally developed. The internal cuneiform bone is pre-
sent, though the toe which is usually articulated to it is Avanting.
It is also the largest of the three, and assists in supporting the
second metatarsal ; posteriorly it is joined with the navicular and
external cuneiform bones, the small middle cuneiform occupying
the space between the external and internal wedge-bones and the
proximal extremities of the two abortive metatarsals. The great
or fourth metatarsal is straight and somewhat flattened ; the ex-
ternal one is compressed and slightly bent outward; the toe
which this supports is armed with a claw similar to the large one,
but the ungual phalanx does not reach to the end of the second
phalanx of the fourth toe, and the whole digit is proportionally
weaker. In the climbing Potoroos (^Hypsijwymnus ursinus and
Hypsiprymnus dorcocephalus), the two outer toes are propor-
tionally shorter than in the leaping species, and are terminated
by curved claws by which they gain a better hold on the branches
and inequalities of trees.

364

ANATOMY OF VERTEBRATES.

§ 181. Skeleton of Rodentia. — A. Vertebral Column, — The Ro-
dentia have seven cer^dcal, and, as a rule, nineteen dorso4umbar
vertebrae. The agile Hares with flexile trunk have long loins,
viz. D 12, L 7, fig. 229. The Jerboas, fig. 232, that bear the

Hare (Lepus timidus).

trunk aloft, like the Kangaroos, have also twelve dorsal and
seven lumbar vertebrae : the burrowing Porcupines and SAvim-
ming Beavers, fig. 230, have their trunk braced by a greater

230

Beaver {Castor Fiber).

number of long moveable ribs, making in Castor
Fiber, D 15, L 4 ; in Hystrix cristata, D 15, L 4 ;
in Hystrix alopha, D 14, L 5. The average Rodent
number is D 13, L 6. Exceptions are few, and
fewer than at first sight, if well looked to ; thus, a

SKELETON OF RODENTIA. 365

skeleton of Dasyprocta Acuchy, showing D 13, L 7, has the supple-
mental lumbar vertebra mth sacral characters and connection on
the left side : Cuvier assigns to the Dormice (Loirs and Lerots)
D 13, L 7 : the burrowing Cape Mole-Rats have twenty or twenty-
one dorso-lumbars : in these I have found i3-7, i4-6, and 14-7,
and the latter is the number of dorsal and lumbar vertebrae
respectively : the Australian Water-Rat {Hydromys chrysogaster)
has D 14, L 7 : the best-marked exception is that of the Capromys,
which has D 16, L 7 = 23. In some Rodents only one, in most
but two, vertebra3 join the ilia : three and four are common
numbers of anchylosed sacrals. In the seemingly tailless Cavies
and Pacas the caudal vertebra? may be but seven, eight, or ten
in number : in the Black Rat and Hapalotis alhipes I have
counted as many as thirty. The Great Jerboa has twenty-nine
caudals, which also have the proportions and perfections of those
in the Kangaroo.

The met- and an-apophyses commence by a common tubercle at
the fore part of the dorsal series ; the anapophysis, fig. 231, D, a,
begins to be distinct at the back part of the series, and the meta-
pophysis, ib. m, to project from above the anterior zygapophysis,
z : both processes are usually well 23 1

developed in the posterior dorsal
and lumbar vertebra?, ib. L : the
diapophysis, d, subsides in the
posterior dorsals and is lengthened ^"T|jC^ d^

in the lumbars, L, by a coalesced ^ , ^ , *^

■> ^ J ^ Dorsal Lumbar

Y\h\Q,t {^pleur apophysis), '^h. d. In vertebra, Lagotis.

the Great Jerboa (^Helamys) the diapophysis is unusually long and
strong in the first dorsal: the anapophysis first projects from
the back part of the eighth dorsal, and the metapophysis from the
fore part of the ninth : both processes are long in the first five
lumbars. The neural spines progressively increase in length to
the last lumbar, and are strongly inclined forward toward that of
the eleventh dorsal, fig. 232, d : the antecedent spines incline
backward to the same vertebra, the spine of which is vertical,
and indicates the centre of motion of the trunk. This arrani^e-
ment of the neural spines is well marked in all the agile flexible-
bodied Rodents. In the Hare, fig. 229, the neural spine of the
ninth vertebra, D, indicates the centre. The anapophyses begin
on the eighth, the metapophyses on the nintli, dorsal : these in-
crease and are continued throughout the lumbar region, where
they are very long. The anapophysis assumes the form of a
ridge in the last dorsal and lumbar vertebrae. The lumbar

366

ANATOMY OF VERTEBRATES.

di-plenr-apopliyses, ib. d, are long and incline forward and down-
Avard. Long hypapophyses, ib. h, are also developed.

The thoracic ribs consist of bony pleur- and gristly h^m-
apophyses : of these the seven anterior pairs, as a rule, directly
join the sternum, which then consists of six bones or ' stern ebers.'
In the Beaver, Porcupine, Coypu, and a few others, there are
eight pairs of ' true ribs : ' in an Acuchy with this number I
found nine sternal bones, the foremost representing an ' epi-
sternal' articulated to the '^manubrium.'
The first rib is the shortest, unusually so in
Hydromys, and has often a partial articu-
lation with the last cervical vertebra. The
neural spine of the second dorsal is com-
monly the longest.

232

In the Beaver, fig. 230, the
sacrum consists of four anchy-
losed vertebrae : the articular sur-
face for the ilium is almost con-
fined to the transverse process of
the first of these vertebrae : those
of the last are the longest. The
sacral nerves directly perforate
the neurapophyses of the last two vertebras, anterior to the vacuity
left between the bases of the transverse processes. The neural
arches of the first six caudal vertebrae are similarly perforated. Their
transverse processes are long, horizontally flattened, and terminally
expanded ; and the vertebrae, after these processes subside, are
remarkable for their large size, and a certain degree of corre-
spondence of shape mth the broad, flat, scaly tegumentary tail

Jerljoa iDipus Sagitta).

SKELETON OF KODENTIA.

167

which they support. In most Eodents with long tails, htema-
pophyses are developed beneath the intervertebral spaces, as in
the Jerboas, fig. 232, h. In one member of the Porcupine family
( Cercolabes), and in one species of Capromys ( C. prehensilis), the
tail has a prehensile extremity.

The seventh cervical vertebra has an imperforate transverse
process in some Kodents, a perforate one in others : in the Hare
I have observed this difference in different individuals. The
pleurapophyses early anchylose to form the vertebrarterial foramen
in the sixth-second cer^dcals. The neural spine is usually longest
in the second and seventh ; it is obsolete in the intermediate cer-
vicals in many Rodents. In the Hare the transverse processes of
the atlas are perforated longitudinally by the vertebral arteries,
which then perforate the neural arch. The hypapophysis, or
so-called body, is ossified, and a small tubercle extends backward
from its under part. In the atlas of the Chinchilla the transverse
process is pierced both horizontally and obliquely, and the verte-
bral artery also perforates the neural arch.

B. Skull. — As in the Marsupialia, the' confluence of the elements
of the epencephalic arch is late, and that of the tympanic is
restricted to the petrosal and mastoid. The squamosal maintains
its individuality, and also much of its long slender proportions,
and the malar is suspended in the middle of the zygomatic arch,

'283

Skull of the Hare,

as in Birds : other characteristics of the Rodent skull will l^p
exemplified in the follomng species.

In the Hare (^Lepus timidus, fig. 233) the superoccipital is
surmounted by a square platform of bone — originally a distinct
interparietal — the posterior angles of which project backward in the
form of two tubercles, from between which a vertical crest descends
to the foramen magnum. The paroccipitals arch downward and

368 ANATOMY OF VERTEBRATES.

outward in close connection with the descending process of the
large subquadrate mastoid, 8, which anchyloses with the petrosal
and tympanic. The long bony ^ meatus auditorius ' ascends
obliquely backward — the direction in which this timid Rodent is
most concerned in ascertaining the sounds that may warn it of an
approaching enemy. The tympanic cavities intercommunicate by
a sinus traversing the basisphenoid. The outer part of the ali-
sphenoid is j^erforated by the ectocarotid artery. The entocarotid
pierces the tympanic bulla. The petromastoid is articulated in a
peculiar manner to the squamosal, which, after expanding beyond
its zygomatic part to be applied to the parietal and alisphenoid,
resumes the form of a narrow thin plate of bone, applied to a
shallow depression upon the mastoid, and thus clamping it, as it
were, to its place. The frontal sends outward a large aliform
curved plate above each orbit, the extremities of which form
postorbital and antorbital processes, the notches which divide the
anterior from the posterior part of the frontal being unusually
deep. The common outlet of the optic nerves extends forward,
so as to occasion a small vacuity at the back part of the inter-
orbital septum. Each orbit presents a wide vacuity at its fore
part, which leads into the lateral nasal cavity, bounded externally
by the singularly reticulate nasal plate of the maxillary, 21. The
zygomatic arch, which is slightly curved downward but scarcely
at all outward, developes a small prominence both from its front
and hind extremity below the points of suspension. The arti-
cular surface for the lower jaw is broad and concave transversely,
narrow and convex longitudinally. The bases of the sockets of
the superior molars form a strong prominence in the orbit below
the anterior vacuity. The nasal bones, 15, are remarkable both
for their length and breadth : they extend further back than the
long slender nasal processes of the premaxillaries, 22. The bony
palate is extensively encroached upon by the prepalatal apertures,
which blend together to form a narrow heart-shaped vacuity
with the apex directed forward, largely exposing the vomer
and the nasal cavities. The palatal processes of the maxillaries
and palatines form a bridge, or platform, extending across oppo-
site the three anterior molar teeth. The nasal processes of the
palatines are of unusual height. The angle of the lower jaw
forms a broad compressed plate, with the lower border rounded
and thickened, so as to project a little beyond both the outer and
inner surface of the ascending plate : the outer ridge is continued
forward to the horizontal ramus, bounding the large masseteric
fossa. The petrotympanics form ' bullae osseas.' The pterygoids

SKELETON OF RODENTIA. 369

clevelope both external and internal plates: the outer plate is
mdely 2^6^'forated at its base; the inner plate terminates in a
liamular process.

The common foramen opticum, the wide palatal vacuities, the
transversely extended glenoid cavity, and the inflected mandibular
angle, indicate affinity to the Marsupials.

In a skull, seven inches long, of a Capybara, fig. 234, with the
entire series of permanent teeth in place, the sutures between
the elements of the occipital bone still remain. The compressed
paroccipitals, 4, are of enormous length. The basioccipital con-
tributes to each condyle its lower extremity. The exoccipitals
almost meet above the foramen magnum, the plane of which is
nearly vertical. The basisphenoid is perforated by a median
vertical canal, and is notched laterally by the entocarotids. The
squamosals are distinct, and essentially like those in the Hare,
sending backward the long compressed lamina which clamps the

234

Skull of the Capybara.

tympanic and mastoid to the side of the cranium. A venous
sinus issues from beneath this process of the squamosal. The
longitudinal groove forming the articular cavity for the lower
jaw is angular, and completed externally by the malar bone, 26.
The meatus auditorius is unusually contracted, is cleft below, and
bounded there by two small tuberosities. The temporal and
orbital fossas are blended together, as in all Rodents. The lacry-
mal bone is of unusual size, and extends forward upon the side
of the face betw^een the frontal, 1 1 , and maxillary, 2 1 . The ant-
orbital vacuity is immense. The nasal bones, 15, are long, large,
and of nearly equal breadth throughout. The nasal processes
of the premaxillaries, 22, are coextensive with them. The sagittal
suture is obliterated, as well as a great part of the frontal suture.
There is no trace of interparietal bone. A single foramen inci-
sivum is situated anterior to the two large normal prepalatine

VOL. II. B B

370

ANATOMY OF VERTEBRATES.

apertures ; the postpalatinc foramina are in the centre of the
bony palate, between the palatines and maxillaries. The pala-
tines are large. The cribriform plate and its median ridge or
* crista galli' project backward into the large rhin encephalic
fossa. Pterygoid sinuses are formed anteriorly by the proper
pterygoids, and posteriorly by the ecto- and ento-pterygoid
plates of the sphenoid. The ectopterygoid plate is perforated by
an * interpterygoid ' canal, above which is a smaller ' ectocarotid '
canal. The lower jaw shows a strong ridge or platform outside
the molar alveoli. The coronoid and condyloid processes rise
very little above the grinding surface of the molars. The chief
process of the lower jaw is the angle, a, which is broad, com-
pressed, and produced far backward, where it terminates obtusely.
The upper surface of the skull is flat, and its contour deviates
little from a straight line, slightly descending toward the occiput

235

236

Skulls of the Chluchilla.

and the end of the nasals. The zygomatic arch is compressed but
deep, especially below the fore part of the orbit. The acoustic
bulla? are comparatively smalL

In Chincldlla lanigera, figs. 235, 236, the mastoid portion, h,
of the large tympanic bidla, «, h, m, rises to the upper surface
of -the cranium, as at a, but it is girt by a process of the
superoccipital, f, which extends outward to articulate wdth the
extremity of the slender process of the squamosal, e. The vacuity
which intervenes between the alisphenoid, parietal, and tympanic,
and which, in other Mammals, is closed by the more expanded

SKELETON OF RODENTIA. 371

squamosal, is here, tlirougli the retention by that bone of its pri-
mitive form as a diverging slender ray, left uncovered. The
meatus is long, wide, infundibuliform, Avith the outlet obliquely
truncate and directed upward and a little backward : the petrosal
bulla, m, continued from its lower extremity, seems to describe
a semicircular curve downward and backward, circumscribing
the large foramen, which directly pierces the bulla beneath the
meatus. The paroccipital is slender ; its point does not extend
below the level of the tympanic bulla. The articular groove for
the lower jaw is deep, and is completed externally by the malar,
k. An almost circular piece seems to be cut out of the zygoma,
above the junction of the malar with the squamosal. The facial
part of the lacrymal extends half-way across the antorbital root of
the zygoma, where the zygomatic part of the maxillary articulates
by suture with the nasal process of the same bone, circumscribing a
large antorbital vacuity. The nasal processes of the premaxillaries
slightly expand at their extremities, which extend beyond the
corresponding ends of the nasals, /. A strong and long oblique
ridge traverses the inner side of the ramus of the lower jaw. The
outer side is irregularly swollen by the bases of the sockets of the
curved molars, but has not the distinct ridge which characterises
that part in the C a vies.

In the skull of an adult 237

Paca ( Coelogenys, fig. 237),
with the mature dentition,
the sutures between the
elements of the occipital, as
likewise the sagittal suture,
are obliterated. There is no
trace of interparietal bone.
The basioccipital, basisphe-
noid, and presphenoid have sk^ii ,f ^i.^ coeiogenys.

coalesced to form a continu-
ous bony floor for the cranial cavity. The third division of the
fifth notches the alisphenoid posteriorly, the foramen ovale being an
irregular fissure between the ali- and basi-sphenoids and the petro-
sal. The petrotympanic is free from tlie squamosal, and rather
loosely suspended beneath the overarching posterior lamella of the
squamosal, which bends down external to the mastoid and paroc-
cipital, 4. The malar, 26, is a slightly curved plate, twice as deep
as it is long, and forms the posterior third part of the zygomatic
expansion, the rest being formed by the maxillary, 21, which is
unusually and enormously developed. The squamosal forms only

B B 2

37-2

ANATO:\rY OF VERTEBRATES.

the base of the zygoma ; it is grooved below for the mandibular
joint, to which the malar contributes the outer part. The nasal
processes of the premaxillary do not extend so far back as the
nasals : the large antorbital vacuity, v, is reduced by the max-
illary zygomatic plate to a crescentic form. The zygomatic
expansion of the maxillary, 21, is deeply excavated on the inner
side; it forms, in the recent animal, a large bony capsule on
each side of the mouth, communicating therewith and lined
by the buccal membrane. A vertical sinus terminating below
in two small foramina, communicating with the orbit, di^ddes
the rhinencephalic from the prosencephalic fossa. A branch of
the lateral sinus leads from above the petrosal to between the
squamosal and tympanic externally. The olfactory cavity extends
backward beneath the rhinencephalic one, but not above it. The
ectopterygoid process joins the proj)er pterygoid, and, mth the
entopterygoid plate, completes a wide interpterygoid canal. The
base of the ectopterygoid is perforated by an ectocarotid foramen.
The squamosal is excluded from the cranial cavity by a fissure
V, hich widens as it descends between the squamosal and petro-
tympanic : a venous sinus occupies this fissure. A horizontal
septum divides an upper from a lower compartment of the anterior
half of the tymjDanic bulla. The sella turcica is shallow, and not
defined by clinoid processes ; the chiasmal platform is subqua-
drate, and leads to a fossa, perforated by the two large and ap-
proximated elliptical optic foramina ; a deep and narrow groove
extends from the optic fossa to the rhinencephalic compartment,
where it di^ddes to terminate at the orbito-ethmoidal foramina.

The foramen rotundum and
foramen lacerum anterius
combine to form a large
subquadrate vacuity. The
cerebellar fossa on the upper
part of the petrosal is very
deep. The meatus internus
is extremely shallow, and
almost immediately divides
into the cochlear and vesti-
bular canals. -

In the Porcupine (^?/5^n>
cristata)^ fig. 238, the occi-
pital region is nearly flat ; the paroccipitals descend only to the level
of the occipital condyles. The mastoid forms but a rough ridge.
The auditory bulhc are moderately developed ; the external meatus

238

Skull of the Porcupine.

SKELETON OF RODENTIA.

373

is short, directed outward and a little forward, and is notched
behind. A fissure, which Avidens at both ends, di^ddes the tym
panic from the clamping process of the squamosal : this articulates
behind by a suture with the mastoid. The parietals, fig. 239, 7, are
broad, but short, and pinched in, as it were, by the temi)oral fossix?,
w hich almost meet at the line of the sagittal suture, which is obli-
terated. The frontals, ib. ii, are more than double the size of the
parietals, and are greatly swollen by the enormous sinuses. Tlie
most remarkable feature of the Porcupine's cranium is the magni-
tude of the nasal bones, 15, especially their great posterior expanse,
which terminates behind on the same vertical parallel as the middle
of the zygomatic arch. This character is contrasted in iig. 239
with the small size of the nasals, 15, in the Manatee and Capuchin
Monkey. The thick anterior pier by which the zygomatic arch is
suspended is formed by the maxillary and lacrymal. The slender

Porcupine.

horizontal process of the maxillary, which bounds the lower part
of the antorbital vacuity, fig. 238, v, appears like a second zygoma.
The premaxillaries progressively contract as they pass backward
and join the frontals, nearly an inch in advance of the hinder bor-
der of the nasals. The bony palate terminates by a thick rounded
border between the last molar teeth. The pterygoids send back-
ward and upward a hamular process, which joins the tympanic
bulla. The cerebellar depression upon the petrosal is very shallow :
the fore part of the petrosal presents a large protuberance. The
rhinencephalic fossa is relatively of large size, and is defined by a
well-marked ridge from the rest of the cranial cavity. Two vascu-
lar canals are continued into its lower part from above the optic
foramina, instead of an open groove, as in the Agouti. The
coalesced prefrontals are compressed. The vomer is deeply cleft
posteriorly, and has coalesced mth the ethmoturbinals, and its
anterior part articulates with the median ascending process of the
premaxillary arching over the wide vacuities which lead from the
nasal passages to the prepalatine apertures, as in most Rodents.

374

ANATOxAIY OF VERTEBEATES.

The cranial air-cells continued from the nasal and tympanic
cavities reach the occiput. The tympanum is divided by a hori-
zontal partition into an upper and lower chamber, intercommuni-
cating posteriorly above the membrana tympani, which is situated
in the lower division, where the meatus auditorius externus ter-
minates in a narrow oblique slit. The extraordinary extent of
the air-sinuses surrounding the fore part of the cranial cavity and
developed in the orbitosphenoids, alisphenoids, squamosals, and
frontals, with the radiating bony septa of those sinuses, are pecu-
liarities of the Porcupine.

In an almost full-grown Beaver, fig. 240, the elements of the
occipital bone are still unanchylosed ; the lower tliird of each
condyle is formed by the basioccipital, the under surface of which
presents a large and deep excavation. The upper part of the
2^Q foramen magnum is com-

pleted by the broad super-
occipital. The mastoid is
larger than in the Porcu-
pines, and articulates ante-
riorly with both the parietal
and squamosal ; it is anchy-
losed to the petrosal. There
is a perforation in the suture
between the superoccipital
and mastoid. The inter-
parietal is large, and wholly
upon the upper surfiice of
the cranium. The squamosal is perforated behind and below the
root of the zygoma. The frontals are small and almost flat above.
The nasal bones extend further back than the premaxillaries, in
the European Beaver, beyond the transverse line which extends
between the antorbital tuberosities. The anterior root of the
zygoma formed by the maxillary is a simple plate which appears
to be imperforate, the orifice of the slender antorbital canal being
concealed by a vertical ridge of the maxillary, which inclines
forward over the maxillo-premaxillary suture.

The epencephalic compartment is lower and broader than in
the Porcupine. The cerebellar fossa of the petrosal is larger
and deeper. The upper compartment of the tympanum is much
less. The length and direction of the auditory meatus is shown,
fig. 240, o : it changes its form into a transverse fissure, as it
approaches the membrana tympani, the plane of which is almost
parallel Avith that of the meatus itself. There are no nasal air-

Skull of the Beaver (Castor Fiber).

SKELETON OF RODENTIA.

375

241

Skull of the Ondatra {Fiber zibcticus).

sinuses in the cranial bones of this aquatic Rodent, and their
texture is denser than in most of the order. The sella turcica
is extremely shallow, and without clinoid processes : the middle
of the basioccipital is reduced by the excavation on its under
surface to extreme thinness. A small vacuity in the basisphe-
noid communicates with the cranial cavity close to the ' fissura
lacera anterior.' The presphenoid is perforated transversely. The
rhinencephalic fossa is well marked. The anterior end of the
vomer articulates Avith both the maxillary and premaxillary bones,
as in the Rat.

In the skull of the Ondatra or Musk Yole {Fiber zibeticus,
fig. 241 ), the basioccipital
is not excavated, as in
the Beaver, but there is
the same perforation be-
tween the mastoid and
superoccipital, and a large
vacuity in the posterior
process of the squamosal
communicating directly
A\ith the cranial cavity.
The squamosal is unusu-
ally expanded above the zygomatic process, and articulates
largely mth both frontal and parietal. The zygomatic process of
the maxillary reaches almost to that of the squamosal, and sup-
ports a great part of the malar bone. The antorbital foramen, v,
is larger than in the Beaver, but is bounded externally, as in it,
by a nearly vertical ridge of the maxillary. The interorbital
septum is perforated behind, beneath the orbitosphenoid. There
is no distinct lacrymal bone ; but the turbinal bones appear at
the fore part of the orbit between the two processes of the
maxillary which join the frontal, and above the aperture com-
municating with the nasal cavity. The anterior j^art of the
maxillary, in front of the antorbital foramen, is swollen, and
forms a curved canal commencing by an oblique aperture su-
periorly, and descending outward and back^vard round the
socket of the superior incisor to terminate in the nasal meatus :
this part may probably protect the lacrymal sac and duct. The
interparietal is a transversely quadrate bone. The sagittal suture
is retained, and the upper surface of the parietal is smooth, and
nearly flat : the temporal ridges meet and develope a crest upon
the narrow frontals, obliterating the frontal suture. The back
part of each ramus of the lower jaw is trident-shaped from the

376

A]S ATOMY OF VERTEBKATES.

242

Skull of the Spalax typhlus.

almost equal develo2:)ement of the coronoid and angular processes,
on each side the base of the narrow process supporting the
condyle.

In the Great Mole-Kat ( Oryctei^ojms capensis), the occipital
region of the skull is very broad and low. The compressed
paroccipitals project downward and backward. The auditory
bulla is pyriform, its apex articulating with the pterygoids. The

temporal fossae meet along
a well-developed crista ex-
tending from the interor-
bital region to the strong
transverse superoccipital
crest. The squamosal forms
a horizontal plate, with a
curved border extending
from the root of the zvo;oma
to above the ' meatus ex-
ternus,' which is directed
upward and forward. The
zygomatic arches are strongly carved outward. The premaxil-
laries extend further backward than the nasals : these are very
long and narrow. In the Blind Mole-Rat ( Spalax typhlus), the
orbit, fig. 242, o, is not defined : the great antorbital vacuity, v,
might be mistaken for it.

In the skull of the Cape Jerboa {Helamys capensis), the occi-
pital region, owing to the enormous developement of the acoustic

bullae, appears as a broad shallow
depression between them at the
back part of the skull. The par-
occipitals are small, slender, sub-
elongate, and project downward,
distinct from the bullae. The
broader mastoid processes are ap-
plied to the outer side of the
petrosal portion of the bullae : the
swollen bases of the mastoids form a tract upon the upper surface
of the cranium larger than the interparietal bone, on each side of
which they are situated. The slender posterior clamping processes
of the squamosals impress the outer sides of the bullae which they
support, above the ' meatus externus : ' this canal is directed
upward and a little outward. The parietals are pushed by the
squamosals entirely to the upper region of the cranium : the
sagittal suture remains, as well as the frontal one. The temporal

243

of the Jerboa (Dipus Sagitta).

SKELETON OF RODENTIA. 377

muscles seem to have been unusually small in this Rodent : their
fossae impress only the small squamosals. The coronoid process
of the lower jaw is obsolete. The movements of the jaws appear
to have been chiefly committed to the masseteric and pterygoid
muscles. The zygomatic arch, which extends from the squamosal
to the premaxillary, is very broad below the orbit, and is traversed
externally by a ridge indicating the powerful origin of the mas-
seter. The antorbital vacuity and the maxillary depression,
bounded externally by the two roots of the zygoma, are larger
than the orbits : the front root of the zygoma is formed by a
combination of the frontal, lacr3^mal, maxillary, and malar bones.
The slender extremities of the premaxillaries terminate on nearly
the same transverse line vnih the back part of the broad nasals.
These are bent down anteriorly, so as to form the sides of the
external nostrils. The deep sockets of the rootless teeth form
protuberances at their bases, where the osseous case becomes
absorbed, converting the socket into a canal open at both ends,
the persistent matrix of the tooth being attached to the peri-
osteum, and protected by the contiguous soft parts. In all the
Rodents with the wide antorbital vacuities, the fore part of the
masseter takes its origin from the facial bones anterior thereto,
and traverses the vacuity in its oblique course beneath the fore
part of the zygoma, to expand and blend with the normal part of
the masseter.

The lower jaw is modified for the lodgement of the pair of
long, curved, scalpriform incisors, the sockets of which may
extend to the middle (Hare) or even to the hind part (Beaver,
Porcupine) of the ramus : in the latter case the prominent inner
wall curves beneath the molar alveoli and forms, as in figs. 238,
241, 242, c, the lower part of the horizontal ramus. The condyle,
crowning this, rises usually high above the grinders ; it is lowest
in the Capybara and some Cavies : in all Rodents the condyle
is convex transversely and extended longitudinally. The chief
work of the teeth being by horizontal movements to and fro, all
that part of the ascending ramus serving for the implantation of
the masseter is expanded, while that for the temporal muscle is
reduced, so that the ^ coronoid ' process is very small, and may
be a mere tubercle {Lagomi/s), while the angle of the jaw usually
forms the whole base of the ascending ramus, projecting beloAV
its fore part, angularly in the Hare, fig. 233, a ; and behind its
back part, extensively in Cavies, fig. 234, «, and Voles, fig.
241, a. In most of these it is long and pointed; but is obtuse
and compressed in Dolichotis : it is subquadrate in Squirrels,

378 ANATOMY OF VERTEBRATES.

Eats, Marmots. In many Rodents the angle is extended out-
ward and subsides, advancing, as a ridge upon tlie outer side, of
the horizontal ramus, as in fig. 242 : in Ctenomys the breadth of
the mandible exceeds the lengtli. Most Cavies show, also, the
external ridge noted in the Capybara's jaw, below the molar
series. The upper jaw is similarly modified in relation to the
masseter, e.g., in those Kodents which have the fore part of the
muscle passing through the wide antorbital vacuity, v, to its peri-
pheral ridges.

C. Bones of the Limbs. — In this extensive and ubiquitous order,
which includes three-fourths of the known species of Mammals,
some have limbs giving power in running, some in swimming,
some in burrowing, some in leaping, some in climbing, and a few
show modifications in relation to parachute-like expansions of
integument for a kind of flight.

In the Hare, fig. 229, the scapula is long and narrow, traversed
externally by a spine extending into an acromion at an unusual
distance beyond the glenoid ca\dty, and there developing a retro-
verted process ; the coracoid is compressed and introverted. The
clavicular ossicles are freely suspended, allowing full swing to the
fore-limb. The humerus, long, slender, and sigmoid, has a large
intercondyloid vacuity. The radius and ulna are in close contact ;
the latter is grooved for the reception of the radius. Their gingly-
moid joint mth tlie humerus restricts the movements to one plane.
The carpus has the ^ os intermedium,' fig. 191, s'. There are five
digits, the innermost very short, though with the normal number
of phalanges. The fore limbs are relatively shorter and stronger
in the burrowing Rabbits ; the ungual phalanges are less com-
pressed, and aiford a closer attachment of the broader claws by
being cleft on the upper surface. In all Leporidce the ilia are
long and subprismatic where they articulate mth the sacrum, the
joint being limited to the first vertebra, fig. 245, a, b. They
extend in advance of this on each side the last lumbar, ib. d, ex-
])anding into a crista, c, which is rough and slightly everted : the
ilia form with the lumbar series an angle of 165°, fig. 229. The
ischia have a process, fig. 244, e, above the terminal tuberosities :
the pubic bones are long and slender, meeting at a long symphysis
produced into a ridge,/: there is a ^ pectineal ' process, d, near the
acetabular end of the pubis. The iliopubic angle is about 120°.

The femur has a third trochanter near the base of the great
one. The medullary artery pierces the inner side of the proximal
third of the bone, and the canal extends downward. The fibula
is anchylosed along its distal half to the tibia : its proximal end

SKELETON OF RODENTIA.

379

■•^c^ 244

projects beyond the tibia, and a 'fabella' is wedged between it
and the outer condyle of the femur ; there is a similar sesamoid
behind this condyle, and a third behind the inner condyle. The
patella is ossified.

The tarsus shows the naviculare, astragalus, calcaneum with a
long lever : the meso- and ecto-cuneifomi bones, and the cuboid.
There is a supplemental ossicle be-
neath the astragalus. The navicu-
lare has a large process. The inner
digit is wanting, and the base of the
metatarsal of the second is extended
backward, like an entocuneiform, to
join the naviculare.

In the Hare-like Cavies of South
America {Dasi/procta) the cla^dcles
are represented, as in the Hares,
by slender ossicles : the supra- and
infra-spinal fossa? of the scapula are
of equal depth : the humerus is per-
forated between the condyles : the
radius and ulna have become anchy-
losed, reducing the interosseous space
to a narrow chink near their proximal
ends in the Acouchy : in an Agouti
I found this confluence not complete.
The fore foot is pentadactyle. The
first row of carpals is formed by the

scapholunar, the cuneiform, and a large pisiform. There is an
termedium ' between the os magnum and trapezoides. The pollex
is shorter in the Agouti than in the Acouchy. The fifth finger
is much reduced in size, but has the normal number of phalanges.
The ungual phalanges are notched at their apex. The femur
gives a feeble indication of the third trochanter at the middle of
its outer side. The tibia and fibula are distinct ; a fiibella is
attached to each femoral condyle. The foot has but three digits.
The long entocuneiform bone has coalesced with the inner side of
the metacarpal of the second toe — here the innermost. Tlie
supplementary ossicle crossing the articulation between the astra-
galus and scaphoides is present. There is a distinct sesamoid
beneath the joint of the cuboid with the external metatarsal {iv):
both the naviculare and cuboid send strong processes to the
plantar side of the tarsus. There are trochlear sesamoids beneath
the metatarso-phalangial joints : the ungual phalanges are notched.

Pelvis of tlie Hare, anterior view.

in-

380

ANATOINIY OF VERTEBRATES.

In the prolific Giiinea-Pig, the pelvis, fig. 245, is long and
laterally compressed, the passage being mnch narrower than the
diameter of the head of the mature foetus. Prior to parturi-
tion the symphysial ligaments become soft and extensile, and the
innominata, gliding on the sacro-iliac joints, diverge at the sym-
physis to the extent shown in fig. 246 during parturition. After
this process the symphysis quickly returns to its former or normal

2-15 246

Pelvis of the Guinea-Pig seventy-two hours
after parturition.

Pelvis of the Guiuea-Pig at the time of
parturition.

state, and in a few days presents only a little thickness and
mobility. The young of the Guinea-Pig are far advanced at
birth, some of the deciduous teeth are shed in utero, and they
run about and begin to eat soon after they see the light.

In the Water-Hog, or Capybara, there is no complete clavicle.
The acromion is long and slender, and bifid at its extremity, with
the longer division directed downward. The humerus is widely
perforated between the condyles, but not above the inner condyle :
both this bone and the ulna are solid. The scaphoides and lunare
are connate. The pollex is wanting in the fore feet, and both
the hallux and the fifth toe are wanting on the hind feet. The
ungual phalano^es are short, obtuse, and broad.

SKELETON OF RODENTIA. 381

The Beaver, fig. 230, is a member of that great division of the
Kodentia in which the clavicles are complete : the acromion scapnlas
bends toward and joins that bone. In the humerus the deltoid ridge
has a tuberosity : both the intercondyloid space and the internal
condyle are imperforate : a coarse cancellous structure occupies
the middle of the shaft. The radius and ulna are distinct. The
femur shows the slender neck and lofty trochanter common to
most Kodents ; it has a third trochanter, and has no medullary
cavity. The rotular surface is distinct from that of the condyles.
A section of the tibia and fibula also shows the absence of that
ca\ity, and the complete confluence of the compact walls of the
two bones at the lowar third of the fibula. The projecting part
of the calcaneum is depressed. The toes are longer and stronger
than the fingers, they support a broad foot which is webbed, and
the second toe has a double oblique nail or broad claw.

In our Water- Yole {Arvicola cmijihihia) the acromion of the
scapula is long and bent downward ; its inferior process is feebly
developed. The deltoid process of the humerus is prominent
and well-defined, compressed, and bent downward. There is
a minute perforation between the condyles, but none above the
inner one. The bones of the fore-arm are in contact and
closely united, except at the narrow space near their proximal
ends. The pollex is represented by its metacarpal bone. The
femur has a third trochanter, with two patellas in front of, and two
fabellse behind, the condyles. I have found, also, a small ossifi-
cation at the anterior end of each semilunar cartilage. The
fibula is anchylosed to the tibia at both its extremities. The
entocuneiform is long, and applied to the inner side of the base
of the second metatarsal, but it supports a short metatarsal with
the first and ungual phalanx of its proper digit, the hallux.

Rodents burrow chiefly for concealment, rarely for food :
the Rabbit needs but a slis^ht modification of the limbs, as com-
pared with the surface-dwelling Hare, to excavate, in loose soil,
its retreat. Perhaps the ' Mole-Rats ' of the Cape are the best
burrowers of the order. In Bathyergus the upper border of
the scapula describes an open angle ; its outer surface is nearly
equally bisected by the spine, which rises to an unusual height,
and sends ofl" a remarkably long subtrihedral acromion, the ex-
tremity of which appears as a thick epiphysis bent toward the
lon«: and strono^ clavicle with which it articulates. A well-
marked deltoid process stands out from the middle of the shaft
of the humerus, which is imperforate at its distal end. The
olecranon is unusually thick and expanded. The femur shows a

382 ANATOMY OF VERTEBEATES.

rudiment of a third trochanter. The fibula is anchylosed to the
tibia. A remarkable accessory ossicle, articulated to the tarsal os
naviculare, projects inward like an accessory or sixth digit of the
hind foot. As in other burrowing animals, the lumbar and pelvic
regions are narrow.

In the Marmot (^Arctomys) the clavicles are complete and
strong. The acromion is long and bifurcate, the anterior division
curves to the clavicle. The humerus shows a thick, but not pro-
minent, deltoid ridge : it is perforate between the condyles^ and
above the inner condyle. The antibrachial bones admit of
rotation. In the femur there is a rudiment of the third tro-
chanter : the tibia is not confluent with the fibula. In all the
Kat-tribe the clavicles are entire : the distal part of the fibula
coalesces with the tibia. In the Black Rat (^Mus rattus) the
deltoid ridge is angular, and commences near the upper end of
the humerus, which is imperforate at the lower extremity. A
strong ridge represents the third trochanter of the femur. There
is a fabella behind each condyle. In an Australian liat {Hajja-
lotis albipes) the humerus is perforated between the condyles.
The radius and ulna are moveably united. There is a third
trochanter in the femur. In the Hydromys the deltoid ridge
projects from the fore part of the proximal half of the humerus,
and is prominent below. The humerus is imperforate. The ulna
sends a process to abut against the radius across the middle of
the interosseous space. The fore foot is pentadactyle, but the
pollex does not exceed the length of the metacarpus of the
index. The femur has a third trochanter and a fabella behind
each condyle. The hallux extends to the second phalanx of the
next toe. The strength of the hinder half of the skeleton, with
the size of the hind extremities, contrasts with the slenderness of
the fore part in most Rats, and especially in this large Australian
aquatic kind.

Among the leaping Rodents the following noteworthy cha-
racters of the limb-bones are seen in the Great Jerboa of the
Cape {Helamys). The lower costa of the scapula forms an acute
angle with the base, and the infraspinal fossa is much broader
than the supraspinal one, the spine of the scapida curving toward
the upper angle. The acromion is moderately long and slender, the
tuberosity answering to the lower division of that in the Caviadce.
The clavicles are strong, and curved backward at their outer half.
The humerus is perforated at the inner condyle, but not betAveen
the condyles. The bones of the fore-arm have a long and wide
interosseous space, and allow of free pronation and supination. The

SKELETON OF KODENTIA. 383

hand is pentadactyle, and the whole anterior extremity much
shorter than the posterior one. The ihac bones extend upward
considerably above their junction with the anterior sacral verte-
brie, and curve outward. The tuberosities of the ischia are un-
usually developed. The obturator vacuities are very extensive,
the size of the pelvis according with that of the hinder extre-
mities. The great trochanter is of unusual length, is expanded
and slightly bent at its extremity. The fossa upon the neck of
the femur is unusually deep ; there is no third trochanter. The
medullary artery enters on the inner side of the base of the
small trochanter. The slender fibula coalesces with the lower
third of the tibia, but both its extremities are free, and the lower
one is detached, as in the Chevrotain, from the rest of the bone.
The calcaneum, astragalus, and cuboid are all remarkable for
their length : the scaphoid sends a long and thick process do^^Ti-
ward and forward to beneath the middle cuneiform and the base
of the inner metatarsal. There are four distinct metatarsals and
four toes. An oblong ossicle, attached to the inner side of the
base of the inner metatarsal, may be a rudiment of the metatarsal
of the hallux.

In the Smaller Jumping Mouse {Dipus Sagitta), fig. 232, may
be noticed the large size of the ischium, as compared with the
ilium, and the coalescence of the metatarsals of the three middle
toes into one bone, m, as in Birds. Both hallux and little toe are
wanting. The lower half of the slender fibula is anchylosed to
the tibia.

The climbing Squirrels {Sciuridce) have four digits on the fore
foot, and five digits on the hind foot, conversely to the Helamys.
All possess complete collar-bones. In Sciurus maximus the
acromion is bent almost at right angles with the spine of the
scapula, and it terminates in three prominences : the coracoid is
unusually long. The humerus is perforate above the inner
condyle, but not between the condyles. In the femur the small
trochanter is unusually prominent : there is also a trochanterian
ridge below the base of the great trochanter. In the Grey
Squirrel {Sc. cinereus) the scapula is remarkable for the num-
ber and strength of the intermuscular cristfe : of these, that
which is commonly called the ' spine ' is the largest, its breadth
being equal to that of the infraspinal fossa : this fossa is bounded
by a second ridge, formed anteriorly by the outwardly bent
lower costa, but being distinct from the costa at its posterior
third. The two principal masses of the ' subscapulars ' muscle
are divided by a longitudinal crest, like the spine, rising from

384

ANATOMY OF VERTEBRATES.

the inner surface of the scapula. Both the acromion and coracoid
are well developed.

The humerus is perforated above the inner condyle : this is a
tuberosity which appears to be supported by four converging
columnar ridges or processes. The deltoid and supinator ridges
are well marked. The shaft of the ulna is much compressed : its
distal portion coalesces with that of the radius. In the carpus
an accessory ' intermedium ' is wedged between the scaphoid and
trapezium. The bones of the pollex support the tubercle that
outwardly represents that digit ; the Squirrel's favourite nut is
mainly held between the ' thumb tubercles ' when operated on
by the chisel-teeth. In the pelvis the epicotyloid tubercle is
strongly developed : the ilia articulate with the first sacral ver-
tebrae exclusively, but the ischia abut against the long transverse
processes of the first caudal: beyond this vertebra the ischia
develope on each side two tuberosities, one at the usual place,
the other and stronger one near the lower end of the symphysis.
The femur shows an almost equal developement of the three
trochanters. The medullary artery enters on the inner side of
the shaft, just below the small trochanter.

The tibia and fibula coalesce distally. There is an inter-
articular ossicle in the knee-joint; a patella; and two fabellag.

one behind each femoral condyle. In the tarsus an
accessory ossicle is wedged between the calcaneuni;
astragalus, naviculare, and entocuneiforme.

The little Flying Squirrel {Pteromys volucella), fig.
247, is chiefly remarkable for the long and strong accessory carti-
lage, a, projecting from the ulnar side of the carpus, which aids
in supporting the lateral fold of integument serving as a para-

SKELETON OF INSECTIVORA. 385

cliute to support this light and delicate species of Rodent,
fig. 154, in its long flight-like leaps from bough to bough. In-
creased stiffness and resistance are imparted to the bones of
the arm by the anchylosis of the radius, 54, and ulna, 55, at
their distal halves. The tibia, 66, and fibula, 67, are similarly
united.

There are few generalisations deducible from the limb-bones of
Rodentia. The absence of clavicles accords, in the main, with
natural groups ; but Lagomys is an exception among LeporidcB
and Chinchilla among Hi/stricidce, Wth. : most non-cla\dculate
Kodents have the tibia and fibula distinct.

Among the bones of the splanchnoskeleton may be noted the
^ OS penis,' which is present in most members of the Kodent
order.

§ 182. Skeleton of Insectivora. — The present like the preceding
Lissencephalous order has species organised, not only, as in
Hedgehogs, for ordinary terrestrial progression, but also for leap-
ing and swimming, and in a more especial degree for burrowing
and flying.

A. Vertebral Column. — In the Hedgehog the vertebral for-
mula is: — 7 cervical, 15 dorsal, 6 lumbar, 3 sacral (or L 5, s 4),
and 14 caudal. The transverse processes of the last cervical are
not perforated. All the processes are small throughout the verte-
bral column, and ofler no impediment to the free inflection of the
spine required in the defensive array of the prickly integument.
The sacrum is narrow and articulates by three vertebra with the
ilia: these form an angle of 130° with the spinal column : the
ilio-pubic angle is about 150°: the symphysis is short and the
pelvic outlet large. The neural canal is widest in the cervical
region, contracts towards the middle of the back, and expands a
little in the loins. Seven pairs of ribs directly join, by hasma-
pophyses often ossified, the sternum, which consists of four bones.
The cancellous structure of the vertebra? is light and open.

The Tenrecs {Centetes) have 19 dorsals with 5 lumbar ver-
tebrae, and the neural spines are longer on the anterior ones and
the contiguous cervical vertebrae, in relation to the larger skull
and more powerful jaws of these tropical Hedgehogs.

In the leaping Macroscelides, with d IZ, I 1 , the neural spines
of the hinder dorsal and lumbar vertebra? are longer, and, with
those anterior to them, indicate '^ a centre of motion' of the trunk.
The caudal vertebrae are more numerous and have hjemapophyses
in part of the series. This part of the skeleton is also Avell deve-
loped in the climbing Tupaias.

VOL. II. c c

386

ANATOMY OF VERTEBRATES.

In the burrowing Mole, fig. 248, the first sternal bone, or
manubrium, is of unusual length, being much produced forward,
and its under surface downward in the shape of a deep keel for
extending the origin of the pectoral muscles. Seven pairs of
ribs directly join the sternum, which consists of four bones, in

248

i 'i \[\\\^-^

Mole (Talpa europwa).

249

addition to the manubrium and an ossified ensiform appen-
dage. The neural spines, which are almost obsolete in the first
eight dorsals, rapidly gain length in the rest, and are antro-
verted in the last two dorsal vertebrae. The diapophyses, being
developed in the posterior dorsals, determine the nature of the
longer homologous processes in the lumbar vertebras. In these
the neural spines are low, but of considerable antero-posterior
extent : the diapophyses are bent forward in
the last four vertebrae : a small, detached,
wedge-shaped hypapophysis, fig. 249, C, «, is
fixed into the lower interspace of the bodies
of these vertebras.

The ossa innominata have coalesced with the
sacrum, fig. 248, s, but not with each other, the
l^ubic arch, 64, remaining open. The bodies of
the sacral vertebras are blended too-ether and
are carinate below : their neural spines have
coalesced to form a high ridge. The acetabula
look almost directly outward. In the cervi-
cal series tlie odontoid process shows a sharp hypapophysis :
the neural spine of the dentata, fig. 249, a, 2, is large and ex-
tended back over the third vertebra : the neural arches of this
and the succeeding vertebrae form, above the zygapophyses, thin
simple arches, without spines; the transverse processes of the
fourth, fifth, and sixth cervicals are produced forward and back-
ward, and overlap each other, ib. 4—6 : in the seventh those

A, B, cervicals, c, lurabars
of Mole. LXXXVI-.

SKELETON OF INSECTIVOEA.

387

250

Pelvis, Pteroptis.

251

processes are reduced to tubercular diapophyses which are not
]:>erforated : the bodies of the vertebra) are dej^ressed and quadrate,
ib. B.

Among the volant Insectivora the vertebral formula, in Ves-
pertilio murhius^ gives — 7 cervical, 12 dorsal, 7 lumbar, 3 sacral,
and 12 caudal. The chief characteristics of the trunk-skeleton in
Bats are : — the gradual diminution of size of the spinal column
from the cervical to the sacral regions; the absence of neural
spines, a keeled sternum, and a feeble slender
pelvis. In a frugivorous Bat {Pteropus fus-
cus, fig. 156) I find the following vertebral
formula: — 7 cervical, 14 dorsal, 4 lumbar,
and 6 sacral. The keel of the laro;e manu-
brium sterni is produced into a process at
each angle : the three succeeding sternal
bones are carinate : seven pairs of ribs di-
rectly join the sternum. The narrow sub-
cylindrical ilia, fig. 250, a, coalesce with the
sacral vertebra3, and are parallel with the
spinal column : the pubis, ib. b, is continued in a line with the
ilium to the symphysis,
ib. c, which is but slightly
closed in the male, and
remains open in most
female Bats. There is a
' pectineal ' process, ib. h,
in Pteropus. The ischium,
ib. d, joins the last sacral
vertebra and defines a
sacrosciatic foramen. Tlie
acetabula look backward (dorsad) as well as outward.

B. The Skull. — This, in Pteropus and Galeopithecus, fig. 253,
manifests the lissencephalous affinity by the squamosal being per-
forated by a venous canal behind the root of the zygoma, by the
suspension of the malar, 26, in the zygoma, by the distinct j^etro-
tympanic, 28, by the vertical occiput, small cranial cavity, and
blended orbital and temporal fossa3. The orbit is partly defined
behind by long and slender processes of the frontal, ib. ii, which
is perforated by a superciliary foramen. The parietals, ib. 7,
usually coalesce at the sagittal suture, but rarely develope a crest.
The occipital condyles, ib. 2, are terminal, and the plane of the
foramen is vertical. The basioccipital, i , is a subquadrate plate.
The lacrymal, ib. 73, is in great part facial. The palatines, 20,

c c 2

Skull of Pteroims.

388

ANATOMY OF VERTEBRATES.

are entire. In Pteropus the palatal processes of the maxillary, 21,
show a long fissure : those of the premaxillaries, ib. 22, are divided
252 t>y ^ triangular ' fora-

men incisivum.' The
mandible has a broad
and high coronoid pro-
cess : the angle is
rounded. In Galeopi-
tliecus the coronoid is
small.

In the cranial cavity
the rhinencephalic fossa
is large and well de-
fined. The petrosal
shows a deep cerebel-
lar fossa, overarched by
the vertical semicircular
Base. Mandible. caual. Thc ^ sclla ' lias

Skull Of Pteropus. ^^ ^^.^^^-^l prOCCSSCS.

In most insectivorous Bats the occipital condyles are sub-
terminal, the superoccipital, fig. 254, 3, sloping backward, and

contributing to the crista
continued forward by
the interparietal and
parietal bones. The oc-
cipital foramen is very
large. The mastoid, 8,
is large and distinct,
giving attachment to the
tympanic, 28. Thebasi-
sphenoid is broad and
flat as in Pterojms, fig.
252, 5. The frontal has
no postorbital process.
The zygomatic parts of
the squamosal, 27, and
malar, 26, are slender.
The premaxillaries are
very small : in some Bats
they are wanting (^Rhi-
nolophus), or are repre-
sented by separate moie-
ties attached to the fore-part of the maxillaries. The mandible

253

Skull of Galeopitliecus.

SKELETON OF INSECTIVOEA.

389

254

Skull of Bat iPhyllostoma).

has the angle usually produced, fig. 254, A. The malleus and
incus are united ; the crura of the stapes are long and slender.

The skull of the Mole {Talpa, fig. 255) is subdepressed,
pyriform, large be-
hind, tapering to the
fore-part, which is
prolonged by the
prenasal ossicle, n.
The outer surface
of the cranium is
smooth and devoid
of crests : it is re-
markable for the
extension of the
superoccipital upon
its upper part, and
for the expanded
mastoids. The very slender zygomata show no distinct malar
bones. The petrosal is largely and deeply excavated by the
cerebellar fossa. The rhi-
nencephalic fossa is large
and well defined. The basi-
occipital and basisphenoid
are thick and of a fine
spongy texture. The orbit
is no way defined from the
temporal fossa : the antor-
bital foramen is large. In
the Cape Mole ( Chrysochlo-
ris) the cranium resembles
that of the bird in its thin
smooth convex walls, its
great transverse and verti-
cal diameters, its allocation
at the back of the skull, and
by the transverse crest ex-
tending, as in some sea-
birds, from one mastoid, over
the vertex, to the other.
The base of the zygomatic
process of the squamosal is
deeply excavated anteriorly, and the zygomata converge, straight,
to the maxilla. Some Shrews {Amphisorex^ have no zygomata.

Mole : magnified.

390 ANATOMY OF VERTEBRATES.

In the Hedgehog the squamosal is traversed by a vertical venous
canal. The malar is applied, like a splint, along the outer and
under side of the junction of the zygomatic with the maxillary.
The cranial cavity shows the rhinencephalic compartment to be
nearly equal in size vnth the epencephalic one : the petrosal is
impressed by a cerebellar fossa. The nasal passage terminates
behind in a hemispheric excavation of the basisphenoid ; and
this bone expands outwardly to form the floor of the tympanic
cavity. There are two oblong vacuities in the palatal bones.

In the Gymnura the bony palate is entire. The premaxillaries
join the anterior half of the nasals. The lacrymal perforation is
in a small fossa at the fore-part of the orbit, which is not defined
from the temporal fossa. The zygomatic process of the squa-
mosal is long and slender, joining that of the maxillary. The
basisphenoid expands to form the floor of the tympanic cavity.
The superoccipital and parietal crests are well developed. The
pterygoid is pierced lengthwise by an ectocarotid canal.

C. Bones of the Limbs. — All the Insectivora have perfect
clavicles. The scapula of the Hedgehog is almost as long as the
humerus ; the acromion is bilobed : the coracoid produced and
thick. The humerus is perforated between the condyles. The
antibrachials are distinct, but closely connected together : the
ulna being the larger and more compressed. The carpus consists
of a scapholunar bone, a cuneiforme and large pisiforme, a
trapezium, trapezoides, magnum and unciforme. A sesamoid is
attached to the outside of the base of the metacarpal of the
digitus minimus. The fibula coalesces at its distal end with the
tibia. The ectocuneiform and cuboides are elongated. The foot
is pentadactyle and plantigrade.

In Aynphisorex the radius and ulna are closely united, and the
fibula appears as a slender process ascending from the middle of
the tibia. In the proboscidian Shrew {Rhynchocyoii) the pollex
is wanting, and the fifth digit has but two phalanges ; but the
index, medius, and annularis present the normal number of pha-
langes supported on long metacarpals. Besides the usual eight
carpals, there is an ' intermedium ' between the scaphoid, trape-
zium, trapezoides, and magnum. In the hind-foot there is a
rudiment of the metatarsal of the first toe, and the fifth has the
usual number of phalanges.^

The ]\Ioles exhibit the extremes of modification of the fore-limb
in relation to the power of making progress in earth. In Talpa

SKELETON OF INSECTIVORA.

391

256

europcBa the scapula, fig. 256, 52, combines ornithic proportions
vA{\\ unusual strength ; its length exceeds its extreme breadth
by six times : it is trihedral, save at the middle, which is cylindri-
cal: the spine is co-elongate, and developes an acromion liga-
mentously connected, for freedom of
movement, with the clavicle. This
bone, ib. 58, is cubical — an unique
form in Vertebrata. The humerus,
fig. 256, 53, fig. 257, is a sub-
quadrate, lamellifbrm bone, with a
proximal articulation for the clavicle,
58, as well as for the scapula, b, c.
The inner tuberosity swells out with
the deltoid, d, and pectoral, p, ridges
into an enormous convex crest, divi-
ded by a short and deep emargina-
tion from the inner epicondylar pro-
cess, i, the base of which is perforated by the median nerve.
The outer tuberosity, t, is produced and unciform ; and a long
and deep emargination divides it from the retroverted produc-
tion of the radial condyle, o. This condyle offers a convexity
to the head of the radius, fig. 257, 54. The olecranon, fig.
257, 55, expands transversely at its extremity, and the back part
of the ulna is produced into a strong ridge of bone. The

Boues of fore-limb. Mole.

257

fO/»n

(iraik

fp!j ,:e]

Humcriis and its comicctions, Mole: in;igiiifled.

carpus, fig. 258, consists of the usual eight bones in two rows,
viz. ' scaphoid ' s, lunare /, cuneiforme c, pisiforme p ; trapezium t,
trapezoides, magnum in, unciforme u : with an ' intermedium,' o,
and a second sabrc-shapcd accessory ossicle at the radial side of
the carpus. The ungual phalanges are bifid.

392

ANATOMY OF VERTEBRATES.

In the Cape Mole {Chrysocliloris) the clavicle is long: the
humerus is short and arcuate, with a single proximal articulation.
The radius and ulna coalesce. The carpus consists of a scaphoid,
usually confluent with a trapezoid, fig. 259, 5, ^; a lunare, of
small size, articulated to both radius, 54, and ulna, and present-
ing the opposite and larger surface to the magnum, m ; a still

258

259

Bones of the fore-foot, Mole : magn.

Bones of the fore-foot, Chrysochlons : magn.

smaller cuneiforme ; and a pisiforme, p, in the form of a long
subcylindrical bone extending from the carpus to the humerus,
and simulating a third antibrachial bone. On the outer side of
the magnum, m, is a small unciforme supporting a rudiment of a
fourth metacarpal. The functional digits are but two : the pol-
lex is represented by a metacarpal and tAvo short phalanges, the
second being styliform, i : the index, 11, consists of a short meta-
carpal, a phalanx representing the first and second confluent, 1, 2,
and a larger ungual phalanx, 3, cleft at the end. The medius,
III, is of monstrous proportions : its metacarpal is broader than
long, to which articulates an enormous ungual phalanx, iii, bifur-
cate through the depth of the terminal cleft. A metacarpal re-
presentative of the fourth digit, iv, is firmly articulated with, and
strengthens the base of, the third digit.

The volant Insectivora are as remarkable for the leno-th and
slenderness of the arm- and finger-bones, as the fossorial species
for the opposite proportions. The Common Bat ( Vesjjertilio
murinus) has long and strong bent clavicles : broad scapulae :
elongated humeri : still more elongated and slender radius and
metacarpals and phalanges of the four fingers, which are without

SKELETON OF BRUTA. 393

claws, the thumb being short and provided with a claw : the
pelvis is small, slender, and open at the pubis : the fibula is
absent, like the ulna in the fore-arm: and a long and slender
styliform appendage to the heel helps to sustain the caudo-femoral
membrane.

In the frugivorous Bat (^Pteropus, fig. 156) the clavicles, 58,
are long, arched, and very powerful. The humerus, 53, is long,
slender, gently sigmoid. The ulna, 55, is slender, and terminates
in a point at the lower third of the radius, 54 : the olecranon is a
detached sesamoid ossicle. The index, ii, has a claw as well as
the pollex, i : the ungual phalanx is wanting in the other three
digits, in which the second phalanx is long, slender, and termi-
nates in a point. The femur, 65, is straight, half the length of
the humerus : the tibia, 66, is more slender, rather longer than
the femur : the fibula is in the form of a slender style ascending
from the outer malleolus and terminating above in a point. The
inner digit of the foot, i, is a little separated from the other four,
V, which are of equal length, and unguiculate for suspending the
body.

In the Colugo (^Galeoj^ithecus) the ulna terminates in a point
at the lower fourth of the radius : all the five digits of the hand,
like those of the foot, have claws supported on deep compressed
ungual phalanges.

Amono^st the most remarkable bones of the scleroskeleton is
the ossification of the raphe between the lateral masses of the
muscles of the nape, forming a styliform bone coextensive with
the cervical vertebrae, in the Mole. The patella in the triceps
extensor cruris, and the fabellae in the tendinous origins of the
gastrocnemii, are present in most Insectivora. The os penis is
also found in this order.

§ 183. Skeleton of Bruta. — A. Vertebral Column, — In the
loricate or Armadillo family this is remarkable for the pre-
valence of anchylosis in unusual parts, e. g. the cervical region,
and throughout the dorso-lumbar regions in the great extinct
Glyptodonts, which have their cuirass in one piece.

In the Nine-banded Armadillo {Dasypus Peba, fig. 260), the
vertebral formula is: — 7 cervical, 10 dorsal, 5 lumbar, 8 sacral,
and 16 caudal. The spine of the dentata is compressed, lofty, and
developed backward beyond those of the third and fourth cervicals,
with which it has partially coalesced : a corresponding coalescence
has taken place between the bodies of these vertebras, which are
unusually broad and flat below. The diapophysial part of the
transverse processes of the last cervical abuts against the tubercle

394

ANATOMY OF VERTEBRATES.

of the first broad dorsal rib : the pleurapophysial part of the
same transverse process is broad and short, and extends down-

260

ward in front of the same rib. The last three cervicals, ib. C,
have no spinous processes ; that of the first dorsal rises to a
considerable height, and those of the remaining dorsals, D, and
lumbar vertebrae, L, attain the same horizontal line. The meta-
pophysis is first fully develoj^ed upon the seventh dorsal, and pro-
gressively elongates to the last lumbar, fig. 261, m: it presents
2(^1 an articular surface at the

under and fore part of its
base to be articulated with
the anapophysis of the ante-
cedent vertebra. The ana-
pophyses increase in thick-
ness rather than in length in
the succeeding vertebra3, and
upon the last dorsal present an
articular surface at their under
part for connection with a pa-
rapophysis, ib. p. These ac-
cessory joints coexist with the
ordinary articulations between the anterior and posterior zygapo-
physes, and there are consequently twelve joints between each
pair of vertebra), in addition to the ligamentous one between the
bodies of the vertebms, ib. c. This mechanism is designed to
give great strength and fixedness to the vertebra) of the trunk
in relation to the support of the bony carapace, ib. h, h, and to

Vertebral architecture for support of carapace,
Armadillo.

SKELETON OF BRUTA. 395

the aifording a firm fulcrum or centre to the powerful muscular
forces exercised by the limbs in the act of burrowing. The
elongated metapophyses have a more direct relation to the sup-
port of the carapace, the spinous processes representing the
' king-posts,' ib. n, and the metapophyses the * tie-beams,' ib. m,
in the architecture of a roof. The sacral vertebra) progressively
increase in breadth after the second, to form an extensive junc-
ture with the ischial bones. The tuberosities of the ischia,
fig. 260, 63, and similar tuberosities at the fore-part of the ilia,
fig. 277, 62, bend outward and upward, to afford four strong
additional supports to the bony carapace : the long diapophyses
of the first caudal vertebra abut ao;ainst those of the last sacral
vertebra and the tuberosities of the ischia. The metapophyses
reappear upon the second caudal vertebra, and continue to the
antepenultimate one, where they are reduced to ridges upon the
anterior zygapophyses. H^mal arches, with short terminally ex-
panded and flattened spines, are present beneath the intervals of
many tail-vertebrae. In Ghjptodoji the caudals coalesce.

The posterior dorsal ribs are deeply excavated upon their
external surface ; five pairs directly join the sternum, which
consists of six bones, a very small one being interposed be-
tween the fourth and the long one supporting the ensiform carti-
lage.

In the Cape Anteater {Orycteropus), the vertebral formula
is: — 7 cervical, 13 dorsal, 8 lumbar, 6 sacral, and 25 caudal:
anchylosis is limited to the sacral region : the cervical transverse
processes overlap each other ; the costal part of the sixth is a
broad plate. The dorsal and lumbar neural spines are much
longer than those of the cervical, and are subequal : they slightly
converge to that of the twelfth dorsal, which is vertical, indicating
a greater extent of inflection of the trunk than in the South
American Anteater ; increased freedom of motion is likewise
favoured by the less complex character and mode of union of the
vertebrae. An accessory tubercle is developed upon the diapo-
physis of the seven anterior dorsal vertebra?, which divides near
the eighth into metapophysis and anapophysis. These progres-
sively increase and diverge from one another in the succeeding
dorsals, and in the first lumbar vertebra the metapophysis pro-
jects upward, outward, and forward upon the outside of the
anterior zygapophysis ; whilst the anapophysis extends backward
from the back part of the diapophysis, which it equals in length.
The anapopliysis decreases in size in the following lumbar verte-
bnc and disa[)pears in the last ; the meta[)ophysis also decreases

396 ANATOMY OF VERTEBEATES.

in size, but is continued throughout the lumbar series and along
part of the sacral. The sacral spines coalesce, leaving interven-
ino- foramina, fig. 262, a : the transverse processes of the three

anterior sacrals loin the ilia,
c, g ; those of the three
posterior ones coalesce to
form a broad depressed plate,
mth the posterior angles
produced, ib. b, but not join-
ing the ischia. These have
a long and broad tuber ischii,
ib. k, I. The pubis, d, is

Pelvis of Orycteropus. tit

long and slender : the pec-
tineal spine, ib. A, is long ; the symphysis pubis is short ; the
lumbo-iliac angle is 140°. Metapophyses are developed from
the outside of the anterior zygapophyses, as far as these extend
along the caudal series, viz. to the eighth vertebra ; beyond these
the metapophyses are developed, independently of the zygapophy-
ses, to near the termination of the tail. The haemal arches com-
mence below the interspace between the second and third caudals,
and are continued as far as that between the sixteenth and seven-
teenth. The neural arch disappears upon the sixteenth caudal
vertebra.

In the Scaly Anteater (^Manis pentadactyla, fig. 158), the
transverse process of the seventh cervical is perforated : its spine
is longer than that of the others. There are 13 dorsal vertebrae.
The nine anterior pairs of ribs directly articulate with the ster-
num, which consists of ten bones. The tenth is of unusual
length, and supports a still longer and much-expanded xiphoid
cartilage. The metapophyses commence as tubercles on the first
dorsal vertebra, and rapidly increase in size in the succeeding
vertebras. The anapophyses are not developed in this genus.
There are 4 lumbar, 4 sacral, and 26 caudal vertebrse. The me-
tapophyses continue to be developed from the sacral series. The
transverse processes of the last sacral suddenly expand both in
leno^th and breadth, and articulate with the tuberosities of the
ischia. Well-developed hfemal arches are articulated to the in-
ferior interspaces of the caudal vertebrae as far as the penultimate
one. The anterior zygapophyses cease upon the fourteenth ver-
tebra, but the metapophyses are continued as far as the penulti-
mate caudal. The neural arch gradually subsides and disappears
upon the twentieth caudal vertebra, which consists of centrum,
diapophyses, metapophyses, and the heemal arch.

SKELETON OF BRUTA.

397

In the skeleton of the Great Anteater {Mp^mecophaga juhata,
fig. 263), the vertebral formula is : — 7 cervical, 15 dorsal, 3
lumbar, 5 sacral, and 35 caudal. The atlas is pierced in two
places obliquely at the fore-part of the neural arch on each side.
The axis has a transverse perforation on each side the neural arch
anterior to the transverse process, which is imperforate. The
transverse processes of the three succeeding cervicals are imper-
forate, the vertebral artery entering the neural canal behind, and
perforating obliquely the base of the neurapophysis, anteriorly.
In the sixth cervical, the canal for the vertebral artery runs
through the base of the transverse process. These processes are
much extended antero-posteriorly in all the cervicals and overlap

263

Myrmecophoga jubata.

each other : their di- and pleur-apophysial . portions are very
distinct in the fifth and sixth cervicals. The spine of the seventh
is lono^er than the rest and truncate above ; it is much exceeded
in antero-posterior diameter by the spine of the first dorsal. A
metapophysial tubercle is developed from the outer side of the
prozygapojohysis in all the five posterior cervicals. It is placed
more outwardly in the first and second dorsals, and gets ujDon the
top of the diapophyses in the succeeding dorsals. In the eleventh
dorsal the metapophysis begins to resume its former position, and
developes an articular surface from its under part, which joins the
upper articulating surface of the anapophysis of the preceding
vertebra. In the thirteenth dorsal, the metapophysis is half-way

398 ANATOMY OF VERTEBRATES.

between the diapophysis and anterior zygapopliysis, and repeats
the same articnlation with the anapophysis. In the last two
dorsal vertebra?, the base of the metapophysis developes a second
articular surface from its inner side, which joins a new or acces-
sory articular surface on the outside of the posterior zygapophysis
of the antecedent vertebra. This tenon-and-mortice articulation
of the metapophysis with the zygapophysis on the inner side and
with the anapophysis on the outer side, is repeated throughout
the whole lumbar series. The anapophysis begins to be developed
from the anterior dorsal vertebra, and even there presents an
articular surface at its under part to join a corresponding surface
on a parapophysis developed from the fore and outer part of
the neural arch of the succeeding vertebra. In the tenth dorsal
a second articular surface is established in the upper part of the
anapophyses for the inferior metapophysial one of the succeeding
vertebra ; here, therefore, the anapophysis begins to be morticed
between the parapophysial and metapophysial articular surfaces,
which surfaces continue to the antepenultimate lumbar vertebra,
from which, forward, to the eleventh dorsal, there are sixteen
joints between each pair of vertebrae. But this complication goes
further ; for, in the penultimate lumbar vertebra, a third articular
surface is developed from the under and outer part of the anapo-
physis, which joins an articular surface on the upper and fore part
of the diapophysis of the last lumbar : and this vertebra is united
in a similarly complex manner with the first sacral vertebra,
which would make eighteen synovial joints, in addition to those
at the ends of the centrum, but that those between the normal
articular processes, or zygapophyses, are now suppressed. The
true serial homology of the processes as ' parapophyses,' de-
veloped from the fore part of the base of the neural arch to
articulate Avith the under part of the anapophyses, is well illus-
trated by the vertebrae of the Great Anteater, as in the Mega-
therium, in which the true diapoj)hyses are better developed than
in the Armadillos.

The spines of the sacrals, ib. s, blend into a bony ridge ; the
transverse processes of the last three join the ischia. Ha3mal
arches articulate with the intervals of most of the caudal
vertebrae.

In the little Two-toed Anteater the dorsal pleurapophyses show
a chelonian expansion ; but overlap, or join by squamous instead
of dentate sutures.

In the Ai {Brachjpus tridactylus, fig. 263), the vertebral formula
is :— c 9, D 16, L 3, s 6, cd 11. The neural arch of the atlas is

SKELETON OF BRUTA

399

perforated by the vertebral artery anteriorly, and by the cervical
nerve posteriorly. The spines of the cervical vertebroe are mo-
derately and equably developed. The pleurapophysial part of the
transverse process of the eighth cervical, fig. 265, «, pi, is more
extended antero-posteriorly than in the preceding cervicals, and
long remains free. The pleurapophysis of the ninth cer\dcal,
ib. b, 2^1, retains its freedom, and is more extended in the direction
of its length, but is very short as compared with the homologous
part, pi, of the following vertebra. The slender neck and head
of this little rib, joining the fore part of its centrum, occasions the
perforated character, as in the antecedent cervical vertebra. A
short metapophysis is developed from the fore part of the diapo-
physis of the penultimate dorsal vertebra, increases in size in the

264

Three-toed Sloth.

last dorsal, and ascends upon the base of the prozygapophysis of
the third lumbar vertebra. The anapophysis is also developed from
the last dorsal and from the three lumbar vertebras ; it is short,
with an articular surface applied to the outer side of the pro-
zygapophysis of the succeeding vertebra. The spinous processes
gradually subside in the posterior dorsals, fig. 264, d, and become
obsolete in the lumbar vertebras, L. The first pair of dorsal ribs,
pi, h, is anchylosed to the manubrium, s: nine pairs directly
articulate with the sternum, which consists of eight bones ; these
are compressed, and progressively increase in depth ; the hinder
ones are divided into a larger posterior and a smaller anterior
part, between which are four articular facets on each side for
the bifurcated extremities of two of the ossified cartilaoces. There

400

ANATOMY OF VEETEBEATES.

205

is a pair of liypapophyses on the fifth, sixth, and seventh caudal

vertebrae. The pelvis con-
sists of five or six sacral
vertebra3 coalesced with each
other, also (1-4) with the
ilia, and (5-6) with the is-
chia, leaving wide ischiadic
foramina, fig. 266, d. The
sacral spines are obsolete,
and the centrums much de-
pressed. The ilia are short
and broad, forming an an-
terior concavity. The is-
chial tuberosities are small,
and the part joining the
pubis to circumscribe the
large obturator foramina is
slender. The pubis is also
slender, and forms a very
short symphysis, c. The
pelvic outlet is wide.

In the Two-toed Sloths
(Cholcepus) the vertebral formula is C 7, B 23, L 3, s 8, cd 4,
or D 24, L 2 ; or D 23, L 4, s 7, the number being essentially the

same. The second and
thn'd cervicals sometimes
coalesce. Cholcepus Hoff-
manni has only six cervi-
cals.^ Twelve pairs of ribs
join the sternum, which
consists of eleven bones.
Not any of the great extinct
Ground Sloths have more
than seven cervical verte-
brae ; but in the number of
dorsal vertebrae, as in every
other bradypodal character,
they manifest their true af-
finities. The Mylodon, fig.
267, offers a singular con-
trast with the Mole, fig. 248, in the proportions of the sacrum :
this, by anchylosis with the three lumbar and last dorsal, dls.

Cervical and dorsal vertebriB, Ai.

Pelvis of the Ai, anterior view.

SKELETON OF BRUTA.

401

includes eleven vertebra, and forms one strong and continuous
bony mass along the whole lumbar region. Its total leno-th is
two feet four inches, and it gradually increases in breadth
to the sacro-iliac union, which is formed by the first, second,
and third true sacral vertebra, and there presents its greatest
breadth. It then contracts slightly, and, at the sixth and last,
expands again to join the ischia, fig. 268, c, with which and

26'

Mylodon rohnstus. xc".

the ilia it coalesces. Its anterior surface is curved both laterally
and vertically. The sj^inal canal is very wide, and the foramina
passing from it mark the primary segments. Their neural spines
form a curved crest, ib. g. There are twenty-one caudal ver-
tebrae, fig. 267, cd. The iliac crest is arched, thickened, and
rough; the al^e notably expanded. The ischia, after effecting
the sacral confluence, at c, arch outward, of slender form, and
expand, at h, fig. 268, to join the still more slender pubis, h,

VOL. II. D D

402

ANATOMY OF VERTEBRATES.

Pelvis of the Mylodon robustus, posterior view. xc'.

and complete the wide obturator hole, o. The tuberosity, /e, is not
well marked.

The vertebral column shows neither in Mylodon nor Mega-
therium any apophysial de-
velopements related, as in
the Armadillos, to the sup-
port of a bony carapace.

The Megatherium has C
7, D 16, L 3, S 5, Cd 18 ; fig.
279. The neural spines elon-
gate in the last two cervical,
and increase in both length
and breadth in the anterior
dorsal vertebrae. The dorsal
hajmapophyses are bony as
in the Mylodon, Sloths,
Anteaters, and Armadillos.
Nine pairs of ribs directly
articulate with the sternum,
which consists of eight bones. Most of the dorsal vertebrae
are peculiar in having a third, medial, zygapophysis between
the ordinary anterior and posterior pairs : they likewise present
three surfaces to the pleurapophysis, one on the centrum for
the ' head of the rib,' one on the neurapophysis for the ' neck,'
and one on the diapophysis for the ^tubercle.' The htemapo-
physes present analogous complex joints with the sternebers,
ha\dng a pair of condyles, synovially articulated with two pairs of
cavities on contiguous sternebers, each such sterneber presenting
ten articulations, one for the antecedent, another for the succeed-
ing sterneber, and two pairs of haimapophysial ca\dties on each
side. The posterior dorsal and lumbar vertebrae present, besides
the articular surfaces for the centrums, and those of the zygapo-
physes, also a pair of metapophysial and a pair of anapophysial
articulations.^ In the confluence of the anterior dorsal pleur- and
haem-apophyses the Megathere ^ resembles the Sloth. The caudal
vertebrae supporting, as in Mylodon, a powerful column, serving
as a prop to the massive hind part of the trunk when the fore
part is raised, as in fig. 267, have long and strong di- and haem-
apophyses : the latter separate in the first caudal, but coalesced at
their distal ends in the succeeding caudals to near the end of tlie
tail.^

XCI-. PI. iii. fiffs. 4 and 5.

lb. PI.

lb. Pis. ii. and viii.

SKELETON OF BKUTA.

403

269

Skull of Mijrmecophaga jabata. cli

The large pelvis, the union of the ischia with the sacrum, and
the speedy osseous confluence of the several pelvic elements, are
common characteristics of the spinal column of the Bruta : in
no other Mammalian order are found such complex vertebral
articulations ; and here alone are manifested the exceptional in-
stances of affinity to certain Ovipara in the lower cervicals with
free ribs of the Three-toed, and in the twenty-three costigerous
dorsals of the Two-toed, Sloths.

B. Skull. — The skull in the insectivorous Bruta is lono; and
slender ; these proportions reaching their extreme in true Anteaters
{Myrmecophaga, fig. 269). The occipital condyles, 2, are large
and terminal ; the superoccipital, 3, inclines forward as it rises to
join the parietals, 7, which
retain their ' sas^ittal ' suture.
The frontals are elongate,
and continue the smooth
transversely convex cranial
roof forward to the nasals, 1 5 ;
these are still longer, being
coextensive with the maxillaries, 21, which, with the mandible,
32, form the walls of the bony tubular sheath of the very long
tongue : the premaxillaries are minute; The orbits are feebly
defined : the lacrymal, 73, is large and chiefly antorbital. A
beginning of the malar is appended to the maxillary : the small
squamosal forms the flat surface for the mandibular condyle, but
developes no zygoma. The tympanic, 28, retains its separate con-
dition. The petrosal is excavated by a hemispheric cavity for
the condyle of the stylohyal, the framework of the tongue in
the Anteaters almost equalling the mandible in its amount of
bone.

In the Pangolins (^Manis, fig. 270) the cranium also shows the
inclination of the occipital
surface from below upward
and forward, the plane of
the foramen magnum being
slightly inclined in the
same direction. The exoc-
cipitals, 2, meet above the
foramen. The superocci-
pital, 3, is rhomboidal, and

its aspect is almost wholly upward. The mastoids, 8, form two
hemispheric protuberances at the sides of the occipital region, and
the petrosals two smaller protuberances at the sides of the base of

D D 2

270

Skull of Munis, cm.

404 ANATOMY OF VERTEBRATES.

the skull : the pterygoids, 24, extend backward beyond them, and
form the sides of a deep and wide postnasal groove. The tympanic
bone forms the lower boundary of a hemispheric bulla, which com-
municates with an equal-sized cavity in the squamosal ; a narrow
strip of the petrosal intervenes between the tympanic and the broad
basioccipital. The zygomatic process of the squamosal, 27, extends
but little beyond the joint for the lower jaw : there is no separate
malar. The premaxillaries, 22, join the nasals, 15. The small
lacrymal, in 3Ianis longicaudata, is wedged in between the fron-
tal, 11, and maxillary, 21, at the anterior angle of the orbit. Two
tooth-like processes project from the fore-part of the alveolar
border of the slender under-jaw.

In the hairy Anteater of the Cape ( Orycteropas) the petro-
mastoid and tympanic are distinct from each other, and retain
their primitive separation from the squamosals. The occipital
condyles are bilobed, the inferior and smaller lobe being developed
from the basioccipital. The zygomatic arch is slender, but entire.
A well-marked venous fossa depresses the inner border of the
foramen magnum ; the sella is large and moderately deep, with
anterior and posterior clinoid processes, bounded on each side by
the carotid channels, external to which are the deeper Gasserian
fosste. There are few mammalian skulls in which the cranial
cavity is more equally divided, than the present, into the epen-
cephalic, mesencephalic, prosencephalic, and rhinencephalic cham-
bers ; but the mesencephalic chamber contains not only the proper
mesencephalon, but also, as in other Mammals, part of the back-
Avardly developed prosencephalon, and especially those inferior
protuberances called *natiform.' The petrosals show very narrow
cerebellar fossae. The maxillary has seven alveoli, the mandibular
ramus has six : but the small anterior ones are obliterated with
the k ss of their teeth in old animals. The hyoid arch is large and

consists of the stylohyal, cera-
tohyal, epihyal, and basihyal
,3 \ elements, ivith the appended
thyrohyals, or ^ cornua majora.'
In the Armadillos {Dasy-
jms, fig. 271) the occipital plane
is vertical. There is no paroc-

Skull of Basypus Peba. CLI. • • i i • •

cipital : the superoccipital, 3, is
bent at a right angle to join the parietals, 7, which obliterate, as in
Orycteropus, the sagittal suture by their union. The mastoid is
perforated by a vein from the lateral sinus, and terminates below
in an obtuse process. The tympanic is a separate semicircular

SKELETON OF BRUTA.

405

plate of bone. The alisphenoids join the parietals. The lacrymal
is large and chiefly antorbital. The petrosal presents a wide and
shallow cerebellar fossa : the canal between the petrosal and the
angle of the superocclpital gives exit to a vein and entry to an
artery. The rhinencephalic almost equals the epencephalic divi-

272

273

Dwarf Arniadillo {Chlamyphoriis trimcatus). Lxxxviii*.

sion of the cranial cavity. The frontals are large, but chiefly
occupied by the nasal chamber : in the Chlamyphorus the outer
table rises into a pair of domes, fig. 272, a, augmenting the olfac-
tory cavity. In most Armadillos there are two small prenasal
ossicles. The premaxillaries are small and lodge the first tooth
in one or two species. The zygomatic arch is complete and
strong: the malar part, fig. 271, 27, curves down outside the
mandible, and there, in Glyptodon, developes a long process for
the service of the masseter.

The zygomatic arch culminates in regard to complexity in the
Sloths, albeit in the small
existing species, ^g. 273, the
squamosal element, 27, fails,
as in the Anteaters, to reach
the malar one, 26, b. In the
Meo-atherioids this union is ef-
fected, fig. 274, and an unusu-
ally massive arch is the result.
The malar, 26, still sends
upward its temporal process,
b, and downward its mas-
seteric one, a. This cranial
developement relates, as in
the recent and extinct Kan-
garoos, to the share of the masseter in the business of mastication ;
and the molars are transversely ridged in Megatherium as in
Diprotodon.

Skull of Ai {Brad, tridactylus), half nat. size.

406

ANATOMY OF VERTEBRATES.

Skull of Megatherium, one-flfteenth nat. size.

The facial part of the skull in the Sloth is as remarkable for its
shortness as in the Anteater for its length. In the Ai, fig. 273,
the interparietal coalesces with the superoccipital, 3, before the
exoccipitals unite Avith the super- and basi-occipitals. The malar
bone, 26, is freely suspended by its anterior attachment to the
maxillary and frontal, and bifurcates behind ; one division, a, ex-
tending downward, outside the lower jaw, the other, h, ascending

above the free termination of
^^^ the zygomatic process of the

squamosal, 27. The premax-
illary is single and edentu-
lous, being represented only
by its palatal portion com-
pleting the maxillary arch,
but not sending any pro-
cesses uj^ward to the nasals.
Within the cranium there is
no bony tentorium : the two
divisions of the meatus in-
ternus commence separately
upon the exterior of the petrosal, which is not impressed by a
cerebellar fossa. The depression receiving the natiform protu-
berance of the cerebellum is formed chiefly by the squamosal.
The walls of the rhinencephalic fossa are entirely surrounded by
the olfactory chamber, which extends above into the frontal and
beneath into the sphenoidal sinuses. A well-marked vascular fora-
men leads downward from the partition between the rhinencephalic
and prosencephalic chambers. The rough exterior part of the
petrosal forms, as it were, the border of a capsule to the tympanic :
the fossa for the stylohyal is well marked at the back part of the
border. The pterygoid forms a large quadrate vertical plate. The
bony septum narium terminates half-way from the large vertical
external nostril. There is a small imperforate lacrymal : the ant-
orbital hole is wanting. In the Unau {Bradypus didactijlus)t\\Q
lacrymal is pierced external to the orbit. In the Megathere the
foramen is at the orbital margin, and there is a large antorbital
foramen : the premaxillaries, though edentulous, are more produced
than in existing Sloths, and there is a corresponding production
of the symphysial part of the lower jaw, which is grooved above,
as in the Anteaters, for the support during its pro- and re-tractile
movements of a long tongue, prehensile in the ISIegathere as in
the Giraffe, in reference to the smaller branches of the trees
yielding food to the extinct giant. Behind the symphysis the

SKELETON OF BRUTA. 407

mandible is deepened for the long roots and matrices of the ever-
growing molars. The extension of the air-sinuses, great in the
climbing Sloths, was still more so in the colossal species, whose
strength enabled them to uproot and prostrate the trees they
browsed on. The skull of the Mylodon robustus in the Hun-
terian Museum shows two extensive fractures of the outer table,
one wholly, the other partially, healed : the latter extending to
near the occiput, but having broken only into the air-chamber,
not into the cranial cavity, the inner, proper or ' vitreous ' table of
which is everywhere divided by sinuses and sinuous bony plates
from the outer table.

Notwithstanding the extreme diversity — singular contrast in-
deed in several particulars — which the skull presents in the order
Bruta, the marks of inferiority of position in the Mammalian
series, according to the cerebral character, are constant through-
out. The terminal position of the occipital condyles and the
aspect of the occipital surface, the degree in which the parts of
the complex ' temporal bone ' of higher Mammals retain their
primitive separation, the position of veins conducting from the
cerebral sinuses, the low facial angle and small proportional size
of the cranial cavity, the small share in which the squamosal
contributes to its walls — all exemplify the inferiority of the
present unguiculate group of animals to the Gyrencephalous
Ungulates.

C. Bones of the Limbs. — In all Armadillos the clavicles, fig.
275, 52', are complete. The scapula,
51, is broad, convex externally, and
presents two spines, the normal one of
which is produced into an acromion,
long in all the species and unusually
so in the Chlamyphore, ib. n ; in most
it sends down a process from its base.
The coracoid curves downward: there
is a well-marked tubercle behind the
neck of the scapula. The suprasca-
pular element is represented by a Bones of foreiimb, chiamyphore,
coarsely ossified cartilage attached to

the base of the scapula, fig. 260, 51. The humerus is remark-
able for its strength and for the great developement of the deltoid
ridges. It is perforated above the inner condyle, but not be-
tween the condyles. The ulna, fig. 276, 55, is considerably
longer and stronger than the radius : the olecranon, fig. 275,
54, is remarkably developed. In Dasfjpus the radius, fig. 276,

408

ANATOMY OF VERTEBRATES.

54, is but half the length of the ulna: in all Bruta it is free, and
rotates on the ulna. The four carpal bones of the proximal row
are distinct from one another.

276

V \

Bones of fore-arm and foot, Dasypus gigas. cli.

The scaphoid, ib. s, is the smallest of the four bones of the
proximal row. The pisiform, p, articulates to the cuneiform, c,
and ulna, and extends, palmad, to the lunare, with which it forms
a large articular cavity, upon which the palmar patella plays. In
some the trapezium, t, is distinct; in others it is connate with
the trapezoides. The magnum, m, in most coalesces with the
base of the cubical metacarpal of the digitus medius, ill. The
outer part of the base of that metacarpal rests upon the unci-
forme, u, which also supports the small but thick cubical meta-
carpus of the annularis, iv, and rudiment of the metacarpal
of the minimus, v. The medius and annularis have each but
two phalanges ; the long and slender index retains the normal
number of three phalanges ; the base of its metacarpal is wedged
between that of the third, the trapezoides, and the trapezium. The
chief peculiarity is the very large sesamoid bone developed in the
flexor tendons, and filling the palmar aspect of the fore-foot : a
second sesamoid is attached by ligament to the apex of the large
palmar one. An accessory ossicle, x, is wedged into the outer
side of the carpus in Das. gigas. In Das. Peha, fig. 260, there
are four digits on the fore-foot, the two middle much exceeding
in length and strength the outer and inner ones : the pollex, i,
is obsolete. The femur, figs. 260, 277, 65, presents a third tro-
chanter. The proximal and distal extremities of the tibia, 66,
and fibula, 67, are connate : their shafts subsequently coalesce
therewith, so that a single epiphysis answers to the shafts of both
bones at each of their extremities, in the immature Armadillos.
The naviculare is remarkable for its two inferior tuberosities,
the interspace between which receives the under part of the
entocuneiform bone. In Das. sex-cinctus it sends downward a
process, like that in some Rodents. The calcaneum is less pro-

SKELETON OF BRUTA. 409

duced in the Chlamyphore, fig. 277, cl, than in the Nine-
banded Armadillo, fig. 260. The hind-foot is pentadactyle in
all. The chief modification of the limb-bones in the extinct
gigantic Armadillos {Glyptodoii) relates to the modification of
unguiculate feet to the support and terrestrial progression of
species too huge for burrowing, and as
heavy as the bulky Pachyderms. The ^U^

ungual phalanges are accordingly obtuse,
short, broad, and thick, for being incased in
hoof-like nails, and their phalanges are fiat
bones, presenting the maximum of breadth
in proportion to length. In the third tro-
chanter and the anchylosed tibia and fibula
the Dasypodoid characteristics are pre-
served.

The limb-bones of the Orycteropus more
resemble those of the Armadillos than of cSjVhVra ""lxS™
the toothless Anteaters. The acromion

scapulae is less elongate : the entocondyloid process of the humerus
is recurved, and widely perforated. The wrist-bones are as in
Dasypus, but the pisiform is long and slender. The pollex is re-
duced to a stunted metacarpal and phalanx, and the hand has but
four claws, of which that of the medius is largest, but less dis-
proportionately so than in Das. gigas. In the hind-limb the femur
shows the third trochanter. There is a fabella behind the outer
condyle. The tibia and fibula coalesce at their upper ends, but
not below : the hind-foot is pentadactyle.

In the Manis, fig. 153, the spine of the scapula is single, is not
prolonged into an acromion, and there are no clavicles : the
coracoid is represented by a small distinct tubercle, forming the
anterior extremity of the elliptical glenoid cavity for the humerus.
The humerus is perforated at the internal condyle. There is an
articular sesamoid developed on the outer side of the capsule
uniting the radius with the humerus. The scaphoid and lunare
coalesce. The digitus medius is disproportionately large, and its
ungual phalanx is deeply cleft : that of the index and annularis
show slightly the same character. These phalanges are so arti-
culated as to admit of flexion, but not of extension, or retraction,
beyond the line of the supporting digit. The femur has no third
trochanter. There is a fabella behind the outer condyle of the
femur. The bones of the leg retain their distinctness: the
extremity of the fibula beyond the outer malleolus bends inwar'^
and terminates in a tuberosity playing in a cavity upon the ^
side of the astragalus. There is an accessory tarsal ossir^

410

ANATOMY OF VERTEBRATES.

inner aide of the entocuneiform and scaphoid. The ungual phalanx
of the hallux is simple ; those of the three middle toes are cleft
at the apex.

In the Myrmecoi)Uacja, fig. 263, the scapula, 5i, is very broad,
with a sub-circular contour, and is traversed by two spines, the
upper one prolonged as an ' acromion ' tow^ard the coracoid, and
supporting a small cLavicular bone {Myrm. juhata) or joined to a
complete cla\TLcle {Myrm. didactyla). The humerus, 53, is greatly
expanded at its distal end, especially by the entocondyloid crest,
which is recurved and perforated. The radius, 54, and ulna are
of nearly equal length, the acromion, 55, has the lower angle pro-
duced. The carpus consists of the usual eight bones, fig. 278,
viz. scaphoides s, lunare /, cuneiforme c, pisiforme p, which is

278

Bones of the hand, Myrmecopha{jajubata. cli.

produced like a carpal calcaneum. The trapezium, t, supports a
slender pollex, i ; the trapezoides, z, a longer and larger index, ii ;
the strong, four-sided, outwardly-ridged metacarpal of the medius,
III, rests its base upon the magnum, m, and unciforme, u ; and is
wedged between that of the index, ii, and annularis, iv. The
minimus, v, which is articulated more to the annularis than to the
unciforme, 7i, has but two phalanges, and is clawless. The ungual
phalanges are dorsally grooved, not notched. In the Myrmecophaga
didactyla the metacarpal rudiments of the pollex and minimus
are liidden beneath the shin : the annularis metacarpal supports
a clawless phalanx : the two conspicuous digits are the index and
medius, the latter the largest. The femur, fig. 263, 65, has a crest
along its outer margin : the tibia and fibula, 67, are distinct : the
foot is i)lantigrade and pentadactyle, with a calcaneum long and
compressed in the great terrestrial species, but short in the

SKELETON OF BRUTA.

411

scansorial didactyle Anteater, in which a supplementary bone on
the inner (tibial) side of the tarsus is produced backward to
increase the power of the heel in grasping.

In the Ai, fig. 264, the scapula, 5i, is broad, and its outer
surface is equally divided by the spine, which is short, but con-
tinued into an acromion arching to join the coracoid. The supra-
spinal notch is converted into a foramen by the extension of
ossification from the superior costa to the base of the coracoid.
The same characteristics are reproduced in the scapula of the
Megathere, fig. 279, 52, under more massive proportions of these
growths for muscular attachments, and with the superaddition of

279

Megatherium amcricanum.

an inferior spine, as in the Anteater. The clavicle is complete in
the Megathere, ib. 58, as in the Two-toed Sloth ( Choloejms) : in
the Ai it exists as a short appendage to the acromion. In the
small climbing Sloths the length of the prehensile fore-limbs is
attained by that proportion of the humerus, fig. 264, 53, and
antibrachial bones, 54, 55 : both the latter are bent, leaving a
wide interosseous space, and are so articulated as to allow of
pronation and supination. In the Megathere the humerus is
relatively shorter, but thicker, and is enormously expanded at its
distal end, fig. 279, 53 : the inner condyle is imperforate, as in
Bradyims tridactylus : in the Megalonyx it is perforated as in
the Brad. {Cholceims) didactylus. The ulna of the Megathere,
fig. 279, 55, is equally remarkable for the vast expanse of its

412

ANATOMY OF VERTEBRATES.

2S0

proximal end, including the olecranon which is twice as broad as
long, and projects backward rather than upward. The proximal
end of the radius, 54, is circular, and its articular modifications
are as well adapted for rotatory and flexile movements of the
antlbrachial bones as in the human arm. The interosseous space
is shorter and much narrower relatively than in the Sloths. Of
these the Ai, fig. 280, has the carpus reduced to six bones, the
scaphoid being connate with the trapezium, s t, and the mag-
num with the trapezoides, m. A rudiment of the metacarpal

of the pollex, i, has co-
alesced with that of the
index, ii, and a rudiment
of the metacarpus of the
minimus with that of the
annularis, x, iv. In the
three functional digits the
proximal and middle pha-
lano;es are confluent, 1...2 :
the unequal ones are of
great length, and restrict-
ed in their movements, by
the production of the back
part of their base, to de-
grees of flexion. The joints of all the digits are deeply trochlear.
The bones of the hand of the Unau (Choloepus) are described
at p. 306, fig. 191, '^ Sloth.' In the Megathere the wrist has a
scapho-trapezium, fig. 191, st, but the trapezoid and magnum
are distinct. The pollex is represented by a stunted meta-
carpal, I: that of the minimus, figs. 191, 279, v, is long and
supports one or two short thick phalanges : the second, 11,
third. III, and fourth, iv, digits are powerfully unguiculate,
but the first and second phalanges coalesce only in the medius,
1, 2, III. The massive metacarpal is squared, firmly attached to
the contiguous ones, with the outer angle of the base produced and
wedged betAveen that of the annularis, the magnum, and unciforme.^
In the Sloths the femur, fig. 264, 65, is straight, like the
humerus, but is thicker and shorter ; the head shows no impres-
sion for a ligamentum teres. The tibia, 66, and fibula, 67, are
opj)ositely bent, leaving a mde interosseous space, as in the fore-
arm, but are still shorter than their homotypes. The inner
malleolus projects backward and supports a grooved process : the
lower end of the fibula fits, like a pivot, into a socket in the
' xcr. p. 53, pi. xxi.

Bones of fore-foot, Ai

SKELETON OF BRUT A. 413

astragalus. In Brad, tridactylus the calcaneum is remarkably
long and compressed. The scaphoid, cuboid, and cuneiform bones
have become confluent with each other and the metatarsals, of
which the first, i, and fifth, u^ exist only in rudiment. The other
three have likewise coalesced with the proximal phalanges of the
toes which they support. In the Brad. didactyJus the ento- and
meso-cuneiform bones, the rudimental metatarsal of the hallux,
and the metatarsal of the second toe are confluent into one bone :
the rudimental metatarsal of the fifth toe has not become united
with that of the fourth toe. The functional toes have long pre-
hensile claws like those of the fingers ; by the peculiar ankle-
joint the foot is turned inward, and the advantage in grasping is
obtained at the cost of the power of stepping on flat ground.

The Megathere has a pivoted articulation of the foot with the
leg, but the process and the cavity are on reverse parts of the
ankle-joint, and the astragalus sends a process to fit a cavity in
the tibia. The result, in the inflection of the hind foot, is nearly
the same : but an enormous calcaneum, fig. 279, cl, and metatarsal
of the fifth toe, ib. v, rest broadly on the ground. The lower
surface of the astragalus transmits the superincumbent weight in
two directions ; backward upon the heel-bone and forward upon
the metatarse. By the naviculare it is transmitted through the
ectocuneiforme and the produced angle of the base of the mid-
metatarsal to the fourth and thence to the fifth metatarsal. The
cuboides receivino; the weigfht from both astras^alus and naviculare
transmits it by its produced fore-part to the base of the fourth
metatarsal, and partly by that medium, but chiefly by direct
articulation, to the side of the fifth metatarsal. The tendency of
the cuboides to yield under this pressure and slip back is resisted
by the abutment of the calcaneum against its back part. The
digitus medius, ib. Hi, was alone developed to sustain and wield
a claw ; but this was of enormous size, and must have had the
power of a pick when worked by the lever of the long heel-bone.
The first and second toes were not present, nor was the ento-
cuneiform bone. The two outer toes, iv and v, terminated in
tuberous phalanges, evidently imbedded, in the living animal,
in a hoof-like thickening of the outer border of the foot. The
outer side of the fore-foot presents a similar modification for quasi-
ungulate progression on the ground. Thus the Megathere, My-
lodon, and allied great terrestrial Sloths seem to have combined
ungulate and unguiculate characteristics in the same extremity.

The principle of viewing structures and instruments, in reference
to the work that they may do, is shown to be good in gaining in-

414 , ANATOIMY OF VERTEBRATES.

sight into the mode of life of extinct animals, in a striking degree
through its application to the skeletons of the Megatherioids.^ The
teeth of these conform so closely in all characters with those of
the Sloths as to suggest leaves rather than roots to have been
their food. In the light slender Sloths the modifications of struc-
ture for clunbing, clinging, and living altogether in trees, are
carried out to an extreme. In the colossal extinct kinds the
foliage was obtained in a different way. The huge single claw
on the hind foot would be applicable as a pickaxe to clear away
the soil from between the ramifications of the roots : a second
claw would have interfered with such work. The foot is organised
to 2;ive oreat strength to that claw ; dislocation of its toe is
specially guarded against: the rest of the tarso-metatarsal structure
relates to the power of the foot to sustain superincumbent pres-
sure, with a position of the claw bringing its side instead of its point
in contact with the ground. The bones of the thigh and leg are
remarkable for their massive proportions, for their thickness, and
especially their breadth in proportion to their length : the femur
in both Mijlodon and Megatherium would rank rather with the
'flat ' than the ' long ' bones. These osseous columns were needed
to support the huge, heavy, expanded pelvis, fig. 267. The iliac
expansions are the chief conditions of the other characteristics of
this part : and they are unintelligible save in relation to adequate
extent of origin of povverful muscles, especially those arising
from the crista ilii, 62, the chief of which muscles concentrate
their force upon the fore-limbs. This indicates that these limbs
were put to some unusual work ; and the inferences from the
teeth and the hind claw lead to its recognition as the pulling
down trees and wrenching off their branches : but, for these
operations, the pelvis must have adequate fixity ; and to the
weight and strength of itself and its supporting limbs there is
added a tail so developed as to serve as a third support and
give the pelvis the basis of a tripod. Without this view of the
function of the hind-parts of the skeleton we can only see that
the peh is is so great and, with its caudal appendage, so weighty
as to require the massive proportions and structure of the hind-
limbs ; and, reciprocally, that these bespeak a proportionate size
and weight of the parts to be sustained : but why such develope-
ment of sustaining limbs and parts to be supported in reference
to any other action and way of life is inconceivable. The excess
of bone in the hind-part of the skeleton once recognised as relating
to the fixed point of attachment of muscular forces working the
fore-limbs, — to the exertion of poAver adequate to prostrate a

SKELETON OF CETACEA. 415

tree, — and the rest of the bony organisation becomes intelligible.
That of the hind-foot has been explained : the concomitant extent
of muscular origin afforded by the broad scapular plate with its
many ridges, crests, and processes, is thereby accounted for. The
necessity of the firmness imparted to the shoulder joints by the
perfect clavicles abutting at one end against a large ^ manubrium,'
at the other end against the conjoined acromion and coracoid, be-
comes obvious. The fore-foot retained three huge claws to effect
an adequate grasp of the trunk or bough : for their due and varied
application the fore-arm enjoys all the variety and freedom of
movements which an arm terminated by a hand possesses. A
tree being prostrated and its foliage thus brought within reach,
every indication in the skull of the size, strength, flexibility, and
prehensile power of the tongue harmonises with the foreo-oino-
teleological conclusions. The Megatherioids, like the Giraffe,
thus plucked off the foliage on which they fed. In the rido-ed
crowns of the grinders of the Giant Ground-Sloth we discern
the power of crushing coarser parts — a greater proportion of
twigs and stems, e.g. — of the foliage than the diminutive Tree-
Sloths take. It needed only evidence of the occasional occurrence
of what might happen to a beast in the fall of a tree which it had
uprooted, to seal the foregoing physiological inferences with the
stamp of truth : and the skeleton of the Mylodon in the Hun-
terian Museum^ shows that evidence above the right orbit, and
at the back part of the cranium, marked/*, fig. 267.

§ 184. Skeleton of Cetacea. — This is characterised by the
coarseness and greasiness of the osseous texture, by the shortness
of the cervical and the length of the caudal regions, by the loose
and diminutive pelvic bones, by the absence of pelvic limbs, and
by the large size of the skull, due in most to that of the jaws,
which in some Whales {^BalcenidcB, fig. 159, Physeter macroce-
phalus) is excessive.

A. Vertebral Column. — Althouo-h there is as little outward sis^n
of a neck in a whale as in a fish, the same number of cervical
vertebrae are present as in the giraffe. The atlas, fig. 283, i, is the
largest, is characterised by its huge and ai)proximate articular cups,
c, for the occipital condyles, and by the substitution of a hypapo-
physis for the true centrum, which coalesces as an odontoid process
with that of the axis : both these vertebra? are antero-posteriorly
compressed and transversely extended, and the five succeeding
cervicals are still shorter in proportion to their height and breadth :
they are, in fact, lamelliform, without reciprocal movement, and
usually exhibit a greater or less extent of confluence, the whole

' XCII-. p. 63, no. 377.

416

ANATOMY OF VEKTEBRATES.

281

forming one mass like a ' cervical sacrum' in the true Whales
{Balatna, fig. 159,c), small Cachalots {Euphijsetes)-' the Grampus,^
the Porpoise : the neural arches of the axis and following cervicals
are confluent in most. The cervicals thus give a firm support to
the large head which has to overcome the resistance of the water

when the swift swimmer is cleav-
ing its course through that ele-
ment. The characters defining the
succeeding vertebras, applicable to
comparisons of species and re-
cognition of range of variation,
appear to be : — the support of free
ribs ; the presence of transverse
processes formed chiefly by coa-
lesced pleurapophyses, fig. 141, t?;
the articulation of haemapophyses,
fig. 282, h, to the centrum, ib. c.
Thus, in a large British Dolphin
{Delphinns tursio), the skeleton of which I prepared (and to take
the bones from the carcase is almost essential to certainty as to
number of ribs and haemal arches), there
are sixty vertebrae. Of the seven cervical
the first two only are anchylosed : thir-
teen vertebrae support free ribs suspended
to terminally expanded diapophyses, fig.
281, ^; then follow twenty-nine with trans-
verse processes only, as in fig. 14,1, d: the
thirty-third vertebra from the skull first
supports a haemal arch, but in that and
the two following vertebrie the piers or
' haemapophyses ' are small and ununited :
the complete arch, as in fig. 282, h, is
continued, diminishing, to the last six
vertebrae, which consist of the centrum
only, much depressed. Thus, between
the thirteenth dorsal vertebra and the
first with haemapophyses, there are thirteen which might be
termed ' lumbar,' fig. 159, D, cd, but hold the place of lumbar and
sacral in other Mammals {Megatherium, e.g., fig. 279, L, s). A
sacrum is never indicated by vertebral confluence in Cetacea, and
only obscurely by the position of the pelvic rudiments, fig. 159,
63, 64, loosely suspended below. In the Delpli. tursio a metapo-

Dorsal vertebra. Whale.

282

Caudal vertebra. Whale.

' XCIII-.

xvnr. p, 520, fig. 214.

SitEleton of CETACEA. 417

phjsis begins to project from the fore part of the diapophysis of
the third dorsal, increases in length to the fonrth, and is gradually
transferred in the sixth and seventh dorsals to the outer side of
the prozygapophyses : in the following vertebrae it seems to take
their place, and to occasion a reversing of the usual relative posi-
tion of the zygapophyses ; for whereas in the cervical and
anterior dorsal vertebrae the anterior ones are overlapped, as in
other Mammals, by the posterior zygapophyses of antecedent
vertebrae,- — in the succeeding dorsals, beginning with the seventh,
the posterior zygapophyses seem to be overlapped and con-
cealed by the anterior ones ; but the appearance is due to the
place of the zygapophyses being taken by the metapophyses.^
These latter processes, in fact, continue after the articular surface
has ceased to be developed, and after the entire disappearance of
the posterior zygapophyses, to project forward from the thirteenth
dorsal to the sixth lumbar vertebra; inclusive ; beyond which the
neural arch is devoid of all exogenous processes, save the spine, s,
until the middle caudal vertebras, where rudiments of the meta-
pophyses again reappear. There are no anapophyses in the
Cetacea.

The four anterior ribs have a head and neck : the rest are sus-
pended by the homologue of the tubercle to the end of the trans-
verse process. The costal cartilages are partially ossified : the
first four pairs articulate ivith the sternum : the original separations
of the parts of that bone have disappeared. The first piece or manu-
brium has an anterior median notch and two broad lateral processes.

In DelpJihius delphis, of the seven cervical vertebras the first
two have become anchylosed together : there are sixty-three other
vertebra), of which the first fifteen bear moveable ribs; thirty-
three vertebra) have transverse processes without ribs : the forty-
second vertebra from the skull begins to support ha3mapophyses :
the eight terminal vertebra) consist of the centrum only, and
are much flattened. The metapophysis begins abruptly, as a
long well-marked process, from the fore part of the diapophysis
of the fourth dorsal, progressively approximates and attains the
outside of the prozygapophysis in the eighth dorsal, performs the
function of an articular process as far as the sixth lumbar, clamp-
ing, as it were, the sides of the back part of the base of the spine
of the antecedent vertebra, disappears in the next dozen lumbar
vertebra), and reappears in the caudal vertebra) at the fore part
of the base of the spine. The six anterior i)airs of ribs support
hasmapophyses which unite directly with the sternum.

' XLiv. No^e, vol, ii, p. 452.
VOL. II. E E

418 ANATOMY OF VEHTEBRATES.

In the common Porpoise {Phoc(Bna communis) all the cervicals
are anchylosed, and the head of the first free rib rests upon their
coalesced bodies : there are fifty-six other vertebrae, thirteen of
which are ' dorsal,' or have moveable ribs. The diapophyses and
spines of the lumbo-caudal vertebra incline forward. In the
Narwhal all the seven cervicals are free : the wielding of the
horn-like tusk of the male is the condition of their greater freedom
of movement in the neck. Beyond the cervicals are fifty-six
vertebrae, twelve of which have moveable ribs, and of these six pairs
join the sternum. In the Bident Dolphin, or Bottle-nosed Whale
{llijiieroodon hidens), the cervical vertebrae have coalesced with one
another: beyond these there are thirty-eight free vertebrae, of which
only the nine anterior bear moveable ribs: the twenty-second
vertebra first bears h^emapophyses attached to the under part of
the centrum. The five anterior pairs of ribs articulate witli the
sternum, which consists of three bones.

In the Balcena mysticetus, fig. 159, there are thirteen dorsals;
as many vertebrae without ribs intervene between these and the
first vertebra with h^emapophyses ; the rest of the column, this
inclusive, consists of twenty-two vertebrae, the last dozen being
reduced to the centrum, which is much depressed, the last two or
three coalesce. The seven cervical, ib. c, are blended into one bone.

In a young or fostal Whale {Balcena austi^dis) ^ the cervical
neurapophyses of one side are disunited above from those of the
other side, as they are from the centrum below : a compressed
diapophysis is sent off from the outer side of each ; it is shortest
and thickest in the atlas. The third and fourth neurapophyses
have coalesced at their upper part on the left side, and those of
the last five vertebrae have coalesced on the right side. The
cortical portion of the centrum of the atlas is ossified, and forms
a wedge-shaped piece of bone, like the corresponding part in the
Ichthyosaurus. The centrums of all the cervicals are connate.
In the adult true Whales {Balcena), the cervicals, fig. 283, 1-7,
are distinguishable mainly by the intervals for the passage of the
nerves between the neural arches. In Balcenoptera rostrata, anchy-
losis does not proceed farther than to unite the atlas with the
dentata, and the sixth with the seventh vertebra. In Bal. boops,
Bal. patachoniclia, and some other Fin- whales, the atlas retains its
individuality. The interval between the lower (pleurapophysial),
fig. 283, /?, and upper (diapophysial), ib. d, part of the transverse
process is wide, often open, and when circumscribed usually leaves
a large foramen. In the seventh cervical the diapophysis, d, alone

' XLiv. vol. ii. p. 440, no. 2437.

SKELETON OF CETACEA.

41^

283

Anchjiosed mass of cervicals,
Balcena ynysticetus.

is developed, as a rule, and the head of the first dorsal pleurapo-
physis abuts against its centrum. The
diapophyses progressively elongate in
the dorsals, and support the corre-
spondingly lengthening ribs. The
discoid terminal epiphyses long retain
their individuality in Cetacean verte-
brae, longest in Balcena.^

The ^ breast-bone ' in PhyseteridcR
consists usually of three sternebers,
each ossified from a pair of centres
which tardily coalesce, save in the first
and largest. Four pairs of ribs directly
unite with this sternum, as in Delphinus
Tursio, in which the sternebers ultimately coalesce into a single
bone. In Hyperoodon and ZipMus there are four sternebers, with
a vacuity at the middle of each articulation, and five pairs of ribs
articulate with the sternum. The sternum in Whales consists of
but one bone, to which is usually connected a single pair of ribs.
The articular surfaces for these mark its sides : in the more active
Balcenoptera the bone is deeply notched in front, produced behind,
fig. 284, where it is ridged below. The sternum
is short and broad, shield-shaped, in Balcena :
rhomboid, sometimes with a central perfora-
tion, in KyphohalcBna, Esch. One or two of
the posterior pleurapophyses are loosely sus-
pended by ligament to the diapophyses of their
vertebra in many DelpMnidcB?

B. Skull. — The cranial neural arches con-
tinue to manifest the peculiar proportions which are shown in an
exaggerated degree in the cervical series. In an advanced foetal
Cachalot {Physeter macrocephalus) I find the elements of the
epencephalic arch unanchylosed. The lateral margins of the
anterior half of the basioccipital are produced and bent obliquely
downward. The exoccipitals are much produced and expanded
laterally, like the neurapophyses of the atlas in fig. 283, i : they
are deeply notched below. The superoccipital contributes the
upper ends of both condyles ; it is in the form of a vertical plate,
convex from side to side, and developes internally a falciform
crest. The superoccipital is overlapped at its lower and lateral

* XL7V., vol. ii, p. 440. In Fin-Whales the anchylosis is noted in certain vertebra)
of no. 2444, p. 441.

- xcviir. p. 8. xcxx'., p. 72, taf. 4 .and 5.

£ E 2

284

Sternum of Balwnoptera.

420 ANATOMY OF VERTEBRATES.

angles by the exoccipitalsj, anterior to whicli it attains to the
alisphenoids, and is notched externally for the reception of the
upper angle of the squamosals. The basisphenoid, a thick hexa-
gonal bone, concave from side to side below, nearly flat above,
is anchylosed to the alisphenoids : it is perforated or grooved by
the entocarotids, but has no clinoid processes nor sella turcica.
The alisphenoids, perforated near the middle of their base by
the foramina ovalia and rotunda, have a thick quadrate plate on
their inner side, forming their cranial surface : they extend into a
point anteriorly, and articulate with both the frontal and with
the parietal angle of the superoccipital. The neural spine of
the parietal vertebra is a thin plate partly detached and partly
anchylosed to that of the occipital vertebra : the lower angles
are confluent with the diapophyses, called ^ mastoids,' whicli
here, as in other Cetacea, are distinct from the petrosals, and
chiefly support the squamosals : these enter a groove of the
suj^eroccipital posteriorly, and receive the alisphenoid in a
groove anteriorly. The presphenoid and the anchylosed orbito-
sphenoids form the anterior wall of the cranial cavity, and
are perforated by the optic foramina: they articulate with the
frontals, sending up a small process into the interspace at the
beginning of the frontal suture, which process is impressed by a
blind fossa like a small foramen olfactorium on each of its sides :
the presphenoid unites with the basisphenoid : the posterior
and lateral parts of the orbitosphenoids unite with the alisphe-
noids: the fore part of the presphenoid is underlapped by the
vomer. There is no cribriform plate. The frontal bones are
large triangular plates, concave externally, with the outer and
fore angle produced into a superorbital process, the channel on
the under part of which contracts as it approaches the cranium
into a long, deep and narrow groove, which lodged the muscles of
the eyeball. The straight median margins of the frontals are
thinned off" and joined by a squamous frontal suture, the right
overlapping the left. The whole posterior and lateral border of
the frontal, as far as the junction Avith the squamosal, presents a
broad, oblique, sutural surface, which joins, by overlapping, the
contiguous border of the superoccipital. The smooth cerebral
surface of the frontals is flat at the middle, arched at the sides,
and not impressed by any convolutions. The vomer expands
into two aliform processes at its base, which is applied against the
presphenoid and orbitosphenoids ; it then becomes subcompressed
and smoothly excavated, but much more deeply at the left side,
where it forms the inner and posterior boundary of the single

SKELETON OF CETACEA. 421

nasal meatus : it again slightly expands, and afterwards is con-
tinued, gradually decreasing, to near the anterior end of the pre-
maxillaries : it is canaliculate above, and occupied by cartilage
continued from the coalesced prefrontals. There is no trace of
nasal bones. The bone, formed by the coalesced prefrontals,
penetrates the posterior part of the groove of the vomer, above
which it expands, unequally, into an obtuse prominence rising
and inclining to the left side : it is grooved on both sides, and
forms the septum of the vertical nasal passage : it is not com-
l)licated with turbinal or rliinal capsules, as in the so-called
' ethmoid ' of other Mammals. The palatine and pterygoid bones
articulate mth the sides of the expanded base of the vomer : the
margins of the canal excavated in the upper surface of the rostral
production of the vomer are overlapped by the premaxillaries.

The palatal is a small, triangular bone, thickest anteriorly,
thin, produced and bent posteriorly and above : it commences
here by its attachment to the anterior and outer angle of the
vomer, bends forward, downward, and inward to circumscribe the
nasal meatus, and receives in a groove on its upper and anterior
border the palatine prominence of the upper maxillary bone.
The whole posterior border of the palatine fits into a groove of
the contiguous border of the pterygoid. The pterygoid, Avhich is
double the size of the palatine, extends backward to the basi-
occipital, articulating in its progress by its expanded upper border
with the pre-, basi- and ali-sphenoids : from this border the bone
descends, arching inward toward its fellow, which it joins along
the anterior half of its extent : the remaining free border is divided
from this by a deep notch, and circumscribes the large posterior
bony aperture of the nostril.

The maxillary expands from its palatine prominence — the
essential point of its suspension — backward, outward, but chiefly
forward, where it gradually diminishes to an obtuse point. It
contracts a union posteriorly with the orbitosphenoid and ali-
sphenoid, and very extensively with the frontal. The nasal
process of the maxillary is traversed by a large vertical canal.
The premaxillaries are applied against the whole inner surface of
the maxillaries between them and the vomer. The right extends
much farther back than the left. The capacious basin on the
upper surface of the skull, which lodges the valuable product
called ' spermaceti,' is formed by the expanded and concave nasal
processes of the premaxillaries and maxillaries, which overlap the
frontals : a stout ridge divides the inner concave from the outer
sloping surface of this part of the maxillary. The malar bone is

422 ANATOMY OF VERTEBRATES.

a moderately long and slender piece, bent upon itself at an acute
angle. The upper portion, wedged between the maxillary and
frontal, is the thickest : the lower and more slender branch is
bent downward and backward, circumscribing the orbit anteriorly
and below, and continued by ligament or fibro-cartilage to the
short obtuse zygomatic process of the temporal. There are no
lacrymal bones. The anterior two-thirds of the middle and under
surface of the maxillary is traversed by a vascular and dental
groove : rudiments of teeth hidden and buried in the gum are
usually found in this groove. The squamosal is a comparatively
small, but strong and thick triangular bone : the upper angle
represents the expanded squamous part in land Mammals, and is
articulated by broad dentated sutural margins to the frontal and
exoccipital : its anterior border is grooved for the reception of the
alisphenoid : the lower angle is, as it were, truncated, and presents
a rough surface for the attachment of the petrotympanic : a short
obtuse anterior angle bends forward as the zygomatic process :
the under surface presents a smooth shallow cavity for the
condyle of the lower jaw ; the inner border of the glenoid surface
being produced downward into a slender styliform process. The
tympanic, here, as in other Cetacea, presents a peculiar conchoidal
shape, and is extremely dense in texture. An outer plate bends
over the thicker, seemingly involuted part, like the outer lip of the
univalve Pyrula, The ^ Eustachian ' outlet is at the fore part; and,
besides this, may be noted, in Physeter, the ^ involute convexity,'
with its ' outer ' and * inner ' lobe, the ' overarching plate,' and
the ' rough tympanic process,' by which it joins and coalesces
with the 'petrosal:' this is characterised by a deep fossa. ^ The
condyle of the mandible projects from the posterior part of the
base or ascending ramus, which is compressed and produced into
a low obtuse coronoid process above, and into a similar angle
below: a Avide excavation, beginning on the inner side of the
ascending ramus, deepens and contracts into the dental canal,
which enters the substance of the horizontal ramus : a fissure is
continued along the inner side of the ramus from this canal, and
is the sole indication of a compound structure of the jaw. The
vessels and nerves emerge from several foramina at the outer side
of the ramus, where it is attached by its long symphysis to its
fellow : the ui)per border of the symphysial part of the ramus is
excavated by a continuous dental canal or groove, now somewhat
resembling that in tlie upper jaAv. The length of the symphysis
in the fatal Cachalot is three-fourths that of the rest of the

* XV11I-. p. 526, figs. 220, 225.

SKELETON OF CETACEA.

423

ramus. In the adult male the disproportionate growth of this
part of the jaw leads to an excess of length of the symphysial part
beyond the rest of the ramus. It is coextensive with the dental
series, which consists, in each ramus, of twenty-seven teeth,
conical or ovoid, according to their state of developement and
usage : the smallest teeth are at the two extremes of the series.
In the young Cachalot they are conical and pointed, but become
obtuse by use, whilst progressive growth expands and elongates
the base into a fang, which then contracts, and is finally solidified
and terminated obtusely. The teeth are separated by intervals
as broad as themselves. In respect to their mode of implantation
they offer a condition intermediate between that of the teeth of
the Ichthyosaurus and Grampus, being lodged in a wide and
moderately deep groove, imperfectly divided into sockets, the

285

Skull, Balccna mysticetus.

septa of which reach only about half-way from the bottom of the
groove.

In a foetal Southern Whale (^Balccna australls), each frontal is
a transversely elongated slender triangle, with its base at the
frontal suture, which is a thick vertical symphysis, and its apex
at the superorbital ridge : the inferior angle of the base rests upon
the prefrontals and upon the sides of the expanded base of the
vomer. The frontals take a very small share in the formation of
the cerebral cavity. Their cranial surface forms a small concavity
at the back part of the base : a half-canal is continued forward
from the lower angle of this surface into tlie nasal cavity. Almost
the whole of the upper and outer surface of the frontals is over-
lapped by the parietals and occipitals, leaving a very narrow ex-
posed transverse strip across the upper part of the skull. Tlie
anterior border of each frontal is joined mesially with the nasal.

424

ANATOMY OF VERTEBRATES.

next with the upper end of the premaxillary, and for the rest of
its extent with the maxillary bone, which is continued onward to
form the antorbital process.

In the mature Mysticete Whale, of which a side view of the
skull (now in the British Museum) is given in fig. 285, the maxil-
laries, 21, are disposed each like an expanded arch along the
outside of the coextended premaxillaries, 22 ; their inferior surface
has two facets separated by a longitudinal ridge, to the sides of
which the plates of baleen are attached. The premaxillaries are
compressecl and diverge from each other posteriorly to form the
long oval outlet of the nostrils, completed behind by the nasals,
which are elongate, as in the Zeuglodon ceto'ides : the frontals, e,
extend outward to form the roof, 1 1, of the small orbit, 0; and there-
with is coextended the back part of the maxillary, 21': a small ma-
2gg lar, fig. 159, 26, is articulated

to the lacrymal, 73, the maxil-
lary, 21, and the squamosal, 27;
the most expanded part of which,
fig. 285, 27, forms the articula-
tion for the mandible, 29-32.
The superoccipital, 3, inclines
forward, as it rises, and forms
almost the whole upper part of
the cranium. The coalesced pre-
frontals are perforated by the ol-
factory nerves. The presphenoid
is sheathed in the hind part of
the canaliculate vomer, i3,which
extends far forward along the
middle of the roof of the mouth.
Each mandibular ramus arches
outward and forward from the
slightly-raised condyle, 29, to the
short, ligamentous symphysis,
32 : it is compressed and subtrenchant at both upper and lower
margins : a coronoid ridge is feebly marked ; there is no ascend-
ing ramus. The skull of the whale is more symmetrical than
that of toothed Cetacea.

In the section of DeljjliinidcB to which the Grampuses and
Porpoises belong {PhoccRiia, Cuv.), the facial bears a less pro-
portion to the cranial part of the skull : the latter is broad, ele-
vated, and convex posteriorly. The superoccipital, fig. 286, 3,
forms the transverse crest dividing the hinder from the upper

Skull of a Grampus {Phocccna fjlubiceps).

SKELETON OF CETACEA. 425

surface, where it is met by the frontals, ii, the overlapped parie-
tals coming into view only at the sides, where they expand into
the mastoids, s. The maxillaries, as they extend backAvard, rise
and expand, 21, covering so much of the frontals, n, as to allow
but a narrow strip of these bones to be seen, except where they
dilate to form the roof of the orbit. The nasals, 15, are oblong
tubercles set deeply in depressions of the frontal, at the back part
of the nostrils, e, e. The premaxillaries, 22, form the front and
sides of these apertures, save at the small portion contributed
by the maxillaries at g. The nasal passages descend almost
vertically. The malar is flattened where it helps to form the
orbit, and is covered by the maxillary : it sends backward a long
and slender process, which articulates with the zygomatic process
of the squamosal, and forms the only lower boundary of the orbit.
The bony palate has a deep longitudinal channel on each side in
some Dolphins.

In the vertical section of the cranium of the Porpoise, fig. 287,
is shown the plane of the occipital foramen, 2, inclined from below

287

Section of skull, Porpoise.

forward : the proportions of the inner Avail of the cranial cavity
contributed by the ex- 2, and super- 3, occipitals, by the alisphe-
noid, 6, the parietal, 7, the orbitosphenoid, 10, and the frontal, 11 :
the small vacuity between the alisphenoid and exoccipital is
blocked up by the loosely attached petrosal. The right nasal
passage is exposed, shoAving the proportion of the septum formed
by the vomer, 13, and the coalesced prefrontals, u : the vomer
extends forAvard to the middle of the upper jaAv, AA^hich is chiefly
composed of maxillary, 21, and premaxillary, 22. The small paka-
tines, 20, articulate Avith the vomer and maxillary, and send back-
Avard the larger pterygoids, 24, Avhich form with the vomer the
internal or loAver nostril, Avhilst the canal for the long conical
larynx is contributed by the pterygoids, 24, and a corresponding
descending plate of the basisphcnoid, 6, and basioccipital, 1. The
squamosal is excluded, as in Birds and loAver Vertebrates, from
the cranial cavity. The prefrontals in the Beluga {Deljjhln-

426

ANATOMY OF VERTEBRATES.

28 S

apterus) are large, and ascend into view at the back part of the
nostrils, where they coalesce with the frontals. The small nasal
bones are wedged into an interspace between them and the frontals
at the summit of the nasal apertures.

In Hyperoodon the skull is remarkable for the developement of
the outer border of each maxillary bone into a broad and lofty
vertical crest, and for the backward prolongation of the posterior
border of the same bones to the occipital region, where it is de-
veloped into what seems to be an occipital crest. In Platanista,
the corresponding borders of the maxillary, after rising to the
vertex, are reflected forward, converging, so as to overarch like a
domed roof the circumnarial part of the skull. In Euphysetes
this concave space is divided behind the nostrils by a vertical
ridge. Euphysetes simus ^ shows the opposite extreme to BalcBna
and Physeter, in the disproportionate shortness of the rostral or
* prenarial ' to the cranial or * postnarial ' part of the skull. In
ParazipMus the vomer is singularly tumid and dense.

The hyoid arch consists, in BalcB7iid(B, of a pair of stylohyals,
fig. 288, 38, ligamentously connected with the mastoids, and

similarly attached by fibrous re-
presentatives of ceratohyals, 39,
to the pair of processes at the
fore part of the basihyal, 4i.
This large, broad bone is pro-
duced outwardly into a pair of
compressed bars, thicker than the
stylohyals, and representing the
thyrohyals.
C. Bones of Limbs. — The clavicle is absent. The scapula is a
flat triangular plate, with one angle truncate to form the glenoid
cavity for the humerus, and without the ^ spine ' along the
outer surface. In Balcena, figs. 159, 289, 51, the triangle is
almost equilateral, with the side forming the base rather convex,
and the part supporting the truncate angle, by somewhat produced,
forming a ' neck.' The acromion, a, projects forward from the
outer part of the neck near the anterior border. In Balcenoptcra
the base is proportionally longer than the other two sides, and
forms a more convex border : in Bal. longimana, Kud., the
acromion is obsolete, and the coracoid is merely an obtuse pro-
duction of the fore part of the glenoid cavity. In the Cachalot
(^Physeter), the convex base is the shorter side of the triangle, the
vertical exceeding the antero-posterior diameter of the scapula :
the acromion is longer and larger than in BalcenidcB, and there is

Hyoid arch, Balcenoptera.

SKELETON OE CETACEA.

427

a long and slender coracoid. In Euphysetes the triangle is more
equilateral, as it is in Ziphius and Hyperooclo7i. In DeljjhinidcB
the convex base of the scapula is usually the longest of the three
sides : the extension of the bone in the axis of the trunk is re-
markable in the Gangetic Dolphin 289
(^Platanista), in which the acromion
projects mid-way between the an-
terior basal angle and the glenoid
cavity.

The humerus, figs. 159, 289, 53,
290, a, is remarkably short in pro-
portion to its thickness : the head
is large, hemispherical ; bent very
slightly out of the axis of the bone ;
with the outer or radial tuberosity
feebly marked in most, rather more
strongly in the Cachalots, and form-
ing a deltoid tuberosity: the shaft
becomes compressed and expanded
toward the distal end, which has
two ill-defined, flattened surfaces
for syndesmotic junction with the
radius and ulna. The latter, ib. 55,
usually sends backward an olecra-
non ; but this is not developed in
Platanista, where the ulna is broader
and longer than the radius : usually
the radius is the larger bone, as in
fig. 289, 54 : both bones are flat-
tened, shorter than the humerus in
Cachalots and Platanists, longer in
Whale-bone Whales, Bottle-nose
Whales {Ilyperoodon Ziphius),
Grampuses, Porpoises, Dolphins.
The contiguous epiphyses of the hu-
merus and antibrachials first unite
with their respective shafts : in an
old Cachalot and Delphinus Tursio,^ the radius and ulna are
anchylosed with the humerus, fig. 290, a. In a Southern Whale
the carpus, fig. 289, 56, consists of seven ossicles: the first on the
radial side answers to the scaphoid and trapezium : the second,
in D. Tiirsio, is wedged into a distal cleft between the radius and
ulna, and corresponds with the lunare in the Chelonian carpus and

' xiAV , no. 2483.

Bones of Pectoral fln : BaUcna australis.

428

ANATOMY OF VERTEBRATES.

that of the Orang : the third is very small, and represents the
cuneiforme : the pisiforme is separated from it by the junction of
the unciforme with the ulna : the unciforme supports the rudiment
of the fifth digit and part of that of the fourth: the magnum
supports part of the fourth finger and a great part of the third :
the trapezoides is moved to the interspace between the third and
second digits, but principally supports the latter. The metacarpal
of the first digit, in D. Tursio, fig. 290, I, supports one small
phalanx : the larger metacarpal of the second digit, ii, supports
seven phalanges : that of the third, iii, supports five phalanges ;
the metacarpal of the fourth, iv, two phalanges : the fifth, v,
is represented only by a rudimental metacarpal bone.

In the Grampuses, Porpoises, and other Delphinidce, the second
and third digits are also the longest, with the excessive number
of phalanges. The fifth metacarpal articulates nearer to the anti-
brachium than the others do. In both the Porpoise and Grampus,
e. g., it is attached to the ulnar border of the carpus, is broader
than long, and supports one or two stumpy phalanges : the
first metacarpal is short and slender, but its base is on the
distal border of the carpus. In the Hi/peroodo7i there are three
carpals in the proximal row, and a second row of four small
ossicles in the fibro-cartilaginous matrix. The metacarpal of the
poUex supports one phalanx : those of the second and third digits
have each five phalanges : the fourth me-
tacarpal has three ; the fifth, which is the
shortest of all, has two phalanges. In theC«-
chalots and Ziphius, the fourth digit more
nearly equals the third in length : in BalcBna
mysticetus, fig. 159, IV, it rather exceeds the
second, ib. ii, and, like it, the metacarpal
supports three phalanges ; the third meta-
carpal, ib. Ill, having four phalanges, and
the fifth, V, two : the first digit is the
shortest, and consists of metacarpal only.
In Platanista the first metacarpal has two
phalanges, the other four each support four
phalanges, the fingers being of nearly equal
length, and more divergent than usual,
supporting a fin correspondingly expanded
to its free truncate end.
In some Piked AYhales {BalcBnoptera) the first digit is obsolete,
tlie third and fourth much longer than the second and fifth. In
Bed. lomjimana {Kyphohalcuna, Esch.), the third and fourth each

290

Bones of rcctoral lin, Dclphinus.

SKELETON OF SIRENIA. 429

support a metacarpal and six phalanges. All the digits in the
entire Cetacean are enveloped in a common fold of integument.
The increase of the phalanges of certain digits beyond the number
three is a remarkable instance of departure from the mammalian
type and of affinity with the extinct enaliosaurs and fishes.

In the DelpliinidcB there are a pair of pelvic bones larger in
males than females, chiefly subserving the origins of the ^ erectores
penis' and 'clitoridis'; and which, therefore, I regard as ischial
bones. In a female Hyj^eroodon 28 feet long, each ischium
was 41 inches long, straight, subtriedal, 8 lines in diameter. In
BalcBna mysticetus there is, besides the ischium, fig. 192, e;?, a
smaller, more slender and curved ossicle, which, being anterior
to it, seems to represent a pubis, ib. 64 : the junction of the two
bones expands into a surface, representing the acetabulum, to
which is ligamentously suspended a bone of similar length to the
pubis, but thicker, and expanding, with some flattening, to a
transversely extended convex surface, like that at the distal end
of a chelonian femur ; ib. 65 : to which is suspended a smaller
rudiment of a tibia, 66. This is the simplest condition of the
limb, or appendage, of the pelvic arch known in the Mammalian
class. ^ There is no outward indication of it in the Whale. The
little bones, of the relative size to the rest of the skeleton as
shown in fig. 159, p. 280, are suspended beneath the last two
lumbar vertebrae, which may thus be regarded as answering to
the sacral in quadrupeds.

§ 185. Skeleton of Sirenia. — In this class of marine Mammals
the hind limbs are absent, as in Cetacea, and the pelvic bones,
where best developed, as in fig. 292, s, h, retain the size and
shape of the small contiguous costal arches. The texture of
the bones is denser, the neck, though short, is longer than in
the Cetacea, and the vertebra? are distinct: but the chief dif-
ferences are found in the relative size and structure of the skull,
and in the better developement of the bones of the pectoral limb,
the digits of which are not composed of more than the normal
mammalian number of phalanges (compare fig. 292 with fig. 159,
p. 280). The known existing representatives of the Sirenian
order are the Dugongs {Ilalicore) and the Manatees {Manntus):
the latest extinct form is the edentulous Sirenian, called ^ Steller's

' The bones described and fif^urcd in cli. t. v. p. 236, pi. xxvi,, figs. 24 and
25, were not seen in situ by Cuvier, but are described as pelvic bones, on the au-
thority of M. Delalande, the Articulator. The discoverers of the rudimental hind
limbs, and authors of lxv', observed the pelvic bones of the whale in situ (p. 151,
tab. II.).

430

ANATOMY OF VERTEBRATES.

Sea-cow' {Rlujtina horealis, 111.), last observed in the arctic seas
off the shores of Bering's Island: the miocene extinct genus
{Halitlieriuiii) has left its remains in southern Europe.

A. Vertebral Column. — In the Dugong, fig. 292, there are
7 cervical, c, 19 dorsal, D, and about 26 lumbo-caudal vertebrae,
L, S, CD. To the 29th vertebra, counting from the skull, the
pelvic arch is suspended, characterising it as a sacral one, s, and
lea\dno- two lumbars in advance, the transverse processes of which
long retain the suture indicative of their pleurapophysial part.
The second vertebra, beyond the sacral, first supports a h^mal
arch, and this is continued to the fourteenth and fifteenth of the
caudal series, which, if counted from the sacrum, would include
about twenty-four vertebrae. Fig. 291 gives the characters of
the transitional vertebras between the trunk and tail, especially
as afforded by modifications of the haemal arch. In the posterior
dorsal vertebrae, the pleurapophysis, 79/, is the sole ossified
element of the haemal arch; it progressively shortens in the

291

Dorsal, lumbar, sacral, caudal, vertebrfe, Ealicore.

16th, 1, 17th, 2, and 18th, 3, vertebrae, retaining its mobility;
and, in the 19th, A, it shortens suddenly, but usually with more
extended ossification in the sclerous basis of the rib than is shown
in the figure. In the vertebra, B and C, the pleurapophysis,
besides being short, becomes confluent with the centrum, as a
'transverse process,' and characterises them as Mumbar.' The
sclerous or tendinous continuations of the pleurapophyses into the
abdominal muscles are indicated by dotted Knes. In the ver-
tebra D, the ossification which extends the pleurapophysis, pi, 7,
beyond the part, d, representing the transverse process, retains
a ligamentous union therewith, and represents the ^ ilium:' a

SKELETON OE SIRENIA.

431

lower ossification in tlie haemal
arch establishes a bony * ha^ma-
pophysis,' h, and represents the
' ischium.' It is ligamentously
connected at its lower end to
its fellow, completing by such
^ symphysis ischii' the pelvic
hiemal arch. In the vertebra,
E, the proximal part only of the
pleurapophysis is ossified, as in
the lumbar series ; and this is
the case with the succeeding
vertebrae : but the centrums ex-
hibit, at their under surface, arti-
culations for parts answering to
the loAver portion, h, of the haemal
arch of the vertebra D. The
parts in question, 9, lo, ii, h, are
severally united together by their
lower or distal ends, at first liga-
mentously, but afterwards by co-
ossification, constituting inverted
bony arches of the chevron shape,
and which are serially homolo-
gous with the bony haemapophy-
ses, h, of the pelvis, and the
sclerous or cartilaginous h^em-
apophyses of the trunk : they are
dislocated from their pleurapo-
physes and approximated to their
centrums, with a slight horizontal
displacement leading to their
partial articulation with that of
the vertebra succeeding their
own (see fig. 188, p. 299). These
haemapophyses, fig. 292, h, Cd,
are not developed in the terminal
vertebrae, the last six of which
are represented by horizontally
flattened centrums, o, sustaining,
as in Cetacea, a horizontal tail-fin.
The ribs of the dorsal verte-
bra3, fig. 292, jA, are massive,

Ungong (Halicore) ,

4S2 ANATOMY OF VERTEBRATES.

peculiarly so in the Manatees : the first in the Dugong has a long
oblique process from the under part of the neck, and a shorter
process, terminated by a rough surface, from the inner border,
two inches from the loAver end of the rib. The first three or four
pairs of ribs join, by cartilaginous ha3mapophyses, the sternum,
which consists of two bones and a xiphoid cartilage: the two
sternebers coalesce into a single bone, of the borders of which the
costal articulation occupy the middle third. From the third to
the sixteenth dorsal, the ribs are of nearly equal length. Many
of the succeeding ribs have a process from the posterior margin,
simulating the costal appendages in Birds. The metapophyses are
not developed so as to supersede the prozygapophyses, as in
Cetacea. The neural spines are of equal length and similar in-
clination slightly backward. In the Dugong, fig. 292 C, the atlas
has short par- and di- apophyses, and the neural arch is per-
forated on each side near its anterior border : in the axis the
transverse processes are chiefly by diapophyses. In the fourth
cervical, the right process was pierced by the vertebral artery ; in
the seventh, the left process : the other diapophyses were notched.
The centrum of the seventh cervical has a facet on each side
for the first pair of dorsal ribs. The side of the centrum
of the first dorsal vertebra bears two articular facets; one
of which is smaller than the other, looks forward, and receives
a part of the head of that rib which articulates with the pre-
ceding vertebra ; the other looks backward, and receives a large
share of the head of the second dorsal rib. The transverse
processes are long and strong, and present on their extremity
an articular facet which receives the tubercle of the first free or
dorsal rib.

In Manatus Americanus the cervicals are also very short, but
only four of these compressed vertebrce intervene between the
axis and the first dorsal : seventeen vertebrae support the move-
able ribs, and are followed by about twenty-two lumbo-caudal
vertebrae : the hasmal arch commencing at the lower interspace
between the fourth and fifth of their series. The pelvic bones
are reduced, as in most Cetacea, to an ischium giving origin to an
* ischio-cavernosal,' and insertion to an ^ ischio-coccygeal ' muscle.
In a half-groA\Ti Manatee I have seen the neurapophyses of the
first twenty-nine vertebras still suturally joined to their centrum.
But two pairs of ribs join the sternum, which soon becomes a
single bone, with a costal process on each side of the middle
part.

The vertebral characters o^ Rhytina agree in the main with those

SKELETON OF SIRENIA.

433

of existing Sirenia.^ Steller assigns to it six cervicals, as in
Manatus. Nine pairs of ribs are said to have joined the sternnm.
B. Skull. — The facial or rostral part of the skull, anterior to
the orbits, is short, especially so in Manatus, fig. 239, in which it
slightly descends : in Halichore, figs. 292, 294, 22, it is bent down
more abruptly: in Rhytina the angle of the upper contour of the
rostrum is greater than in Manatus, that of the lower contour less
than in HalicJwre, exemplifying, as in other parts of the skeleton,
an intermediate character. All the skull-bones are massive in
Siren ia, and, save in the in-

293

stances of anchylosis, are
somewhat loosely connected
too;ether. In the Dugono; the
basioccipital, fig. 294, 1, is a
triradiate bone, the two short
rays diverging posteriorly to
join the exoccipitals, and
formino' the lower end of each
condyle. The exoccipitals, 2,
almost meet above the fora-
men magnum ; they have a
short rough paroccipital pro-
cess. The superoccipital, 3,
is early anchylosed to the
parietals, which have equally
coalesced into a sino^le sub-
quadrate -massive bone, fig.

293, 7, with the sides bent
down at nearly a right angle
with the almost flat upper
part, which is perforated by a ' foramen parietale.' A falciform
ridge descends from the inner surface. The basisphenoid, fig.

294, 5, has coalesced with the alisphenoids, wliich are grooved
both behind and before, not perforated, by the trigeminal nerve.
The massive pterygoids are anchylosed to the base of the ali-
sphenoids : the posterior ends of the palatines, which are wedged
into the interspace between the ento- and ecto- pterygoid pro-
cesses, send upward a part wliich appears in the temporal
fossa behind the maxillary. The presphenoid, as a compressed
' rostrum,' is wedged between the lamln;i3 of the vomer, and has
coalesced with the confluent orbitosphenoids which it supports.
There is no ' sella turcica.' The orbitosphenoids are perforated

Skull of Dugoi

{Ualicliorc indicus).

VOL. II.

xciv. p.
F P

95.

434

ANATOMY OF VERTEBRATES.

294

Skull of DugoDg iHalichore) .

by widely separated optic foramina: tliey are anchylosed with
the coalesced prefrontals, fig. 294, 14. The cribriform plates are
lodged in deep fossae, betAveen which is a crista galli. The fron-
tals, 1 1 , are not confluent ; their orbital processes extend far forward
and outward from the anterior angles : they are excavated below
almost to the posterior margin by the rhinal cavity : the median

angles of the nasal border are
slightly produced, but there is
no trace of a suture there mark-
ing out the proper nasals. The
cranial plate of the frontal forms
a small concave surface, not ex-
ceeding the depth and thickness
of the posterior part of the bone
to Avhich it is confined. A small
part marked off by a fissure from
the fore end of the orbital pro-
cess represents an imperforate
lacrymal, fig. 292,/.
The maxillary, fig. 294, 21, is deflected anteriorly; its nasal and
malar processes do not meet and circumscribe the great antorbital
foramen, but this is closed by the upper end of the malar bone, 26.
The premaxillary, 22, is remarkable for its very large and long
deflected alveolar portion, and for its slender nasal portion,
fig. 293, c: it is excavated by the deep alveolus of the incisive
tusk, {. The squamo-mastoid forms no part of the inner surface
of the cerebral cavity, but is deeply and smoothly excavated for
the lodgement of the dense petro-tympanic. The mastoid part
forms a thick rugged process, 8, wedged between the tympanic, 28,
and paroccipital, 4. The zygomatic parts of both squamosal, 27',
and malar, 26, form a strong arch. The petrotympanic fits closely
the cavity in the squamo-mastoid, and partially closes the vacuity
between it, the occipital and sphenoid bones ; the tympanic, 28,
describes two-thirds of a circle for the support of the ear-drum,
and is less than the dense otic capsule with which it is confluent
at both ends. The stapes is an elongate, subcompressed pyramid,
with a minute perforation near the base, and an epiphysis at the
apex : the incus is also long and narrow ; the malleus broad and
bilobate.

The mandible, figs. 292, 294, 32, is deep in proportion to its
length : the coronoid rises with a slight backward curve : the
condyle is small and convex : the ascending ramus has a convex
hind border, curving to an advanced feebly-marked angle: be-

SKELETON OF SIEENIA. 435

tween this and the deflected symphysial part the lower border is
deeply concave : the sockets for the molar teeth, originally five
or six in number, like those in the maxillary, are reduced to two
or to one in the old animal : the deflected symphysis forms a flat
oval surface anteriorly, with four or five pairs of small alveoli, in
one or more of which may be an abortive incisor, fig. 160, «, d i 3,
covered by the thick horny plate attached to the flat rough sur-
face ; the dental canal, beginning in advance of the ascending
ramus, ends by a wide oblique opening from which channels
diverge on the outside of the deflected symphysis.

In the Manatee, a large otocrane is also smoothly excavated in
the mastoid, squamosal, and exoccipital bones, to which the
petrosal closely fits without coalescence, its posterior surface ap-
pearing in the space left between the mastoid, super- and exoc-
cipitals. The basi-sphenoid coalesces with the alisphenoids, prior
to confluence with the basioccipital and presphenoid : the latter
similarly coalesces with the orbitosphenoids, and is continued,
like a rostrum, into the vomerine fissure. I find no distinct nasals
anterior to the frontal suture in the new-born Manatee ; nor
other representatives of them than the small amygdaloid bones,
fig. 239, 13, 13, articulated to the frontals at the posterior angles
of the nasal aperture : this is large, subrhomboid, horizontal.
The wide antorbital foramen is entirely surrounded by the maxil-
lary, ib. 26. The suborbital plate of the malar rests upon the
platform extending horizontally outward from above the anterior
molars, and extends the floor of the orbit an inch beyond the
roof, the eyeball resting upon the concavity of the malar, as on a
shelf. The zygoma, ib. 27, is unusually massive. The premaxil-
laries, ib. 2>, in the young Manatee, show a pair of alveoli for
abortive incisors : a similar pair imjDresses the fore part of the
mandibular symphysis, and a slight groove extends downward
from each. The symphysis is deeply hollowed out behind. The
coronoid is produced obliquely upward and forward; the angle of
the jaw is not marked.

The ossified parts of the hyoid arch are the basihyal, fig. 294, a\,
stylohyals, 3s, and the thyrohyals, 43 : the ceratohyal, 40, is carti-
laginous : the arch is suspended to the angles between the mastoid
and paroccipital.

C. Bones of the Limhs. — These are limited to the pectoral pair,
and their supporting arch is reduced to the scapula, with a short
coracoid as a tuberous process. The scapula, fig. 292, 5i, is sub-
longate, recurved, with the convex anterior costa continued into
the base, with an angle feebly marked in the Manatee. The

F F 2

436 ANATOMY OF VERTEBRATES.

posterior costa is concave, deepest in the Dugong. The outer
surface has a spine about half the length of the bone, marking off
a broad pre-spinal, from a narrow post-spinal fossa : the spine
is produced into a slender acromion in the Manatee, not in the
Dugong.

The humerus, ib. 53, has the normal mammalian character,
though of small size, wdth the head, tuberosities, and deltoid crest,
the twisted shaft, the epicondyloid processes and intermediate
trochlear articular surface, for synovial articulation with the
coalesced proximal ends of radius, 54, and ulna, 55. The latter
developes an obtuse olecranon : the distal ends of the antibrachial
bones are extensively united and ultimately by bone. In the
Manatee there are six carpals, three in each row : the outermost
and largest represents a cuneo-pisiform, and articulates with both
the ulna and the fifth metacarjoal. The trapezium and trapezoides
are represented by one bone articulating with the first and second
metacarpal : the magnum supports the third, and the unciforme
the fourth and part of the fifth metacarpals. In the Dugong
there are but three carpals : the scapho-lunar and cuneo-pisiform
in the first row, 56, and a single transversely oblong bone repre-
senting the second row, but leaving the major part of the base of
the fifth metacarpal to articulate mth the cuneiform. The pollex, I,
is represented by a styliform metacarpal : the other digits have
each three phalanges ; and most of the ungual ones, in Manatus,
support nails. All the limb-bones, like those of the rest of the
skeleton in Sirenia, are solid.

The herbivorous Sirenia have not to move far from their
favourite localities for food ; they contrast, in that respect, with
the Cetacea that pursue a living prey : hence the difference in the
specific gravity of the bones, which in Sirenia is such as to re-
quire an effort on the part of the animal to reach the surface of
the water for breathing, but enables them to browse, at ease, the
vegetation clothing the bottoms of their seas, estuaries, or rivers.
The massiveness of the zygomatic arches in the skull contrasts
singularly with the slenderness of those parts in Whales: the
pterygoid productions offer a similar difference : the external
bony nostril is as remarkable for expanse in Sirenia as for con-
traction in Cetacea. The movements of the head and jaws, in
browsing, call for a flexibility of the short neck in Sirenia, in-
compatible mth the fixation of that part which prevails in most
Cetacea : the dorso-lumbar vertebras are articulated by true zyga-
pophyses, not metapophyses. The pleurapophyses are as remark-
able for thickness and density in Sirenia, as in similar-sized Cetacea

SKELETON OF PROBOSCIDIA. 437

for slenderness and oily porosity of texture. Although the bones
of the pectoral limbs are swathed in skin, the fins project more
freely from the trunk, the elbow is better marked ; the limb-joints
are synovial, not syndesmotic merely, as in Cetacea ; and although
there are clearer indications of the digits in the fin of Sirenla,
none of the digits have more than three phalanges.

§ 186. Skeleton of Proboscidia. — With the exception of a very
small cavity in the femur and tibia, a light cancello-reticulate struc-
ture occupies the centre of the long bones, which have tliick and
compact osseous walls. The skull-bones are extensively pneumatic.

A. Vertebral Column. — In the giant mammal of the land, as in
that of the sea, the neck is short, and through loss of length, not
of number, of the cervical vertebrae. In the Indian Elephant,
fig. 162, the vertebral formula is: — 7 cervical, c, 20 dorsal, d,
3 lumbar, 3 sacral, and 31 caudal. Anapophyses are developed
from the sixteenth dorsal, and articulate with metapophyses from
the seventeenth. The same joints are superadded to the ordinary
articular processes, as far as the last lumbar. Five pairs of ribs
directly join the sternum, which consists of four bones. The
epiphyses continue detached from the bodies of the vertebrae to
nearly full growth.

In a half-grown Elephant, the neurapophyses of the atlas are
distinct from the hypapoj)hysis, and united to each other above by
suture : the centrum is also distinct, but attached to that of the
axis, of which it forms the * odontoid ' process. The neurapophyses
develope both upper and lower transverse processes, which circum-
scribe the vertebrarterial foramen. The same is the case with the
neurapophyses of the axis, which blend together above and de-
velope a thick bifurcate spine before coalescing with the centrum.
The removal of the terminal epiphyses of the short flat bodies of
the other cervicals shows that the upper fourth of the body is
contributed by the neurapophyses, the rest by the centrum. In
the fifth cervical vertebra, a short and slender spine is developed
from the summit of the neural arch. The antroverted costal part
of the transverse process is connate with the par apophysis, and
afterwards coalesces with the diapophysis. In the seventh cervical
vertebra, the transverse processes consist of diapophyses only.
The articular surface for the head of the first free or dorsal rib is
formed, half by the neurapophysis, and half by the centrum. The
neural spine has much increased in length, but is slender.

The first dorsal vertebra is remarkable for the strenojth as well
as the height of the neural spine. The diapoj^hyses are shorter
and thicker than in the neck. The surfaces for the first and

438 ANATOMY OF VERTEBEATES.

second ribs meet at an acute margin below : they are formed as
in tlie preceding vertebra. In the fourth dorsal vertebra, the
spine is still more remarkable for its height and strength: the
vertebral body has a greater antero-posterior thickness, but the
anterior and posterior costal surfaces still meet below. A larger
proportion of these surfaces is contributed by the neurapophyses.
In the ninth dorsal vertebra, the posterior costal surfaces, which
are almost exclusively formed by the neurapophyses, are separated
by a non-articular tract from the anterior ones.

The sixteenth dorsal vertebra shows only a single pair of costal
surfaces, which are wholly formed by the neurapophvses : the
metapophyses are well developed. In the remaining dorsals the
costal surfaces decrease in size. The first and second ribs are
almost straight, and expand to join their short sternal parts : as
the ribs lengthen, they ]n-eserve their slenderness, and are straighter
at their lower halves than usual : the vertebral third is bent, sub-
cyKndrical, and grooved anteriorly. The lumbar diapophyses are
short and depressed. The neural spines of the dorso-lumbar
series incline backward, gradually decreasing in height, and in-
dicate no centre of inflexion in the capacious well-ribbed trunk.
The thick sides of the three sacrals which join the ilia consist of
pleurapophyses which coalesce with both centrum and neural
arch. The neural spine subsides after the seventh or eighth
caudal : diapophyses continue to the twelfth, and zygapophyses
to the fifteenth : the rest are reduced to the centrum.

B. Shidl. — The cranial much exceeds the facial part in size :
its upper part forms an expanded dome: but a section, as in
fig. 296, shows that the cavity for the brain occupies but a small
proportion of the back part of the dome's base : the rest being
formed bv air-sinuses, bounded bv plates of bone, extendinof
between the remote outer and inner * tables * in the form of sinuous
plates so disposed as to give greatest strength with least material.
The occipital condyles are small, approxhnate below, and project
backward from the upper half of the posterior surface of the
skull. The occipital slopes as it rises to curve forward to the
vertex, and more so in the African than in the Indian species.
The position of the epencephalic compartment of the cranium,
fig. 296, t\ the suspension of the malar bone, fig. 29o. 2(3. in the
middle of the zygomatic arch, the size and connections of the
premaxillaries, 22, and their deep and large alveoli for the single
pair of incisors, recall characters of Rodentia. The cranial sutures
become obliterated ; but examination of the skull of a very
young Elephant (Indian) has enabled me to give the following

SKELETON OF PKOBOSCIDIA.

439

details: — The basioccipital is uotclied behind, and contributes
there the lower ends of the occipital condyles : it increases in
thickness as it advances to form the liat rough surface for
junction with the centrum in advance (basisphenoid). There is a
rough depression on each side of the under surface for the inser-
tion of the ' recti capitis antici.' The exoccipitals form small,
inferiorly approximate condyles, fig. 295, 2, have no precondyloid
foramina, and do not develope paroccipital processes : they meet
above to complete the foramen magnum. The superoccipital is
much expanded, and supports two supplementary bones (inter-
parietals) : it is deeply impressed by the insertion of the liga-

295

296

mentum nuch*. The basisphenoid has coalesced with the ali-
sphenoids. which are separated from their neural spine (pariet-
als, :) by the intercalated squamosals, g. The pterygoid processes
ai'e long, much expanded and excavated anteriorly, and are per-
forated at their base. The alisphenoids are perforated by a wide
* foramen ovale." The basisphenoid when united with the pre-
sphenoid receives air into the cells with which the bone, as it
acquu'es vertical extent, is excavated. The vomer retains its
character as a vertical plate, fig. 296, 13. The orbitosphenoids
have coalesced with each other at their base, and also vrixh the
prefrontals (laminae media? »thmoidei) : they are perforated by the
optic foramina, and notched posteriorly for the foramen rotundum.

440 ANATOMY OF VERTEBRATES.

The portions of the olfactory capsule closing the anterior orifice
of the cranial cavity form extensive ' cribriform ' plates. The
frontal, fig. 295, ii, is excessively expanded by the air-cells, fig.
296 ; its hind border is convex, its front one concave, and ex-
tended outward to form the superorbital ridge. The nasals, 15,
are short, triangular, and pneumatic : they ultimately coalesce
with the frontals. The mastoid is confluent with the squamosal,
and, bending forward to near the back part of the zygomatic pro-
cess, circumscribes the meatus auditorius externus. The tympanic
completes the inner part of the meatus, contributes to the back
part of the glenoid cavity, and expands into a broad horizontal
plate supporting the large ear-drum : it early coalesces with the
petrosal. The apex of this bone is grooved by the ento-carotid.

The epencephalic compartment of the cerebral cavity, fig.
296, e, as in Lissencephala, is wholly behind the pros- and mes-
encephalic ones : the rhinencephalic compartment is well defined.
The ' sella ' has slightly-marked clinoid processes. The orbits
are continuous with the large temporal fossae. The palatines
form the posterior half of the intermolar part of the roof of the
mouth, and bound the hinder nostril ; they soon coalesce with the
pterygoids and maxillaries, 21 : these are remarkable for the large
proportional size of their alveolar part, in advance of which the
bone extends upward to be wedged between the frontal and pre-
maxillary, downward and forward to strengthen the socket of the
tusk, and backward to form the anterior pier of the zygomatic
arch and the lower part of the orbit. The maxillary is perforated
by a large antorbital foramen. The premaxillary, figs. 152,
295, 22, mainly consists of the part which lodges the base of the
great tusk : but its ascending portion reaches the frontal, 11, and
excludes, as in Rodents, the maxillary from the nasal : the alveolar
part is grooved mesially by the long incisive canal. Both maxil-
lary and premaxillary are pneumatic, fig» 296. The mandible,
fig. 295, z, is short, the ascending being as extensive as the
horizontal ramus, and being also excavated for the formative
alveolus of the succeeding molar. The condyle is small, convex,
rising above the coronoid process, which is low and projects
obliquely forward. The dental canal is wide in reference to the
unceasing supply of material for the growth of the great molars.
The symphysis is short, small, pointed : in some extinct Probos-
cidians it was excavated for the alveoli of a pair of tusks ; and in
one aberrant form {Deinotherium) the symphysial tusk-bearing
part of the mandible was enlarged, lengthened, and deflected.

The bony nostril, formed by the nasals and premaxillaries, is

SKELETON OF PROBOSCIDIA. 441

small, transversely sub-bilobed, and elevated in position. The
rhinal cavity expands as it extends backward to be divided by
the vomerine septum, fig. 296, 13. The inferior turbinals are
slightly-curved laminae, one on each side the lower border of the
^ lamina perpendicularis,' where is the aperture admitting air to the
singularly extensive pneumatic structure of the skull. The lacry-
mal is a small protuberant imperforate bone, serving chiefly to
give attachment to the tendon of the ^ orbicularis palpebrarum.'

From the middle of the stylohyal a slender pointed process is
sent off at an acute angle. There is no bony ceratohyal. The
basihyal is transversely extended ; and articulates at each end to
a gristly epihyal, and a long bony thyrohyal. The base of the
stapes is an oval convex plate, with a marginal groove : one crus
is thinner than the other, and it is very slender.

297

Skeletou of the Mastodon (Mast, gujanteus).

§ C. Bones of the Limbs. — The scapula of the elephant, figs.
162, 297, 51, is second only to that of the Megatherioids, fig.
279, 51, in the proportion of breadth to length (dorso-humeral
diameter) : but the margin answering to the ' inferior costa ' of
anthropotomy, instead of being the longest, as in the Megathere,
is the shortest : it is very concave : the ' base ' is convex or bent
at almost a right angle ; a thick epiphysis is attached to its
border ; the spine extends into a short pointed acromion, and, as

442 ANATOMY OF VERTEBRATES.

in some Rodents, sends down a process : the coracoid is a mere
tuberosity : the glenoid cavity is shallow, twice as long as broad :
it looks downward, the scapula rising vertically above the hu-
merus.

The humerus, ib. 53, has the great tuberosity extended antero-
posteriorly, and rising above the sessile hemispheric head of the
bone : the deltoid ridge descends below the middle of the bone :
the occipital groove is deep : the ectocondylar ridge rises straight
for one-third the length of the humerus, and forms a low angle
before subsiding upon the shaft. The distal articular surface is
a simple shallow trochlea. The proximal ej^physis is in two
parts, one capping the head, the other the great tuberosity : the
distal epiphysis is single. The centre of the shaft is almost
Avholly occupied by a delicate cancello-reticulate structure.

The antibrachial bones are distinct and cross obliquely, the ra-
dius passing in front of the ulna to the inner side of the carpus,
as in the Megathere : but the prone position of the fore foot
cannot here be changed ; for the head of the radius, ^g. 297, 55,
is wedged between two processes of the ulna, ib. 54, and the ex-
panded distal half has a rough ligamentary union mth that bone.
The proximal articulation with the humerus is transversely elon-
gate, partly convex and partly concave. The ulna is the larger
bone ; its olecranon is thick and convex : the proximal epiphysis
covers only this process : the distal one forms the articulation
for both radius and carpus. This segment includes a small sca-
phoid, fig. 297, 5, a larger lunare, /, cuneiforme, c, and pisiforme,
with the usual four bones of the distal row. In the scaphoid,
the small surface for the radius is remote from that which joins
the trapezium, t, and trapezoides, d. The single surface of the
pisiforme has two facets, the smaller of which joins the ulna.
The trapezium extends along half the metacarpal of the index.
The phalanges, tw^o in the first and three in each of the other
four digits, are broad and short, especially the last, which is
firmly encased in the corresponding division of the hoof.

The hind limbs and pelvic arch present opposite proportions to
those in the Megatherioids : the skeleton of the extinct Probos-
cidian leaf-eater, fig. 297, contrasts singularly in this respect
with that of the extinct Megatherioid one, fig. 267. To both
these giants among land quadrupeds the forests of the primeval
world afforded sustenance ; but their ways of obtaining it were
difierent, and called for preponderance of developement in the
hind part of the skeleton in the one, and of the fore part in the
other. The pelvis descends vertically at almost a right angle

SKELETON OF PROBOSCIDIA.

443

Pelvis of the Elephant, front

Avith the trunk, fig. 162, 62, the ilia forming Avith the lumbar
series an angle of 120°: the ischium and pubis are short, and
form a symphysis, fig. 298, g, the axis of Avhich runs at an ano-le
of 100° with that of the ilium. This bone arches out from its
sacral joint almost transversely, the thick rough crista descendino-
with its angle, a, produced to a level Avith the acetabulum : the
anterior or abdominal surface is concave. The ischium, /, has
the tuberosity, e, directed
dorsad : the pubis shoAvs
a pectineal ridge, h. The
sciatic notches are AAadely
open : the obturator fora-
mina are smaller than the
acetabula, the planes of
which incline from the per-
pendicular about 70°, — a
favourable position for trans-
mitting the Aveight upon
the heads of the femora :
these, as in the Megathere,
have no round ligament, and
the acetabulum is simplified
accordingly. In a young Elephant I have observed an accessory
pelvic ossicle Avedged betAveen the ischium and pubis behind the
acetabulum.

The great trochanter does not rise so high as the head of the
femur : the small one is almost obsolete : the post-trochanterian
fossa is shalloAv: the shaft, figs. 162, 297, 65, is straight, simple,
and compressed from before backAA^ard. The rotular trochlea is
subsymmetrical, occupying one-third of the breadth of the distal
end : the condyles are divided by a deep popliteal cavity. The
proximal epiphysis consists of the part forming the articular ball
and that forming the trochanter. The medullar}^ artery enters
the back part of the loAver third of the shaft, and ascends to a
very small medullary cavity.

The tAA^o proximal articular surfaces of the tibia, ib. 66, are
transversely oval, separated by a conical prominence : there is a
large rough depression in front of the head of the bone : the
middle of the shaft is triedral, the hinder surface is very concave
superiorly. The distal articular surface is semicircular, convex
behind, and rising externally on the shaft to give articulation to
the fibula. The medullary artery passes transA^ersely from the
back of the shaft forAvard to a small medullary cavity. The

444

ANATOMY OF VERTEBRATES.

fibula, 67, retains its distinctness from end to end in the Probos-
cidian Ungulates. The patella, 66^ is slightly convex lengthwise,
and concaA-e transversely at its articular surface. The bones of
the foot are described at p. 309, fig. 193.

§187. Skeleton of Peris sodactyla. — A. Vertebral Column. All
the existing, and so far as is known the extinct, species of this
order have more than nineteen dorso-lumbar vertebrae. The
Tapir ( Ttf/?z>?z5 america7ius, fig. 299) has 7 cervical, 18 dorsal,
5 lumbar, 6 sacral, and 13 caudal vertebrae. The pleurapophysial
part of the transverse process extends forward in the third cer-
vical, and underlaps that of the second : the corresponding part
of the transverse process progressively expands in tlie succeeding

299

American Tapir (Tapirus americanus).

vertebrpe to the sixth, where it forms a broad hatchet- shaped plate
of bone directed downward and a little outward. In the seventh
cervical the transverse process consists of a diapophysis only, and
is therefore imperforate. In the anterior dorsal vertebrae the
base of the neural arch is perforated on each side by the spinal
nerve. In both these and the cervical vertebrae the fore part of
the centrum is convex, the hind part concave.

The neural spines gain rapidly in height to the third dorsal, and
gradually shorten to the eleventh ; after which, they increase in
fore-and-aft extent, and, from slightly inclining backward, be-
come vertical. Eight pairs of ribs directly join the sternum,
which consists of seven bones, with the xij)hoid cartilage. The
transverse processes of the last two lumbar and first sacral vertebrae

SKELETON OF PERISSODACTYLA. 445

are articulated to one another. Only tlie first two of the anchy-
losed sacrals afford articular surfaces to the ilia. Sometimes a
coalesced caudal adds a seventh vertebra to the sacrum. The
atlas has a recurved hypapophysis : its articular cups are deep ;
the base of the transverse process is tmce perforated by the
vertebral artery, the anterior hole opening upon the groove
which leads to the foramen in the neural arch common to the
vertebral artery and the first spinal nerve.

In the Rhinoceros, fig. 165, the vertebral formula is — 7 cer-
vical c, 19 dorsal D, 3 lumbar, 4 sacral, and 22 caudal. In the
atlas, the hypapophysis developes a process from the lower part
of the anterior surface. The neural arch is perforated trans-
versely by the vertebral artery. In the axis the centrum supports
a simple diapophysis, inclining downward and backward. The
neural spine is thick, short, tuberculated, and divided by a deep
and broad groove into tAvo : the upper part of the spine is pro-
longed obliquely upward, giving the whole a trifid character.
The pleurapophyses, from the fourth to the sixth cervical ver-
tebrae inclusive, have the form of broad subquadrate plates : in
the seventh the diapophysis only is developed, and the transverse
process is consequently imperforate. The spine of this vertebra
suddenly acquires great increase of length, which continues more
gradually to the second and third dorsals, beyond which the
spines shorten, but gain in antero-posterior extent to the eleventh
dorsal, beyond which they continue of the same size, shape, and
inclination to the lumbar region. A metapophysis rises in the
fourth dorsal from the back of the diapophysis, from which it
becomes distinct in the sixteenth dorsal. The diapophysis, which
gradually subsides in the dorsal, reappears suddenly in the first
lumbar : it becomes shorter in the second ; and still more so in
the third, in which it is very broad. The lower edge of the dia-
pophysis of the second lumbar articulates witli the upper edge of
the diapophysis of the third, and the third articulates in the same
manner with the first vertebra of the sacrum. The metapophyses
are distinct, and are situated on the anterior zygapophyses in the
first two lumbars : in the last they have become rudimental, and
almost obsolete. The centrum is strongly convex anteriorly, and
concave behind, in the cervical vertebra? ; the dorsals are opis-
thocoelian in a less degree.

The ribs are slender in proportion to their length, and more
curved than in the Elephant. In the first rib the tubercle is
large, with a corresponding articular surface : both this and the
second are almost straight, become expanded distally, and have no

446 ANATOjMY of VERTEBRATES.

groove on the posterior margin. The tAvelfth rib is the longest,
measurino: three feet. In the nineteenth rib the articular surfaces
of the head and tubercle are almost confluent, and the shaft de-
creases in thickness distally : its length is one foot four inches.

In the sacrum the articular surface for the ilium is formed by
the first three of the four coalesced vertebrae. The metapophyses
are distinct in the first two. The neural spines are long, strong,
and tubercular at the end ; the last curves very much backward.
The three interarticular cartilages between these four vertebras
lonof remain unossified. In the caudal series the neural canal
does not extend beyond the seventh vertebra.

The little Hyrax has not fewer than twenty-nine, or even
thirty, dorso-lumbar vertebrae. In the twenty-two dorsal ver-
tebrae of the skeleton of H, capensis,^ the spines incline toward
the thirteenth, which is vertical, and indicates the centre of motion
of that part of the trunk. In their forms and proportions they
resemble those of the Rhinoceros. Seven or eight pairs of ribs
directly join the sternum, which consists of six bones. The meta-
pophysis commences on the third dorsal, and attains the outside of
the zygapophysis on the fifteenth : it exceeds the diapophysis in
length in all the posterior dorsals. In the eighth lumbar verte-
brae the diapophyses suddenly acquire great breadth, and gradually
increase in length to the last lumbar ; the metapophyses are con-
tinued throughout the series. No anapophyses are developed.

The transverse process of the atlas is perforated vertically at
its fore part by the vertebral artery, which afterwards perforates
the neural arch. The hypapophysis developes a short process.
The simple transverse process of the dentata is perforated at its
base for the vertebral artery, and the neural arch is perforated on
each side by the second cervical nerve. The pleurapophysial
part of the transverse process is much expanded in the third to
the sixth cervical vertebrae inclusive : I have found it wanting on
the left side of the seventh vertebrjB, but present as a distinct
element, or rudimental cervical rib, on the right side, where it
completes the foramen for the vertebral artery. The sacro-caudal
vertebrae are fourteen in number, of which the first three articulate
with the ilia, and the four succeeding have transverse processes.

In an extinct S. American Perissodactyle ( Macrauchenia),^
the cervical vertebrae are remarkable for their length, as the
name implies ; also for the flattening of the terminal articular
surfaces, and the imperforate character of the transverse processes,

' XLiv. p. 524, no. 3097. * xcv. p. 35, pis. v. vi. vii.

SKELETON OF PERISSODACTYLA.

447

the vertebral artery entering the neural canal and perforating
the neurapophysis, lengthwise. The transverse processes of the
last lumbar present each a concave articular surface to corre-
sponding convexities of those of the sacrum.'

In the Horse, fig. 300, the vertebral formula is — 7 cervical,
19 dorsal d, 5 lumbar, a, h, c, d, e, 5 sacral,/* — I, and 17 caudal,
p — r. Eight pairs of ribs directly join the sternum, which con-

sists of seven bones and an ensiform cartila^'e. The neural

Ilorsc (Equiis cahalhis).

arches of the last five cervical vertebra? expand above into flat-
tened, subquadrate, horizontal plates of bone, with a rough
tubercle in place of a spine: the zygapophyses are unusually
large. The perforated transverse process sends a pleurapophysis,
z, downward and forward, and a diapophysis, r, backward and
outward, in the third to the sixth cervicals inclusive: in the
seventh the diapophysial part alone is developed, and is imper-
forate. The neural s})ines suddenly and considerably increase in
length in the first three dorsals, and attain their greatest length

' xcv, pi. viii. fig. 1 , 0.

448 ANATOMY OF VERTEBRATES.

in tlie fifth and sixth, after which they gradually shorten to the
thirteenth, and continue of the same length to the last lumbar.
The metapophysis, commencing as a tuberosity above the diapo-
physis, passes gradually from that part to the outer side of the
prozygapophysis, which it finally attains in the seventeenth dorsal
vertebra, and continues in the same place throughout the lumbar
series. There are no anapophyses. The lumbar diapophyses are
long, broad, and in close juxtaposition ; the last presents an arti-
cular concavity adapted to a corresponding convexity on the fore
part of the diapophysis of the first sacral.

The cervical vertebrae, though shorter than in Macrauchenia,
are longer than in other Perissodactyles, and rise Avith an arch to
support the head : the joints of the centrums are opisthocoelian.
In the third cervical the pleurapophysis is developed below the
arterial canal, and extends forward, outward, and downward.
The neural spine, u, has subsided to a low rough ridge. The
hypaj)ophysial ridge and tubercle, o, are well marked, as are also
the anterior convexity and posterior conca\dty of the centrum.
The inner surface of each neurapophysis is pierced by a small
canal in the same place and direction as that which transmits the
vertebral artery in Macrauchenia ; but the artery traverses the
base of the transverse process in the Horse, as in most other
mammals. In the axis the neural spine, k, is a strong but low
rugged ridge, which bifurcates posteriorly, and subsides upon the
zygapophyses. The diapophyses are short and triangular, with
their bases perforated by the vertebral artery. A strong ridge
on the under part of the centrum leads to the hypapophysis, h.
The posterior articular surface of the centrum is deeply exca-
vated. In the atlas, c, the anterior articular cavities do not meet
below : the diapophysial ridges, «, bend down, forming large con-
cavities : the vertebral artery twice pierces their base, which is
also traversed by a canal leading to the neural canal, anterior to
which the neural arch is perforated on each side. The hyj^apo-
physis developes a strong tubercle.

In the skeleton of a Quagga {Equus Qiiagga^ I have observed
19 dorsal, 6 lumbar, 5 sacral, and 18 caudal vertebrae; in that of
a Zebra {Equus Zebra), 18 dorsal, 6 lumbar, 5 sacral, and 17
caudals ; whilst in the skeleton of an Ass {Eqiius Asinus), there
were 18 dorsal, 5 lumbar, 5 sacral, and 17 caudal vertebrae. The
sixth lumbar, fig. 299,/, becomes the first sacral by coalescence.

B. Skull. — Some common characters of this part of the skeleton
in Perissodactyles are given at pp. 283, 284. In the Malayan
Tapir (^Tapirus indicus), the paroccipitals are compressed and

SKELETON OF PERISSODACTYLA.

449

301

Skull of American Tapir.

sHglitly incurved : they are strengthened by a long post-tympanic
process, developed from the squamosal and articulated to the fore
part of the base of the paroccipital, so as to circumscribe a space
occupied by the true mastoid which is confluent with the petrosal.
One or two vacuities are left in this space for the exit of veins.
The post-glenoid process is much developed. The base of the
l^terygoid process is perforated lengthwise by the ectocarotid ; the
apex is slightly recurved, and unites with the palatine by a
squamous suture. The en-
topterygoids are thin, small,
curved lamellaa applied to
the inner side of the base
of the pterygoid processes,
and uniting with each other
below, and clear of, the pre-
sphenoid. The major part
of the palatine enters into
the formation of the laro:e
oblique hinder aperture of
the nasal passages : the smaller anterior division completes the bony
palate which terminates behind between the first and second true
molar. The lacrymal canal commences by two distinct orifices.
The bases of the nasal bones are deeply grooved, and articulate with
the frontals parallel with the back part of the orbit. There is no
superorbital foramen or canal. The premaxillaries terminate
behind at a considerable distance from the elevated nasals. In
the American Tapir (Taphnis Americcmus), fig. 301, the super-
occipital is narrower and more deeply excavated than in the
Malayan Tapir : a smaller proportion of the petromastoid is
visible between the exoccipital and squamosal, r/ : the frontals, ii,
are less expanded and less elevated above the nasals, is. The
petromastoids fit, but not closely, the vacuities on each side the
basioccipital. In the cranial cavity the rhinencephalic fossa is
well defined.

In the (Sumatran) Rhinoceros, a smaller proportion of the
palatine bones enters into the formation of the bony palate than
in the Tapir; they chiefly form the sides of the hinder nasal
aperture, the anterior boundary of which is opposite the first true
molars. The pterygoid processes are perforated at their base,
lengthwise, by the ectocarotid arteries. The nasofrontal suture
is in advance of the orbits. The postglenoid process is long,
subtrihedal, and obtuse : the })ost-tymi)anic process takes the
place of the mastoid and is here a strong quadrate process

VOL. II. G a

450 ANATOMY OF VERTEBRATES.

applied to the base of the paroccipital. The orbits are very
obscurely marked off from the temporal fossie : there is no
postorbital process. The lacrymal canal commences by two
apertures defended by a rough protuberance of the lacrymal
bone. There is a well-developed pit for the origin of the in-
ferior oblique. The premaxillaries are small and do not join
the nasals. The air-sinuses extend from the frontals to the
superoccipital ridge.

In the Indian Rhinoceros {Rhinoceros Indicus, fig. 302), the
bones, 3, 7, ii, 15, forming the expanded neural spines of the
302 cranial vertebrae, are so

curved, that the summit of
the superoccipital, 3, and
the centre of the nasals, 15,
form the two pillars from
which are suspended the
parietals, 7, and frontals, ii,
forming an inverted arch.
The highest part of the
nasals shows the rough flat-
tened surface for the attach-
ment of the horn : from

Skull of Iiidiau Rhiuoceros. i • i . , i

wnicn part tney curve
downward, ending pointedly. The premaxillaries, 22, are small,
support a pair of incisors, articulate with each other and the
maxillaries, and terminate remotely from the nasals. In the
African two-horned Rhinoceroses, the premaxillaries are almost
obsolete, and usually edentulous in the adult.

In certain extinct Rhinoceroses the septum narium was partially
{Rh, leptorliinus) ^ or wholly {Rh. tichorrhinus) ossified. The arti-
culation between the basi- and pre-sphenoids long remains. There
is no interparietal. The entopterygoid swells into a tuberosity,
and overlaps the palato-pterygoid suture.

In the Hyrax the elements of the occipital bone are late in
coalescing. I have seen an interparietal wedged into the back
part of the sagittal suture, and also the upper half of the super-
occipital detached from the rest. The ascending process of
the malar articulates with the postorbital i3rocess which is
formed by both the parietal and frontal bones. The tympanic,
which forms the bulla ossea at the basis cranii, has not coalesced
with the petrosal. The hinder halves of the palatines enter into

' xviir. p. 356, figs, 131, 138.

SKELETON OF PERISSODACTYLA.

451

the formation of the palato-nares. The lacrymal canal commences
by one or two foramina, defended by a process. The maxillary
forms the floor of the orbit, as in the Rhinoceros and Tapir ; but
the premaxillaries join the nasals. The lower jaw, 7, is remark-
able for the backward expanse of the ascending ramus. The
coronoid process is perforated lengthwise at its base.

If the equine skull, fig. 303, be compared with that of the
Rhinoceros, the basioccipital will be seen to be narrower and
more convex. The mastoid, 8, intervenes, as a tuberous process,
between the post-tympanic and paroccipital processes, clearly
indicating the true nature of the post-tympanic in the Rhino-
ceros ; the Tapir shows an intermediate condition of the mastoid

303

Skuil of Horse, Equus CabalUis.

between the Rhinoceros and Horse. The latter differs from both
the Tapir and Rhinoceros in the outward production of the roof
of the orbit and the completion of the bony frame of that cavity
behind by the junction of the postorbital process, i, 2, c, with the
zygoma, ?-: Equus resembles Macrauchenia in this particular.
The temporal fossa, 7, is small in proportion to the length of the
skull : the base of the postorbital process is perforated by a
superorbital foramen, h : the lacrymal canal begins by a single
foramen. The premaxillaries, 22, extend to the nasals, 15, and shut
out the maxillaries, 21, from the anterior aperture of the nostrils.
The chief marks of affinity to other Perissodactyles are seen in
the shape, size, and formation of the posterior a])crture of the
nostrils, the major part of which is bounded by the palatine bones,

o G 2

452

ANATOMY OF VERTEBRATES.

304

of which only a small portion enters into the formation of the
bony palate, which terminates behind opposite the interspace
between the penultimate and last molars. A narrow groove
divides the palato-pterygoid process from the socket of the last
molar, as in the Tapir and Rhinoceros. The pterygoid process
has but little antero-posterior extent: its base is perforated

by the ectocarotid. The en-
topterygoids are thin plates
applied like splints over the in-
ner side of the squamous suture
between the pterygoid processes
of the palatines and alisphenoids.
The postglenoid process is less
developed than in the Tapir.
The Eustachian process of the
petro-tympanic is long and
styliform. There is an ante-
rior condyloid foramen, and a
wide ^ fissura lacera.' The broad
and convex bases of the nasals,
fig. 304, 8, 8, articulate with the
frontals, y, a little behind the
anterior boundary of the orbits.
The space between the incisors
and molars is of greater extent
than in the Tapir, fig. 301 : a
long diastema is not, however,
peculiar to the Horse, and,
although it allows the applica-
tion of the bit, that application
depends rather upon the general
nature of the Horse, and its
consequent susceptibility to be
broken in, than upon a particu-
lar structure which it possesses
in common with many other
The air-cells do not extend farther back than the
fore part of the frontals above the cranial cavity, and of the
basisphenoid beneath. Ossification extends into the base of the
tentorium and its continuation into the falx. The upper boundary
of the rhinencephalic fossa is much developed.

There is a foramen, fig. 303, 9, in the premaxillary suture.
The zygoma, fig. 303, r, is chiefly formed by the squamosal, s.

Skull oi iIor,-.e.

Herbivora.

SKELETON OF PERISSODACTYLA.

453

The malar extends upon the face, beneath the lacrymal, in
advance of the orbit. The ascending ramus of the mandible has
a convex hind border curving from the condyle, 20, to beneath
the last alveolus, where it ends by a slight projection below the
inferior border of the horizontal ramus. The coronoid process,
19, is long, narrow, and recurved.

305

Hyoid arch, Horse.

The stylohyals, fig. 305, st h, long and rib-like, articulate by a
rounded ^ head ' to the petromastoid ; expanding beyond this,
to form a sort of ^ tubercle,' and continued, slightly contracting, to
the short epihyal, e, p, h ; by means of which they articulate
with the ceratohyals, c, h ; which unite with the basihyal, b, h,
where this is joined to the thyrohyals, h, h. The basihyal
supports a glossohyal, g, h. The homology of the thyrohyals
with the ceratobranchials in Fishes and Batrachia is illustrated
by the figures B, h b, introduced (reversed) in the same cut.

4c 4 ANATOMY OF VERTEBRATES.

C. Bones of the Limbs. — These are cliiefly modified in their
proportions with reference to degree of swiftness of course in the
different species : which have diverged, in this respect, from the
okl tertiary type as exemplified by the Paloaothere, in two di-
rections, the extremes of which are now shown in the Rhinoceros,
fig. 165, and the Horse, fig. 300. The segments farthest from
the trunk are the seats of chief variety, and here the elongation
and attenuation of the bone is attended with suppression of certain
of the digits.

The scapula is long in proportion to its breadth, and most so in
the Horse, fig. 300, 5i : the anterior angle is largely rounded off:
the spine developes no acromion, but gradually subsides as it ap-
proaches the neck of the scapula : it is situated nearer the hind
border in the Tapir (fig. 299, 5i), nearer the front border in the
Horse, mth concomitant differences in the areas of the supra- and
infra-spinal fossa? : in the Rhinoceros it equally bisects the blade-
bone, and is most prominent at its upj)er third. The coracoid is
a mere tuberosity in all. The front border or ' costa,' in the
Tapir, has a wide and deep notch. Macrauchenia differs most
from other Perissodactyles in the continuation of the spine, with-
out loss of height, to the neck of the scapula, above which it forms
a slightly produced angle and is perforated.

In the Rhinoceros, fig. 165, the humerus is remarkable for the
strength of the tuberosities and deltoid ridge, and for the smooth
basal surfaces between the tuberosities and on the outside of the
external one. The medullary artery enters the back part of the
bone, and proceeds obliquely forward and downward. In the
radius, the surface for the ulna extends along the back part of
the rido-e boundino- that for the humerus. The two antibrachial
bones interlock at their distal ends by reciprocally adapted cavi-
ties and tuberosities. The usual eight bones are present in the
carpus : but the trapezium does not support a digit, and the unci-
forme is small and has only the digit answering to the fourth :
this, with the medius and index, being alone developed in the
Rhinoceros. The ilia are massive, short, and less expanded than
in the Elephant, sub vertical in position, concave anteriorly, and
also behind in the transverse direction. The terminal angle of
the rough thick crest is bifurcate. The ischia are relatively
longer than in the Elephant, with thick outwardly-bent tuberosi-
ties. The ischio-pubic symphysis is prominent. The lumbo-
iliac ano'le is 125°.

The head of the femur is impressed by a deep semicircular pit
at its margin. The third trochanter, fig. 165, 65, is a remarkable

SKELETON OF PERISSODACTYLA. 455

feature, from its great size and forward curvature. Ossification
sometimes extends from tlie great trochanter to the third tro-
chanter. The rotular surface is distinct from those on the con-
dyles. The inner wall of the trochlear surface for the patella is
thicker, more prominent, and is prolonged farther up the shaft of
the femur than the outer wall is ; the condyles are nearly of the
same length. The medullary canal commences at the back part
in the upper half of the shaft, and inclines forward and down-
ward. The bones of the hind-foot are explained at p. 309,
fig. 193.

In the Tapir, the intercondyloid part of the humerus, fig. 299,
53, is perforated, as it is likewise in the Hyrax. I have found
the radius, 54, and ulna, 55, partially anchylosed at their distal
ends in the Malayan Tapir, and have observed their distal
epiphyses to coalesce with each other before uniting with their
respective shafts. The carpus resembles that in Rhinoceros ; but
the unciforme is rather larger, and supports the metacarpal of a
fifth, as well as of a fourth digit. The first or trapezial digit is
absent, and the one articulated to the magnum, answering to the
third, is the largest and of symmetrical shape, the whole fore-foot
plainly showing the perissodactyle type, though mth four toes.
The little Hyrax and an extinct hornless Rhinoceros {Acero-
tlieriuiTi) have a similar unsymmetrically tetradactyle fore-foot.
That of the Macrauchenia was tridactyle. The expanded part
of the ilium of the Tapir, ib. 62, is an oblong quadrate plate with
the upper and hinder angle articulating with the sacrum. The
canal for the medullary artery of the femur, which begins near
the small trochanter, extends downward to a small medullary
cavity at the middle of the shaft, 65 ; which is longer than that of
the tibia, 66. The bones of the hind-foot closely resemble those
of the Khinoceros, forming the same number of toes : the heel-
bone, d, is more prominent.

In fig. 190, 'bones of the fore-limb of the Horse,' the supra-
scapular cartilage is ossified and confluent with the base of the
scapula, ^ : o is the infraspinal fossa, p the supraspinal fossa, i the
prominent and thickened part of the spine, h the neck, m the an-
terior border or ' costa,' I the posterior ' costa ; ' the line from n to
n marks the base of the scapula supporting the suprascapula ; k is
the coracoid protuberance. In the humerus, a is the shaft of the
bone, h the lower part of the deltoid ridge where the ' teres
major ' is inserted, e is the great tuberosity which is grooved by
the tendon of the biceps,/* is the ' neck.' The proximal epiphysis
of the young bone forms both the head and the tuberosity. At

456 ANATOMY OE VERTEBRATES.

the distal end, K marks the trochlear surface for the radius, the
fore part of which bone, o, passes into the depression Z, when
fully flexed : k is the inner condyle, i the outer condyle ; m the
posterior fossa for the olecranon, when the antibrachium is ex-
tended. The ulna, represented by its olecranon, 5, and upper
part of the shaft, w, coalesces by the latter, in aged Horses, with
the radius : it presents a small articular surface, f, for the hu-
merus. The radius and ulna coalesce in Macrauchenia. The
equine carpus includes, in the proximal row, the scaphoid w,
lunare x, cuneiforme y, and pisiforme z, which latter is large and
prominent. The os magnum, 2, in the second series of carpal bones
is remarkable for its great breadth, corresponding to the enor-
mous developement of the metacarpal bone of the middle toe, 4, 5,
which forms the chief part of the foot. Splint-shaped rudiments
of the metacarj)als, answering to the second and fourth, 6, of the
pentadactyle foot, are articulated respectively to the trapezoides
and the reduced homologue of the unciforme, 3. The miocene
Hipparion retained stunted hoofs supported by the second and
fourth digits of the fore-foot, as in the hind-foot, fig. 194 : but all
modern and existing representatives of the genus Eqiius have the
digital developement concentrated on the medius : of which, in
fig. 190, 12-13 shows the proximal phalanx, called in Hippo-
tomy the ^ great pastern'; 14-15, the middle phalanx, called the
^ small pastern'; 16, the ungual phalanx, called the ^coffin-
bone': 11 and 17 are ' sesamoids,' the latter being called the ^ nut-
bone.'

The ilium of the Horse, fig. 300, 62, is longer and less ex-
panded superiorly than in the Tapir ; but it articulates by the
corresponding part to the sacrum, which renders it hammer-
shaped. The femur is characterized by the partial division of the
great trochanter, and, as in other Perissodactyles, has the third
trochanter. The medullary artery enters the middle of the shaft
at its postero-internal side, and inclines slightly upward. In fig.
195, a is the shaft, h the ' neck,' c the head ; d d, the great tro-
chanter, of which the upper division is called ' the spoke ; '/"is the
^ third trochanter,' g marks the place of a deep fossa giving origin
to the gastrocnemius externus, h is the outer condyle. In the tibia,
s-io is the protuberance and ridge for the rotular ligament, v the
articular head of the bone, u the outer concavity. The distal end
is excavated by a deep oblique double trochlear cavity for the
astragalus, 5. The fibula is represented by its head, 1, and a
slender styliform portion of the shaft, ending in a point, at 2.
There is no representative of the distal end, as in Macrauchenia

SKELETON OF ARTIODACTYLA.

457

and the Ruminants. The bones of the foot are described at
p. 308, fig. 193 (Horse).

The astragalus shows the extreme perissodactyle modification
by the depth and obliquity of the superior trochlea, and by the
extensive and undivided anterior surface, which is almost entirely
appropriated by the naviculare : the ectocuneiforme, which is the
homotype of the magnum in the carpus, is equally remarkable for
its large size, since it supports that metatarsal, answering to the
middle one in pentadactyle quadrupeds, which constitutes the
chief part of the hind-foot in the Horse.

§ 188. Skeleton of Artiodactyla, — Some of the common osteo-
logical characters of this order, with the genera representing it,
are given at pp. 285, 286.

A. Vertebral Column. — In the Hippopotamus, fig. 306, the

306

Eip-popotamus amphibius.

vertebral formula is : — 7 cervical, 15 dorsal, 4 lumbar, 6 sacral,
16 caudal. The pleurapophysial parts of the transverse processes
of the third to the sixth cervical inclusive develope hatchet-
shaped plates, progressively increasing in size, which overlap each
other. The second and third cervical s have bituberculate hypa-
pophyses. The transverse processes of all the cervicals are per-
forated by the vertebral arteries. The neural spines elongate
from the third to the seventh cervical, C. Six pairs of ribs
directly join the sternum, which consists of five bones and a
broad ensiform cartilage. A metapo})hysial ridge is developed
above the diapophyses of the eighth dorsal, changes its position
and shape with increase of size in the two succeeding vertebras,
in the eleventh projects forward from above the prozygapophysis.

458 ANATOMY OF VERTEBRATES.

and so continues throughout the rest of the dorsal and the lumbar
series. There are no anapophyses, but a broad plate is developed
from the back part of each transverse process of the last lumbar,
which presents an articular convexity for a corresponding con-
cavity on the fore part of each transverse process of the first
sacral vertebra.

In the Peccari {Dicotyles)^ the vertebral formula is : — 7 cervical,
14 dorsal, 5 lumbar, 5 sacral, and 6 caudal. The axis vertebra
has a short pointed diapophysis : the third vertebra has a pleura-
pophysial lamella coextensive with the centrum. The corre-
sponding lamella increases in the fourth, the fifth, and very re-
markably in the sixth cervical, and they overlap each other.
The bony plate between the anterior zygapophysis and diapo-
physis is perforated by the spinal nerve in the last four cervical
vertebrae : the third and fourth terminate above in a large
platform of bone supported by vertical neurapophysial walls,
without a neural spine ; in the fifth a neural spine is developed,
and the spine progressively increases in length and inclines for-
ward in the sixth and seventh cervicals. The neural spines of
the first and second dorsals are vertical, and as long as the
pleurapophyses of the same vertebra. The succeeding dorsal
spines gradually diminish in length and incline backward to
the twelfth, which is short and vertical. The metapophyses begin
to be developed at the third dorsal, and increase in length to the
eleventh, after which they rise upon the zygapophyses. The
neural arches of all the dorsal vertebrae are directly perforated
by the spinal nerves, and the base of the diapophysis is vertically
perforated. The diapophysis of the fourteenth dorsal vertebra
begins to show the increase of size which characterizes the lumbar
series. Seven pairs of ribs directly articulate with the sternum,
which consists of six bones.

In the Hog {^us Scrofd), the vertebral formula is : — 7 cervical,
13 dorsal, 6 lumbar, 4 sacral, and 23 caudal, with varieties, chiefly
depending on the number of moveable ribs developed in the
domestic breeds. The fifth and sixth cervical vertebrae are re-
markable for the great expanse of the lamelliform, overlapping,
and doA^mwardly directed costal parts of the transverse processes,
and the seventh cervical for the absence of the pleurapophysis
and the sudden increase in the length of the neural spine. This
is far surpassed by the spines of the anterior dorsal vertebrae;
after which those processes progressively decrease in height to
the last three dorsals, where they gain in antero-posterior extent :
the verticality of the spine of the eleventh dorsal indicates the

SKELETON OF ARTIODACTYLA.

4o9

centre of motion of the trnnk. The dorsal nenrapophyses are
directly perforated by the spinal nerves, and a bar of bone con-
nects the end of the diapophysis with the hind part of the cen-
trum, circumscribing a vertical perforation on each side. The
metapophysis commences as a tuberosity upon the diapophysis of
the middle dorsal vertebra?, projects forward midway between the
di- and prozyg-apophyses in the tenth, passes upon the prozyg-
apophyses of the eleventh dorsal, and is continued in that position

There are no anapophyses.

throuo'hout the lumbar series

307

Dromedary.

In the Dromedary, fig. 307, and Camel (Camelus hactrianus),
the vertebral formula is : — 7 cervical, 12 dorsal, 7 lumbar, 4 sacral,
and 18 caudal. Seven pairs of ribs articulate directly with the
sternum, which consists of six bones, the last being greatly ex-
panded and protuberant below, where it supports the pectoral
callosity in the living animal. The cervical region is remarkable
for its length and flcxuosity ; the vertebra? are opisthococlian,
but resemble those of Macrauchenia in the absence of the perfo-
ration for the vertebral artery in the transverse process, with the
exception of the atlas ; tliat artery, in the succeeding cervicals,
enters the back part of the neural canal, and perforates obliquely

460 ANATOMY OF VERTEBRATES.

the fore part of the base of the neurapophysis, as shown in the
longitudinal section, fig. 308.^ The costal part of the transverse
process is large and lamelliform in the fourth to the sixth cer\dcal
vertebrae inclusive : in the seventh it is a short protuberance : in
^ „ this cervical the neural sijine be-

3(38 . ^.

comes conspicuous. Ihe metapo-
physial tubercle is developed from
the diapophysis in the eleven ante-
rior dorsal vertebra, and passes upon
the zygapophysis in the twelfth, con-

Section of third cervical, Camel. ,. . . ,i, •■• ,i ^ .

tmumg m that position throughout
the lumbar series. There are no anapophyses. The spinous pro-
cess in the first dorsal suddenly exceeds in length that of the last
cervical, and increases in length to the third dorsal ; from this to
the twelfth dorsal the summits of the spines are on almost the same
horizontal line, and are expanded and obtuse above, sustaining
the substance of the hump (Dromedary) or humps (Camel) ; the
spines of the lumbar vertebrje progressively decrease in length.
The diapophyses of the last six lumbar vertebrae are very long :
those of the last lumbar do not articulate, in the Camelidce or in
any Ruminant, with the sacrum.

In the Llama {Auchenia) the last sterneber is not so expanded
as in the Camel : the vertebral formula is the same : the fifth
lumbar has the largest spine : the cervicals, besides ha\dng im-
perforate transverse processes, resemble those of Macrauchenia
in the flatness of the terminal articular surfaces, and the neck is
habitually less bent down than in the Camels.

In the Musk-deer {^Moschns moschiferus), the vertebral formula
is: — 7 cervical, 14 dorsal, 5 lumbar, 5 sacral, and 6 caudal. The
atlas has a hypapophysis, but no neural spine. The transverse
process is a broad thin plate coextensive with the length of the
vertebra : it is perforated transversely from the neural canal
outward to beneath its base, for the exit of the nerve, and then
vertically, by the vertebral artery, which also perforates the
neural arch. The axis has a sharp hypapophysial ridge extending
from below the base of the odontoid process to beyond the poste-
rior surface of the centrum, where it underlaps the next vertebra.
A similar ridge and backwardly produced process are developed
from the two succeeding cervicals, beyond which the ridge gra-
dually subsides to the seventh vertebra. From the third to the
sixth cervical inclusive, the pleurapophysial part of the transverse

' XCII-. p. 218, no. 925, a., figured in xcv. pi. vi. fig. 2, also in xcvi, fig. 344.

SKELETON OF AKTIODACTYLA. 461

process equals or exceeds the length of the vertebra, and those
parts are arranged so as to overlap each other. There is a dis-
tinct, but less extensive diapophysial portion projecting external
to the vertebrarterial canal : this part alone represents the trans-
verse process in the seventh cervical. The spines of the third
and seventh cervical vertebras are vertical, those of the inter-
mediate ones incline forward. The spines of the anterior dorsal
vertebra) are remarkable for their height, those of the posterior
dorsal and of the lumbar vertebrte for their antero-posterior
extent, the anterior angle being produced forward and overlapping
the spine in advance. A distinct metapophysis begins to be
developed from the second dorsal, and attains its greatest length
on the twelfth. There are no anapophyses. The notches for
the nerves increase in depth as the vertebrae recede in position,

309

and in the last dorsal the neural arch is completely perforated by
these, which is likewise the case in most of the lumbar vertebra;.
Eight pairs of ribs directly articulate with the sternum, which
consists of seven bones. The tubercle disappears from the penul-
timate pair of ribs, and the diapophysis is reduced to a short
rough tuberosity ; but in the last pair the costal tubercle with its
articular surface reappears, and the diapophysis resumes its
normal size and articulation with the rib. In the first lumbar
vertebra the diapophysis suddenly increases in length and breadth,
and is probably augmented by the ossified and coalesced beginning
of a rib.

In the common Ox (^Bos Taurus, fig. 309), the vertebral for-

462 ANATOMY OF VERTEEKATES.

mula is; — 7 cervical, 13 dorsal, 6 lumbar, 5 sacral, and 21 caudal.
The spines of the cervical are short, save in the last, and they in-
cline to that of the third cervical, as the centre of the movements
of the neck : these are facilitated by the ball-and-socket articula-
tions of the bodies, common to the true Ruminants with most
other Ungulates. The neural spine is longest in the third and
fourth dorsals, whence the spines gradually shorten to the tenth :
the metapophysis passes from the diapo^Dhysis to the zygapophysis
in the tenth, eleventh, and twelfth dorsals. In the first lumbar
the diapophysis exchanges its short, thickened, obtuse shape for a
long, broad, vertically compressed plate : these processes increase
in length to the fourth lumbar. The foramina for the spinal
nerves directly perforate the neurapophyses of the dorsal vertebra? ;
they escape by conjugational foramina at the interspaces of the
lumbar vertebrae.

The European Bison has 14 dorsal and 5 lumbar vertebras, the
American Bison has 15 dorsal and 4 lumbar, and this is the
extreme reached, in the Ruminant order, of moveable pairs of
ribs, equalling in number those of the Hippopotamus. The ribs
are more slender in Bison than in Bos.

In the Roan Antelope {Antilope equina), the vertebral formula
is : — 7 cervical, 14 dorsal, 6 lumbar, 4 sacral, and 14 caudal.
The atlas and dentata send out strong diapophyses : from that of
the third cervical a broad pleurapophysial ridge extends forward
and underlaps the diapophysis of the axis : a similar structure is
presented by the fourth and fifth cervicals, and in the sixth the
pleurapophysis forms a broad subquadrate plate extending down-
ward and a little outward. This element is absent in the trans-
verse process of the seventh vertebra, which is imperforate. The
dorsal spines begin progressively to shorten from the fifth ; that
of the thirteenth is vertical, and indicates the centre of motion of
the trunk. A metapophysis is developed from the front of the
diapophysis of the second to the ninth dorsal vertebrae inclusive,
where it begins to be transferred to the anterior zygapophysis,
from which it extends in the last four dorsals and in all the
lumbar vertebrae. There is a short anapophysis in the last two
dorsals, but not in any of the lumbar vertebras. Nine pairs of
ribs directly join the sternum, which consists of eight bones and
the xiphoid cartilage.

These characters are found in the vertebral column of most
Antelopes.

In the Wild Sheep of Thibet ( Ovis Nahura), as in the English
domestic Ovis Aries, the vertebral formula is: — 7 cervical, 13

SKELETON OF AETIODACTYLA. 4g3

dorsal, 7 lumbar, 4 sacral, 10 caudal, the latter being subject to
variety. Tlie pleurapophysial parts of the transverte processes
of the third, fourth, and fifth cervicals underlap the diapophysial
parts of those m advance: the pleurapophysis of the sixth cervical
is an oblong quadrate plate; the seventh is imperforate, as in
Rumniants generally. The neural spines increase in height from
the tlnrd to the seventh cervical, and are suddenly and'' greatly

surpassed in height by those of the anterior dorsals. The meta-
pophysis is developed on the second and succeeding dorsals;
attams the anterior zygapophysis in the eleventh ; and projects
from that part in all the lumbar vertebra. The last pair of ribs
are joined by the head, only, to tlie vertebra : the seven anterior
pau's directly join the sternum, which consists of six bones.

The Giraffe is, in some respects, intermediate between the

464

ANATOMY OF VERTEBRATES.

^ hollow-horned ' and ^ solid-horned ' Ruminants, though partaking
more of the nature of the Deer.

In the Nubian Giraffe (^Camelopardalis Giraffa, fig. 310), the
vertebral formula is : — 7 cervical, 14 dorsal, 5 lumbar, 4 sacral,
and 20 caudal. The vertebral artery perforates the fore part of
the neurapophysis of the atlas twice, vertically and transversely :
the atlas has a hypapophysis : this process in the dentata is a
long thin ridge : the upper and fore part of the transverse process
is perforated by the vertebral artery in this and the succeeding
cervicals : a pair of exogenous processes is developed from the

Female liein-deer {Cervus tarandus).

under and fore part of the body in the third to the seventh cer-
vical inclusive : the second to the sixth are remarkable for their
length and almost w^ant of neural spines : the short one of the
seventh cervical is antro verted: those of the dorsals rapidly
increase to the third, which, with those of the fourth and fifth,
raise the outline of the back, like a hump : they then gradually
diminish to the last dorsal. The ribs are long, corresponding
with the great depth of the chest. Seven pairs directly join the
sternum, which consists of six bones.

In the Rein-deer {Cervus tarandus, fig. 311), the vertebral

skp:leton of aetiodactyla.

465

formula is: — 7 cervical, 14 dorsal, 5 lumbar, 4 sacral, and 11
caudal. The pleurapopliyses of the third, fourth, and fifth
cervicals are developed forward as well as backward ; those of the
sixth are also of great breadth, and are more joroduced downward.
The metapophysis is distinctly developed upon the second and
succeeding dorsal vertebrae, and attains the outside of the zyga-
pophysis in the eleventh. All the dorsal ribs are biarticulate, re-
taining both head and tubercle. Eight pairs of ribs directly join
the sternum, which consists of seven bones. In the Megaceros,
fig. 166, as in the Fallow and most other Deer, there are thirteen
dorsal and six lumbar vertebras.

The opisthoca3lian ball-and-socket joints of the cervical ver-
tebrae facilitate the habitual inflections of the neck in the grazing
and browzing actions in all Kuminants, while the long spines of
the anterior dorsals afford adequate surface of attachment to the
elastic and muscular structures sustaining the head — heavy in
most of them with horns or antlers.

B. Skull. — This presents great diversity of shape in the Artio-
dachda, ^\\i\\ some common

312

characters, already noted,
which distinguish it from
that of Perissodactyla.

In the Hippopotamus,
fig. 312, the occiput is sub-
vertical : from the upper
part of its crest the con-
tour of the skull runs
nearly straight to the fore
ends of the nasals, 1 5. The
orbits, small and with an
entire, or almost entire, rim
of bone, singularly project both upAvard and outward, the frontals,
11, rising toward them, and arching lengtliwise across their upper
half. The upper jaw, c, which is almost cylindrical in advance of
the molar series, suddenh^ expands to form the alveoli of the upper
tusks, the mandible similarly expanding for those of the lower
tusks, c ; in the upper jaw a second terminal expansion, divided by
a deep groove from the first, increases the space for the large tusk-
shaped incisors. The depth of the temporal fossai renders that part
of the cranium, 7, narroAver across than any part of the face : the
fossae meet above to form a parietal crest in old males. The facial
part of the lacrymal is extensive, but the small deep-seated orbital
part is perforated by the lacrymal foramen. The malar, 26, sends

VOL. IT. H H

Hippopotamus amphibius.

466 ANATOMY OF VERTEBRATES.

up a process to the postfrontal, which it rarely reaches : it ex-
tends backward to the glenoid cavity, and forms the under part of
the zygoma : the upper part is due to the squamosal, 27. The ex-
ternal nostril is terminal, vertical, and formed by the nasals and
premaxillaries : the maxillaries are perforated by a moderately
large antorbital foramen far in advance of that cavity : the lateral
series of molar alveoli slightly diverge anteriorly — a disposition
which Cuvier regarded as peculiar to the Hippopotamus among
Mammals. The bony palate is deeply notched anteriorly between
the premaxillaries : there are two pairs of ' foramina incisiva.' The
ascending ramus of the mandible, i, has a j)Osterior convexly-
curved outline descending to an antroverted angular process ;
the horizontal rami, divided by a deep notch from the angle, run
forward almost parallel with each other, and expand at the sym-
physis, along whose upper and anterior broad truncated border
the incisor sockets, four in existing, six in some extinct. Hippo-
potami, form a straight transverse line, between the tusks, c.

In a very young Hippopotamus may be observed the following
evidences of cranial structure. The basioccipital has partially
coalesced with the basisphenoid, but not with the exoccipitals ; it
forms no part of the occipital condyles, and developes no processes
from its under surface : its lateral synchondrosal surfaces are
divided into two facets, one for the part of the exoccipital behind
the precondyloid foramen, the other for the smaller part in front.
These parts of the exoccipital have not coalesced on the inner
side of that foramen, which is single : the exoccipital developes,
besides the condyloid process, the i:)aroccipital and a broad process
to join the mastoid. The superoccipital is a thick, rhomboid,
vertical plate. The alisphenoids have coalesced with the basi-
sphenoid : they are short, and are grooved behind by the boundary
which they contribute to the foramen common to the foramen
ovale and the basicranial foramen lacerum, and more deeply in
front by the part they contribute to the foramen common to the
foramen rotundum and foramen lacerum anterius : they develope
long pterygoid processes, which are imperforate, and articulate
along their inner sides with the entopterygoids. The presphenoid
has coalesced with the orbitosphenoids and with the rudimental
prefrontals, which are connate, compressed, and form the median
septum of the great anterior outlet of the cranial cavity. The
vomer is a long, slender, pointed bone, deeply grooved above.
The parietals articulate with the alisphenoids, orbitosphenoids,
squamosals, mastoids, frontals, superoccipital, and each other.
The under part of the frontal is divided into a cranial, orbital, and

SKELETON OF ARTIODACTYLA.

467

olfactory surface ; the orbital surface being the largest, and the
superorbital ridge broad and much produced. The petrosal, mastoid.

313

314

Skull of Young Pig (Sus).

tympanic and squamosal elements of the temporal have coalesced.
The meatus internus is a deep fossa divided into a cribriform
surface below and a canal above : the
tympanic swells into a large three-
sided conical protuberance below. The
palatines prolong the bony palate be-
yond the series of grinding teeth in
use.

The composition of the Mammalian
skull has been more fully exemplified in
the young of the genus Sus (p. 300,
fig. 189). In fig. 314, is given a back
view of the neural arch of the occipital
vertebra, showing the flattened cen-
trum (basioccipital), c 3, the neurapo-
physes (exoccipitals), c 2, with their
convex post-zygapophyses or ' con-
dyles,' and long descending diapophy-
ses (paroccipitals). The neural spine (superoccipital), c i, is a

n H 2

Occiput (Sus).

468

ANATOMY OF VERTEBRATES.

vertical, quadrate, expanded plate, which completes the upper
part of the neural canal (foramen magnum).

The superoccipital enters into the formation of the upper sur-
face of the skull, as at 3, fig. 313. The parietals present flat supra-
cranial, ib. 7, 7, temporal, and intra-cranial surfaces, fig. 315, 7.
The frontals present, also, a flat supracranial surface, fig. 313, ii,
an orbital, and an intra-cranial surface, fig. 315, ii. The postorbital
process is not joined by a malar one : the superorbital canals are
large, as in Ruminants. The nasals, 15, are long and pointed:
the premaxillaries, 22, unite and circumscribe with them the ex-
ternal nostril. There is a prenasal bone, <9, which strengthens
the uprooting snout in most of the hog-tribe. The maxillary, 21,

315

Section of Skull of Young Pig {Sus\

in the adult Boar, developes a large outwardly-curved alveolus
for the tusk ; strengthened above, in the Indian wild Boar, by a
longitudinal ridge : the antorbital perforation is of moderate size :
the maxillary unites posteriorly with the large facial plate of the
lacrymal, fig. 313, 73, and with the malar, 2f. This has no post-
orbital process. It is united with the zygomatic part of the squa-
mosal, 27, by a double notch. The small cranial plate of the
squamosal is shown at d, fig. 315. The articular surface for the
mandible is convex from before backward, concave transversely,
in which direction it is most extended. The alisphenoid is marked
/, in figs. 313 and 315. The floor and sides of the long nasal
canal are formed by the premaxillaries, fig. 315, 22, the maxillaries,
21, and the palatines, 20 : to the latter succeed the pterygoids,/:
the depth of the canal is gained by depressing the backwardly-

SKELETON OF ARTIODACTYLA.

469

extended bony palate below the level of the basis cranh, 1-9. The
petrotympanic bulla, id, is large, prominent, and subcompressed.
In the interior of the cranium the rhinencephalic compartment, h,
is large and well defined.

The skull of the Babyroussa {^Sus Babi/russa), as compared
with that of Sus Scrofa and Sus larvatus, shows a broader and
lower occiput ; the mastoids are larger ; the temporal fossae more
approximated on the upper part of the cranium ; the bony palate
is more produced beyond the last molars. The mastoids show a

316

317

Skull of Wart-hog (PhacochcBrics).

M<andible of Wart-hog.

pneumatic cellular structure, and become confluent with the tym-
panic and squamosal, not with the petrosal. This bony capsule of
the acoustic organ retains its primitive individuality, as such, and
may be detached from the surrounding bones forming the oto-
crane : neither paroccipital nor mastoid are dismemberments
thereof, as misinterpreters of developmental phenomena allege.
There is no ossified prenasal. In the maxillary the long sockets
of the canine tusks bend upward ; the naso-maxillary part of the
cranium being slightly compressed between them. A remarkable
peculiarity is also presented by the fossa? at the inner side of the
base of the pterygoids, which lead to sinuses communicating on
one or both sides with the sphenoidal sinus. The air-cells extend
from the nose to the occiput.

In the Wart-hog {Phacochairus ^liani, fig. 316), the fronto-
parietal region is broad and flat, except transversely, where it is
rendered concave, as in the Hippopotamus, by the orbits being
raised above its level : those cavities, e, are placed farther back
than in the other Suidce, and are partly defended by a post-orbital
process of the malar. The paroccipital processes are long and

470

ANATOMY OF VERTEBRATES.

slender. The mastoids are compressed and pointed^ and are much
less developed than in the Wild Boar, the Masked Boar, or the
Babyroussa. The pterygoid fossa? are simple ; not divided into
an external and internal compartment, as in the Babyroussa, but
they are more extended backward. The sockets of the canines, c,
have not the process from the upper part, as in the Sus larvatus.
The maxillo-premaxillary suture is early obliterated, except at
the apex of the premaxillaries which extend beyond the sockets of
the tusks. The nasals, 15, are of great length. The fore part of
the lower jaw, fig. 317, is expanded for the sockets of the tusks, c,
and truncate, as in Hippopotamus ; but the sockets of the incisors
are soon obliterated. In the interior of the skull a tentorial ridge
is developed.

In the Peccary a strong ridge extends from the lower border
of the malar. The pterygoids have not the fossae shown in the
Babyroussa and Wart-hog, and are less laterally expanded. The
paroccipitals rise more to the outside than in Sus. The articular
surface for the mandible is concave from before backward.

In the skull of a Camel (^Camelus bactrianus, fig. 318), the
occipital condyles are divided into two surfaces meeting at an

acute angle, and they
come in contact with each
other beneath the basi-
occipital, Avhich contri-
butes an equal share
with the exoccipitals to
their formation. The
paroccipitals are small,
and shorter than the
mastoids. The occi-
pital, II, and parietal, 9,
crests are sharp : the
zygomatic arches, in relation to the laniariform teeth, .<?, «, o, are
longer and overspan a wider temporal fossa, i o, than in true Rumi-
nants. The orbit has an entire bony rim. The premaxillaries, ] , do
not reach the nasals, 7, and the maxillaries, 2, contribute to form
the external bonynostriL In the Llama and Vicugna (^^^c/^e/^^«),
the premaxillaries exclude the maxillaries from the nostril. A
vacuity between the maxillary, lacrymal, frontal, and nasal re-
mams large in Llamas, but is reduced in old Camels to a small
size, between the frontal, 8, and maxillary, 2 ; or it may be obli-
terated, as is usual in the Vicugna. The antorbltal foramen, h,
opens above the last premolar. The orbital plate of the lacrymal

Skull, Camelus dactrianus.

SKELETON OF ARTIODACTYLA. 47 1

shows two perforations. The external pterygoid process is
formed by the alisphenoid, the internal one by the true ptery-
goid ; both are far behind the bony palate, which is divided
from the last molar alveolus by a notch. The cranial wall in
the Camel is unusually thick, with a close cancellous diploe,
save where the air-cells penetrate the frontal and presphenoid.
There is no bony tentorium. The lateral sinus bifurcates above
the petrosal into two w4de venous canals. The hinder one again
di\ddes, one branch terminating on the superoccipital surface,
above the mastoid, the other descending to terminate at the
ordinary ' foramen jugular e : ' the anterior canal descends to the
base of the zygoma, where it also divides, one division opening
on the inner and the other on the outer side of the post-glenoid
process. In the Llama the venous opening above the rpot of the
zygoma is large : and there is a smaller one at the fore part of
the root. The foramen rotundum is blended with the foramen
lacerum anterius. The rhinencephalic fossa is narrow but deep.
The osseous septum is coextensive with the nasal bones in old
Camels. The angle of the mandible, id, is singularly elevated,
and the contour of the ascending ramus makes a convex sweep
to the lower border of the horizontal one. The outlet of the
dental canal, r, is below the laniariform premolar, s. The fore
part of the symphysis expands horizontally for the incisor
alveoli.

In the true Ruminants the skull is characterised by the small
size and edentulous condition of the premaxillaries, the slender
zygomatic arches, the entire
bony rim of the orbit, the large ^^^

facial plate of the lacrymal, and
by the processes of the frontal
bone for the formation of horns
or antlers. These latter, how-
ever, are wanting in both sexes ^^
of the Musk-deer {Moschus,
Tragulus),?i^\n the Camel tribe.
The occipital condyles, fig. 319,

•, 1 'ill Skull, Moschus vioschiferus.

closely approximate below :

the paroccipital is longer than the mastoid. The temporal fosste,
in the formation of which the parietals, 9, take a large share, with
the squamosals, 10, are divided above by a parietal crest, and
resemble those of the Camel. There is a small vacuity between
the frontal, 8, lacrymal, 3, maxillary, 2, and nasal, 7, in Moschus
moschiferus, which does not exist in Tragulus. The malar, 4, is

472

ANATOMY OF VERTEBRATES.

320

marked by a ridge continued from the lower border of the orbit.
The petrotympanic forms, in the smaller Musk-deer ( Tragulus)
and Antelopes ( Ceplialoplius), a large ' bulla ossea : ' and the orbits
gain in proportional size as the bulk of the species decreases.
The lateral emarginations of the bony palate are usually deeper
than the median one, in true Ruminants, the reverse being the
case in the Llama and Vicugna. In Micr other ium the premaxil-
laries do not reach the nasals, nor yet quite in Hycumosclius.

In the skull of the Bovidce
I have usually seen that, al-
though the full size and mature
dentition have been acquired, the
suture between the exoccipitals,
fig. 320, n', u', and that between
these and the superoccipital, ib.
11, remain distinct. The occipi-
tal condyles, i, are wide apart, as
in Antelopes and Deer. The
paroccipital, i, and fig. 321, a'',
descends much below the mastoid, lo ; the exoccipitals complete the
foramen magnum, above : the basioccipital has a pair of tubercles.
In the Ox (^Bos faurus)the whole of the upper surface of the cranium

321

Skull of the Giiur, from behind.

Skull of the Ox (Bos taurus).

is formed by the frontals, fig. 321, c: the parietals, which, at
an earher period, encroach upon the back part of the upper sur-
face, are now pushed quite to the posterior or occipital aspect.
This deposition does not take place in the Bison, fig. 320, but the
frontals, at the interspace between the horns, are, with the con-
joined parietals, 9, developed into a ridge rising above that formed
by the superoccipital, ii. The petro-tympanic, fig, 320, lo, 321, e' ,
is prominent and rough. The squamosal, e, has a venous outlet
above the base of the zygoma. The malar forms the lower part

SKELETON OF ARTIODACTYLA.

473

of the orbit and extends largely upon the face, at k, to join the
maxillary, h. The corresponding plate of the lacrymal is still
more extensive and here joins the nasally, leaving a small fissure
between those bones and the frontal, c. This very extensive bone
has a large superorbital fissure. The nasals are cleft at their
fore end. The premaxillary, g, has but a small or loose junction
with the nasals. The maxillary, h, is extensive, the antorbital
foramen, h\ perforates it above the first premolar. In Bison
europceus the horns arise in advance of the ridge formed by the
superoccipital bone, the parietals advancing to the upper surface
of the skull and being interposed between the frontal and super-
occipital. The Bison differs from the Buffalo {Bubalus) in the
greater breadth and convexity of the frontal, and in the much
greater extent of the orbital processes of that bone, which, with the
coextensive processes of the lacrymal and malar, form a prominent
cylinder. The nasals are relatively shorter and broader than in the
Ox (Bos) ; but the chief distinction between the Bison and the Ox
is seen in the shorter premaxillaries, which do not rise to join the
nasals : here, therefore, six bones enter into the formation of the
external nasal aperture, instead of four, as in Bos and Bubalus.

The frontal sinuses extend into the horn-cores in all Bovines,
but not so in the majority of
Antelopes. In this rumi-
nant group, Aidth some ex-
ceptions, e. g. Aigoceros,
Lyroceros, Strepsiceros, Di-
cranoceros, the facial plate
of the lacrymal is impressed,
often deeply, by the antor-
bital cutaneous sac, com-
monly called ' lacrymal.' In
the Duykerbok ( Cephalo-
phus mergens), the parietals
are produced in an angular
form between the bases of the horn-cores, which spring as usual
from the frontals. In the Chickara ( Tetraceros) the frontal deve-
lopes two pairs of horn-cores : and this peculiarity was also mani-
fested by some gigantic Antelopes {Bramatheriiim and Swathe-
rium), now extinct, of the same continent (India) : in which, also,
the posterior horn-cores were ramified, as in the Prong-horn (Z)t-
cranoceros furcifer). The Sivathere was also remarkable for the
shortness of the facial part of the skull and the termination of the
nasals in a down-bent point, fig. 322. In the Duykerbok, Cha-

322

Frout view of the crauiuin of the Sivathcriur

474

ANATOMY OF VERTEBRATES.

523

mois, Goral, Saiga, Cliiru, and one or two others, the premaxillaries
do not join the nasals ; but this junction is seen in most Antelopes.
In all, as in the Sheep and its allies, both the superoccipital,
fig. 323, 11, and fig. 324, «, and the parietals,
ib. 9 and b, maintain their position at the
back part of the vertex : the frontals, ib. 8, 9,
and c, still fiarm the chief part and alone
develope the horn-cores ; the nasals, 7, are not
expanded posteriorly, as in CamelidcB. Both
frontals, c, and malars, k, fig. 324, extend far
in advance of the orbit, d, but are exceeded
in this extension by the lacrymals, z, which
articulate with the nasals, /*, for an equal
extent with the maxillary, h. In the wild
Oois Ammon there is a lacrymal pit, and this,
in Ovis Virjnei, deeply impresses the facial
plate of the bone. The premaxillaries in the
same wild Thibetan sheep join the nasals
suturally, but in the domestic Ovis Aries, the
premaxillaries, (/, barely touch the nasals.
In the Nahura Argali {Ovis Nahura), the premaxillaries do not
reach the nasals : nor is the lacrymal impressed with the pit. The
' incisive ' fissures in the palatal plates of the premaxillaries, figs.

324

Skull of Sheep.

Skull of Sheep, h(jrnless rar.

168 and 323, «, are long and narrow. The maxillo-palatal sutures,
fig. 168, d, turn obliquely outward and backward to the inner
Avail of the socket of the last molar, opposite the hinder half of

SKELETON OF ARTIODACTYLA. 475

which are three posterior palatal notches. The pterygoids form
no part of the bony palate.

The follomng differences may be noticed in comparing the
skull of the Goat ( Capra Hircus) with that of the Sheep ( Ovis
Aries). In the Sheep the postorbital process or plate is broader
and more bent outward, forming a deep depression between it
and the origin of the horn ; it also turns the plane of the orbit
more obliquely forward : in the Goat the aspect of this plane is
more directly outward. The occiput is higher in proportion to
its breadth in the Goat than in the Sheep. The petrosal is
relatively longer and deeper in the Goat than in the Sheep.
The nasals are relatively smaller in the Goat, where they are
shorter than the premaxillaries ; their upper surface is concave
lengthwise, except at the free points, where they are slightly
bent doAvn. In the Sheep the nasals are relatively larger, are
longer than the premaxillaries, and their whole upper surface is
convex lengthwise. There are also differences in the connections
of these bones ; in the Sheep the nasals join the lacrymals, rarely
the premaxillaries, whilst in the Goat they join the premaxillaries
but not the lacrymals, — a vacuity, which is not present or is
rudimental in the Sheep, separating them from the lacrymals.
The upper border of the maxillary bone is relatively shorter in
the Goat, and the anterior border is not notched to receive the
upper end of the premaxillary, as it is in the Sheep. The pre-
maxillary is narrower at its alveolar end in the Goat, and its
upper end rises so as to overlap the side of the nasal : in the
Sheep the premaxillary is relatively broader, and rarely rises to
touch the nasal. The lacrymal bone of the Goat is shorter in
proportion to its breadth, and is not impressed on its facial
surface by a lacrymal fossa ; it does not touch the nasal : in the
Sheep the lacrymal is longer in proportion to its breadth, and is
more regularly quadrate in form ; it joins the nasal, and thus
obliterates that vacuity which is present in the skull of the
Goat ; its facial plate is usually impressed by a concavity for the
cutaneous lacrymal pit. In comparing the upper contour of the
skull, from the occipital ridge to the free extremity of the nasal
bones, it forms, in the Goat, nearly a right angle, with the two
sides equal : in the Sheep it forms a more open angle, with the
anterior side twice as long as the posterior one.

In the skull of the Giraffe {Camelopardalis Giraffa, figs. 325,
326), the exoccipitals form a marked protuberance above the
foramen magnum and below a deep fossa for the implantation of
the ligamentum nuchas. The parietals are chiefly situated on

476

ANATOMY OF VERTEBRATES.

325

the upper surface of the skull ; the osseous horn-cores are
originally distinct^ v,ith their bases crossing the coronal suture,

and resting equally upon the parietals
and frontals : they, however, coalesce
therewith in old males, and the frontal
and parietal sinuses extend into the
lower fourth, the rest of the horn-core
being a solid and dense bone. The pro-
tuberance upon the frontal and contigu-
ous parts of the nasal bones is due to
an enlargement of those bones (as ob-
vious in the section, fig. 326), and not
to any distinct osseous part : its surface
is roughened by vascular impressions,
undermining the basal periphery and
simulating a suture. The lacrymal is
separated from the nasal by a large
vacuity intervening between those
bones, the frontal and the maxillary.
The premaxillaries, which are of un-
usual length, articulate with the nasals.
The petro-tympanic is a separate bone.
The symphysis of the lower jaw is
unusually long and slender. The arti-
cular surface of the prominent occipital
condyles is so extended vertically as
to admit of the head beino' raised into a line with the neck, and

Skull of female GirafiEe.

Section of Skull of male Giraffe.

SKELETON OF ARTIODACTYLA. 477

even slightly bent back beyond that line. The great freedom
given to the movements of the head relate, like the length of neck
and general altitude of the body, to the culling of lea^4 from the
trees browzed on by the Giraffe. The part of the skull to which
the elastic ligament is attached is raised considerably above the roof
of the cranial cavity by the extension back^vard of laro-e sinuses
or air-cells, as far as the occiput, fig. 326. The sinuses com-
mence above the middle of the nasal ca^dty, and increase in

Skull of narl)ary D.-or (Cerrns elajihiis)

depth and Avidth to beneath tlie base of the horns, where their
vertical extent equals that of the cerebral cavity itself. The
exterior table of the skull, thus widely separated from the vitreous
table, is supported by stout bony partitions, extended chiefly in
the transverse direction, and with an oblique and wavy course.

478

ANATOMY OF VERTEBEATES,

328

Two of the most remarkable of these bony walls are placed at the
front and back part of the base of the horns, interceptmg a large
sinus immediately over the middle of the cranial cavity, and
from a third and larger one behind. The pre-sphenoidal sinuses
are of a large size.^

The chief peculiarity in the skull of the Deer-tribe is the
annual development, from the frontals, of the solid deciduous
exostoses which serve as weapons (fig. 326, d, h) during a portion
of the year, in the males of all kinds and in both sexes of the

Rein-deer. Most species likewise
show vacuities between the frontal,
8, nasal, 7, maxillary, 2, and lacry-
mal, as in figs. 327 and 328. The
base of the zygoma is perforated
by a vein from the lateral sinus.

The chief peculiarity of the skull
of the Elk (^Alces) is seen in the
great length of the premaxillaries
and of the edentulous portion of
the maxillaries, and in the short-
ness and breadth of the nasal bones,
which do not join the premaxilla-
ries. The vomer is carinate be-
neath.

In the Eein-deer ( Tarandus) the
antlers spring from within an inch
of the superoccipital crest, and the
frontal bones are proportion ably
extended backward on each side of
the parietal, in which the sagittal
suture becomes obliterated : the
frontal suture is persistent, and is complex in its dentations at its
posterior half. The large lacrymal presents two canals upon its
orbital border and a deep oblong depression on its facial surface,
above which is the vacuity leading to the olfactory chamber.
The premaxillaries do not join the nasals. In the Fallow-deer
(Dama) the frontal bones do not extend so far back as in the
Rein-deer, and the antlers, in consequence, rise at a greater
distance from the occipital crest. The lacrymal bone has two per-
forations at its outer border, and its facial plate is nearly equally
divided into an upper convex and a lower concave surface. The
antorbital depressions show but a small perforation, if any.

' XOVII-, p. 235.

Skull, Cerviis Mantjak.

SKELETON OF AKTIODACTYLA

479

The skull of the Barking-deer ( Cervus Muntjak) is remarkable
for the great length of the persistent pedicles (fig. 328, c, c)
which support the antlers, and which are continued from two
strong ridges that traverse the outer side of the frontal bone from
its junction with the nasals. The lacrymal presents a deep and
well-marked fossa, anterior to which is the antorbital vacuity.
The sockets of the upper canines are largely developed in the
maxillaries.

In all Riuninants, and especially the horned kinds, the tem-
poral fossa; are small, the zygomatic arches weak, the coronoid
processes of the mandible fig. 319, g, narrow, the base of the
ascending ramus expanded; in short, the attachments of the
biting muscle are restricted, those of the chewing muscle ex-
panded. That for the masseter is shown by the ridge and
fossa continued forward from the zygoma below the orbit : that
for the ' pterygoidei ' by the

backwardly produced and 329

rounded angle of the lower
jaw. The exceptions to the
edentulous premaxillaries
have been noted. The arti-
cular surface for the mandi-
ble is broad, slightly convex,
with a posterior semicircular
channel bounded by a ridge.

The hyoid arch includes
long, compressed, hammer-
shaped * stylohyals,' fig. 329,
1, having at their promixal
end the articular, a, and muscular, h, jirocesses, the short ^ epi-
hyals,' 2, the ceratohyals, 3, the basihyal, a,, and thyrohyals, 5 ;
attached to posterior angular processes of the basihyal.

C. Bones of the Limbs. — Artiodactyles have the limbs ter-
minated by feet of 4 or 2 toes, in symmetrical pairs : but, as in
other Ungulates, almost restricted to locomotive functions. The
Hippopotamus and the Gazelle manifest in the even-toed series
analogous extremes in the proportions of the limbs, as do the
Rhinoceros and Horse in the Perissodactyles. The blade-bone
is long and narrow ; but the spine is more commonly produced
into an acromial angle in the Artiodactyles. In the Hi2:)po-
potamus, fig. 305, this angle is slightly produced : the coracoid
is recurved. The greater tuberosity of the humerus is divided
into two subequal processes, the inner one separated by a deep

Hyoid arch, Sliecp.

480 ANATOMY OF VEKTEBEATES.

and wide bicipital fossa from the lower inner tuberosity. The
ulna and radius have coalesced at their extremities and at
the middle of their shaft, the interosseous space being indicated
by a deep groove and two foramina. The trapezium does not
support any digit : of the other four, the two middle ones,
answering to the third and fourth, are most developed.

In the pelvis the ilia expand and bend outward from their
sacral attachments almost into the same plane with the broad and
flat sacrum : the lumbo-iliac angle is about 150°. The ischia,
fio*. 305, 63, are long and with the dorsal angles of the broad and
thick tuberosities produced toward the caudal vertebras, as
in other Artiodactyles, figs. 308 and 310. The ischio-pubic
symphysis is long and more backward than in the Rhinoceros ;
the obturator vacuities are large ; the acetabula look downward
and outward, their planes being about 50° from the perpendicular.
The femur has a straight subcyHndrical shaft. The canal for the
medullary artery commences at the upper and fore part of the
shaft. The fibula is distinct from the tibia, and extends from its
proximal end to the calcaneum. The internal cuneiforme is
present in the tarsus, but there is no rudiment of the innermost
toe : the proportions of the other four resemble those of the
fore-foot: the bones of the hind foot are noted at pp. 308, 309,
and figured in cut 193, ' Hippopotamus.'

In the Wild Boar ( Siis scrofa) the spine of the scapula is most
developed at its middle, where it is bent back : there is no
acromion. The coracoid is a low tubercle : the glenoid cavity is
nearly circular. The humerus has an intercondyloid vacuity, as
in the Peccari ; in which the inner division of the great tuberosity
rises above the head of the bone, higher than in Sus. The
radius and ulna are distinct in Sus, but invariably connected by
a rough longitudinally grooved surface. The olecranon is large
and compressed: the distal end of the ulna presents a small
trochlear surface for the carpus and a narrow strip for the radius.
In the Peccari the radius and ulna coalesce throughout nearly
their whole extent. The trapezium and pollex are not present :
the ' index ' and ' miminus ' digits are small ; the ' medius ' and
' annularis ' large, and chiefly serviceable in progression.

The pelvis is longer and narrower, relatively, in Suidce than in
the Hippopotamus : the hmibo-iliac angle is 145°, the ilio-pubic
angle 120°. The medullary artery of the femur enters the fore
part of its upper third and the canal slopes downward. The
tibia and fibila are distinct, and the latter fully developed in both
Sus and Dicotyles. In both, the symmetrical pair, which are

SKELETON OF ARTIODACTYLA. 481

most developed and chiefly serviceable in progression, answer to
the third and fourth digits of the pentadactyle foot : but in Sus
the homologues of the fifth and second are present ; whilst in
Dicotyles the fifth as well as the first toe are wanting in the hind
foot : in this the second toe is small ; the third and fourth are very
large^ and form a symmetrical pair, showing that the Artiodactyle
structure essentially prevails, although the toes, by the non-
development of the fifth, are, exceptionally, reduced to three in
number in the hind foot of the Peccari.

In the CamelidcB, fig. 306, the scapula though longer than
in the non-ruminant Artiodactyles, . is broader, relatively, than
in horned Ruminants : its spine is produced into a short pointed
acromion : the coracoid is grooved below, or sub-bifid. The
humerus is weaker than in the Ox, stronger than in the Deer,
longer relatively to the rest of the limb than in the Giraffe : the
great tuberosity does not rise above the head : the ridge upon
the outer condyle is less marked. The ulna has coalesced with
the radius, and appears to be represented only by its proximal
and distal extremities. The carpal bones have the same number
and arrangement as in ordinary ruminants, but the pisiforme is
proportionally larger. There is no trace of the digits answering
to the first, second, and fifth in the pentadactyle foot : the meta-
carpals of those answering to the third and fourth have coalesced
to near their distal extremities, which diverge more than in the
ruminants, giving a greater spread to the foot, which is supported
by the three phalanges of each of those digits. The last phalanx
deviates most from the ordinary form, by its smaller j^roportional
size, rougher surface, and less regular shape : it supports, in fact,
a modified claw rather than a hoof. The ilium, in proportion to
the ischium, is longer than in the Hippopotamus. In the femur,
the chief deviation from the ordinary Ruminant type is seen in the
position of the orifice of the canal for the medullary artery, which
enters the back part of the middle of the shaft, and inclines
obliquely upward. The fibula is represented by the irregularly-
shaped ossicle interlocked between the outer side of the distal end
of the tibia and the calcaneum. The scaphoid is not confluent
with the cuboid as in the normal Ruminant: the rest of the hind-
foot deviates in the same manner and degree from that type, as
does the fore-foot. In both metacarpals and metatarsals, notwith-
standing the intimate blending of the two bones apparent exter-
nally, their medullary cavities arc distinct : the canal of the
medullary artery enters the back part of each, above the middle,
and ascends obliquely to its respective cavity.

VOL. II. II

48-2

ANATOMY OF VERTEBRATES.

•In true Ruminants the spine of the scapula is not produced,
as in CamelidcR, but terminates in an acute {Bos) or a right
angle {Cervus): the Musks and Chevrotains agree Avith the
horned families in this character, but the coracoid is a better
defined process in the latter : in all, the scapula is a long slen-
der triangle, with two equal or subequal sides, the infraspinal
division chiefly expanding to the base, which is truncate in Bos,
fig. 309, Antilope and Cervus, fig. 311 ; but rounded oif at the

hinder angle in Camelopardalis,
fig. 310 ; in this Ruminant the
cervix scajDulte is unusually long.
The humerus, fig. 330, A, is
short, but strong, with slightly
expanded ends : the outer tu-
berosity, at the proximal one,
rises above the head of the bone,
and bounds, with the inner tu-
berosity, a deep bicipital groove:
the deltoid crest, i, is less pro-
minent than in the Horse. The
distal articular end presents
three prominences answering to
the hollows of the head of the
radius, the internal one being
the broadest and lowest. The
supracondylar ridges are but
little produced: the olecranal
fossa is deep, and perforated in
Musk-deer, Chevrotains, and
Microtheres, as in the Hog-
tribe. In the Gnu (^Antilope
Gmi) the humerus is as long
as the metacarpus : in the Ox,
fig. 309, it is longer ; in the
Giraffe, fig. 310, and Gazelle,
fig. 330, A, it is shorter. The
radius, fig. 330, A, 2, is the chief
bone of the antibrachium : its proximal trochlear surface offers
three eminences and as many depressions to the humerus, restrict-
ing the movements of the fore-leg to one plane. The shaft is
slightly bent forward : the distal end is moulded to the irregularities
of the carpus, and is most impressed by the scaphoid, especially
> XLiv. p. 605, uos. 3672 and 3673.

Bones of the fore and hind limbs of the Indian
Antelope, xcvi-.'

SKELETON OF ARTIODACTYLA .

483

in the Clievrotains. The chief part of the ulua, ib. 3, is its com-
pressed olecranon : the slender shaft may be continued to the
carpus, as in MoschidcB, most Antelopes, Sheep, the Elk, the
Rein-deer, fig. 311; the Fallow-deer, and the common Ox. In
the Chevrotains it longest maintains its individuality : in the
Musk-deer and Elk the distal extremity coalesces with that of
the radius ; in the Rein-deer the shaft, also ; in the Ox this is so
confluent as to be hardly traceable from the olecranon to the
styloid extremity. In the Giraffe the ulnar shaft is interrupted
at its lower third, but the distal end reappears, as the * styloid
process,' but is connate with the distal epiphysis of the radius.
The radius and ulna are so interlocked that the fore-foot is kept
' prone,' or with the surface answering to ^ palm '
turned back and downward : there is a narrow cleft
at the upper part of their line of union, and some-
times a second lower down. In the carpus the usual
four bones of the proximal row remain distinct : in
fig. 330, A, c, 4 is ' scaphoides,' 5 lunare, 6 cuneiforme,
7 pisiforme : the distal row consists of the ' trape-
zoides,' a, in some, and in all of the ' magnum,' 8, sup-
porting the moiety of the metacarpal answering to the
' third ' one of the pentadactyle foot, and the unci-
forme, 9, supporting the moiety answering to the
' fourth ' metacarpal. These metacarpals early coa-
lesce into a single '^ cannon-bone : ' but a longitudinal
section, as in fig. 331,^ shows the medullary canal of
each distinct, in Megaceros, as in most Ruminants ;
in a few, e.g. the Yak {Bos grunniens) the septum
becomes partially absorbed.^ Longitudinal grooves
at the fore (fig. 330, A, lo) and back parts of the
cannon-bone, with antero-posterior perforations, are
the outward signs of the original separation : they are
most strongly marked in the Chevrotains ( Truf/uliis) ; and the
severance persists in the Water-Musk {Hycemoschus) as in the
extinct Dichodons, Anoplotheres, and Microtheres. Each moiety
of the cannon-bone has its distinct distal trochlea, fig. 331, «, h,
which is traversed by a median ridge, c, from before backward. To
each trochlea articulates a proximal phalanx, fig. 330, A, ii, sup-
porting a middle, 12, and this an unequal phalanx, 13, of a triedral
conical shape, modified to be sheathed in a hoof; the unsymmetry
of each hoof being such as to form a symmetrical pair. They re-
semble the single hoof of the horse cleft in twain : whence the

Section of a
metacarpal of

Megaccros.

XCVI'.

xcir. p. 260, no. 1162.

lb. vol. ii. p. 628, no. 3852.

484 ANATOMY OF VERTEBEATES.

Ruminants are said to ' divide the hoof.' In the Giraffe, fig. 310,
Antelopes, fig. 330, and Deer, fig. 311, the proximal phalanx is longer
than the next : in the Ox and Musk-deer the difference is small :
in the Chevrotains, they are more nearly of the same length. In
the Giraffe, as in the Camel-tribe, there is no trace of other toes :
in most true Ruminants stunted portions of them are suspended to
the back part of the distal end of the cannon-bone, whence dangle
the pair of ' spurious hoofs,' fig. 330, h. In the Bison the bones
of these consist in each of the middle and distal phalanges : and
there is a styliform representative of the proximal end of their
respective metacarpals articulated, in the fore-foot, one to the
connate trapezoid, the other to the unciform and cuneiform bones. ^
In Deer the spurious hoofs are supported by the three phalanges
proper to the second and fifth digits, and by a styliform distal
end of their respective metacarpals with the point upward : these
hooflets are large enough in the Rein-deer, fig.311, to usefully
increase the base of the ' snow-shoe,' formed by its broad hairy
and horny foot, with the advantage of their collapse as the foot is
withdrawn. The Moschus moschiferus has a similar bony structure
of the second and fifth digits; while the still smaller Chevro-
tains, like the embryos of larger Ruminants, show so much more
of the generalised foot-structure as is exemplified by the ex-
tension of the slender metacarpals of those ' spurious hoofs '
from them to the carpus.

The OS innominatum is elongate with the iliac portion con-
cave lengtliAvise, convex across, externally, mth the expanded
anterior end divided by a ridge into the portions h and c, fig.
332, articulating mth the sacrum, a, and rising as high as, or
above, the sacral spine : the portion, c, is thickest and broadest
in the heavier Ruminants : the ilium joins the spine at an angle
of about 145°. The ischium extends back from the acetabu-
lum, two-thirds or three-fourths the length of the ilium, with
the tuberosity, e, bending upward : the tuberosity is strength-
ened in Deer, Antelopes, and Oxen by a ridge, g. In the
male Chevrotains the ischia join the elongated sacrum by ossi-
fications of the sacrosciatic ligaments, but in the females these
retain their normal extensile texture. The tendons and apo-
neuroses of the dorso-spinal muscles become more or less ossified
by age, and a thin roof of bone may thus overarch the pelvis, as
e.g. in Tragulus jav aniens, Tr. Kanehil^ ho.. The pubics,/*, are
slender : they converge to the symphysis at an iliopubic angle of
about 135°. The iliopectineal spine is well marked in some

> CXL. p. 31, fig. 5. - LXXII-. p. 581, no. 3498.

SKELETON OF ARTIODACTYLA.

485

Pelvis of Ox (Bos).

The Harderian groove of
and breaks through the border

Deer. In the Ox, fig. 332, the symphysis pubis is placed ob-
liquely, so as to cause the anterior pelvic opening to be longer
than the posterior one : in the Deer, fig. 333, the symphysis runs
more parallel vdth the sacrum. The acetabula are carried by the
length of the ilia opposite the last sacral vertebra, at the apex of
the wide arch of the os innominatum : the plane of the aperture is
inclined about 40° from the perpendicular. In the Cow, near the
period of parturition, the
ischial tuberosities, by the
relaxation of the lio^aments
and sinking of the sacrum,
become more protuberant
than at other times. In
the Giraffe the posterior
concavity between the
ilium and ischium, as in
the Deer, fig. 333, is
scarcely interrupted by
the prominence of the con-
joined bones above the acetabulum
the acetabulum is wide and deep,
of that cup.

The hind-limb, fig. 330, B, exceeds the fore-limb, ib. A, in
length in all Ruminants :
least so in the CamelidcB
and Giraffe, most so in
the bounding Deer and
Antelopes.

The femur of Rumi-
nants, ib. B, 1, as of other
Artiodactyles, has no third
trochanter ; and the me-
dullary artery enters the
fore part of the shaft, us-
ually at the upper third,
and ofoes downward and
backward to the medullary cavity : the antero-posterior expanse
of the distal end is great, especially in the Giraffe : and the
inner border of the rotular channel is more produced than in the
Hog-tribe, without developing an irregular prominence as in the
Perissodactyles. The Camelidce offer the exception in the position
of the foramen and canal of the mcduHary artery, and in the sub-
equal development of the borders of the rotular channel. The

333

Pelvis of Stag (Cervus).

486 ANATOINIY OF VEKTEBRATES.

MoschidcB agree in botli characters with the horned Kuminants ;
but the rotular channel is unusually long and narrow in the
Chevrotains. The head of the femur turns but little out of the
longitudinal axis of the shaft, of which the great trochanter is
the highest part: the articular surface extends from the head
toward the base of the trochanter, in a subtrochlear form : the
ligamentous pit is in the middle of the hemispheric part of the
head. The back part of the proximal end is flattened, especially
in CamelidcB : the trochanterian fossa is deep, that above the
outer condyle is shallow ; its outer border is continued from the
' linea asj^era,' and is rough : there is a rough eminence at a
similar distance above the inner condyle.

The tibia, ib. B, 2, like its homotype the radius, is the chief
bone of its segment ; it is also the longest bone of the hind limb.
The proximal end is most expanded : the two articular surfaces
rise at the middle of the head, and that of the inner surface
higher in BovidcB than in CervidcB : there is a tuberosity at their
posterior interspace : the broader base of the anterior spine fills
up the anterior one, but is separated from the outer condylar
surface by a deep groove : the spine projects from the fore part of
the upper fourth of the shaft, inclining outward : it subsides to-
ward the inner side of the shaft, the back part of which is flat-
tened and marked by longitudinal intermuscular ridges. The
distal articular surface is subquadrate, with a notch and articular
fossa on its outer side for the ossicle representing the distal or
'malleolar' extremity of the fibula,^ fig. 193, 67, fOx); this coa-
lesces with the tibia in Chevrotains. In the Rein-deer, as in
Moschus moschiferus and M. aquaticus, the proximal end of the
fibula projects downward as a short styliforai process from the
outer part of the head of the fibula : in Tragulus Napu it extends
more than half-way down the tibia,^ and the shaft exists as
a sclerous tissue in all Ruminants. The distal articular surface
of the tibia presents a pair of deep antero-posterior channels
divided by a transversely convex tract of equal extent : they
are less oblique than in the Horse-tribe ; the inner malleolus
descends the lowest.

The tarsus, fig. 193, ' Ox,' consists of astragalus, a, calcaneum,
cl, scapho-cuboid, s-h, and ectocuneiform, ec : the confluence of
the naviculare or scaphoid with the cuboid does not take place in
CamelidcE : it does so in Moschidce, and the fusion extends to the
ectocuneiform in Tragulus.^ A mesocuneiform is present in

' CLi. torn. IV. p. 18. - XLiv. p. 580, no. 3495.

^ Ib, and LXXI1-. p. 59.

SKELETON OF CARNIVORA.

487

334

Bones of hiud-foot of
Clievrotaiu (Tragulus).

XCVI-.

Chevrotains for the support of the slender metatarsal of the toe
answering to the second of pentadactyle feet. The corresponding
metatarsal, fig. 334, c, of the fifth or outermost toe, ib. b, articu-
lates with the cuboid, 9. In Moschus aquaticus, the second and
fifth metatarsals coexist with an almost complete
severance of the third and fourth, which, in a
state of confluence, represent the metatarsal seg-
ment in other Ruminants. The true Musk-deer
and most horned Ruminants have the distal ends
of the second and fifth metatarsals ossified, and
supporting the small digits terminated by the
'spurious hoofs,' fig. 193, ii, v: in the Giraffe
and Camel tribe these are wholly absent, as are
their homotypes in the fore-foot. The digital
phalanges of the hind-foot, fig. 330, B, ii, 12, 13,
h, closely correspond with those of the fore-foot.

In all Uno'ulates the encasino- of the end of
the digit in a hoof is accompanied by a junction
of the radius and ulna such as to jDrevent recipro-
cal rotation of those bones on each other, and by
a joint with the humerus restricting the movements of the anti-
brachium to flexion and extension in one plane. The expansions
of the humerus for attachment of pronator and supinator muscles
are uncalled for ; while the proximal processes gi^^ng leverage to
the permitted motors of the limb may project in a degree which
would impede its more varied and freer motions. The length of
the blade bone and of muscles arising from it is increased at the
expense of their breadth ; the acromion is stunted, and clavicles
are absent. The concomitant modifications of the skull and jaws
in relation to masticating vegetable food are best exemplified in
the Ruminant Ungulates, and have been specified at p. 471.

§ 189. Skeleton of Carnivora. — In the Unguiculate Gyren-
cephala the whole frame is modified, in degrees corresponding
with the perfection of the claws as prehensile weapons, for
mastery and destruction of other animals. The mandible, fig.
341, 32, is short and strong, it is articulated by a close-fitting
joint to the skull almost restricting its movements to one plane,
as in opening and closing the mouth, for biting, and for dividing,
not pounding the food. The coronoid process giving insertion to
the temporal muscles is broad and high; the fossae from which
they rise are large and deep, and augmented by peripheral ridges
of bone. The zygomatic arch spans across the muscle, bending
outward to give space for its passage, and arching upward for the

488 ANATOMY OF VERTEBRATES.

more extensive and favourable attacliment of accessory fascicles.
Each toe has its distinct metacarpal or metatarsal. The digits,
especially in the fore-limb, enjoy freedom of motion and power of
reciprocal approximation and divarication ; the terminal phalanx is
compressed and deep, with a plate of bone reflected forward from
the basal periphery, beyond which the apex of the phalanx pro-
jects like a peg from a sheath : the claw is fixed upon the peg, its
base being firmly wedged into the interspace betAveen the peg and
the sheath. In the Felines, which are the most perfect carni-
vorous Unguiculates, the claw phalanx is retractile. The fore-
paw, so armed, is attached to the radius and ulna, which are entire,
distinct, and strong bones : these articulate with the humerus by
a joint, which, although well knit, allows both freedom of motion
in bending and extending, and also a reciprocal play of the two
bones, the radius rotating on the ulna, and carrying Avith it, by
the greater expanse of its lower end, the paw, which can thus be
turned ' prone ' or * supine,' whereby its efficacy as an instrument
for seizing and tearing is enhanced. The humerus has strong
ridges from the outer and inner sides above the condyles for ex-
tending the origins of the muscles of the paw ; and, to defend the
main nerve and artery of the fore-leg from compression during
the action of these muscles, a bridge of bone spans across them in
the feline, and some other Carnivora. The upper end of the
humerus has a long and strong deltoid ridge ; but the tuberosities
do not project beyond the round head of the bone so as to impede
its movements in the socket. The scapula is of great breadth,
with well-developed spine, acromion, and coracoid. A small
clavicular bone is interposed in most Carnivora between a muscle
of the head and one of the arm, giving additional force and de-
termination of action to them. Such are the chief modifications
of the framework of the unguiculate as contrasted with the
ungulate Gyrencephala.

A. Vertebral Columri. — This part of the skeleton of Carni-
vora is modified in relation to the medium of life, degree of car-
nivority, and modes of motion of the species. In no Carnivore
do cervical vertebra3 articulate by ball-and-socket joints ; and in
all, the seventh has the transverse processes imperforate, consist-
ing only of diapophyses. The Harp Seal {Phoca groenlandica,
fig. 332) has 15 dorsal, d, 5 lumbar, L, 4 sacral, s, and 8
caudal. Ten pairs of ribs directly join the sternum, which
consists of eight bones : the manubrium, 52^, is much produced,
for extending the fore-and-aft origins of the pectoral muscles. The
neural arches of the middle dorsal vertebras are slender, leaviiio-

SKELETON OF CARNIVORA.

489

wide intervals of the neural canal. The bones of the neck are
modified to allow of great extent and freedom of inflection. The
perforated transverse processes of the third to the sixth cervicals
inclusive are remarkable for the distinctness of their di- and pleur-
apophysial parts. Metapophyses arc developed on the last five
dorsal vertebra : the strong hypapophysial ridge of the lumbar
vertebrae divides into two tuberous processes. These processes
indicate the great developement of the anterior vertebral muscles,
e.g. the ^ longi colli ' and ^ psoag,' and relate to the important share

335

larp Seal (Plioca grcvnhmdica) . Lxxiil'

which the vertebra and muscles of the trunk take in the loco-
motion of the Seal-tribe, especially when on dry land, where they
shuffle along on their belly.

In the Sterrink or Saw-toothed ^Qni {StenorhyncMis serridens),.
with 15 dorsal, 5 lumbar, 3 sacral, and 11 caudal, the metapo-
physes commence as tubercles outside the prezygapophysis on the
second dorsal, are distinct on the third dorsal, pass on the fore
part of the diapophysis in the fourth, and continue rudimental as
far as the tenth dorsal, on which they are well and distinctly
developed ; they again pass upon the outside of the prezygapo-
physis in the eleventh and twelfth dorsals, and so continue
throughout the lumbar, sacral, and anterior caudal vertebra?.
The anapophyses are mere rudimental projections from the back
part of the diapophysis. The transverse processes of the axis are
more developed than in the Phoca grcenlandlca ; they show^ as
distinctly as in the other cervicals, but on a smaller scale, the
pleur- and di-apophysial parts of the process. The cervical and

490

ANATOMY OF VERTEBRATES.

anterior dorsal vertebras have a hypapophysial riclge, which, in
the latter, is produced into a tuberosity : the lumbar vertebrae
are characterized by a pair of hypapophyses from near the hinder
end of the centrum. The eared Seals have the same vertebral
formula : the anterior sacral vertebrae are narrow.

The Walrus ( Trichecus Rosmarus), like the Otter, has 14
dorsal and 6 lumbar vertebras. Nine pairs of ribs directly join the
sternum, which consists of eight bones. The anterior sacrals
have o^reater relative breadth than in Phoca or Otaria : as in
true Seals the tail is short, with 9 or 10 vertebrae.

In the Bear-tribe, as in the Seal-tribe, the number of true
vertebrae is 27, as a rule, and 14 of these usually bear movable

336

Polar Bear {Ursus maritimus). Lxxiii-

ribs; but I have seen 15 ^ dorsal ' vertebrae in Ursus maritimus,
fig. 333, and in U. lahiatus, the latter having 5 lumbar instead of
6, which is the common number. Nine pairs of ribs articulate
directly mth the sternum, which consists of eight bones, mth a
xiphoid appendage. The manubrium is truncate anteriorly. The
number of anchylosed sacral vertebrae may vary from 5 to 7, that
of the caudal vertebrae rarely exceeds 10. The met- and an-
apophyses are distinct on the twelfth dorsal, diverge and increase
on the succeeding dorsals, the metapophyses continuing throughout
the lumbar series ; the anapophyses, after underlapping the pro-
zygapophyses of the first and second lumbar, rapidly subside.
The neural spines are better developed than in the Seal-tribe,

SKELETON OF CARNIVORA. 491

but do not indicate a centre of motion, save in the smaller and
more active subursines. In the Racoon they converge to the
twelfth dorsal : the caudal vertebrae, 16 in this plantigrade and 18
in the Badger, increase to 31 in number in the Kinkajou, where
the tail is prehensile, whence the name Cercoleptes caudivol-
vulus. The Benturong (Artictis) has a similar caudal develope-
meut, with haemal arches on the ten anterior vertebrae. In the
last five cervical vertebras of the Ratel the neural arches are
longer than the centrums and overlap each other in an imbricated
manner, giving great strength to the articulations of this part of
the vertebral column. The number of dorsal vertebrae is 15, as
in My dans and Meles, wdth 5 lumbar ones.

In the more digitigrade Mustelines, the Sable (^Mustela ziheU
Una) has 14 dorsal, 6 lumbar, 3 sacral, and 18 caudal. The eleventh
dorsal vertebra is that toward which the spines of the other
trunk-vertebra3 converge. The anapophyses begin to be de-
A^eloped upon the ninth dorsal, and are continued to the penulti-
mate lumbar vertebra. Ten pairs of ribs directly join the
sternum, which consists of nine bones, with a xiphoid cartilage.
In the Ermine (^Patorius ermineus), with a similar vertebral
formula, the spines of the tenth and eleventh dorsal vertebrie
converge towards each other and almost meet, indicating the
centre of motion of the trunk. Ten pairs of ribs directly join the
sternum. The neck is strengthened by the overlapping of the
costal parts of the transverse processes of the third to the sixth
cervical vertebrae. Some of the anterior caudal vertebrae have
hasmapophyses. The Otter {Lutra vulgaris) has 25 or 26 caudal
vertebra. Ten pairs of ribs directly join the sternum, which
consists of nine bones and an ensiform cartilage. The spine of
the eleventh dorsal vertebra is vertical, and those before and be-
hind it converge towards it. The metapophyses begin to be
developed on the twelfth dorsal vertebra, and are continued
throughout the lumbar series; they are low and obtuse. The
anapophyses commence at the eleventh vertebra, and are con-
tinued to the penultimate lumbar. The spines of the three sacral
vertebrae have coalesced to form a vertical crista. Hasmapophyses
are developed beneath several of the anterior caudal vertebra? ;
they are articulated, and some of them become anchylosed to
short hypapophyses or exogenous processes from the under and
fore part of the centrum, and then are continued in several of the
succeeding vertebra, wliich have not the haemal arch complete.
The neural arch is incomplete beyond the eighth caudal vertebra.
The entire tail is longer and much stronger than in the terrestrial

492 ANATOMY OF VERTEBRATES.

Mustelidm : it is the chief organ in regulating the course of the
Otter through the water.

In the Civet ( Viverra civettci) the transverse processes of the
atlas have a more extensive origin than in the Otter, and are per-
forated both horizontally and vertically by the vertebral artery
before it pierces the neural arch. In the axis the median inferior
ridge, and the two lateral ones continued upon the transverse
processes, are longer, deeper, and sharper than in the Otter.
Certain Yiverrines, e.g. the Palm-cats {ParadoxuriLs) have the
tail organised for prehension, including upwards of 30 joints, with
h^mal arches beneath the interspaces of the first eight or ten.
The prozygapophysis of one lumbar vertebra is received into the
interspace between the postzygapophysis and the anapophysis of
the antecedent vertebra : this interlocking which commenced in
the plantigrade and musteline Carnivora, is continued in the pre-
sent (viverrine) and subsequent families.

Among the CajiidcE the Wolf {Ccmis lupus), has 13 dorsal,
7 lumbar, 3 sacral, and 15 caudal. Eight pairs of ribs articulate
directly with the sternum, which consists of eight bones. The
eleventh dorsal vertebra is that towards which the spines of the
other trunk-vertebrae converge. Metapophyses begin to be de-
veloped on the eighth dorsal, and are continued to the fourth
lumbar vertebra.

The Dog agrees with the Wolf in vertebral characters.

In a Fox (^Canis rufus) the vertebral formula is the same,
save that the tail-joints are more slender and numerous, being 22.
A few of the anterior caudal vertebrae have hsemapophyses : the
supporting processes or ' hypapophyses ' are developed from a
greater number. The sacrum is remarkable for its sudden dimi-
nution of size, as compared with the lumbar vertebras, and only
the first sacral vertebra articulates directly with the iliac bones.

The Hyenas have 15 dorsal and 5 lumbar vertebrae : the striped
kind {H. vulgaris) has 3 sacral and 23 caudal : the spotted kind
(^H. cTocutci) has 4 sacral and but 16 or 18 caudal. Eight pairs
of ribs articulate directly mth the sternum, which consists of
eight bones. The transverse processes of the atlas are perforated
longitudinally and vertically by the vertebral artery before this
perforates the neural arch. The strong spine of the axis is bifid
posteriorly. The convergence of the dorso-lumbar spines towards
that of the thirteenth dorsal is feeble compared with other Car-
nivora. Anapophyses begin to be developed on the thirteenth
dorsal and subside on the penultimate lumbar vertebrae.

The Lion (Fells leo, fig. 337) has 13 dorsal, 7 lumbar, 3 sacral.

SKELETON OF CARNIVORA.

493

and 23-25 caudal vertebrae. The spine of the axis has great
height, length, and posterior breadth, arching forward and back-
ward, overlapping the third, of which the spine is obsolete ; that
of the fourth is short and vertical, indicating a centre of the motions
of the neck. The anterior dorsal spines are lofty and strong, for
the origin of muscles implanted in the ridged and pitted back
part of the skull, whereby the head can be raised together with
the prey which the jaws have seized : a Lion thus draws along
the carcase of a Buffalo, and can with ease raise and bear off the
body of a man. The eleventh dorsal is that toward which the

337

Lion i^Felis Leo). Lxxiii-.

spines of the other trunk-vertebra3 converge: the anapophyses
begin to project backward from this vertebra, and are continued
to the penultimate lumbar. Eight pairs of ribs directly join the
sternum, which consists of eight bones. The lumbar diapophyses
are long and antroverted. The tail is the chief seat of variety
in the vertebral column of the feline group. The Lynx (F.
Lynx) e.g. has the number of caudal vertebra? reduced to 15.
In a tailless .variety of domestic cat a stunted mass of 4 or 5
coalesced caudals has become hereditary.

The carnivorous unguiculate do not, like the herbivorous ungu-
late Gyrencephala, show^ two series by numerical characters of
trunk-vertebrjjc ; the constancy of twenty dorso-lumbars is re-
markable and significant : the exceptions are not only rare, but

494

ANATOMY OF VERTEBEATES.

abnormal. Where the trunk is lithe and subject to varied and
agile turns and bends, the number of pairs of free elongate pleur-
apophyses is small, and that of the vertebrae wanting them great;
thus the springing Cats, the swift-footed Dogs and Foxes, the
climbing Benturong, have 13 dorsal and 7 lumbar: the Viverrines
and Mustelines commonly show 14 dorsal and 6 lumbar; the
stifFer-trunked Hyaenas, Bears, and Seals have 15 dorsals and
5 lumbar : and mostly, where an exceptional excess occurs in any
of these groups in one series of vertebra3, it is balanced by as
exceptional a deficiency in the other series.

B. Skull. — In the Harp Seal (^Phoca groenlandicd) the basi-
occipital is a thin plate, and shows a vacuity in front of the
foramen magnum : it early coalesces with the basisphenoid : the
paroccipital is small, subretroverted : the mastoid large, swollen,
not prominent. The frontal, fig. 338, ii, gives its larger proportion
to the orbital and olfactory chambers. In the latter the confluent
prefrontals and vomer form an extensive bony septum between
the meatuses which are blocked up anteriorly by the complex
turblnals. Both the tentorium and posterior part of the falx are
ossified. The shallow ' sella ' has overhanging posterior clinoid
processes. The petrosal is perforated by the entocarotid and
impressed by a deep transverse cerebellar fossa. The tympanic
forms a ' bulla.' The meatal portion of the tympanic is slightly
bent and directs the external auditory aperture obliquely forward
and upward. The squamosal has a small cranial plate, g, and a

large thick zygomatic pro-
cess, 27, with rises at its
junction with the malar, 26,
to partially define the orbit
posteriorly.

The seals, like other car-
nivora, have the orbit, e,
incomplete behind, and con-
tinuous with a large tem-
poral fossa ; the nasals, 15,
are short, and the nostril looks more or less upward, in refer-
ence to their common sojourn in water and the necessity of
rising to the surface to breathe. The condyle is the hindmost
part of the mandible.

In the Grey Seal {Halichoerus griseus) the skull is remarkable
for the straightness of its upper contour and the sudden bending
down of the equally straight line formed by the deej:) and narrow
premaxillaries. There is a deep depression in the superoccipital.

838

Skull of a Seal {Plioca).

SKELETON OF CAENIVORA. 495

overarched by a thickly-developed occipital ridge ; the squamosal
and malar rise abruptly at their junction at the middle of the
zygoma. The acoustic bulla receives the meatus auditorius by
an expanded and oblique opening. The olfactory fossa3 contain,
as in all Seals, large and complex turbinal bones. The bony
palate is terminated behind by a semicircular notch.

In the Monk Seal (^Pelagius monachus) the upper contour of
the skull presents a sigmoid curve. The temporal ridges meet,
and form a low sagittal crest over the posterior half of the
frontals and parietals. The upper jaw is much less deep than in
the Haliclioerus, the canines are relatively larger and the nasal
bones are much shorter. The entocarotid canal perforates the
back part of the petrosal as in the Phoca grcenlandica : the ecto-
carotid does not pierce the pterygoid process.

In the Sterrinks {Stenorhi/jichus) the skull is longer, more
' canine ' in the proportions of jaws to cranium, than in other
Seals. The malar is long and slender, defining the orbit below :
a lacrymal process of the maxillary projects from the anterior
rim. The basis cranii is long and narrow in Stenorliyncus lept-
onyx. In the saw-toothed Sterrink {Stenorhynchus serridens)
the facial part tapers more gradually than in the Stenorhynchus
leptonyx. The paroccipitals are small, but distinct. The pe-
trosals are perforated posteriorly for the entocarotids ; the
pterygoid processes are imperforate. The temporal ridges meet
upon the sagittal suture, but do not develope a crista. The malar
bones are slender, strongly curved, bifurcate posteriorly, the
upper prong rising to form, mth the zygomatic process of the
squamosal, the postorbital boundary. There is no corresponding
process from the frontal. The antorbital process of the maxillary
is small, but distinct. The premaxillaries are narrow and slender,
but do not reach the nasals. The posterior border of the bony
palate is terminated by a deep semi-elliptic notch. A single
superoccipital venous canal opens, in Sten. lej^tonyx, within the
border of the foramen magnum. The basioccipital shows two
depressions. The sella turcica is very shallow, and is defined
only by a posterior clinoid ridge, between which and the platform
for the optic chiasma there is a long tract. The petrosals termi-
nate by obtuse subdepressed apices. The foramina lacera anteriora
are of unusual size, and appear to include the foramina rotunda :
there is no ridge indicating the division between the anterior and
middle lobes of the cerebrum. The rhinencephalic fosste are small,
but deep and well defined, and completely divided by a broad and
thick crista galli.

496 ANATOMY OF VERTEBRATES.

In the Ursine Seal {Arctocepltahis australis) the border of
the superoccipital, forming the upper part of the foramen mag-
num, shows the orifices of two venous sinuses. The posterior
border of the bony palate has an angular notch. The pterygoid
processes are pierced for the ectocarotids. The frontal developes
a superorbital plate. The mastoid projects free of the tympanic.
The olfactory chambers extend backward exterior to the rhinen-
cephalic fossa.

In the Hooded Seal ( Cystophora cristatci), the thin basioccipital
shows a small vacuity. The superoccipital inclines from below
upward and forAvard. The temporal cristte have not met above
the parietals. The premaxillaries do not reach the nasals : they
form with the maxillaries an antorbital prominence. In the great
Proboscis-Seal, or Sea-Ele^^hant (Cystophora prohoscidea), the
occipital condyles meet upon the basioccipital : the paroccipitals
are less prominent than in the Cystophora cristata. Traces of the
suture between the basisphenoid and the basioccipital and between
the basisphenoid and presphenoid long remain. The entocarotid
canals at the back part of the petrosals are very conspicuous :
there are no ectocarotid canals. The sagittal crista is feebly in-
dicated, but the occipital crest is conspicuous for its great height
and thickness ; the lower border of the superoccipital j)resents
two vertical venous perforations, which are likemse present in the
Cystophora cristata. The tentorium is less ossified than in the
Otaria leonina. The walls of the cranium formed by the parietals
are thick with a coarse diploe : a very small proportion of the
squamosals enters into the formation of those walls : the mastoid
has a dense structure where it coalesces Avitli the base of the zygo-
matic process. Two vertical venous sinuses terminate above
the foramen magnum : the basioccipital is also perforated by a
similar venous sinus near its middle part. The petrosal is ex-
cavated by a deep but narrow cerebellar fossa ; a long groove or
notch upon its upper surface leads to the meatus auditorius
internus : the petrosal is, as it were, bent upwards upon this
groove. The tympanic bulla supports the under part of the
petrosal like a capsule. The tympanic cavity is divided into two
chambers, one above the termination of the meatus externus, the
other beneath and internal to it. The carotid canal perforates
the tympanic internal to this part of the chamber. The Eus-
tachian groove commences from the angle between the supra-
and infra-meatal divisions, and grows deeper and wider until
it forms the canal at the fore i^art of the tympanic bone. The
rhinencephalic fossa is di\^ded by a strong and sharp crista

SKELETON OF CARNIVORA. 497

gain. The frontal bones form an unusually small proportion of
the cranial cavity : they are extensively overlapped posteriorly
by the parietals. Besides its superior size, the skull of Cysto-
phora proboscidea differs from that of the Ci/stophora cristata in
the form and proportions of the palatine bones, the posterior
borders of which present three notches ; in the relatively shorter
extent of the nasal processes of the premaxillaries ; in the greater
prominence of the antorbital processes of the maxillaries ; and the
absence of the depression beneath the antorbital foramen. In
the skull of a young Proboscis- Seal I have seen traces of a suture
partially dividing the orbital from the rostral part of the maxillary,
extending from the side of the nasal aj^ertiux into the antorbital
foramen : this incompletely separated part might be compared mth
a large lacrymal, but there is no trace of a distinct bone or of any
lacrymal perforation.

In the ' Sea-Lion ' (^Otaria jiibata) the superoccipital is broader
and more nearly vertical than in the preceding species of Seal : the
basioccipital is carinate below ; the paroccipitals form an obtuse
angle, but are less prominent than the large mastoids. The
petrosals and tympanies are not expanded into a bulla ossea, but
send down a subcompressed smooth tuberosity : the entocarotid
pierces the petrosal. The pterygoids are pierced by the ecto-
carotids. The bony palate is very long, and remarkably concave,
from the bending down of its sides : its posterior border is trans-
versely truncate. The sagittal and occipital cristoe are singularly
elevated. Each frontal sends out an obtuse process near its
junction wdth the parietal, into the middle of the extensive tem-
poral fossa, and each developes large, horizontal, triangular, post-
orbital processes. In old males, the parietal also sends out a
ridge, and the great temporal muscle seems thus to have been
divided into three masses : there is a ridge from the inner side of
the parietal, dividing the middle from the anterior lobe of the
cerebrum, parallel with the external ridge projecting into the
temporal fossa. The maxillaries develope antorbital processes.
The nasals are short and broad, and articulate with the pre-
maxillaries as well as the maxillaries.

The posterior part of the falx and the whole of the tentorium
are ossified. The superoccipital sinus, commencing by a common
aperture at the hinder extremity of tlie longitudinal sinus, diverges
on each side into the substance of the exoccipitals, and terminates
in a deep and wide fossa on the inner side of the condyle, from
which fossa one canal leads backward to open external to the
condyle, and another downward and inward to terminate in the

VOL. II. K K

498 ANATOMY OF YEETEBEATES.

foramen jugularc. The bony tentorium terminates anterior to
the petrosal, wliich has an obtuse expanded inner apex, and shows
no petrosal pit. There is no Gasserian fossa. A ridge divides
the foramen ovale from the foramen rotundum. The sella turcica
is broad and shallow : it is defined by posterior clinoid processes :
there are no anterior ones. The rhinencephalic fossa is narrow,
but of unusual longitudinal extent ; the optic nerves traverse a
common canal of nearly an inch in extent before it divides. The
ascending plates from the palatine processes of the maxillary form
a deep groove for the reception of the vomer. The superior
turbinals occupy that part of the olfactory fossa wdiich overarches
the rhinencephalic chamber: this is divided by a broad crista
galli. A large oblong vacuity at the outer and posterior side
of the nasal passages between the frontal, presphenoid, pala-
tine and maxillary bones, is closed by membrane in the recent
animal. There is a smaller vacuity in the corresponding part of
the skulls of some other species of Seals.

In all Seals, the convex mandibular condyle is transversely ex-
tended, terminal, the border of the jaw extending from below the
condyle forward, and rarely developing an angle : this is best
marked in Phoca groenlandica ; in Otaria it seems to project
just below the condyle.

The hyoid arch consists of stylo- epi- and cerato-hyals, and of a
basi-hyal in form of a transverse bar, with a pair of thyro-hyals :
the stylo- hyals are attached by ligament to the outer side of the
petrosals.

In the Walrus {Tricliecus rosmarus, iig. 339), the basioccipital
is subcarinate below. The superoccipital, 3, inclines a little up-
ward and forward, is di^dded by a median crista, and is bounded
above by a broad rugged tract. The venous fossa on the inner
side of the condyles is di\dded by a bony bar. There is a wide
sphenopalatine vacuity. The paroccipitals are broad, but not
very prominent : the hinder surface of the skull is much ex-
tended laterally by the great development of the mastoids, 8.
The alisphenoid is excluded from the parietal, 7, by the junction
of a small part of the frontal, ii, with the squamosal, 27. There
is no trace of a lacrymal bone, but a small elliptical canal per-
forates the base of the antorbital process of the frontal slightly
upwards. The zygomatic process of the squamosal is remarkably
thick. The malar sends up a lofty postorbital process, but there
is none on the frontal : the maxillary, 21, developes a large but
low sub-l)ilid antorbital process : it is perforated by a large ant-
orbital foramen, and excavated by a large and deep socket for the

SKELETON OF CARNIVORA.

499

canine tusk. The premaxillaries, 22, are minute. There is a
large oval vacuity in the lateral wall of tlie posterior nares. The
skull is singularly expanded, short, obtuse, and, as it were, trun-
cated anteriorly ; and, being constricted between the orbits, the
upper surface presents an hour-glass form. The parietes of the
cranium are thick and dense, witli a diploc, gradually degene-
rating into a coarse cellular texture, in the enormous mastoids.
The tentorium is bony, the sella turcica large and shallow, with
anterior and posterior clinoid processes, and the crista galli is
jn-ominent. The petrosal terminates below in three obtuse pro-
cesses, but there is no bulla ossea. The pterygoid process is per-
forated by the ectocarotid. The bony roof of tlie palate is very
concave towards the mouth, and terminates behind by a broad
biangular notch. The tympanic cavities are smooth, and almost
hemispheric : the antorbital canal is large : the nasal fossai con-
tract as they pass forward to the vertical external nostril. The
osseous part of the septum narium is formed by the canaliculate
vomer and the coalesced plates of the prefrontals, dividing the
posterior halves of the olfactory chamber. The lateral sinuses
are completely surrounded by bone. A vein perforates the back
part of the parietals and terminates in the longitudinal sinus.
The bony tentorium terminates above the base of the petrosal ; a
thick, smooth ridge enters the lower half of the fissure between
the anterior and posterior cerebral lobes. A similar but shorter
ridge from the inner side of the frontal more completely defines
the rhinencephalic chamber : an elliptic foramen leads from the
lower and outer corner of this fossa into the back part of the
orbit between the orbitosphenoids and
frontals. The mandible, S2, articulates
by a thicker condyle than in true
Seals : it is terminal : the feeble angle
slopes forward from it : the coronoid
is oblique and rounded.

In the Bear-tribe, as in the Seals,
the tentorium is ossified : the inter-
parietal unites with and forms a trian-
gular process of the superocci})ital :
the alisphenoid articulates with the
parietal : the ectocarotid pierces the
l^terygoid process. There is no ptery-
goid fossa.

In the European Black and Brown Bears ( U?\sits arcfos) the

339

of Walrus {Trirhccus nKimayiis).

frontal region of the skull is

•aised and convex.
K K 2

In the A

merican

500

ANATOMY OF VERTEBRATES.

Grisly Bear ( Ursus ferox), the facial part of the skull is re-
latively longer than in the Ursus arctos, and the nasal processes
of the premaxillaries are much longer, are more slender, and ar-
ticulate directly with the anterior processes of the frontals. In
the Brown Bear, the maxillaries articulate with the small part of
the nasals and separate the premaxillaries from the frontals. In
the Polar Bear ( Ursus rnaritimus, fig. 340), the lower extremities
of the occipital condyles are united hy a ridge, which, however,
is less prominent than in the Ursus ferox. The precondyloid
foramen is exposed. The superoccipital, 3, terminates above in a
strong ridge overhanging the condyles. Both paroccipitals, 4,
and mastoids, 8, are well developed, but the latter are the larger

340

processes. The temporal ridges, commencing at the postorbital
processes, converge at a right angle and meet at about two
inches behind the orbits, and form a long and prominent sagittal
crest, the upper border of Avhich is straight ; the frontal region
is low and flattened. Within the cranium the cerebellar fossa is
formed by the bony tentorium above, and by a shorter osseous
ridge below, separating the cerebellum from the upper part of the
medulla oblono-ata. The commencement of the entocarotid canal
may be seen distinct from the fore part of the fossa jugularis ; the
petrosal fossa is divided into two cells for the reception of the
cerebellar appendages. The mastoid is occupied by a close
diploe, which receives no air-cells from the tymjoanic cavity.
The meatus auditorius terminates obliquely within the tympanic
cavity. A triangular constriction separates the prosencephalic
from the rhinencephalic chamber. The malar, 26, alone forms the
postorbital rising : the squamosal, 27, does not reach so far ;
it developes a low subquadrate cranial plate, r/. The mandible

SKELETON OF CARNIVORA. 501

developes a long angular process, so, which rises toward the
condyle.

In the Racoon {Procyon), and Coati (Nasua), the entocarotid
pierces the inner border of the tympanic bulla : there is no ecto-
carotid canal. The mastoid is thicker than the paroccipital.
The bony tentorium terminates upon the petrosal above the
shallow depression of the cerebellar appendage. The upper cra-
nial parietes are moderately thick and with a diploe. In the
Coati the olfactory chamber, with the superior turbinals, extends
above the whole rhinencephalic fossa, and forms in part the
frontal elevation of the cranial contour. In the Benturong
(Ailurus), the ectocarotid perforates the pterygoid, as in Bears.

The skull of the Badger {Meles taxus) is chiefly remark-
able for the closeness with which the transverse condyles of the
lower jaw are grasped by the borders of the articular grooves at
the base of the zygomatic processes, so that the mandible cannot
be disarticulated without some violence. The lateral sinus termi-
nates behind the glenoid cavity, as in other UrsidcB, and the sub-
petrosal sinus terminates at the entocondyloid foramen. There is
no ectocarotid canal.

In Ratelus the transversely extended base of the paroccipital
is applied to the back part of the bulla. In the Glutton ( Gulo)
the cranial cavity is less expanded posteriorly, and less constricted
anteriorly, than in the Ratel. There is a smooth articular sur-
face in the basioccipital, but it is less distinctly continuous with
the occipital condyles than in the Ratel. The zygomatic arches
are larger, stronger, and more curved : the palate is relatively
broader : both the paroccipital and the mastoid processes are
feebly developed.

In the Stoats and Weasels {Piitorius), the meatus auditorius is
an oblique perforation in the lateral and inferior parietes of the
skull, directed from within outAvard and forward, and not pro-
duced upon an auditory process. The bulla tympanica is very
extensive. The bony tentorium, which projects rather from the
upper than the back wall of the cranium, terminates upon the
back part of the petrosal, above the deep circular pit for the cere-
bellar appendage. The rhinencephalic fossa is less distinctly
defined than in Plantigrades from the rest of the cranial cavity ;
the olfactory chamber extends backward both above and beneath
that fossa, causing the cranium to appear dilated at that part ; the
air must be filtered, as it were, through the complex turbinals
before passing into the canal of the posterior nares.

In the Otter (^Lutra), a narrow articular surface upon the basi-

502 ANATOMY OF VEKTEBEATES.

occipital connects together the two condyles : the temporal ridges,
commencing from the postorbital processes, meet at an open
angle, and extend backward, as a low and straight sag-ittal crest,
as far as the broader occipital crest. The zygomatic arches are
strong and boldly curved ; they bifurcate anteriorly to surround
the large antorbital foramen. The cranial walls are thin, >vithout
diploe : the impressions of the convolutions are strongly marked :
there are no frontal sinuses. The cranial cavity is remarkable
for its great posterior expanse and its extreme contraction be-
tween the prosencephalic and rhinencephalic divisions. The bony
tentorium terminates upon the petrosal above the small pit for the
cerebellar appendage. The sella turcica is shallow. The tract
for the optic chiasma is long and narrow. The crista galli
extends backward through nearly the whole of the rhinencephalic
fossa. The longritudinal sinus communicates behind with two
small venous foramina in the superoccipital bone. The olfactory
chamber commences directly in front of the rhinencephalic fossa,
the cribriform plate, or back part of the olfactory capsule with
the coalesced prefrontals, separating them. The entry to the
nasal passages is almost blocked up by the large and complex
turbinals.

In the Civet ( Viverra Civetta), the occipital condyles are sepa-
rate from each other at their lower extremities. The paroccipitals
and mastoids have coalesced and form a triangular plate of bone,
applied to the posterior part of the tympanic bulla, like the cap-
sule of the acorn to the seed. This bulla is more circumscribed
and mucli more developed than in the Otter : the bony meatus
auditorius is much shorter, and opens directly into the tympanic
cavity. The nasal processes of the upper maxillaries extend
backward much further than the nasal bones, tlie reverse being
the case in the Otter. The pterygoid processes are perforated
by the ectocarotids. The cranial cavity is longer and narrow^er,
and the postorbital constriction much less, than in the Mustelidos.
The bony tentorium is continued forward beyond the petrosal,
and terminates above the foramen rotundum. The petrosal is
impressed by a deep pit for the cerebellar appendage. A ver-
tical inverted tract of the cranial walls divides the prosence-
phalic from the rhinencephalic compartments. The olfactory
fossa is continued backward above as w^ell as beneath the
rhinencephalic compartment. The crista galli is rudimental.
When the squamosal is removed, the extensive surface of the
parietal and alisphenoid is exposed to which it v> as applied, and the
small vacuitv in the suture between those bones which was left

SKELETON OF CARNIVOliA. 503

for it to cover in completing the cranial walls. In some Viver-
rines {Ichneumon, Mangusta), the orbital processes of the frontal
and malar meet and circumscribe the rim of the orbit.

In the Common Fox ( Canis Vulpes), the paroccipital is tri-
angular, and applied to the back part of the acoustic bulla, but is
smaller and thicker than in the Viverrines^ and stands off more
from the bulla. The alisphenoid articulates with the parietal.
The interparietal, which has anchylosed with the superoccipital,
penetrates the posterior interspace of the parietals. The nasal
processes of the maxillaries are truncate, and terminate on the
same transverse line as the nasals. The maxillaries directly
articulate mth the middle part of the nasals below the bony ten-
torium, which appears to be developed from the superoccipital.

The skull of the Wolf ( Canis Lujjus), as of the Jackal ( Canis
aureus'), diifers from that of the Fox in the median depression
and transverse convexity of the frontal region produced by the
bending down of the postorbital processes ; in the greater pos-
terior extension of the nasals, as compared with the maxillaries ;
and in the encroachment of the lacrymal on the face. The frontal
bones of the Wolf preserve a more uniform breadth than in the
Jackal, being less expanded posteriorly where they join the
parietals. The short and wide meatus auditorius terminates
obliquely in the tympanic bulla. The base of the zygomatic
process is pierced by a vertical venous canal.

Like the Jackal and Wolf, the Dingo {Canis Australis) differs
from the Fox in the greater transverse convexity of the frontals,
especially opposite the postorbital processes, and in the greater
longitudinal depression between the frontals ; in the greater
posterior extension of the nasals, as compared with the maxil-
laries ; and in the encroachment of the lacrymal bone upon
the face. In a comparison of the skull with that of the
Marsupial Carnivore ( Thylacinus Harrisii) from the same part
of the world, which equals the Dingo in size, the most
striking difference is the comparative superiority of the cere-
bral cavity in the wild Dog, and of the olfactory cavity in the
Thylacine, the proportions being reversed in the two speci-
mens. The superoccipital overhangs the foramen magnum in
the Dog, but is on the same vertical plane with it in the
Thylacine. The paroccipitals are more compressed in the Thy-
lacine, and their base is not applied to the acoustic bulla, Avluch is
of much smaller size and formed exclusively by the alisphenoid,

* The extinct p;enus Galecynus of the CEuingcu niioceiie indicates the transition
from Viverra to Canis, civ. p. 55.

504 ANATOMY OF VERTEBRATES.

not by the petrosal and tympanic, as in the Dog. The tympanic
has preserved its distinctness in the Thylacine, but has coalesced
with other elements of the temporal bone in the Dog. A wide
and deep groove divides the bulla from the basisphenoid in the
Thylacine, but the sides of the basisphenoid in the Dingo are
swollen and abut against the large tympanic bullas. The arti-
cular cavities for the lower jaw are much nearer the occiput in
the Thylacine than in the Dingo, and the malar bones enter
partially into their formation. There are two large vacuities in
the back part of the bony palate in the Thylacine, but this part
is entire in the Dingo. The antorbital foramina are larger in the
Thylacine, and much nearer the orbits than in the Dingo ; they
are also formed partly by the malar, and are not wholly per-
forated in the maxillary bone, as in the Dingo : the lacrymal
bone is much larger in the Dingo, and encroaches much more
upon the face : the nasal bones are broader posteriorly in the
Dingo, and extend further back, as compared with the maxillaries.
The petrosals are much larger in the Dingo, and send bony plates
into the tentorium, which plates are not present in the Thylacine.
The chief bony part of the tentorium projects from near the
middle of the occiput, and does not reach the petrosal in the
wild Dog. The sella turcica is defined by the posterior clinoid
processes in the Dingo, but not in the Thylacine. The foramina
optica and lacera anteriora are blended together in the Thylacine,
but are distinct in the Dog. Although the olfactory chamber is
so much larger in the Thylacine, the rhinencephalic fossa is
smaller than in the Dog. The lower jaw, besides its greater
length and slenderness in the Thylacine, differs by the bending in
of the angle, which is the characteristic of the Marsupials. In
most of these distinctions the Thylacine manifests its nearer
affinity to the oviparous type of skeleton.

The chief distinction between the wild and domestic Doofs is
the greater proportional size of the cranium to the face in the
latter, and this increases as the size of the variety diminishes.

The affinity of the Hytena to the Viverridce is shown, in the
skull, by the broad, triangular, rough plate formed by the paroc-
cipital and mastoid, and applied to the back part of the acoustic
bulla: but the pterygoid processes are not pierced by the ecto-
carotids. The strength of the muscles which work the jaw is
shown by the extent of the temporal fossae, the height of the
sagittal crest, the thickness and the expanse of the zygomatic
arches, the height of the coronoid processes, and the depth of the
strongly-defined fossa3 into which the great muscles of mastication

SKELETON OF CAKNIVORA.

505

are inserted. The antorbital foramina are small semilunar slits.
The nasal processes of the maxillaries extend further back than
the nasals.

The specific character of the Lion (Fells Leo), as compared
with the Tiger (Felis Tigris), is shown by the obtusely-pointed
termination of the nasal process of the maxillary, and its ex-
tension backward to the same transverse line as that which the
hinder ends of the nasals reach. In the Tiger the nasal bones are
relatively longer and extend further back than the nasal processes
of the maxillaries, which are, as it were, truncated. The concavity
of the frontal platform between the deflected postorbital processes
is narrower than in the Lion ; the suborbital foramina are smaller.

The carnivorous character of the skull, fig. 341, as exemplified
by the sagittal, 7, and occipital, s, crests, by the strength and
expanse of the zygomatic arches, 27, by the depth and shortness
of the jaws, by the height and breadth of the coronoid processes,
and by the extent of the muscular fossoe of the lower jaw, reaches
its maximum in the skull of the old males of both these laro^e
Felines. The triangular occipital region is remarkable for the
depth and boldness of the sculpturing of its outer surface.
The conjoined par occipital, 4, and mastoid, 8, form a broad and

34]

Skull of Lion.

thick capsular support for the back part of the acoustic bulla.
The pterygoid processes are imperforate. A well-marked groove
extends on each side of the bony palate from the posterior to the
anterior palatine foramina. The premaxillaries, 22, are compa-
ratively short, and one half of the lateral border of the nasals, 15,
directly articulates with the maxillaries, 21.

The bony tentorium extends above the petrosal to the ridge
over-hanging the Gasserian fossa : the petrosal is sliort, its apex is
neither notched nor perforated : the cerebellar pit is very shallow.

506 ANATOMY OF VERTEBRATES.

The sella turcica is deep, and well defined 'by both the anterior
and posterior clinoids. The rhinencephalic fossa is relatively
larger than in most Carnivora, and is defined by a well-marked
angle of the inner table of the skull from the prosencephalic
compartment : the olfactory chamber extends backward both
above and below the rhinencephalic fossa : the upper part of the
chamber is divided into two sinuses on each side : the superior
turbinals extend into the anterior sinus, and below into the
presphenoidal sinus. The inner surface of the squamosal is tripar-
tite ; the upper facet rough for the broad squamous suture, the
anterior and inferior one smooth and deep for the natiform pro-
tuberance of the hemisphere, and the posterior facet smooth and
undulated where it is applied to the petrosal capsule, its juncture
with which is effected by the medium of the mastoid, which is
anchylosed to both.

The strengthening of the cranium in Carnivora, in reference to
the forcible action of the muscles attached thereto, is gained by
the growth of bone in the form of ridges both from the outer and
the inner surfaces of the cavity. This is so completely filled by
the brain, its blood-vessels and membranes, that were any con-
cussion conceivable of cerebrum against cerebellum through an
active bound or leap, an interposed membrane so elastic as to yield
and recover would best meet the contingency : to suppose that a
hard plate between the two soft masses had any such relation to
the spring of the stealthy feline implies both dull physiological
reasoning and limited knowledge of the comparative osteology of
the Carnivora : the commonly ascribed final cause of the bony
tentorium of the Cat is refuted by the presence of that part in the
plantigrade Bears that do not move by bounds, and in the pin-
nigrade Seals that can only shuffle along the ground, and are
pillowed by the waves during their swiftest and most habitual
movements.

The hyoid arch of Felines consists of stylo-cerato- and basi-
hyals, with the appended thyro-hyals. The stylo-hyals, as a rule,
connect the arch to the base of the skull : but in the Lion a long
ligament intervenes between the stylo- and cerato-hyals, allowing
more freedom of motion to the base of the tongue and larynx, in
relation to the characteristic vibratory roar of the king of beasts.*

C. Bones of the Limhs. — The general characters of these in
the Carnivora have been defined, and the principal modifications
determining the pinni- planti-, and digiti-grade modes of loco-
motion are illustrated in figs. 172-175, pp. 288, 289.

The pinnigrades are pentadactyle, and without trace of clavicle.

' ccxxxvi , ol. vii. p. 38.

SKELETON OE. CARNIVOIIA. 507

The scapula is broad and curved backward, the anterior and
basal borders are continued in Phoca by a bold convex line
to the angle terminating the posterior costa, which is as strongly-
concave, fig. 335. In Otaria the breadth is increased by the
production of the fore part of the sciipula, causing a dispropor-
tionate extent of the prespinal surface, on which is a low acces-
sory ridge, anterior to the true ' spine,' not posterior to it as in
Megatherium. The spine is farther from the posterior costa in
Trichecus, In all PhocidcE it terminates in a short acromion.
The humerus is shorter than the scapula in Phoca, longer in
Otalgia ; it is remarkable for the great development of the inner
tuberosity and of the deltoid ridge, which is deeply excavated on
its outer side. The inner condyle is perforated in Phoca, not in
Otaria, Monachus, and Trichecus. The middle of the distal
end is excavated by the articular trochlea : an olecranal fossa is
feebly or not at all marked. The antibrachial bones are com-
pressed, and firmly united, the interosseous space being widest in
Otaria : the olecranon is large and hatchet-shaped. The fore-
part of the lower half of the radius is produced. The scaphoid
and lunar bones are connate : the fifth metacarpal articulates with
the cuneiform as well as with the unciform: the magnum is the
least of the carpals. Alt/iough the pollex or the first digit exceeds
the third, fourth, and fifth in length, it presents its characteristic
inferior number of phalanges, by wdiich the radial border of the
fin is rendered more resisting. The pelvic arch is remarkable
for the stunted development of the ilia, and the great length of
the ischia and pubes : the symphysis is short, and divaricable in
parturition, as in the Guinea-pig (p. 380). The femur is equally
peculiar for its shortness and breadth : its head has no pit for a
' round ligament.' The tibia and fibula present the more usual
proportions, but are anchylosed at their proximal ends. The
astragalus, fig. 173, a, has its proximal articular surfiice in two
facets, one for the tibia, h, the other for the fibula, m : a part of
the bone projects ^ proximad ' of these surfaces ; and it is produced
* distad ' to articulate with the naviculare, s : the co-extended
calcaneum, cl, is applied to the tibial side of the astragalus. In
Otaria the calcaneal process is longer. The entocuneiform, /,
mesocuneiform, ectocuneiform, c, and cuboides, b, have the usual
connections. The bones of the foot are much developed, and arc
modified to form the basis of a large and powerful fin : in Phoca,
the middle toe is the shortest, and the rest increase in length to
the margins of the foot : in Otaria and Tricliecus the toes are
subequal in length. The long-bones of Seals have no medullary
cavity.

508 ANATOMY OF VERTEBRATES.

In the plantigrade Carnivora the clavicle is wholly wanting.
In the Bear-tribe, the scapula, fig. 336, si, is remarkable for its
almost quadrate form, and for the strong development of the
ridge between the infraspinatus and teres major, constituting
almost a second spine. The inner condyle of the humerus is not
perforated, save in Ursus ornatus. The antibrachials little, if at
all, exceed the humerus in length ; their shafts are of equal
strength. The scaphoid and lunar bones of the carpus have
coalesced: the pisiforme is elongated and expanded at its free
end like a calcaneum. The fore-foot is 5-dactyle, the pollex
being a little shorter than the other toes, Avhich are subequal in
length ; the basal sheath of the ungual phalanges is thickened
and tuberculate below : the claw-bearing part is long, subcom-
pressed, and slightly arched. The ilia are shorter, thicker, and
broader than in Digitigrades : the ischia are short and expanded,
forming with the strong pubics a long symphysis. The acetabula
are large and deep ; the ilio-pubic angle is 125°. The femur is
remarkable, in Bears, for its great length, and superficial resem-
blance to that in man ; but its shaft is relatively thicker,
straight er, and rather flattened from before backward ; it differs
also in the more shallow pit for the round ligament, in the great
trochanter being longer though less prominent above, in the less
projection of the small trochanter, in the minor expansion of the
distal condyles, and in the smaller size of the rotular channel.
The medullary cavity is confined to the middle third of the bone.
The medullary artery, which enters at the posterior and inner
side, below the middle of the shaft, takes an oblique course up-
ward. The tibia is one-fourth shorter than the femur : the fibula
is much smaller and compressed : but the medullary cavity ex-
tends through nearly the whole of the shaft of this slender bone.
In fig. 174, cl marks the calcaneum, s the naviculare, e the ecto-
cuneiform, h the cuboides ; the astragalus is almost as broad as
long, mthout a calcaneal process. The hallux is rather shorter
than the other toes, which are of subequal length, and form the
basis of a broad flat foot.

In the scapula of the Kacoon {Procyon), the pre- and post-
spinal fossae are of equal extent. The inner condyle of the
humerus is perforated as in all Subursines. In Nasua and Arc-
tictis, a supplementary carpal ossicle is wedged between the scaplio-
lunar and the metacarpal of the pollex, external to the trapezium :
the tarsus shows a corresponding ossicle wedged between the
naviculare and entocuneiform. In the Kacoon, the fibula is
characterised by three processes behind its distal end : the malle-

SKELETON OF CAENIYOEA. 509

olar process is very short, but plays upon a well-marked articular
surface of the astragalus. In a Kiukajou ( Cercoleptes), I have
seen the condyle notched in the right and perforated in the left
humerus. In the Badger {Meles taxus), the scapula presents a
subquadrate form, crossed diagonally by the spine, and with one
angle produced to form the glenoid cavity : the coracoid is repre-
sented by a low tubercle : there is no inferior ridge or spine. In
a Katel (Ratelus mellivorus), mth a similar shaped scapula, the
coracoid is sub-bifid, and the acromial tubercle is slightly pro-
duced. I have seen both humeri perforated between the condyles,
only the right one above the inner condyle. There is no medul-
lary ca\dty in the tibia. The humerus of Myclmis shows both
the intercondylar and entocondylar holes. In the Grlutton
( Gulo), the scapula is of a trapezoidal form, equally and obliquely
bisected by the spine, Avhich developes a bifid acromion : there is
a distinct coracoid tubercle. The inner condyle of the humerus
is perforated. The deltoid ridge terminates on the middle of the
shaft. Both pollex and hallux are relatively shorter to the other
toes, in most Subursines, than in the true Bears. Besides the
patella, the fabell^ are commonly present at the knee-joint.

In MustelidcE the acromion is more distinctly bifurcate than in
SuhursidcB : the posteriorly produced plate is broad in the Pole-
cat (^Putorius), in which the glenoid surface is continued upon the
coracoid tubercle. In that of the Otter may be noticed the
greater expanse of the prespinal portion and the well-marked
division of the acromion, the broader and posterior part bending
down, and the narrow and anterior one extending forward : the
coracoid tubercle is rudimentary. The humerus is remarkable
for the compression of the shaft, which is strongly bent forwards,
and for the continuation of a ridge from the deltoid as far as the
distal condyles. The inner one is perforated. The ulna is much
longer, and is stronger than the radius. The supplementary
ossicle answering to that marked i in fig. 361, is 2:)resent in the
carpus of both Liitra and Putorius. The diminution of the
pollex proceeds : that of the hallux in a less degree : the third
and fourth dio^its are the lono-est in both fore and hind feet.

In the ViverridcB the scapula is longer, more quadrate, and
more equally bisected by the spine than in Mustelidce, : the acro-
mion is bifid, but the divisions are less distinct. There are de-
tached clavicular styles. The innermost digit is relatively shorter
tlian the rest in both fore and hind feet, taking no share in the
support of the body. In Mangusta tetradactyla the pollex is
absent. In the Civet, and Cynogale, the humerus is pierced

510 ANATOMY OF VEKTEBKATES.

between the condyles, but not, or rarely, above tlie inner condyle.
In the Genet, the humerus shows the entocondylar, but not the
intercondylar hole. In the femur a ridge extends from the great
trochanter more than half-way down the shaft of the bone. In
the Ichneumon {Mangusta), the upper contour of the scapula is
slightly sigmoid, very convex anteriorly, and the prespinal is
larger than the postspinal fossa. The acromion is bifid. The
humerus is pierced both betAveen the condyles and above the
inner condyle. The supplementary ossicle at the radial side of
the carpus is present in most ViverridcB. Its homotype exists in
the tarsus of Cynocjale and Bassaris. The hallux is wanting in
both Mangusta j)enicillata and M. tetradactyla.

In the CanidcE the scapulae, and especially the limb-bones, are
longer and more slender, relatively, than in the foregoing car-
nivorous families. There are clavicular styles. The humerus
has the intercondylar vacuity, not the entocondylar perforation.
The pollex is reduced to the ' dew-claw ' appendage ; and, in
Canis jnctus, to a metacarpal style, which is concealed. The ulna
and radius are closely and extensively united : swift course is the
characteristic of the present digitigrade family. The slender
fibula closely adheres to the lower half of the tibia. The hallux
is reduced to a minute beginning of the metatarsal. The acces-
sory carpal ossicle and the fabella? are present.

In the Hycena, the humerus is usually pierced between the
condyles: it is thicker in proportion to its lengtli than in the
Dos:, but is more bent and twisted : the same characters mark
the radius and ulna, which are still shorter in proportion than in
the Dog. The pollex is reduced to a rudiment of its metacarpal.
In fig. 191 {Hycena, p. 306), si marks the ^ scapholunar ' common
to the carpus of all Carnivora, c is the cuneiforme, p tlie pisi-
forme ; t trapezium, d trapezoides, m magnum, and u unciforme.
The femur is more compressed antero-posteriorly than in the Dog,
and the small trochanter is more posterior in position. The neck
is longer, and the head of the bone larger : there is a fabella be-
hind each condyle. The tibia is shorter than the femur : the rotular
ridge is less produced than in the Dog. The fibula is less flat-
tened at its lower half, and more independent of the tibia than in
the Dog. The entocuneiform supports a rudiment of the meta-
tarsus of the hallux, as in the Dog : the calcaneal process is shorter
and thicker.

All Felines have the clavicular bone s. The humerus per-
forated above the inner condyle, but not between the condyles. In
the Lion, fig. 337, the supraspinal fossa of the scapula, 51, is less

SKELETON OF QUA DRUM ANA.

511

342

deep than tlie infraspinal one, and its border is almost uniformly
convex : the acromion is bifid, the recurved point being little
larger than the extremity or anterior point. A supplementary
ossicle is wedged in the interspace between the prominent end of
the scapho-lunar bone and the proximal end of the metacarpal of
the pollex. The ilia, fig. 342, c, are long and narrow, but thick ;
placed so obliquely upon the vertebra?, «, as to form an angle of
about 155° with the lumbar series : the ischia, e, are also long
and directed on the same antero-posterior plane : the length,
ridged strength, and great obliquity of the ' innominate ' bone,
afibrd powerful attach-
ment and advantageous
leverage to the muscles
acting upon the hind
limbs. The boundary of
the ischiatic notch is fee-
bly marked at g. The
pubis is short, but the
ischio-pubic symphysis, f,
is long: the ilio- pubic
angle is 120° in the Lion.
The posterior exceeds the
anterior pelvic outlet in
size. The os penis exists in all
developed in Bears and Seals.

The pollex, in the Felines, is retained on the fore-foot, and, like
the other toes, is terminated by a large, compressed, retractile
ungual phalanx, forming a deep sheath for the firm attachment of
the large curved and sharp-pointed claws. This highly-developed
unguiculate structure, with the dental system and concomitant
modifications of the skull, completes the predatory character of
the typical Carnivora.

§ 190. Skeleton of Quadrumana. — The Quadrumana combine
the opposable thumb in the hind limb with complete clavicles,
and a greater relative capacity of cranium than in foregoing
Gyrenceiihala. The orbits are turned more forward, have the
bony rim entire, and in most of the order are partitioned off" by
bone from the temporal fossa. In no Quadrumane is the hyoid
arch complete, or articulated by bone to the basis cranii.

To the (Quadrumana the transition is, not from the Gyr-, but
from the Liss- encepltala. For promoting the Colugos to the
Lemurs the grounds are almost as good as for degrading them to
the Bats. It has required a thorough knowledge of the structure

Pelvis of the Lion, side view.

Carni

and is remarkably

512 ANATOMY OF VERTEBEATES.

of the Aye-aye to gain a majority against keeping Cheiromys
amongst the mice. The singular group of Lemuricloe, which, from
the superior brain-development, especially the posterior extension
of the cerebrum over the cerebellum, I associate with the Gyren-
cephala,^ and by the hinder thumb with the Quadimmana, offers
great diversity in dentition and minor characters.

A. Vertebral Column. — All Quadrumana have the seven cer-
vical vertebra?. In the Lemurine or Strepsirrhime group the
folio wins; are the numbers of the other vertebras : —

D

L

s

c

Galeopithecus

13 or 14

6 or 7

3

or

4

18 or 19

Tarsius spectrum .

13

6

2

or

3

29 or 30

Cheiromys viadagascariensis .

13

6

2

or

3

22 or 23

Perodicticus Potto .

15 or 16

6 or 7

2

or

3

19 or 20

Stenops tardigradus

16

8

3

7 or 8

„ gracilis

14 or 15

9

3

5 or 6

Otolicnus Peli

13

7

3

23

„ crassicaudatns

13

6

3

27

Lichanotus Indri .

12 or 13

8 or 9

4

10 or 11

Tarsius spectrum .

13

6

3

29 or 30

Lemur . . . . .

13

6

2

or

3

28 or 29

The majority, including the type-form, of the LemuridcB thus
have 19 dorso-lumbar vertebras: the slow nocturnal species have
longer and less flexible trunks, approaching in tlie number of
dorso-lumbars — 24 — to the vertebral characters of the lissence-
phalous Sloths. The tail is, as usual, the seat of the greatest
diversity ; the slow lemurs, again, in the shortness of this terminal
appendage, recal a bradypodal character. In Stenops gracilis a
metapophysial tubercle is developed on each of the twelve anterior
dorsals : on the thirteenth it takes the place of the diapophysis,
and in the fourteenth extends forward, and offers an articular sur-
face for the outer side of the postzygapophysis : it has the same
disposition in the lumbar series, Avhere the diapophyses are serial
repetitions of the base supporting the anchylosed rib in the first
lumbar vertebra. The succeeding lumbars slightly decrease in
size as they approach the sacrum. Xo centre of motion of the
trunk is indicated by the direction of the dorso-lumbar neural
spines. In the more active and flexible-bodied Lemuridce the
trunk-vertebras resemble in proportions, connections, and direc-
tion of neural spines those of the agile Carnivora. In Lemur

' See CI*, p. 8, pi. xi. figs. 6, 7. The extension of the ccrebelhim over more
or less of tlie cerebrum is the primary and more constant character of the group
called, from the secondary character of convolutions, ' Gyrencephala.' The smooth
brain of the small jMonkey {Midas rufimanus) is figured in lxiv. to illustrate such
primary character. To bo consistent, INIr, Murray would have to remove the JNIar-
mosets as well as the Galagos to the Inscctivora; ci.* pp. 9 and 10.

SKELETON OF QUADRUMANA.

513

nigrifons the metapophysis begins to be developed in the middle
dorsal vertebrae, and, in the tenth, projects above, but distinct
from, the diapophysis. In the eleventh the diapophyses have
disappeared, and the metapophysis is on the outside of the prozyg-
apophysis. From this vertebra a well-marked anapophysis is
developed, which is continued from all the succeeding vertebrae.
The diapophysis reappears upon the first lumbar, and increases
in length and breadth as the other lumbar vertebrae approach the
sacrum. The centre of motion of the back is indicated by the
vertical spine of the tenth dorsal vertebra, towards which those of
the other dorsal and of the lumbar vertebrae incline.

343

Skeleton of the Aye-aye, (Cfieiromys madajascariensis.) B. Hand of Potto.

In the Aye-aye ( Clieiromys), fig. 343, the true vertebra? describe
one slight curve convex backward from the middle dorsal to the
penultimate lumbar, beyond which there is a slight bend in the
opposite direction to and including the sacrum. The bodies of
the dorsal vertebra? gradually lengthen and deepen as they ap-
proach the loins, with a narrower and at last almost carinate
under surface. The diapophysis, longest on the first dorsal, very
gradually shortens to the eleventh, where the beginnings of the
metapophysis and anapophysis are manifest. These processes
become widely separated in the twelfth and thirteenth dorsals,
and the diapophysis is lost. The neural spines are of equal length
throughout the dorsal series. The vertical one is on the eleventh

VOL. II. L L

514 ANATOMY OF VERTEBRATES.

dorsal^ toAvards which the rest of the dorso-lumbar series slightly
incline.

The vertebro3 go on increasing in size to the fifth of the
lumbar series, — ^the diapophyses more especially, which recom-
mence in the first lumbar ; these processes are directed forward
and doAvnward, as well as outward, are truncate, Avith the anterior
angle a little produced ; that of the last lumbar is similar in shape
and direction, but is smaller than the two preceding. The ana-
pophysis overlaps the front margin of the following vertebra to
the fifth lumbar, in which it becomes too short ; it disappears in
the sixth. The metapophysis overhangs the back part of the
neural arch of the preceding vertebra. The neural spine de-
creases from the third to the last lumbar, where it has 3 lines
of length. The last two ribs join their own centiiim close to the
front intervertebral space ; the rest have the usual intervertebral
articulation of the head. The first rib is the shortest (9 lines)
and thickest ; the others increase in length to the ninth, and
then gradually shorten to the thirteenth, which is 1 inch 3 lines
in length. The tubercle and diapophysial articulation exist to
the eleventh rib ; the twelfth and thirteenth articulate only by
the head. The first cartilage articulates with the manubrium,
the second to the seventh inclusive with the joints of seven
sternebers, the eighth with the seventh, and the ninth to the joint
between the seventh and eighth sterneber.

The bodies of the cervical vertebrae are broad, short, and
flattened below in the last five. The last three have no neural
spines: there are tubercular beginnings of these in the fourth
and third ; in the second it is 2 lines long, thick, and produced
anteriorly ; in the atlas it is as a small tubercle. The seventh
cervical has a simple slender diapophysis, 2 lines in length ; in
the sixth it coalesces with the tubercle of a short pleurapophysis,
also confluent by the head with the centrum, and projecting
outward, backward, and doAvnward, with an obtuse end. The
vertebral artery, in its forward course, enters the canal between
the pleur- and di-apophyses. The pleurapophysis simply com-
pletes that bony canal in the fifth cervical, making a short an-
gular projection outward and forward in the fifth, fourth, and
third cervicals. The low flat neural arch is narrowest in the fifth.
The shape and disposition of the zygapophyses give an imbricate
character to the union of those arches in the last six cervicals.
The body of the axis is carinate below ; that of the atlas has
the usual state of an ' odontoid process ; ' the hypapophysial bar
uniting with the neurapophysial pillars or crura of the atlas is

SKELETON OF QUADRUMANA. 515

carinate. Besides the wide canals for the vertebral arteries in
the ^ transverse processes ' of the atlas, the neural arch is perfo-
rated above the base of that process on each side for the passage
of a nerve.

In the short-tailed Indri {Lichanotus Indri\ the atlas has a
short hypapophysis, but no neural spine : the transverse process
is moderately long and broad, and is perforated lengthwise and
vertically by the vertebral artery, which afterwards pierces the
neural arch. The transverse process is perforated in all the
other cervical vertebras: the pleurapophysial portion of that of
the sixth forms a broad lamella directed downward and out-
ward. Each of these cervicals has its hypapophysial ridge and
neural spine, the latter moderately long and slightly increasing to
the seventh. The broad neural arch is fissured behind. The
spines of the dorsal vertebras are continued of equal length
throughout that region, and have the same direction. The dorsal
diapophyses support each a metapophysial tubercle, which aug-
ments as they diminish, and seems to take their place in the
eleventh and twelfth vertebrae, the ribs of which have no tubercle.
In the twelfth dorsal the metapophysis projects from above the
prozygapophysis, and is continued backward upon a well-deve-
loped anapophysis, which commences at once in that vertebra,
and continues to be developed, although decreasing in length,
to the penultimate lumbar inclusive. The metapophyses, which
are prominent in the anterior lumbar vertebra, gradually subside
as these approach the sacrum. The diapophysis has a low rough
tubercle on the first lumbar, which is developed into a depressed
plate increasing in length and breadth as the succeeding lumbars
approach the sacrum. As in the true Lemurs, eight pairs of ribs
directly join the sternum, which consists of seven bones and an
ensiform cartila2:e.

Nineteen is the usual number of dorso-lumbar vertebra? in the
Platyrrhine group, the Spider-monkeys {Afeles) offering the ex-
ception of eighteen, viz. d u, l 4 : the varieties which have been
formulised in the type-genus Cebus are due to freedom or con-
fluence of pleurapophyses, as e.g. D 12, L 7, Cebus liijpoleucus\
D 13, L 6, C capucinus ; D 14, L 5, in most Capuchins. The tail
is long in all, and prehensile in most Platyrrhines ; it rarely
has so few as 18 (^CalUthrix sciureus and C. Spixii), usually
30 vertebras, or upwards, as in Ateles iKiniscus, which has 33
caudals.

In the little Ouistiti {Hapale Jacchus), the accessory tubercle
appears upon the middle dorsal vertebra ; it divides into met- and

L L 2

516 ANATOMY OF VERTEBRATES.

anapophyses on the tenth dorsal, where a diapophjsial prominence
still articulates with the tubercle of the rib. The diapophysis
disappears in the succeeding dorsals in which the met- and an-
apophyses become distinct and remote, with progressive increase
of size. The diapophysis reappears in the first lumbar as a short
depressed process, and increases in length and breadth to the
penultimate lumbar. In this vertebra the anapophysis becomes
much shorter, and almost disappears in the last lumbar. The
transverse process of the atlas is perforated lengthwise and ver-
tically by the vertebral artery, and the neural arch is perforated.
The bodies of the succeeding cervicals are produced posteriorly
into a convex prominence which fits into a concavity on the fore
part of the centrum behind. Eight pairs of ribs directly arti-
culate with the sternum, which consists of seven bones.

In the Capuchin ( Cebus capucinus), the tubercles representing
met- and an-apophyses project distinctly, the one from the fore
part, the other from the back part, of the diapophysis of the fifth
dorsal : they progressively increase in size, and become quite dis-
tinct in the thirteenth dorsal, in which the metapophysis has
risen upon the anterior zygapophysis. The anapophyses continue
to be developed to the penultimate lumbar. The diapophyses
progressively increase in length from the first to the last lumbar
vertebra). Ha3mal arches are articulated to the inferior inter-
spaces of the six anterior caudals, and are supported by distinct
hypapophyses from the fourth caudal, Avhich processes continue
to be developed after the hgemapophyses have ceased to be so.
Nine pairs of ribs articulate directly with the sternum, which
consists of seven bones and an ensiform cartilage.

In the black Spider-monkey (Ateles niger), the tuberosity
above the dorsal diapophyses becomes a ridge in the eleventh
dorsal, and is produced forward into an angular metapophysis :
in the thirteenth dorsal it is produced to the same extent back-
ward into an anapophysis : in the fourteenth dorsal these pro-
cesses are distinct and well-developed^ but the diapophysis has
disappeared. The anapophysis is developed from the first and
second lumbar vertebra), and the diapophysis from all the lum-
bars, progressively increasing to the penultimate one. A pair of
liypapophyses begin to be developed from the fifth caudal, and
increase in size in the sixth and seventh. The hajmal arch is
anchylosed to these processes in the eighth and ninth caudals,
but the hypapophyses continue to be developed, without the
addition of that arch, throughout the succeeding caudal vertebra).
The anterior zygapophyses disappear in the ninth caudal, but the

SKELETON OF QUADRUMANA. 517

metapopKyses which support them in the preceding caudals
continue to be developed to near the end of the tail. The
diapophyses are single on each side in the seven anterior
caudals, but are divided into an anterior and posterior portion
on each side of the vertebrae throughout the rest of the tail.
The third to the sixth cervical vertebrae inclusive show an
anterior concavity and a posterior convexity of the articular ends
of the centrums in the transverse direction, an anterior convexity
and posterior conca\'ity in the vertical direction, producing an
interlocking joint, combining strength with freedom of motion,
and analogous to that in the neck of birds. The pleurapophysial
part of each transverse process is a broad depressed plate, with its
anterior margin j^roduced, and progressively increasing in size
from the third to the sixth vertebra. A similar increase is pre-
sented by the neural spines, especially in the sixth vertebra. As
in the Capuchins, the transverse process of the atlas of the
Spider-monkeys is perforated lengthwise only by the vertebral
artery, which afterwards perforates the neural arch. The atlas
has a hypapophysial ridge, and the axis shoAvs a corresponding
tubercle. Nine pairs of ribs articulate directly with the sternum,
which consists of eight bones and an ensiform cartilage.

The vertebral column of the Platyrrhine Quadriimana is the
seat of greater and more important varieties : the caudal por-
tion is reduced to a stunted * coccyx,' the lumbar region is
shortened and strengthened, and the sternum is composed of
fewer and broader bones in the Apes properly so called. In the
Monkeys and Baboons, the dorso-lumbar vertebrae are nineteen
in number as a rule, either D 13, L 6, or D 12, L 7. The latter is
the common formula in the Macacques : the caudals varying from
upwards of 20 in Macacus radiatus to 15 in M. rhesus, and being
reduced to 3 or 4 in M. inuus. In the Baboons ( Cynocephalus),
the caudals also vary from 25 in C. porcarhis to 10 very small
and stunted vertebras in the Mandril ( C papio, fig. 344). In this,
as in the Black-faced Drill ( C. porcarius) and Thoth ( C. Thotli),
the dorso-lumbar vertebrae are reduced to D 12, L 6. An an-
apophysial tubercle is developed from the diapophysis of each
dorsal vertebra, increasing in length to the two last, in which it
has an independent origin. The metapophysis is suddenly de-
veloped from the tentli dorsal, and presents an articular surface
to a second facet on the outer side of the hinder zygapophysis of
the vertebra in front. The anapophyscs continue to be developed
from all the lumbar vertebrae, progressively decreasing as these
approach the sacrum, and appearing in the last as a mere ridge

518

ANATOMY OE VERTEBRATES.

on the upper part of the base of the diapophysls. The homotypal
ridge may be recognised on the first sacral vertebra. There are
rudiments of hypapophyses on the middle caudal vertebrae.
Seven pairs of ribs articulate with the sternum, which consists of
seven bones and an ensiform cartilage. The transverse process
of the atlas is perforated lengthwise and vertically by the verte-
bral artery ; which afterwards pierces the neural arch : the neural
spine is represented by a small tubercle, and there is a hypapo-

344

elvmrraMS'.sj

Mandrill. (Papis Maimon.)

physial ridge. The centrum of the axis is much produced back-
ward, underlapping that of the third vertebra : this character is
gradually lost in the succeeding vertebrte : the transverse process
of the axis ends in two tubercles. The lower (pleurapophysial)
division of the process is compressed in the third cervical, and be-
comes developed into a plate, progressively increasing, and dis-
proportionately so in the sixth cervical: it is absent in the
seventh cervical, the transverse process of which is, however,
still perforated by the vertebral artery. The neural spines are

SKELETON OF QUADRUMANA. 519

Simple, and increase in length from the third to the seventh
cervicals. Those of the dorsal vertebras are lono^er and strongrer,
but diminish in length as they approach the loins ; that of the
tenth indicates the centre of motion of the trunk.

In the Pig-tailed Macacque (^Macacus nemesti^inus), the atlas
has a strong hypapophysis, but no neural spine or tubercle : the
transverse process is perforated obliquely. The back part of
the centrum of the axis is much produced ; that of the third cer-
vical is less produced. The spine of the axis is long and bent
backward. A pleurapophysial plate extends obliquely from the
transverse processes of the third, fourth, and fifth cervicals, and
projects downward and outward as a distinct broad plate from
that of the sixth vertebra. The long and simple transverse pro-
cess of the seventh is not perforated by the vertebral artery.
Metapophysial tubercles are developed upon the diapophyses of
the second and succeedino; dorsal vertebra3, increasinor in distinct-
ness and size to the tenth ; in the eleventh the anapophyses
become separate processes, and the metapophyses develope a facet
for the accessory articular surface of the posterior zygapophysis
of the tenth vertebra. This additional interlocking is continued
to the antepenultimate lumbar, the joint being further strength-
ened by the underlapping of the long anapophyses : these dis-
appear in the last lumbar. The diapophysis is a rudimental
ridge in the last dorsal, but becomes a distinct depressed sharp
plate in the first lumbar, and progressively increases in size with
an antroverted direction in the succeeding lumbar vertebn^.
Eight pairs of ribs articulate directly with the sternum, which
consists of eio'ht bones and an ensiform cartilao;e.

The Doucs (^Colobus, Nasalis, Semnopithecus) have commonly
D 12, L 7 : but sometimes D 13, L 6 (aS'. melalophis). In Scinno-
jntJiecus Entellus, the cervical transverse processes incline down-
ward : their pleurapophysial divisions from tlie second to tlie sixth
increase ; but this part is wanting in the seventh, and the trans-
verse process is imperforate. The accessory tubercle is well
developed on the diapophysis of the ninth and tenth dorsals ; the
diapophysial part disappears on the eleventh and twelfth dorsals,
in which the accessory tubercle becomes divided into well-marked
met- and an-apophyses. The diapophysis reappears on the first
lumbar, and progressively increases to the antepenultimate one.
The metapophysis exists as an elongated tubercle outside the
prozygapophysis from the eleventh dorsal to the last lumbar,
and the anapophysis is present from the tenth dorsal to tlie sixth
lumbar. The haemal arch is present in a few of the anterior

520 ANATOMY OF VERTEBRATES.

caudal vertebrae. Seven pairs of ribs directly articulate mth the
sternum, which consists of six bones, slender as in all previous
Quadrumaria.

In the Gibbons, with D 13, the lumbar vertebrae are 5, save in
Htjlohates syndactylus, fig. 189, where they are reduced to 4. In
the Silvery Gibbon {H. leuciscus), the transverse process of the
atlas is only perforated lengthwise and the neural arch grooved
by the vertebral artery. A pleurapophysial part of the trans-
verse process begins to project forward on the fifth cervical, and
becomes a distinct and larger depressed plate on the sixth : the
transverse process of the seventh is a simple diapophysis, and is
imperforate. The metapophysis and anapophysis become distinct
in the twelfth dorsal, and diverge from each other with increase
of size in the thirteenth. The anapophysis disappears in the
lumbar vertebrae, whilst the diapophysis reappears and the met-
apophysis is retained. The interlocking joints, common to the
preceding Quadrumana with Carnivora, here and henceforth
cease. Seven pairs of ribs directly join the sternum, which con-
sists of the manubrium, the body, which consists of two or more
anchylosed broad and flat bones, and a slender bony base of the
* ensiform cartilage.' Two pairs of ribs, and part of a third pair,
articulate with the manubrium.

In the Siamang (//. syndactylus, fig. 189), the last dorsal shows
well the separate diapophyses, metapophyses, anapophyses, and
zygapophyses, more particularly the distinction between the an-
terior zygapophysis and the now superadded metapophysis. The
diapophyses are broad depressed plates, progressively increasing
in the first three lumbar, whilst the anapophyses diminish and
disappear on the third lumbar. The metapophysis recedes from
the anterior zygapophysis in the last lumbar, and becomes quite
distinct from it in the first sacral, in which, nevertheless, the ar-
ticular surface of the zygapophysis has a nearly vertical position.
The sacrum, by its greater breadth and the number of vertebrae
forming it, indicates the nearer affinity of the Siamang, than of
other Gibbons, to the Orangs.

In the Orang-utan (Fithecus Satyrus), the vertebral formula
is: — 7 cervical, 12 dorsal, 4 or 5 lumbar, 5 or 6 sacral, 2 or 3
caudal. The transverse process of the atlas is bituberculate, and
is perforated lengthwise by the vertebral artery, which afterwards
grooves the neural arch : there is a low hypapophysial tubercle,
but no neural spine. The transverse process of the axis is deeply
grooved, but not perforated ; consisting almost entirely of the
pleurapophysial portion. In the third vertebra the two portions

SKELETON OF QUADRUMANA. 521

of the transverse process are united, external to the perforation by
the vertebral artery. In the fourth cervical the pleurapophysial
part projects distinctly below the diapophysial part, and progres-
sively diverges in the fifth and sixth, increasing in size, especially
in the latter, without, however, acquiring that antero-posterior
breadth which gives it the lamelliform character in the inferior
apes. The transverse process of the seventh cervical consists
of the diapophysis only, and is grooved below, not perforated, by
the vertebral artery. The distinct nature of the equally simple
transverse process in the second and seventh cervical vertebras of
this Orang is well shown by their different relative positions to
the groove with which the vertebral artery has impressed them.
The neural spine of the axis is bifurcate ; that of the third
cervical is simple, long, and slender ; those of the succeeding
cervicals are still longer, and progressively increase in thickness
as well as length. The metapophysis appears as a tubercle near
the base of the anterior zygapophysis of the twelfth dorsal : it is
equally distinct on the first lumbar, but subsides to a slight emi-
nence on the succeeding lumbar vertebrae. The anapophysis is
only distinguishable from the diapophysis upon the first lumbar
vertebra ; it is not so developed as to interlock, but serves to illus-
trate the relation of the diapophysis of that vertebra to those of
the antecedent dorsals and the succeeding lumbars. The spine of
the third dorsal has an anterior and posterior prominence: the
succeeding spines gradually diminish in length, but increase in
breadth and antero-posterior extent to the penultimate lumbar.
Seven pairs of ribs directly articulate with the broad sternum,
which consists of the manubrium and four pairs of ossicles, the two
lower pairs of which have coalesced. The manubrium is relatively
shorter than in the Gibbons, and receives only the first and part
of the second pairs of ribs. As a rule, the number of dorso-
lumbar vertebrae, in Pithecus, is 16: that of the sacro-caudal
vertebra 8. The first rib is less curved, and describes a smaller
portion of a circle than in Man : its head is relatively larger, and
is supported on a shorter neck : it has an epiphysis, as in Man.
The distal portion is relatively less expanded than in Man. The
other ribs chiefly differ in their more compressed form and their
more gradual and equable curvature.

In the Chimpanzee (^Troglodytes iiiger, fig. 345), the vertebral
formula is: — 7 cervical, 13 dorsal, 3 or 4 lumbar, 5 or 6 sacral,
and 2 or 3 caudaL The pleurapophysial portion of the transverse
process of the atlas is shorter than in the Orang, and has not
united with the longer diapophysial division : the canal for the

522

ANATOMY OF VERTEBRATES.

345

vertebral artery is thus not quite circumscribed by bone : tlie
artery afterwards j^ierces the neural arch on the left side, and
deeply grooves it on the right side. The two portions of the
transverse process of the axis have coalesced, and form a thick
tubercle externally, surrounding the vertebral artery : this tubercle

increases in breadth in the third, and
in length in the fourth ; in the fifth it
sends a distinct tubercle from its lower
part, and the answerable part forms an
antroverted, obtuse, broad process in
the sixth. The pleurapophysial ele-
ment is wanting in the seventh, in
which the diapophysis is deeply grooved
below for the vertebral artery. The
spines of the 4 — 7 cervicals are long
and simple. A metapophysis may be
distino^uished in the eleventh and
twelfth dorsals, which becomes distinct
from the diapophysis in the thirteenth,
and projects from the outside of the
prozygapophysis in all the lumbar ver-
tebrae. The diapophyses are longest
in the first and second lumbars, are
shortest in the third, and are augmen-
ted in the fourth by the developement
of a thick anapophysis at their back
part, which here articulates with the
first sacral vertebra. In old males the
fourth lumbar becomes the first sacral
by a more complete coalescence. Seven
pairs of ribs directly join the sternum,
which consists of five flat bones and
an ensiform part : the fourth and fifth
bones have coalesced : the manu-
brium, as in the Orangs, is the broad-
est, and receives the first pair and part
of the second pair of ribs. These are
shorter, and their neck relatively
longer than in the Orang, and they
are more curved. The thirteenth rib
retains a distinct articular tubercle and neck.

In the Gorilla ( Troglodytes Gorilla, fig. 346), the dorso-
lumbar vertebra?, as in the Chimpanzee, are 17 in number, the

Cliinipaiizec (Troglodytes Niger), cur.

SKELETON OF QUADRUMANA.

523

346

tliirteentli dorsal answering to the first lumbar in Man, with the
pleurapophyses retained as distinct elements. The bodies of the
middle dorsal vertebras
are shorter in propor-
tion to their breadth;
the diapophyses are
thicker, stand more di-
rectly outward, and the
costal surfaces are
more concave and ob-
long than in Man ; the
metapophysis, which
projects distinctly in
the eleventh vertebra
in Man, does not so
appear until the twelfth
in the Gorilla. In the
first dorsal the diapo-
physis projects directly
outward ; the propor-
tionate increase of the
centrum is greater than
in Man ; the neural
spine is less obliquely
bent baclvAvard, and is
thicker antero-posteri-
orly, though not lon-
ger; the anterior zyga-
j)ophyses are more pro-
duced; the diapophyses
are broader and some-
what shorter. In the
eleventh dorsal the
neural spine is much
expanded at its extre-
mity. In the twelfth,
there are distinct and
well-developed meta-
pophyses, projecting
from the fore part of
the diapophyses, and

OVerhano;ino: the ante- Gorma. Clrogludylcs GonlUO. cm-.

rior zygapophyses : this vertebra corresponds in this character

524 ANATOMY OF VERTEBRATES.

with the eleventh of the Human subject. The neural spine is
broader and thicker, especially superiorly ; there is but one costal
surface on each side ; the diapophyses are reduced in size, the
metapophyses equalling them, the body and neural spine increas-
ing. The thoracic ribs are longer and thicker, more convex on
their inner side, with the subcostal groove not defined, except in
two or three of the longest ribs near their vertebral end ; the neck
is shorter and thicker than in Man ; the longest rib is one foot four
inches in length, — that of the longest rib in an average-sized man
being thirteen inches. The manubrium sterni is much broader than
in Man (fig. 183), and less deeply excavated for the clavicles ; the
three or four sternebers which coalesce to form the ' body ' of the
breast-bone have a like character. The cervical vertebras differ
most from the Human in the extraordinary length of the spines
of the last five vertebras ; that of the fourth cervical is not less
than three inches and a half ; the spines of the sixth and seventh
cervicals gradually decrease in lengtli and increase in thickness :
the spine of the dentata is trihedral, the surfaces being divided
by produced sharp ridges : the canal for the vertebral artery de-
creases in diameter from the sixth forward to the atlas. The
bodies of these vertebrae are longer in proportion to their breadth
than in Man, and the lower (pleurapophysial) part of the trans-
verse process of the sixth is more suddenly increased in length
and breadth, and diverges more from the upper division of the
same process. The atlas is narrower than in Man, with a wider
neural canal, especially between the condyles, which are smaller
than in Man. An obtuse process is developed backward from
the part representing the body, which is broader than in Man ;
the perforation of the transverse process is smaller, and that pro-
cess is narrower, especially vertically; the groove behind the
upper articular processes is deeper and narrower. The axis or
dentata differs chiefly in the greater size of the neural canal, and
in the greater length and less breadth of the neural spine ; the
zygapophyses are smaller, the transverse processes are more
directly perforated by the arterial foramina, and the diapophyses
are more produced.

In the first lumbar vertebra, fig. 346, 2, the metapophysis is
still large and distinct ; the anterior zygapophysis becomes more
convex and oblique in position ; the diapophysis is suddenly elon-
gated, as compared with that of the corresponding (second)
Human lumbar vertebra ; the chief difference is seen in the
smaller size of the neural canal which relates to the inferior
developement of the lower extremities. The same difference

SKEL-ETON OF QUADRUMANA. 5-25

obtains in the second (s, answering to the third Human) lumbar
vertebra ; the diapophyses are broader and more depressed in the
Gorilla ; a fossa divides the anterior zygapophysis from the meta-
pophysis ; the centrum is as broad as in Man, but is deeper and
longer ; the neural spine extends more obliquely backward, and
its expanded apex is bifid. In the third lumbar vertebra, 4, the
difference is very striking in the minor expanse of the centrum
in the Gorilla, especially behind, in the much smaller and more
depressed form of the neural canal, in the shorter and broader
diapophysis, the more distinct metapophysis, in the convex an-
terior and more approximated posterior zygapophyses, and in the
greater length of the centrum. In old males this vertebra is
included by the ilia. The whole series of true vertebrae in the
Gorilla form but one curvature, which is slightly concave forward,
especially in the dorsal region.

The sacrum departs in a greater and more instructive degree
from the Human type ; it consists of five or six anchylosed
vertebrae, but they are longer and narrower than in Man, and
present a very slight curve, with the concavity forward ; the
neural foramina are much smaller, the neural sj^ines much more
developed, and coalesce to form a single strong bony ridge, ex-
tended over and gradually subsiding on the last sacral vertebra,
the neural arch of which is entire ; the first sacral vertebra, ib. 5,
answers to the fifth lumbar in Man ; the zygapophyses are
smaller, but the metapophyses are present and well developed.
The posterior outlets for the sacral nerves are very small, and
the whole neural canal is much more contracted than in Man.

B. The Skull— The skull of the Aye-aye, fig. 343, in com-
parison with that of lower mammals of similar size, is remarkable
for the large proportion of the cranium to the face, and the
extreme shortness of the latter in advance of the orbits. Its
profile contour, from the upper border of the foramen magnum,
curves rapidly from the occipital to the parietal region, and is
continued with a bold convexity to the root of the nose, whence
it slopes straight to the nostril. The cranium is still more con-
vex transversely ; it expands a little in advance of the lambdoid
ridge, and gradually, but very slightly, contracts to the post-
orbital processes ; these, meeting with the malars, complete the
rim of the orbit, which opens widely beneath that part of the
frame into the temporal fossa.

In the complete circumscription of the rim of the bony orbit
Chiromys exemplifies its quadrumanous affinity ; whilst it shows
the special family to which in that order it belongs by the

526 ANATOMY OF VERTEBRATES.

deficiency of the wall partitioning the orbital from the temporal
cavity. The Lemurs, in this defect, indicate the transition to the
lower unguiculate Mammalia, ih.Q Galeojyithecus, ^g. 253, offering
the last step by the incompleteness of the orbital frame-ring
behind. The outlook of the orbits, in the Aye-aye, obliquely
forward, upward, and outward, but least so in the last direction,
differs significantly from the direct outward aspect of those ill-
defined cavities in most Rodents.

The basioccipital extends to the fore part of the large tympanic
bulla3, to abut against which its margins are slightly produced.
The occipital condyles are long and narrow. The plane of the
foramen magnum forms with the basioccipital an angle of 125°,
its aspect being downward and backward. The paroccipital is a
low eminence, and the mastoid in front of it is hardly more pro-
minent ; neither process extends freely downward. The super-
occipital, ib. 3, is a thin plate moulded on the middle and lateral
lobes of the cerebellum, and showing outwardly their respective
prominences. The petrosal is impressed by the pit for the cere-
bellar appendage.

There is a small triangular interparietal. The basisphenoid is
expanded by a large sinus, and coalesces with the presphenoid.
The alisphenoid developes the ectopterygoid ridge, extending
from between the squamosal and tympanic to the outer side of the
entopterygoid ; both plates are imperforate. The natiform protu-
berances form deep depressions in the alisphenoid, on each side
the flat square platform of the cranial surface of the basisphenoid,
in the middle of which is the subcircular pituitary pit. There are
no clinoid processes. The alisphenoids join the parietals, which
contribute the greatest share to the formation of the calvarium.
The tympanic, coalescing with the petrosal, is, together with that
element, expanded into an oval bulla on each side the basi-
sphenoid. The parietals, 7, impressed from within to transparent
thinness by the longitudinal convolutions of the cerebrum, do not
exceed half a line in thickness elsewhere.

The coronal suture crosses the cranium transversely three lines
behind the postorbitals : the frontal suture remains, as in other
LemuridcB, and, like the sagittal, it is a harmonia. The fore part
of the frontals, ii, project a little between the origin of the nasals,
and also between the nasals and maxillaries ; they then join the
lacrymals, form the upper half of the inner wall of the orbit, and
unite behind with the orbitosphenoid, alisphenoid, and parietal.
The rhinencephalic fossa is subcircular and large : the median
septum is produced into a ' crista galli.' The frontal sinuses give

SKELETON OF QUADRUMANA. 527

no outward indication, but are extensive ; they are divided from
each other by a median bony septum ; each division communi-
cates mth the nasal chamber by a median orifice and by a lateral
one with the antrum. The nasals, 15, join above with the frontals
and at the sides with the premaxillaries, 22. The presphenoid is
short, smooth on the under surface, and concave there trans-
versely. The vomer quickly assumes the form of a vertical plate,
with the free hind border concave. The palatines form the
hinder third of the bony palate ; the suture of each with the
maxillary is slightly convex forward : they are divided from the
inner alveolar wall of the last two molars by a groove which
deepens into a fissure, bounded beyond the last molar by the
pterygoid. The maxillary forms more than the middle third of
the palate, leaving the smallest share of the roof of the mouth to
the premaxillary. The facial plate of the maxillary, 21, extends by
a narrow produced apex to the lacrymal, 73, but is excluded from
the frontal by the junction of the lacrymal with the premaxillary ;
it is perforated by a small antorbital foramen. The premaxillaries
constitute a larger share of the facial wall, rising as high as the
nasals, between which and the maxillaries they interpose a broad
plate, circumscribing, with the nasals, the external nostril. The
socket of the incisor curves upward and backward to the max-
illary, in which it is continued to beneath the orbit. The malar
bone, 26, is long and deep, especially below the orbit, of which it
forms the lower half; and where it bends outward to expand that
cavity, it unites with the lacrymal and extensively with the max-
illary anteriorly, and bifurcates behind, — the narrower branch
mounting to the postorbital, the broader one continuing back-
ward to the squamosal, 27. This essentially facial or maxillary
element is anchylosed not only with the mastoid and petrosal, but
also with the tympanic ; its cranial plate terminates by a convex
border overlapping the contiguous borders of the alisphenoid and
parietal. The articular surface for the mandible is broad and
flat, save where its inner border bends down upon the side of the
petro-tympanic bulla. There is no riclge behind it to prevent the
free movements of the mandible backward and forward, accom-
panying the rodent action of the great scalpriform incisors : in
this the Aye-aye differs from other Lemuridcc.

The mandible, 32, is short and deep : each ramus is compressed
and straight ; they converge at an acute angle to a short ligament-
ous symphysis. The condyle is sessile, narrow, rather long, convex
both across and lengthwise, and the latter most so, looking back-
ward and upward, and })laccd on tlic level of tlie grinding-teeth.

528

ANATOMY OF VERTEBRATES.

The thin borders of the ascending ramus diverge from the con-
dyle as they pass, the one downward and inward to the low angle,
and the other forward and upward to the better-marked and more
advanced coronoid, the obtuse end of which is nearer the last
molar than the condyle. A slight ridge above the angle bounds
the surface for muscular insertion behind ; and here the angle is
a little inflected.

In the Woolly Lemur {Liclianotus laniger, fig. 177), the cranium
has a short paroccipital and a shorter mastoid process which
coalesces with the base of a large petro-tympanic bulla. The
squamosal is perforated by a venous foramen anterior to the
auditory meatus. The malar extends backward almost to the
glenoid cavity, which, as in follomng LemuridcB, is defended by
a posterior ridge. The large orbits reduce the intervening part
of the frontal to a narrow channel. The premaxillaries are
divided anteriorly by an angular cleft separating in the same
deecree the anterior or mid-incisors from each other. The lower
jaw is remarkable for the great production of its broad and
rounded angle : the back part of its symphysis is also produced.

In Stenops gracilis, and especially in Tarsius spectrum, the
most remarkable feature in the cranium is the expanded frame of
the orbits, which are closely approximated above the nasal bones.
These overhang the premaxillaries, the most produced part of
which forms the lower boundary of the external nostril, from
which, in the Slender Lemur, the premaxillaries slope downward
and backward to the incisive alveoli. The temporal ridges are
widely separated along the upper part of the globular cranium,
where the coronal and fr on to-sagittal sutures intersect each other

at right angles. As in the
Aye-aye and most Lemur-
idcB, the cranial sutures are
' harmonias.'

In the Slow Lemur (^Ste-
7iops tardigradus), the orbits
are less closely approximate
than in the Ste7iops gracilis,
and the anterior surface of
the small premaxillaries is
more nearly vertical. The
vomer divides the nostrils to their posterior apertures.

In the Potto {Perodicticus, fig. 347), as in other Slow Lemurs
(Stenops), the cranial expansion behind the meatus auditorius
forms one-third the length of the skull, owing to the great pro-

347

Potto. LXIX*

SKELETON OF QUADRUMANA. 529

portional size of the occipital and mastoid. The interorbital space
is broader than in Stenops tardigradus.

In the true Lemurs the facial part of the skull is more pro-
duced ; it is formed by the lacrymals, nasals, and maxillaries ;
the premaxillaries continuing very minute. In Lemur Macaco
the petrosal has a large and deep cerebellar fossa ; a short ten-
torial ridge projects anterior to this. There is a low postclinoid
ridge. The lateral sinus pierces the petrosal where it joins the
parietal and meets a second venous channel traversing the middle
fossa of the cranium to terminate at the postglenoid foramen.
The foramen ovale is a small fissure between the petrosal and
alisphenoid, less than the foramen rotundum, Avhich is close to
the foramen lacerum anterius : the outlet of the foramen ovale
is in the Eustachian fossa.

The grey Lemur {^Chirogaleus griseus, fig. 348) has the more
common abbreviation of the antorbitai
part of the skull, in which the lacry-
mal foramen is conspicuous. The
malar is perforated by the ' nervus
subcutaneus mala).' The coronoid pro-
cess of the mandible, well developed
in all Lemuridce, is here very high.

The anterior cornua of the hyoid,

^, . 1 xl T -J t^i'^J' Lemur, lxix-.

m (Jlieiromys and other Lemuriacs, are

longer than the posterior, and include epi- and cerato-hyals, sup-
porting a cartilaginous stylo-hyal.

In the Platyrrhines the cranium is proportionally larger and
the jaws less, as the species are smaller in size : they thus ex-
emplify the immature characters of the larger species. The
cranium is more globular, the occiput more protuberant, the
' foramen magnum ' more advanced in position, and with a more
downward aspect, in the Marmosets (Jacchiis), and Ouistitis or
Ti-tis ( Callithrix), than in the Howlers {Mycetes). The frontal
suture is obliterated in all, and the single bone, thence resulting,
is triangular with the apex extending back, between the parietals,
in some Capucins {Cebus) as far as the superoccipital (fig. 239,
Cehus) : thus repeating a piscine collocation of supra-cranial
bones. The entocarotid perforates the back part of the petrosal.

In all Platyrrhines a division of the lateral cerebral venous
sinus excavates the base of the petrosal to terminate at the post-
glenoid fossa, as in most Lemurs : the malar is similarly per-
forated by a facial nerve : the plate which divides the orbital
from the temporal fossa exhibits a small unossified vacuity in

VOL. II. MM

530

ANATOMY OF VERTEBRATES.

most Platymiines.^ The petrosal has a deep cerebellar depres-
sion. The postclinoid plate is more developed, the rhinencephalic
fossa is smaller, and the orbital walls project more into the cranial
cavity than in the Strepsirrhines. The lacrymal is not extended
upon the face, and the foramen is within the orbit.

In Callitiirix sciureus the orbits do not communicate with the
temporal fossae. There are no paroccipitals, and only a feeble
mastoid ridge. The petrosals are slightly swollen at the basis
cranii. The parietals articulate mth the malars. There is a
vacuity in the interorbital septum.

In Cebus, also, there are neither paroccipitals nor mastoids, and
the petrotympanics form slightly swollen convexities. Besides

the postglenoid venous foramen,
there is a second at the end of
the squamosal suture. The fora-
men ovale is between the petro-
sal and alisphenoid. The super-
occipital plate has two large
depressions, as in Callitiirix.
The orbital plate of the malar
shoAvs a small hole near its junc-
tion with the alisphenoid.^ The
basi-hyal is excavated behind;
not so in Callitiirix : the anterior cornua are long, and formed by
epi- and cerato-hyals ; the thyro-hyals are broader, not longer.

In the Spider Monkeys {Ateles) the paroccipitals and mastoids
form rough tubercles. There is the same venous foramen as in
Cehiis, formed by the meeting of two converging sinuses between
the squamosal and alisphenoid. Ossification has extended into
one half of the tentorium. The cerebellar fossa in the petrosal is
of great depth. The foramen ovale is formed by the petrosal and
alisphenoid. The vomer extends to the posterior nares. The
incisive foramen is large and single.

The symphysis of the lower jaw is completely anchylosed, and
the angle of the jaw rounded oif, as in most Platyrrhines. The
condyles and small coronoid processes are of equal height : in
Marmosets the coronoid is higher, and in Hapale Jacchus the
mandibular angle is slightly produced. The basi-hyal is a convex
plate : the cerato-hyals are shorter than in Cebus : the thyro-
hyals are longer.

' CIV. pi, vi. {Cebus, Douroucouli, Cliamek.)

2 These relics of the orbito-tcmporal \ acuity Avere first noticed as such by Prof.
Filippi.

Cnpurin (Cebnn Apella). LXix-

SKELETON OF QUADRUMANA.

531

Uowlei (My cUtswbinus) LXix

lu the Red Howler (yMycetes seniculus, fig. 350) the superocci-
pital region is ahnost flat and vertical, at right angles with the
parietal surface, from which it is separated by a well-defined
ridge : the foramen magnum looks almost directly backward.
The maxillo-premaxillary sutures demonstrate the junction of the
premaxillaries with the nasals. The ectopterygoids much exceed
the entopterygoid plates in size. The
large malar foramen communicates with
the orbit : the suborbital foramina of
the maxillary are two in number, and
small. The chief feature of peculiarity
in the skull of the Howler is the extra-
ordinary depth of the mandibular rami,
especially of their angular and ascend-
ing portions. This development relates
to the protection and support of the
still more extraordinarily developed
hyoidean and laryngeal apparatus — the
organs of the loud and dissonant cries which have procured for
these South American Monkeys their common name. The
superior length of the postglenoid process, in relation to the
larger and heavier lower jaw, is worthy of notice. An obtuse
paroccipital ridge extends from the condyle to the mastoid ridge.
The precondyloid, jugular, and carotid foramina all open into
an irregular fossa between the petrosal and paroccipital ridge.
There is a small venous foramen outside the mastoid, and a
second at the anterior border of the squamosal. The hyoid arch
is reduced to the basi- and thyro-hyals ; but the former is
enormously developed, and expanded into a capacious sac mth
thin walls, and a posterior opening, admitting a laryngeal pouch.
A narrow transverse plate descends from the roof of the bony
sac. The cerato-hyals are obsolete. The thyro-hyals long, for
suspending the sac to the upper angles of the large thyroid car-
tilage.

There is much greater diversity, and more marked ascending-
steps of structure, in the skull of the ' Old World ' than of the
' New World' Monkeys. No Catarrhine shows ossification of
the tentorium ; and in all the preclinoid, as well as postclinoid,
processes defend the sella. The same remark, as to concur-
rence of immature proportions of cranium and jaws with in-
fantile stature, applies to the Catarrhine as to the Platyrrhine
Quadrumana. But the larger s^^ecies of the lower groups ( Cj/-
nocejyhalus, Papio, e.g.) show more carnivorous or brutish pro-

M M 2

532 ANATOMY OF VERTEBRATES.

portions of skull than do those (Orang, Gorilla) of the higher
group.

In the Black-faced Drill (^Cynocephalus porcarius, fig. 351)

the facial much exceeds the
^^^ ^^^ cranial part of the skull. The

superoccipital is almost flat :
but, sloping upward and back-
ward, forms an acute angle with
the parietal, from which it is
divided by a strong ridge, where
the diploe is obliterated. The
mastoid is more developed than
skuu ,ci>noce,naius porcarius^. Lxix-. ^hc paroccipital promiuencc ; but

both are low. The jugular fossa
is distinct from the precondyloid and carotid foramina ; outside the
latter is a short ' vaginal ' process. The petrosal bifurcates anteri-
orly into a ' eustachian ' and an ^ apical ' process: the latter under-
laps the base of the pterygoid process : the inner surface of the
petrosal is closely applied to the basisphenoid and basioccipital as
far as the ^ foramen jugulare : ' there is, thus, no ' foramen lacerum
basis cranii.' The squamosal is perforated near its middle by one
or two small foramina, but there are no ^ post-glenoid ' outlets of
the lateral sinuses. The foramen ovale is between the petrosal
and alisphenoid, and the nerve which it transmits pierces the base
of the broad ectopterygoid : the entopterygoid plate is compara-
tively small, but ends in a hamular process. The glenoid arti-
cular surface projects from the under part of the base of the
zygoma, and is slightly convex : it is defended by a postglenoid
process. The vomer divides the posterior nostrils, and there is a
venous sinus or foramen between its base and the presphenoid.
The coalesced nasals are prominent and gradually expand as they
advance forward : they unite with a small proportion of the pre-
maxillaries. The fossae between the nasals and maxillary tuber-
osities are short and Avide. The pterygoid fossae are large and
deep. The alisphenoid is separated by the squamosal from the
parietal. The upper angle of the mastoid is wedged between the
superoccipital and parietal. The limits of the interparietal may
be traced upon the inner surface of the calvarium. There is a
shallow cerebellar fossa above the meatus internus. The optic
foramina are approximated. The entry to the rhin en cephalic
fossa is much contracted by the bulging prominence of the roofs
of the orbits.

In the Magot (Macacus Inuus, fig. 352) and other Macacques,

SKELETON OF QUADRUMANA.

133

general characters are those

352

Skull of Macacus Inuus

with a general reduction of the size of the animal, the jaws are
concomitantly reduced, so that the cranial cavity forms one half
of the leno-th of the skull. The
noted in the Drill. In Ma-
cacus nemestrinus, a process of
styliform shape is developed
from the lower end of each
mastoid. The posterior clinoid
plate is largely developed and
is perforated. The cerebellar
fossa is moderately deep ; the
foramen ovale is between the
alisphenoid and petrosal. The
entry to the rhinencephalic
fossa is contracted by a pair of lateral processes.

In the still smaller Monkeys {Cercoplthecus, fig. 353) the
cranial cavity forms a larger portion of the skull. In C. ruber,
the alisphenoid joins the parietal on the left side, not on the right.
In all the premaxillaries rise high between the maxillaries and
nasals : the interior of the cranium shows the cerebellar pit of the
petrosal, and the well-developed crista galli dividing the deep
rhinencephalic fossa. The postglenoid process is pointed, and in
some ( Cere, albogularis) the mastoid also :
the entocarotids pierce the petrosals. The
Doucs (^Sernnopithecus) have a similar pro-
portion of cranial cavity : in which the
cerebellar fossa of the petrosal is both large
and deep. The entry to the rhinencephalic
fossa is constricted by the approximation of
its lateral margins, which almost touch at
the middle. The foramen ovale is between

the petrosal and the alisi)henoid. The tympanic air-cells extend
into the mastoid and squamosal.
The bony septum between the
orbital and temporal fossae is
entire in all Catarrhines.

In the Gibbons (^Hijlohates,
fig. 354) the jaws are more
shortened, the cranium more ex-
panded. The alisphenoid is per-
forated by the foramen ovale, and
joins the parietal. The premax-
illaries do not reach the nasals. Sia.naag (Uulohates syndacUjlm). LXIX-,

353

Skull of Monkey {Ceropithecus
ruber).

354

534

ANATOMY OF VERTEBRATES.

The petrosal still shows the cerebellar fossa : its exterior surface
is no longer swollen into a cellular bulla, but exhibits a well-
marked eustachian process. The ento- and post-glenoid processes
are well developed. The orbital border is thick and prominent,
but the superciliary portions do not meet above the nasal. In
the skull of a young Gibbon I have seen the exceptional exten-
sion of the frontal backward to the occipital, as in fig. 239 ( Cehus).
The mandibular symphysis is more nearly vertical and the angle
more produced in the Siamang than in other Gibbons.

In the Orangs and Chimpanzees the foramen ovale is pierced

in the alisphenoid, and the
entocarotid traverses the
petrosal, which has no cere-
bellar pit. The cranial and
facial parts of the skull
are about equal in the adult
males, with fully developed
laniary canines : in the fe-
males, with smaller canines,
the jaws are less ; and the
cranial cavity predominates
still more in the immature
individuals. In some va-
rieties of Orang [Pithecus
Satyi'us, fig. 355) the cra-
nium rises higher than in
others : and this feature is
increased, in old males, by
the growth of the parietal crest, Avliich bifurcates anteriorly, de-
fining a flat triangular space upon the frontal, and posteriorly to
form the lambdoid crests, — a provision, as in Carnivora, for the
large and powerful temporal muscles. The superorbital ridge does
not project above the nasal bone : this, usually single and small, is
flat. The premaxillaries coalesce with the maxillaries when the
sockets of the permanent laniaries are developed : and about the
same time the basisphenoid coalesces with the basioccipital. The
sphenoidal sinus is almost wholly formed by the presphenoid, and
it is divided by a longitudinal septum. The lower border of the
basi-occipito-sphenoidal floor of the cranium is parallel with the
bony palate or floor of the nostrils. The plane of the occipital
foramen forms an open angle with the straight basi-occipito-sphe-
noidal line. The alisphenoid, 6, joins the parietal, 7 ; the precondy-
loid foramina are usually double on each side. The mastoid is not a

Orang {P'dhccu^ Sotijrus, male), cii

SKELETON OF QUADRUMANA. 535

prominent process ; the tympanic air-cells are continued therefrom
into the squamosal. The interorbital sinuses do not ascend to
within half an inch of the upper level of the orbits, and there is
consequently no proper frontal sinus : a cancellous structure occu-
pies the usual place of this, beloAv which the part of the interorbital
septum formed by the hinder crista of the nasal bone and the
frontal presents a very compact dense structure. The small venous
canal continued from the foramen c^cum traverses the base of this
septum to terminate at the lower end of the short nasal bone.
The ' lamina perpendicularis tethmoidei,' or coalesced prefrontals,
presents a quadrate form. The floor of the nasal cavity is long
and thick, as compared with that in Man, and a larger proportion
of it is contributed by the premaxillary. The orbits are directed
forward and have a full oval shape. The area of the nasal cavity
equals more than one third of that of the cranial cavity. The
most anterior part of this cavity is formed by the deep, narrow,
and well-defined rliinencephalic fossa : the ^ crista galli ' is rudi-
mental. The division of the prosencephalic compartment, for the
anterior and middle lobes of the cerebrum, is very slightly
defined by the orbitosphenoid. The tentorial ridge is not con-
tinued backward beyond the petrosal. The nasal end of the
incisive canal is divided by the process extending from the pre-
maxillary to the maxillary ; but this is the only part of the pre-
maxillary which does not coalesce with the maxillary. The
turbinal plates are less developed than in the Gorilla ; the lower
one is shorter than the one above ; and there is not any plate
answering to the small superior turbinal in the Gorilla and in
Man. There is, in some Orangs' skulls, a process, formed by the
anchylosed base of the stylo-
hyal, which is defended in
front by a low and obtuse
vaginal process. The com-
pact wall of the mandibular
symphysis is thick and dense.
The symphysis slopes from
above downward and back-
Avard.

In the genus Troglodytes,
the squamosal, fio-. 356, 27, ^, . ^ ,

-■■ . , *^ . , Cbiinpaiizee {Troglodytes niger, male), cm-.

usually articulates with the

frontal, 11 ; the premaxillaries coalesce with the maxillaries earlier
than in Pithecus, the alveolar part of the suture being obliterated
before the nasal portion ; the palatal part long remains. In the

536

ANATOMY OF VERTEBRATES.

smaller species of Chimpanzee (Tr. niger) the temporal ridges
meet, in old males, upon the sagittal line, but rarely develope a
crest : the lambdoidal boundary-ridges are better marked.

Independently of the superiority of size of the Tr. Gorilla
over the Tr. niger, the skull of the former, figs. 357 — 359,
presents well-marked differences of form, differences in the deve-
lopement and proportions of the intermuscular ridges, in the dis-
position of certain sutures, and in the structure and proportions of
certain teeth. Compared in profile, the skull of both species,
figs. 356 and 357, presents a striking difference from that of
the Orang, fig. 355, in the prominence of the superorbital ridge ;
but the temporal ridges, after their junction upon the frontal,
rise, in the Tr. Gorilla, into a strong and lofty sagittal crest,

which is continued to the
lambdoidal crest, the great
extent of which masks the
posterior convexity of the
occiput. The zygoma-
tic arch is proportionally
much stronger in the Go-
rilla, and also differs from
that in Tr. niger by the
squamosal part being of
equal depth with the malar
part, and by its having its
upper border convex, or
produced into an angle
instead of being straight
or slightly concave. The
alisphenoid is longer and narrower in Tr. Gorilla, and contri-
butes less to the back wall of the orbit than in Tr. niger, in
which it forms a much smaller proportion of that part than in
Man. The spheno-maxlllary fissure is not only larger in Tr.
Gorilla, but is narrower and more vertical, not angularly bent
as in Tr. niger. The extent of the premaxillary bones below
the nostril is not only relatively but absolutely less in Tr.
Gorilla, and the profile of the skull less convex at that part,
or less ' prognathic,' than in Tr. niger. The breadth of the pre-
maxillaries and of the incisor teeth is the same in both, whilst
in all other dimensions the Tr. Gorilla greatly surpasses the
Tr. niger-. this is seen in the height of the sagittal crest, the
thickness of the great superorbital bar of bone, the prominence
of the ectorbital walls, and of the inferior tumid malar boundaries
of the orbits, fig. 358, 26. The nasal bones have united together

Gorilla (Tr. Gorilla, male), cii

SKELETON OF QUADRUMANA

537

in Tr. Gorilla as in Tr. niger^ but less completely, a linear indi-
cation of the median suture remaining along the exterior surface :
the coalesced upper portions of the nasals ascend higher above
the nasal processes of the maxillary than in Tr. niger, become
contracted between those processes and there project slightly,
their median coalesced margins being produced forward : they
expand at their lower halves, and articulate not only with the
maxillaries, 21, but with an expanded superior portion or dis-
memberment of the premaxillaries, 22. In the immature Tr.
niger, the maxillo-premaxillary sutures show that each pre-
maxillary bone terminates above in a point which does not
reach the nasals. The orbits have
a more subquadrate form, with the

358

.^

Gorilla, cm

angles rounded oiF, in Tr, Gorilla
than in Tr. niger ; but their peri-
phery is less sharply defined, espe-
cially below, than in Tr. niger. The
ethmoidal cells are more swollen
out, giving the interorbital space
a greater breadth below and the
lachrymal fossae a more anterior
aspect in Tr. Gorilla. The infra-
orbital canal issues upon the face
relatively lower and further from the
orbit. The whole nasal bone is rela-
tively longer, and the distance from
the orbits to the external nostril greater in the Tr. Gorilla.
The malar bone, 26, is more convex outwardly, and is more remark-
able for its vertical extent : it is flatter and developed more trans-
versely in the Tr. niger. The larger proportional size of the
canines in Tr. Gorilla impresses a corresjoonding difference upon
the alveolar part of the maxillary bone in that species. Fig. 357
contrasts the broad flattened superoccipital surface of the Gorilla
mth the convexity of the same part in the Tr. niger, fig. 'd5Q> : the
difference is due to the much thicker and broader lambdoidal
ridge in the larger species, which prolongs the surface beyond the
cerebellar fossa, and gives the condyles and foramen magnum a
rather more advanced position as compared with the Tr. niger.
The next character, ex[)licable in relation to the greater weight of
the skull to be poised upon the atlas, is the greater prominence of
the mastoid processes in the Tr. Gorilla, which are represented
by only a rough ridge in the Tr. niger. These protuberances are
cellular, and with a very thin outer layer of bone in the Tr.
Gorilla. The lower surface of the long tympanic or auditory

538

ANATOMY OF VERTEBRATES.

359

process is smooth and flat, or slightly concave, in Tr. niger, and
developes a slight tubercle anterior to the stylo-hyal pit : in the
Tr. Gorilla the same process is more or less convex below, and
developes a ridge, answering to the vaginal process, on the outer
side of the carotid canal. The processes posterior and internal to
the glenoid articular surface are better developed, especially the
internal one in the Tr. Gorilla, than in the Tr. niger : the ridge
which extends from the ecto-pterygoid along the inner border of the
foramen ovale terminates in Tr. Gorilla by an angle or process
answering to that called ' styliform ' or ^ spinous ' in Man, but of
which there is no trace in the Tr. niger.

The palate is narrower in proportion to its length in the Tr.

Gorilla, but the premaxillary
portion is relatively longer in
Tr. niger. Two anterior palatine
foramina, one on each side the
almost confluent incisive fora-
mina, are more constant and
conspicuous in Tr. Gorilla : the
posterior palatine foramina are
nearer the posterior border of
the bony palate in Tr. niger.
The pterygoid fossa? are relatively
deeper and longer in Tr. niger.
The stronger zygomatic arches,
with the more developed sagittal
and lambdoidal crests, are adap-
tive developments concomitant
on the presence of larger ca-
nines and stronger mandible in
the Gorilla ; but the larger proportional molars and the smaller
proportional incisors, the prominence of the nasal bones at
their median line of coalescence, and the reappearance of the
premaxillarles upon the face above the nostril with their longer
enduring sutures, constitute a series of diff'erential characters of
more importance than such as are due to greater bulk or activity
of muscles, and are inexplicable by the operation of external in-
fluences. The basi-hyal, as in the Chimpanzee, is deeply excavated
behind : the cerato-hyals are obsolete : the thyro-hyals long and
nearly straight. Further characteristics of the skull of the highest
known Quadrumanous species will be shoAvn in comparison with
the cranial characters of the lowest races of Man.

C. Bones of the Limhs. — In Quadrumanes, as in Quadrupeds,

Base of skull, Gorilla, ciir.

SKELETON OF QUADRUMANA. 539

both pairs of limbs are concerned in support and locomotion ; but
are made prehensile in relation to an arboreal sphere of life by
an opposable thumb-like condition of the innermost of the five
digits, always conspicuous upon the hind-limbs, and, in most, upon
the fore-limbs. Complete clavicles, and an elbow-joint allowing
both rotatory and flexile movements of hand and fore-arm, are
present in all.

The scapula of CMromys^ fig. 343, 5i, differs from that of Rodents,
and resembles that of Lemurs, in the proportions of the pre- and
post- spinal fossae. The subscapular surface does not show the inter-
muscular cristiB which are usually so well marked in Kodents.
The length of the acromion, a, is 6 lines ; that of the coracoid is 7
lines : it is a simple compressed process. The glenoid ca\ity is a
long oval, with the apex above and rather produced. The clavicle
has a double bend upward and outAvard, and a half twist on itself.

The head of the humerus, 53, has a long-oval form, regularly
convex, and surpassing in both breadth and length those dimensions
of the glenoid cavity. The great tuberosity projects on one side
to the same height ; the small tuberosity is somewhat lower. A
sharp deltoid ridge extends from the fore part of the great tube-
rosity halfway down the shaft. The supinator crest begins belov/
the middle of the shaft, near its back part, standing well out, and
thence passes in an almost straight line to the ectocondyloid tube-
rosity. The internal ridge projects from nearly the fore part of
the distal fourth of the shaft, bridging over the humeral artery
and median nerve on its way to the entocondyloid tuberosity
where it coalesces with a shorter and sharper ridge, completing
the epicondyloid foramen. The inner tuberosity is much more
prominent than the outer one. The anconeal fossa is oblong,
of moderate depth, and imperforate. The tubercle for the radius
forms nearly half of the fore part of the elbow-joint ; the back
part is exclusively formed by the well-defined trochlear cavity
for the ulna. The humerus reaches to the tenth rib, when bent
upon the chest : and this proportion of length is characteristic of
most LemuridcB.

The radius, 54, is of equal length Avith the humerus ; the head is
nearly circular. The ulna, 55, is the longest bone of the fore-limb :
it is compressed below the humeral joint, and gradually narrows
to the lower fifth of the shaft.

The wrist-bones, 56, are ten in number, including a supplemental
sesamoid on the outer side of the scapho-trapezial joint. The
scaphoid is the longest, presenting its convex articular surface to
the outer two thirds of the radial concavity, and articulating with

540 ANATOMY OF VERTEBRATES.

the lunare, which completes the wrist-ball ; at its distal surface it
joins the ' intermedium,' the trapezium, and the trapezial sesamoid :
the cuneiform offers a cup for the hemispheric end of the styloid
process of the ulna and a flatter surface for the pisiform ; this
wrist-bone is long, and its articular surface is divided between the
ulnar process and the cuneiform. The intermedium and cunei-
form combine to form the cup for the ball common to the magnum
and unciform, of which the latter bone contributes the larger
share. The intermedium articulates with the trapezoid. The
distal series of carpal bones have the usual relations to the
metacarpals. The first, second, fifth, and fourth metacarpals, 57,
progressively increase in length, with similar proportions as to
thickness ; but the middle metacarpal is double the length of the
second, and suddenly contracts into a shaft more slender by half
than the contiguous metacarpals. The phalanges of the same
digit. III., are filamentary, and support the hooked probe-like finger
adapted for the extraction of the xylophagous larvas — the favourite
food of the Aye-aye — from the canal in the Avood which has been
exposed by the scalpriform incisors.

The ilium, 62, is long and narrow, slightly expanded at both
ends : it articulates with the two first sacral vertebrrs, just touching
the second by a projection above its middle. The iliac bones
incline to the acetabula at an angle of 140° with the lumbo-
sacral axis. There is an elongate tuberosity above the acetabu-
lum for the origin of the rectus femoris. The ischia, 63, are
continued almost in a line mth the ilia, the posterior contour
describing a very feeble curve concave backward ; the tuberosities
are slightly everted : a small projection behind the lower part of
the acetabulum divides the great from the small ischiadic notches,
both of which are very shallow. The obturator vacuities are
large. The pubic oones, 64, pass from the acetabula at almost a
right angle mth the ilio- ischial axis ; they converge to a short
symphysis. There is a slightly marked ilio-pectineal promi-
nence. The femur, 65, has a straight shaft, one third longer
than that of the humerus. The neck is short: the great tro-
chanter rises to the height of the head, and at the outer and
lower part is developed into a small tubercle. Opposite to this
the lesser trochanter projects from the inner side to a greater de-
gree. The orifice for the medullary artery is at the back part, one
fourth of the length from the head ; the canal ascends. The inner
condyle is rather the larger. The outer border of the rotular
groove projects most. There is a sesamoid bone ( ' fabella ' ) in
each origin of the gastrocnemius. The tibia, 66, is about two

SKELETON OF QUADRUMANA. 541

lines shorter than the femur, and soon contracts below the head
to a compressed shaft, giving a long and narrow subelliptic section ;
at the upper half it is very slightly bent, with the convexity
forward. A roughish surface is continued from the tuberosity
nearly one third of the way down the fore and outer part of the
shaft. The orifice of the medullary canal is one fourth of the way
down, just within the posterior border ; the canal slopes downward.
The tibials one fifth longer than the ulna. The fibula, 67, touches
the tibia only by the two extremities articulating mth that bone,
lea\ang an interosseous space co-extensive with their shafts. The
outer malleolus is shorter and thicker than the inner one. There
is a sesamoid in the external lateral ligament of the knee-joint, at
its insertion into the head of the fibula.

The tarsal bones, 68, are seven in number. The naviculare has
its shallow concavity for the astragalus supplemented by the
strong ligament arising from its posterior and inferior margin, and
inserted into the fore part of the inner malleolus ; anteriorly it
articulates with the three cuneiform bones, and externally at its
fore part with the os cuboides: its depth exceeds its leno-th.
The calcaneum offers two articular surfaces to the astragalus,
rather far apart ; the lever projects moderately beyond the hinder
surface, and is curved a little upward and inward. The ento-
cuneiform offers at the anterior half of its outer part a trochlear
surface, concave in one direction, convex in the opposite, to
the powerful hallux. The meso- and ecto-cuneiform bones are
narrower, the outer one is of nearly equal length with the inner,
the middle one being the shortest. The cuboid is large and
long, with the lower half of its calcaneal surface convex, the
upper half concave, for an interlocking joint with that bone;
it is grooved externally and beneath for the peroneus longus,
and, as usual, supports the two outer toes. The base of the
metatarsal of the hallux is broad, and its under border is pro-
duced into contact with that of the second metatarsal. The
third metatarsal is a little longer than the second ; the fourth
has nearly the same length, and so has the fifth, 69, by reason of
the backward production of the outer angle of its base. The
proximal phalanx of the fourth toe is the longest. Fig. 343 shows
how little the phalanges of ii-v differ in length or breadth.

With the exception of the attenuated state of the third digit
of the fore-foot, the characters of the limb-bones of Chiromys
are closely repeated in other Lemuvid(B. The Pottos {Perodic-
ticus), however, offer an anomaly, in the fore-hand, by the
stunted phalanges of the index digit ; and the poUex is large and

542

ANATOMY OF VEETEBKATES.

360

opposable, fig. 343, b. The Galagos ( Otolicnus) and the Spectres
are, also, exceptional, by the excessive length of the calcaneum
and naviculare in the hind-hand, whence the generic name Tar-
sius given to the latter Lemurs. In the relative length of the
tarsus to the leg and to the rest of the foot Chiromys most re-
sembles Lichanotus and Pj^ojnthecus : it is rather shorter than
in Lemur proper, being less than one third the length of the
tibia, and only about one fourth the length of the whole foot.
The scaphoid and calcaneum are proportionately rather shorter
than in Lemur jjerodicticzcsK

In the Indri (^Lichanotus) the scapula is remarkable for the
length and strength of its coracoid process. The humerus, as in
Chiromys, is perforated above the inner condyle, but not between
the condyles. The interosseous space is consider-
able between the long and slender radius and the
more slender ulna. The ilium has a strong tuber-
cular process above the acetabulum. The femur
is so long as to equal in length seventeen verte-
bras of the trunk, measured from the first dorsal
backwards. The fore part of both the astragalus
and calcaneum is unusually produced. In the
slender Lemur {Stenops gracilis) the humerus is
perforated above the inner condyle, and has a
Avide intercondyloid vacuity. The iliac bones, fig.
360, a, are long, slender, and extended almost in
the same line with the sacrum. The pubic bones,
b, c, join the ilia at a right angle, and are in-
clined to each other at an angle of 40° ; they form
a very short symphysis. There is a small ossi-
fied patella. The feeble development of the vertebrae in the long
lumbar region, the small sacrum, and contracted pelvis are points
of resemblance with the Bat-tribe ; and, together with the long
and slender bones of the extremities, relate to the slow move-
ments of this climbing quadruped.

In Lemur Catta I have found the pubic symphysis ossified ; the
ilium has an epicotyloid ridge. The coracoid and acromial pro-
cesses of the scapula are subequal. The humerus is perforated
above the inner condyle. Two fabellas are usually attached to
the capsule of the knee-joint. The fourth digit is the longest
on both limbs of all LemuridcB.

In Hapale Jacchus the coracoid sends a short process backward.

* The tarsal bones figured as those of Chiromys in civ. ' Lemurs,' pi. v., belong to
the Otolicnus crassicaudatus, cir. p. 35.

Pelvis of tlie slender
Lemur.

SKELETON OF QUADRUMANA. 543

The humerus is not perforated either above or between the con-
dyles. The ungual phalanges are compressed and falcate, and the
pollex is on a line with the rest of the digits of the fore-limb, not
opposed to them. In the hind-limb the ungual phalanx of the
hallux is depressed for the support of a nail, and it is opposed as
a thumb to the other digits which have falcated ungual phalanges.
The ilium is long and narrow, with a supracotyloid ridge. In the
Marmoset ( CalHthrix sciureus), the pollex is partially opposable ;
as it is also in Cebus. In a young C. capucinus I have found the
humerus perforated both between the condyles and above the
inner condyle. There are fabellae behind the knee-joint. A sesa-
moid is wedo-ed between the entocuneiform and metatarsal of the
hallux. A pair of sesamoids are developed beneath the proximal
joints of each of the toes, and a single sesamoid beneath the last
joint of the hallux.

In the Spider-monkeys (Ateles) the long and large coracoid
has an angular tuberosity, which sometimes joins the anterior
costa, so as to circumscribe the prescapular notch. The humerus
is not perforated either above or between the condyles. This
bone, and, still more, the radius and ulna, are remarkable for their
length and slenderness ; as are also the bones of the digits, wdth
the exception of the pollex, which is reduced to a rudiment of its
metacarpus, and is concealed beneath the skin in the recent
animal. The femur, tibia, and fibula are longer than in the
other Platyrrhines, but the tibia is not attenuated in the same
proportion. The inner border of the naviculare is much produced.
The thumb of the hind-foot is complete and well-developed. The
prehensile tail compensates for the loss of that quality in the hand.

In the Catarrhine group the African Doucs ( Colohus) repeat
the abortive condition of the pollex ; but in all the rest it is a true
thumb, though smaller and weaker than that of the hind-hand.

In the Baboons the coracoid shows an angular ridge, but less
developed than in the Capucins. In Macacus nemcstrinus the
short and broad coracoid has an angular tuberosity. I have ob-
served an intercondyloid vacuity in this species ; but, as a rule,
the humerus is imperforate at its distal end. The ' intermedium '
is present in the carpus of all Baboons, Macacques, and Doucs,
as in the Gibbons and Orangs, fig. 361, A; and there are fabellie
behind the knee-joint. In most there is an ossicle, ib. i, wedged
between the scaphoid, «, and trapezium, d, in the wrist, and
between the cuboid and fifth metatarsal in the ankle. The
ischia expand into rough flattened tuberosities in all those Catar-
rhines that have the corresponding dermal callosities.

544

ANATOMY OF VERTEBKATES.

In the Long-armed Apes {Hylohates, fig. 180) both acromion
and coracoid are large, and much produced. The clavicles are of
unusual length, equalling the extent of the eleven anterior dorsal
vertebrae. The bones of the arm and fore-arm are still more
remarkable for their length and slenderness, as well as those of
the fino-ers of the hand, the thumb of which is comparatively
short and slender. The femur is long and nearly straight. The
tibia is slightly bent. The thumb of the hind-foot is strong and
well-developed, with two phalanges.

The great length of the pectoral limbs, and the provision made
for the extensive origin of some of their muscles by the breadth
of the thorax and the size of the scapulae and clavicles, relate to
the chief share which these limbs take in the rapid and character-
istic locomotion of this species, which swings itself thereby from
branch to branch, with a force that propels the body through
considerable distances.

The Siamang offers the peculiarity of a common tegumentary
sheath of the proximal phalanges of the second and third digits
of the hind-hand, whence the name {Hyl. syndactylus).

In the Orangs (Pithecus) the clavicle is less curved than in

361

Carpus of the Oraiig. lxix-

Man, and the distal end is less expanded. The scapula approaches,
by its breadth, to the form of that of Man, but the acromion is
narrower, longer, and more antroverted. The humerus, in some
Orangs, shows a small perforation between the condyles. The

SKELETON OF QUADRUMANA. 545

radius and ulna are remarkable for their length, and the extent
of the interosseous space. The wrist, fig. 361, consists of nine
bones, as in the inferior Apes, — resulting, as in them, from the
presence of the intermedium, h : the scaphoid, a, and lunare, b,
articulate with the radius ; the cuneiform, c, is attached by liga-
ment to the styloid process of the ulna ; the ' sesamoid,' i, is
imbedded in the tendon of the abductor longus pollicis. The
metacarpals have only half the breadth of the proximal phalanges
at their middle part. The phalanges are long, bent towards the
palm, and expanded at their middle. The bones of the thigh and
leg are disproportionately short : the articulation of the latter with
the tarsus is adjusted to turn the sole obliquely inward. The
hallux is disproportionately short, and, in some Orangs, has but
one phalanx. The bones of the other toes have great length,
especially the metatarsals and proximal phalanges, which are bent
toward the sole, indicating the habitual application of the foot in
the act of grasping and climbing. The joint of the hind-limb is
made as free as that of the fore-limb, by the absence of the inter-
articular ' ligamentum teres.' The calcaneum projects but little
beyond the astragalus, the tibial surface of which is inclined
obliquely inward, so that the foot presents its outer edge to the
ground, — a mode of articulation favouring its prehensile power.

In the Chimpanzee, fig. 345, the clavicle, 58, is relatively
shorter than in the Orang ; the sigmoid curvature is more marked,
the sternal end is thicker, and the acromial end broader : the
scapula is longer in proportion to its breadth, and the acromion is
broader than in the Orang. The bones of the anterior extremity,
especially those of the fore-arm, are shorter than in the Orang.
The humerus, 53, is imperforate at its distal end ; it is shorter
and stronger than the Orang ; both tuberosities are more deve-
loped, especially the inner one, and the bicipital groove is deeper :
the antero-internal surface, bounded outwardly by the deltoidal
ridge, is flatter than in the Orang : the supinator ridge commences
above the middle of the shaft. The trochlear prominence of the
distal articulation is more developed, and the canal which sepa-
rates it from the ball for the radius is both deeper and wider.
The radius, 54, is shorter in proportion to its breadth, and pre-
sents a more marked sigmoid curvature ; the borders of the
circular proximal end are more produced ; the trihedral character
of the distal half is better marked. The distal end is more sud-
denly expanded, and the grooves for the extensor tendons are
deeper and better defined. The ulna, 55, diifers from that in the
Orang in the proportion of its length and thickness. The outer

VOL. II. N N

546 ANATOMY OF VERTEBRATES.

or ulnar di\asion of the great sigmoid cavity is less developed than
in the Orang, and its margin is more extensively interrupted at
its middle part : the radial division of the same cavity extends
more nearly to the back part of tlie olecranon. The lesser sigmoid
ca^dty is more nearly semicircular than in the Orang. The ridge
continued a short way do^wnward from the inner and ulnar angle
of the great sigmoid cavity is sharply defined, but the fossa which
it bounds is much less deep than in the Orang. The interosseous
ridge is not marked, the bone being there rounded off in the
Chimpanzee. The styloid process is better developed than in the
Orang. The carpus consists of eight bones, as in Man. The
thumb, 1, is relatively longer and stronger than in the Orang.
The pelvis is longer in proportion to its breadth than in the
Orang. The tuberosities of the ischia are expanded, flattened,
and bent outward, as in the Orang. The expanded part of the
ilium, 62, is slightly concave anteriorly, but in the Orang it is
plane. The spine of the ischium is parallel transversely with the
middle of the obturator foramen, but in the Orang it is parallel
^vith the upper border of that foramen. The ilio-ischial angle is
165°. The ischio-pubic symphysis is longer than in the Orang :
but retains its longitudinal parallelism with the sacro-lumbar
series of vertebra?. The posterior wall of the acetabulum is still
the deepest. The bones of the hind extremity are relatively
longer and stronger, especially the femur, than in the Orang ; but
the most marked distinction between the two great anthropoid
Apes is seen in the length and strength of the hallux, i, in the
Chimpanzee. The articulation of the tarsus A\dth the leg still,
however, favours the oblique position of the foot, and adapts it
for grasping. The femur, 65, shows the pit upon its head for the
ligamentum teres : both trochanters are relatively larger than in
the Orang : the neck is longer, thicker in proportion to the head,
and passes oif at a less obtuse angle with the shaft. The shaft
is slightly bent forward ; it is not straight : the condyles are more
expanded, especially the inner one.

In the Gorilla, fig. 346, the scapula is broader than in the
Chimpanzee, but difi^ers from that of Man in the more oblique
course of the spine, wliich gives greater extent to the superior
costa ; in the greater length and breadth of the coracoid, 52 ; in
the straightness of the inferior costa ; and in the greater con-
vexity of the base, especially as it approaches the lower angle :
the plane of the glenoid cavity is less parallel with the base than
in Man, it looks more obliquely upward ; the suprascapular notch
is not defined.

SKELETON OF QUADRUMANA. 547

The clavicle, 58, is thicker than that in Man, with a subtrihedral
shaft and the sigmoid flexure less marked ; the sternal articular sur-
face is less oblong ; the acromial end is broader and flatter below.

The humerus, 53, though surpassing iii length that of Man,
fig. 183, 53, is thicker and stronger in all its ridges and processes ;
especially at the lower extremity, the transverse diameter of
which surpasses that of the upper extremity of the bone in a
greater degree than in Man : both tuberosities are relatively
greater, the ' lesser ' one more especially. Immediately above
the distal articular surface are two depressions divided by a ridge
continued to the prominence between the radial and ulnar arti-
culations ; the outer or radial depression is the smaller and shal-
lower, the inner or ulnar one is larger : it answers to the
* coronoid fossa ' in Man, but becomes a foramen in full-grown
Gorillas, by absorption of the thin plate of bone dividing it from
the anconeal fossa behind. The ectocondyloid prominence is
more marked than in Man : the entocondyloid one is more pro-
duced, is angular, and compressed. The back part of the humerus
shows, as in Man, the musculo-spiral tract dividing the ridges
for the external and internal heads of the ' triceps extensor.'
The configuration of the lower articular surface is closely similar
to that in Man ; the whole surface extends a little further below
the condyloid prominences, allowing to that extent a more free
sweep of the fore-arm in flexion and extension, and adding power
to the leverage of the tendons inserted into the antibrachial bones.

The medullary artery enters the fore part of the shaft, but
nearer the middle of the bone in the Gorilla than in Man : in
both the course of the canal is towards the elbow-joint. The
head of the radius, 54, has an elliptical contour : the shaft bends
outward so as to leave a wider interosseous space than in Man.
The neck expands to the tuberosity wdiich shows an oblong rough
prominence for the insertion of the tendon of the biceps, behind
or ' ulnad ' of the smoother prominence supporting the bursa
interposed between it and the tendon. Below the tuberosity the
shaft assumes a pyriform transverse section through the develope-
ment of the interosseous rido^e, which extends to near the * sis:-
moid cavity.' The styloid process is represented by a prominence
which gives a larger surface than in Man for the insertion of the
tendon of the ^ supinator longus.' It is not impressed, behind or
externally, so deeply by the two grooves for the extensor muscles
of the metacarpal and first phalangeal bones of the thumb : a still
stronger tuberosity divides the fossa for the radial extensors of
the wrist, from the Avider and deeper one for the strong tendons

N N 2

548 ANATOMY OF VERTEBEATES.

of the extensor communis digitorum. The semicircular depression
for the lower end of the ulna is well marked : the distal articular
surface is divided, as in Man, by two concave facets, the larger
one for the os scaphoides, the lesser for the os lunare: the anterior
border of the latter is much produced, giving a greater propor-
tional antero-posterior extent to the ' lunar ' surface than in Man.
The orifice for the ' arteria meduUaris ' is situated as in Man,
and the direction of the canal is ' proximad ' or towards the elbow-
joint.^ The shaft of the ulna, 55, presents two slight opposite
curves, the upper one concave, the lower one convex, on the
ulnar or inner aspect. Viewed sideways the whole bone has a
slio'ht bend convex backward. The lower half of the shaft
becomes subcylindrical as it descends. The ridge, commencing
below the lesser sigmoid cavity, is strongly marked and more
vertical than in Man. The distal end of the ulna suddenly ex-
pands into a convex reniform articular surface, thickest at the
middle, where it plays upon the lateral concavity of the radius.
The difference from the Chimpanzee, most significant of their
relative position in the Quadrumanous series, presented by the
antibrachium of the Gorilla, is its inferiority of length compared
with the humerus ; fig. 346, with figs. 345 and 180.

The bones of the wrist, 56, agree in number and relative position
with those of Man ; but the differences of shape and proportion
give a greater breadth to the carpal segment in proportion to its
length, in the Gorilla. The radial surface is nearly circular in
shape, instead of being oval and oblong as in Man. The pisi-
forme of the Gorilla is much longer in proportion to its breadth
than in Man; whilst the articular surface for the cuneilbrme
is but little larger: its superior length gives stronger leverage
to the great ulnar flexor of the wrist. Tlie trapezium of the
Gorilla differs most from its homologue in Man, by the production
of its outer unarticular surface into two diverging tuberous pro-
cesses : the articular surface, moreover, for the metacarpal of the
thumb is relatively much smaller than in Man. This meta-
carpal, 57, is a little longer than in Man, but not quite so broad :
the proximal trochlea is more concave vertically and more convex
transversely, and the distal surface is more convex. The proximal
phalanx is one fifth longer, and is more slender than in Man.
The metacarpals of the other fingers are more than one third
larger and longer than in Man, their shaft is more bent; the

' It may be noted tliat the hair covering the arm and fore-arm has a direction
corresponding with that of the medullary arteries of the bracliial and antibiacliial
bones.

SKELETON OF QUADRUMANA. 549

tuberosities beneath the proximal articular surfaces are better
developed. The proximal phalanges differ not only in their
greatly superior size, but in the deep excavation of their under
or anterior surface, which is bounded by rough lateral ridges ;
they are also more flattened and rather more bent. The distal
phalanges of the anterior extremity are longer, more slender, and
less expanded at their rough terminations.

Each OS innominatum in the adult male Gorilla, 62, is one foot
three inches in length, that of Man being seven inches and a half:
the breadth of the ilium is eight inches and a half, that of jSIan
being six inches. The ilium is less concave, of a more triangular
figure, the anterior border being much longer and straighter. The
more elongated and narrower form of the sacral surface corresponds
with what has been noticed in the sacrum : the posterior angle or
spine of the ilium is above that surface, not behind it as in Man :
the distance between the antero-superior and antero-inferior spines
is much greater in the Gorilla : the antero-inferior spine is situated,
as in Man, just above the acetabulum. The upper ischiatic notch
is much less deep than in Man, and there is a very feeble rudiment
of the tuberosity dividing it from the lower notch. The aceta-
bulum is not much larger than that of Man : the posterior is
deeper than the upper wall, providing for resistance to the femur
in a semi-flexed rather than in an erect position. The ischium
extends, as in the Chimpanzee, far below the acetabulum, where
it forms a strong subtrihedral column, terminating in a large
flattened outwardly bent tuberosity, the aspect of which is wholly
downward, not backward, as in INIan : the united plates of the
ischium and pubes, bounding the obturator foramen internally,
are considerably broader than in INIan. The plane of the ilium is
twisted almost at right angles with that of the ischium and pubes.

The femur, 65, is shorter than in Man, and much shorter in
proportion to the breadth of the shaft : the head is more relieved
from the neck, and shows a less deep depression for the ligamentum
teres ; the neck is less oblique than in Man ; the great trochanter
rises to a level with the upper border of the head ; the small tro-
chanter is less prominent, but has a larger base than in Man, and
is more remote from the great trochanter. The linea aspera is
less developed, and the back part of the lower half of the shaft is
flat and smooth : tlie inner angle of the popliteal space presents a
well-marked rough depression, which is not present in the Human
femur, and the shaft more gradually expands to the condyles.
The outer articular condyle is narrower than the inner one, the
reverse being the case in Man : the inner condyle is not longer

550 ANATOMY OF VERTEBRATES.

than the outer one, as in Man. The rotular surface is shallower,
the lateral borders are better defined : the medullary artery enters
the middle of the back part of the shaft, and the course of the
canal is proximad or upward.

The length of the tibia is one foot six lines, and its shaft is
as thick as in Man, and expands more gradually to the distal end :
the conformation of the proximal surface is similar to that in Man ;
the spine is rather stronger, and an anterior spine or tuberosity is
more distinctly developed. The internal tuberosity in front of the
fibular one is better defined ; the interosseous ridge is very feebly
marked in the Gorilla, and the anterior ridge of the shaft is much
less marked than in Man, The astragal ar surface is more undu-
lating, less concave, and more directly continued upon the internal
malleolus : the side of the distal end next the fibula, instead of
being concave, forms an angular projection. The fibula is stronger
in proportion to its length than in Man; the lower articular
surface of the fibula is flatter, and divided into tAvo facets more
distinctly, than in Man.

The astragalus of the Gorilla equals in size that of Man,
but is broader in proportion to its length: the surface for the
tibia is less defined, especially from the inner facet, which in the
Gorilla is almost horizontal and appears as a concave inner termi-
nation of the upper surface. The anterior surface is more convex,
especially vertically, and more directly continued into the anterior
calcaneal surface. The inner tuberosity is larger and more ad-
vanced : the Gorilla differs from the Chimpanzee in the greater
size of this process, and in the greater proportional size of the
scajohoid convexity, in which respect its astragalus more resembles
that of Man. The calcaneum of the Gorilla is a lonirer and more
slender bone than in Man, which is chiefly due to the greater
length and slenderness of the posterior or calcaneal process. The
lower surface of the bone is smoother, narrower, and more concave
longitudinally : the groove for the flexor tendons beneath the inner
astragalar surface is wider and better defined: that astragalar
surface is broader in proportion to its length, and there is a deep
longitudinal groove on the outer side below the outer astragalar
surface, which does not exist in Man. The anterior cuboidal sur-
face is placed further from the outer side of the bone than in
Man ; the outer side forming a rough convex protuberance at its
anterior half. The naviculare is one third larger than in Man, the
increase being in its transverse extent, and due to the greater
development of the rough convex protuberance at the inner end of
the bone. The entocuneiform has an equal vertical, but a minor

SKELETON OF QUADRUMANA. 55 i

longitudinal, extent than in Man, and chiefly differs in the con-
vexity of the articulation for the hallux, which articular surface in
Man is nearly flat : this difference is very significative of the dif-
ferent function of the hallux in the two species ; the chief fulcrum
of the foot requiring a firm articulation in Man, but in the Gorilla
great extent of motion for the functions of an opposable grasping
thumb. The metatarsal of the hallux is fully as large as that in Man ;
it differs in the deeper concavity of the proximal articular surface,
and in the more prominent convexity of the distal one. The
proximal phalanx of the hallux also equals that of Man in size ;
the borders of its proximal concavity are less neatly defined. The
ungual phalanx is somewhat less than that of Man, especially in
its terminal rough tuberosity ; it is concave below instead of being
convex. The remaining metatarsals of the foot are much longer
and stronger than in Man ; the upper border is more bent. The
first and second phalanges are larger and more bent. The ungual
phalanges are longer and narrower in proportion than in Man.

In all the characters by w^hich the bones of the foot of the Go-
rilla depart from the Human type, those of the Chimpanzee recede
in a greater degree, the foot being in that smaller ape better
adapted for grasping and climbing, and less for occasional upright
posture and motion upon the lower limbs. The lever of the heel
is relatively shorter and more slender ; the hallux has still more
slender proportions, and the whole foot is narrower in proportion
to its length, more curved towards the planta, and more inverted
in the Chimpanzee.

On a retrospect of the skeletons of the latisternal tailless
Catarrhines, it may be observed that no Orang, Chimpanzee, or
Gibbon has mastoid processes ; they are present in the Gorilla,
but smaller than in Man. In the Chimpanzee, as in the Orangs,
Gibbons, and inferior Simice, the lower surface of the long
tympanic or auditory process is more or less flat and smooth,
developing in the Chimpanzee only a slight tubercle, anterior to
the stylo -hyal pit. In the Gorilla the auditory process is more
or less convex below, and developes a ridge, answering to the
vaginal process, on the outer side of the carotid canal. The
processes posterior and internal to the glenoid articular surface,
especially the internal one, arc better developed in the Gorilla
than in the Chimpanzee ; the ridge which extends from the
ectopterygoid along the inner border of the foramen ovale ter-
minates in tlic Gorilla by an angle or process answering to that
called ' styliibrm ' or ' spinous ' in Man, but of which there is no
trace in the Chimpanzee, Orang, or Gibbon.

552 ANATOMY OF VERTEBRATES.

The orbits have a full oval form in the Orang ; thev are almost
circular in the Chimpanzee and Siamang, more nearly circular, and
Avith a more prominent rim, in the smaller Gibbons ; in the Gorilla
alone do they present the form which used to be deemed peculiar
to Man. The occipital foramen is nearer the back part of the
cranium, and its plane is more sloping, less horizontal in the
Siamang than in the Chimpanzee and Gorilla. Considering the less
relative prominence of the fore part of the jaws in the Siamang,
as compared with the Chimpanzee, the occipital character of that
Gibbon and of other species of Hi/lobates uiRrks well their inferior
position in the quadrumanous scale. The characteristics of the
limbs in Man are their near equality of length, but the lower limbs
are the lousiest. The arms in Man reach to below the middle of
the thigh ; in the Gorilla, fig. 346, they nearly attain the knee ; in
the Chimpanzee, fig. 345, they reach below the knee ; in the Orang
they reach the ankle ; in the Siamang, fig. 180, they reach the sole :
in most Gibbons the whole palm can be applied to the ground with-
out the trunk being bent forward beyond its naturally inclined
position on the legs. These gradational differences coincide with
other characters determining the relative proximity of the Apes
compared with Man.

In the Gorilla, the humerus, though less long compared with
the ulna than in Man, is longer than in the Chimpanzee ; in the
Orang it is shorter than the ulna ; in the Siamang and other
Gibbons it is much shorter. The peculiar length of arm in those
^ long-armed apes ' is chiefly due to the excessive length of the
antebrachial bones.

The difference in the length of the upper limbs, as compared
with the trunk, is but little between Man and the Gorilla. The
elbow-joint in the Gorilla, as the arm hangs down, is opposite the
' labrum ilii,' the wrist opposite the ^ tuber ischii ; ' it is rather
lower down in the Chimpanzee ; is opposite the knee-joint in the
Orang ; and opposite the ankle-joint in the Siamang. The iliac
bones are not so broad in proportion to their length in any ape as
in the Gorilla. In the Orang they are flat, or present a concavity
rather at the back than at the fore part. In the Siamang they are
not only flat, but are narrower and longer, resembling the iliac
bones of tailed monkeys and ordinary quadrupeds.

The lower limbs, though characteristically short in the Gorilla,
are longer in proportion to the upper limbs, and also to the entire
trunk, than in the Chimpanzee : they are much longer in both pro-
portions and more robust than in the Orangs or Gibbons. But the
guiding points of comparison here are the heel and the hallux.

SKELETON OE BIMANA.

55S

362

The heel in the Gorilla makes a more decided backward projection
than in the Chimpanzee ; the heelbone is relatively thicker, deeper,
more expanded vertically at its hind end, besides being fully as
long as in the Chimpanzee. Among all the tailless Apes the cal-
caneum in the Siamang and other Gibbons least resembles in its
shape or proportional size that of Man. Although the foot be
articulated to the leo- with a slio;ht inversion of the sole it is more
nearly plantigrade in the Gorilla than in the Chimpanzee. The
Orang departs far, and the Gibbons farther, from the Human type
in the inverted position of the foot. The great toe which forms
the fulcrum in standing or walking is perhaps the most charac-
teristic peculiarity in the Human structure ; it is that modification
which differentiates the foot from the hand, and gives the cha-
racter to his order (Bima?ia). In the degree of its approach to
this developement of the hallux the quadrumanous animal makes a
true step in affinity to Man. The Orang-utan and the Siamang,
tried by this test, descend far and
abruptly below the Chimpanzee
and Gorilla in the scale. In
the Orang the hallux does not
reach to the end of the metacarpal
of the second toe ; in the Chim-
panzee and Gorilla it reaches to
the end of the first phalanx of
the second toe : but in the Gorilla
the hallux is thicker and stronger
than in the Chimpanzee. In both,
however, it is a true thumb by
position, diverging from the other
toes, in the Gorilla, at an angle of
60 degrees from the axis of the
foot.

§191. Skeleton of Bimana. —
The parts of the bony frame of
Man, fig. 183, are co-ordinated
for station and locomotion on and
by the pelvic limbs, which sus-
tain the trunk erect, and liberate
the pectoral, now the upper limbs,
for other uses.

A, Vertebral Column. — This is disposed in an undulating series
of opposite curves, fig. 362 ; backward in the chest and sacrum,
forward in the loins and neck. The vertebra) which rest on the

Diagram of the curves of the vertoJ)raI column, as
supported on one leg, in the act of walking.

554

ANATOMY OF VERTEBRATES.

363

base of the broad sacral wedge gradually decrease in size to the
third cervical. In regard to breadth, they decrease to the fourth
dorsal, then increase to the first dorsal, and again decrease to the
second cervical. A soft elastic cushion of ' intervertebral ' sub-
stance lies between the bodies of the vertebrae. The distribu-
tion and libration of the trunk, ^^ith the superadded weight of the
head and arms, are favoured by these gentle curves, and the
shock in leaping is broken and diffused by the numerous elastic
intervertebral joints. The expansion of the cranium behind, and
the shortening of the face in front, give a globe-like form to the
skull, which is poised by a pair of condyles, advanced to near the
middle of its base upon the cups of the atlas ; so that there is but
a slight tendency to incline forward when the balancing action of
the muscles ceases, as when the head nods during sleep in an
upright posture. The free or ' true ' vertebra3 are c 7, D 12, L 5.
The metapophysis becomes distinct in the eleventh and well-
developed in the twelfth dorsal, in which the anaj)ophyses are
recognisable, and the diapophyses reduced to tubercles without
an articular facet. The neural spines increase in length and

inclination ' sacrad ' (downward in
Man, backward in brutes) from the
fourth to the twelfth dorsal, and in
length and direction ' dorsad ' from
the fourth dorsal to the last cervi-
cal : they all have tuberous termi-
nations.

The dorsal series of twelve verte-
bra, with all their elements, consti-
tute the * thorax ' in anthropotomy,
fig. 363, the parts of the much deve-
loped hajmal arches, not anchylosed
like those of the neural arches ^\ith
the centrum, being reckoned as
distinct bones. The pleurapophyses
are termed ' costae ' or ribs, the
htemapophyses ' costal cartilages '
being rarely ossified : as many of
the haemal spines as may be ossified
are called ' sternum.' The first and
largest, which longest retains its
individuality, is the ' manubrium,'
it receives the cartilages of the first pair, and part of

Bones of humau thorax, cxxiii-.

fig. 364, h 1

those of the second pair of ribs.

The four succeeding

sternebers,'

SKELETON OF BIMANA.

,55

Deveiopment of human steniuni. cxxi

ib. e, s, s, coalesce to form the ^ gladiolus ' or ' body ' of the
sternum : the sixth piece, which commonly remains distinct, is the
' xiphoid appendage, x.' The parts of the sternum are usually
developed each from a single centre, as at Z», i , 2, 3, 4 : but occa-
sionally, and usually the lower ones, are developed from a pair of
centres, c, 1, 3, 4, as in the
broader breast-bone of the
Gorilla and Orang : a fissure
or foramen may persist as
an anomaly, fig. 364, d, s :
but the union of the pairs
transversely usually precedes
that in a longitudinal direc-
tion. In fig. 364, a repre-
sents the primordial cartilages
of the dorsal haemapophyses
and spines ; ib., Z> and c,
varieties in the ossific nuclei.
Occasionally a pair of tuber-
cles, ib. *d *, indicate epister-

nal rudiments.^ The second to the seventh pairs of costal cartilages
articulate with the sternal body : the second between it and the
manubrium : the seventh between it and the xiphoid appendage :
the first to the manubrium exclusively. The ribs which thus join
the sternum are called ' true ;'
the five remaining pairs ' false,'
and of these the last two are
' floating ' ribs. The propor-
tions of the dorsal pleurapo-
physes, or bony ribs, and
their degrees of curvature,
are shown in fig. 363, in their
position after deep expiration.
In each is distinguished the
' head,' fig. 365, c, the ^ neck,'

/, the ' tubercle,'^, and the ' shaft,' the part of the curve marked
h being called the ^ angle : ' <:/ is the ' sternal,' or rather hasmapo-
physial end to which the shaft usually slightly expands. The first
and last three ribs have a single articular surface on the head : in
tlie rest it is divided into two facets. The tubercular articular
surface is wanting in the last tAvo pairs. When the pleurapophyses

365

The fourth rib: Human.

' cviir. p. 91.

556 ANATOMY OF VERTEBRATES.

of the last cervical or first lumbar vertebrae happen to be elongated
and free, they are added to the numbers of ^ pairs of ribs ' in an-
thropotomical computation.

As a rule, the coalesced pleurapophyses make long ^ transverse
processes ' in the lumbar vertebrae ; in the first of Avhich, as com-
pared with the last dorsal, the centrum is much increased in size,
and the neural spine in extent. The metapophysial tubercles are
also enlarged, but do not project so freely, by reason of the ex-
tension of the articular surfaces of the anterior zygapophyses
upon the inner sides of their base. Tlie anapophysial tubercles
are still distinct. The second lumbar vertebra chiefly differs
from the first by a slight increase in the size of the centrum
and in the length of the diapophysis. The anterior zygapo-
physes are larger and look more directly inwards. Both metapo-
physial and anapophysial tubercles are distinct. The backward
production of the posterior zygapophyses occasioning the deep
posterior emargination of the neural arch is a characteristic dis-
tinction of the Human lumbar vertebrae. Both metapophysial
and anapophysial tubercles continue distinct on the third lumbar
vertebra. The body of the fourth lumbar vertebra, though much
broader, is not longer than that of its homologue, the third lumbar,
in the Chimpanzee. It likcAvise shows a marked diminution in the
antero-posterior extent of the neural arch, occasioned principally
by a diminished length and increased breadth of the posterior
zygapophysis. The anapophysial tubercles are distinctly deve-
loped. The fifth lumbar vertebra is characterized not only by its
superior size, but by the great transverse expansion of the hinder
part of the neural arch concomitant upon the superior develop-
ment and outward expansion of the posterior zygapophyses. The
diapophyses and neural spine are shortened: the anapo2)hyses
appear like a part of the upper border of the base of the diapo-
physis pinched up and produced backwards. The metapophysial
tubercles are separated by a groove from the anterior zygapo-
physes.

The sacrum, fig. 366, consists of five anchylosed vertebra?.
They differ from those of the Gorilla by their greater breadth
and by their anterior concavity both lengthwise and transversely.
The anterior nervous foramina, h, are relatively much larger : the
spinous processes are shorter and thicker. The coalesced pleura-
pophyses, p/, h, of the two anterior sacrals chiefly form the sacro-
iliac joint. The neural arch of the last two sacral vertebras, r/,
c, is incomplete.

The first coccygeal vertebra, ib. c, e, is less flattened and is

SKELETON OF BIMANA.

557

shorter than in the Chimpanzee : the neurapophyses^ h, are longer,
the cliapophyses, c, are shorter : the terminal coalesced vertebrag,
c, d, are reduced to their * centrums.' Each of the three upper

366

Anterior surface and base of human sacrum.

sacral vertebra3 are developed from five primary nuclei, one, fig.
367, «, for the centrum, a pair for the neurapophyses, and a second
pair, h, for the pleurapophyses : the accessory ossifications form,
as epiphyses, the articular
surfaces of the centrums.
In the fourth and fifth
sacrals the transverse pro-
cesses are exogenously
developed.

The spines of the six
lower cervicals are short
and bifurcate. As a rule,
the vertebrarterial canal is
completed in the seventh
as in the other cervicals.

In the atlas there is a tubercle from the hypapophysis repre-
senting the body, and a rough surface on the neural arch in
place of a spine. The vertebral artery perforates the transverse
process lengthwise, and afterwards grooves the neural arch
behind the produced angles of the anterior zygapophysis. The
body is longer and deeper in proportion to its breadth than in
the Gorilla. The surface for the odontoid is more nearly
circular and better defined. The cavities for the condyles are
relatively larger, deeper, with their margins more produced. The

Development of the human pelvis, cv*
A, innominatuni ; ii, sacrum.

558

ANATOMY OF VERTEBRATES.

arterial foramina are relatively larger and the posterior zygapo-
physes are relatively much larger than in the Chimpanzee and
Gorilla.

These differences chiefly relate to the more secure articulation
and support of the vertically sustained head in the Human species,
and to the larger size of the cerebral organ in part nourished
by the vertebral arteries. The develoj^ment of the zygapo-
physes gives a greater antero-posterior extent to those parts of
the atlas, and the transverse processes are thicker in proportion
to their length.

The foregoing observations on individual vertebra} are drawn
from an examination of the vertebras of a male Australian.

B, Skull. Taking the lowest form of Human skull that has
come under my observation, figs. 368-370, the difference is
great and abrupt from that of the highest Ape, in the superior
capacity of the cranium and small size of the face. On a com-
parison of a front \dew, fig. 368, with fig. 358, the cranial dome

368

369

370

Side.
Cranium of a native Australian. XLiv.i

forms the background for all the parts of the skull above the
zygomata. The frame of the orbits is not produced clear of the
dome, so as to project beyond it. The malars and contiguous
parts of the maxillaries have, relatively, much less depth. The
nasals are arched transversely. The bony nostril is larger and
higher in position, rising to between the orbits. The alveolar
border is arched transversely, and the curve is not interrupted by
excessive expansion of the socket of any single tooth. On com-
paring the side views, fig. 369, with fig. 357, the larger cranium
of the savage is still more conspicuous ; the expansion is not only
upward and lateral, but backward and downward, bringing the

' Vol, II. p. 823, no. 530-J.

SKELETON OF BIMANA.

i59

floor of the cavity to the level of the lower teeth, when the man-
dibular ramus rests on a horizontal plane. The supranasal ridge is
not so produced as in the Gorilla. The zygomatic arch is shorter
and more slender; the mandible shows both the angle and the
' mentum,' instead of being rounded off at both ends as in the
Gorilla. But the most important differences are brought out in
the base-views, figs. 370 and 359. In the lowest as in the high-
est Human race, the foramen magnum is placed nearer the centre
of the base of the skull, the anterior end of the condyles reach-
ing the transverse line which equally bisects the base. The con-
dyles are relatively larger. The mastoids are developed into pro-
cesses of the size and form which gave rise to the name. The
zygomatic arches are in the anterior half of this view of the skull,
but are opposite the middle third in the Gorilla. The stylo -hyals
are anchylosed, and are supported anteriorly by a ridge from the
tympanic called the ' vaginal process.' The eustachian process of
the petrosal is shorter. A short styliform process is developed
from the lower and outer angle of the alisphenoid. The glenoid
cavity for the mandibular condyle is deeper, and is formed behind
by the tympanic. There is also a low postglenoid prominence.
The bony palate is much shorter, but is proportionally deeper
and broader, and the teeth are arranged in a full semielliptic con-
tour without any natural interspace, the croAvns being of equal
leno'th. In the Gorilla the alveoli of the molars and canine
of one side are in a straight line, parallel with those of the other
side.

As a general rule the form of the
Human cranium, seen from above,
fig. 371, is a full oval, with the
small end forward, and the largest
diameter across the ' parietal emi-
nences,' fig. 375, c. The bones seen
in fig. 371 are the superoccipital, o,
the parietals, p, and the frontal, F ;
the sutures are the ' lambdoid,' c,
the ' sagittal,' h, and ' coronal,' a.

In fig. 372, O marks the expanded
and outwardly convex superoccipital,
articulated by the ' lambdoid' suture,
c,with the parietal, and by the 'mast-
occipital ' suture with the mastoid :

g marks the poster-inferior angle of the parietal, P, which unites
by the 'mast-occipital' suture with the mastoid: this angle

371

or upper view of human
cranium.

560

ANATOMY OF VERTEBRATES.

372

is impressed on the inner side by the lateral sinus; e is the
^ squamous ' and a the ' coronal ' suture. The frontal, F, is
joined by the "■ external angular process/ i, to the malar, which,
with the alisphenoid, divides the orbital from the temporal fossa.

The alisphenoid, s, and co-
articulated portion of pa-
rietal, /, divide by a broader
tract the frontal, F, from the
temporal, T, as compared
with the Australian. In
more intellectual races the
cranial cavity is relatively
larger, especially loftier and
wider. The fore-parts of the
upper and lower jaws, con-
comitantly with earlier wean-
ing, are less produced, and
the contour descends more
vertically from the longer
and more ])rominent nasals.
The ascending ramus of the
mandible, K, is loftier. The
malar, i, is less protube-
rant, and the mastoid, m, more so.

The vertical longitudinal section, fig. 373, of a well-formed
European skull, best exemplifies, in comparison with fig. 395, the
characteristic proportion of the human cranial cavity. The basi-
occipital, 1, coalesces with the basisphenoid, 5, and this with the
presphenoid, such base of the cranium rising as it advances. The
chief part of the foramen magnum is formed by the exoccipitals, 2 ;
the plane of the foramen looks downward, with a slight inclination
forward. The superoccipital, 3, is expanded and bulged outward
by the cerebellum and posterior cerebral lobes. The petrosal,
perforated by the foramen auditorium internum, is 16 ; betAveen
this and the alisphenoid, 6, is the squamosal ; they contribute but
small proportions to the cranial walls, which are chiefly due to the
expanded neural spines called 'parietal,' 7, and 'frontal,' ii, with
the above-mentioned superoccipital, 3 : i4 is between the 'orbito-
sphenoid ' (' lesser ala of the sphenoid,' in anthropotomy) and the
coalesced 'prefrontals '('perpendicular plate of the ethmoid ' with the
' crista galli,' ib.). The rhinencephalic fossa is shalloAv, ill-defined,
relatively small, and floored by the ' cribriform plates.' In the
nasal cavity the inferior ' turbinal,' d, and the ' middle turbinal,' c,

Skull of a well-formed European.

SKELETON OF BIMANA,

561

are shown. The bony palate arched both lengthwise and trans-
versely is formed by the palatines, 20, maxillaries, 21, and small
confluent premaxillaries, 22, supporting the incisor teeth. Xhe
pterygoid appendage is marked 25.

373

374

Longitudinal vertical section of European skull.

The * liyoid bone,' fig. 374, consists of a ' body ' (basi-hyal), two
'lesser cornua' (stunted cerato-hyals) , and two 'greater cornua'
(thyro-hyals). The body, B, 41, is compressed antero-posteriorly,
curved and extended transversely, with a prominent tubercle from
the fore part, answering to that
which supports the ' glosso-hyal,'
fig. 305, gh, in the horse ; it is not
expanded and excavated behind,
as in Apes. The cerato-hyals,
40, are reduced to mere pisiform
nodules of bone projecting from
the line of union of the basi- and
thyro-hyals. The ligaments which
pass from the ' lesser cornua ' to
the ' styloid processes ' represent
the rest of the ' cerato-hyals ' with
the ' epihyals,' in primitive scle-
rous tissue. The greater cornua,
46, are attached to the body by
an expanded end ; a layer of car-
tilage intervenes to a late period ;
the opposite end is slightly expanded and sometimes bears an

VOL. II. o o

Human liyoid-boue, a upper
nat. size.

562

ANATOMY OF VERTEBRATES.

375

Skull of child at Ijirtli

epiphysis : they are joined by ligament to the thyroid cartilage ; on
which account, although homologous mth a pair of the ' cerato-
branchials' of fishes and batrachians, they are termed ' thyro-hyals.'
The Human skull presents varieties related to sex, age, and
race. Those of sex are exemplified in the smaller size of the female
skull, the more delicate proportions of the facial bones, the minor
prominence of the malars, mentum, and angles of the jaw.

In the skull of the child at birth, fig. 375, the jaws, through the
non-developement of the teeth and their sockets, are relatively
smaller than in the adult ; but the facial angle, owing to the rapid
growth of the brain, is, perhaps, nearer to the Greek ideal, at the
period when the deciduous teeth are in
place: both the cerebral cavity and the
orbits are then relatively greater. The bones
of the face are shorter vertically, through
the non-developement of the ethmoidal and
maxillary sinuses ; the regular convexity of
the forehead is not broken by the promi-
nences of the frontal sinuses. The sutures
of the cranium are more linear, less den-
tated, and more numerous, through the
non-coalescence of the elements of the adult cranial bones. The
angle is more open between the ascending and horizontal ramus
of the mandible : the mentum is vertical or recedes.

In the adult, fig. 371, the vertical extent of the jaws is in-
creased by the growth of the teeth and their sockets, while the
whole face is expanded by the developement of the maxillary

sinuses and olfactory csLxity,
through the full growth of
the nasal and turbinal bones
and of the ethmoidal sinuses.
The palatine arch has ex-
tended backward, and the
posterior nares have become
more vertical. The ascend-
ing mandibular ramus forms
almost a rio-ht angle with
the horizontal one or ' body '
of the bone.

In extreme age, fig. 376, the teeth are lost, the alveoli become
absorbed, and the jaws are reduced in vertical extent to infantile
proportions. The mandibular angle again becomes more open ;
but the chin projects and is brought nearer to the nose when the

Skull of aged Individual

SKELETON OF BIMANA, d6Z

iiioutli is shut. Some of the ordinary cranial sutures of the adult
become obliterated.

The observed range of ethnic variety in the configuration of the
Human skull and proportions of its parts is much more limited
than in domesticated breeds of lower Mammals, e. g. the canine
races. There is no osteological or dental difference of specific
value. Assuming the skull of the Australian, figs. 368 — 370,^
to be the lowest known form, the extent of variation will be
exemplified by comparing the figures given with corresponding
ones of the European skull, figs. 389 — 391. Besides the in-
creased capacity of cranium concomitant with increased size of
the intellectual organ in the educated Man, the orbital rim is
more sharply defined, though thinned and less protuberant ; the
malars are less prominent ; the nasals more prominent and longer :
the alveolar parts of both jaws are more vertical anteriorly, and
their entire extent is less, owing to the relatively smaller size
and less complex implantation of the molar series of teeth ; the
ascending ramus of the mandible is deeper, and the angle less
everted or squared. The profile \aews, figs. 369 and 390, show,
in the Australian, the greater longitudinal and less vertical ex-
tent of the face, the produced jaws and receding forehead, the
deep depression between the superorbital ridge and the shorter
nasals: the base views, figs. 370 and 391, wdiilst exhibiting the
same position of condyles and great foramen in relation to the
erect posture, alike differentiating both extremes of Humanity
from the nearest allied Ape, fig. 359, show the vacuities resulting
from the stronger zygomatic arches and the narrower inter-
temporal part of the cranium in the Australian. The vertical
longitudinal section, fig. 396, also shows, as compared with fig. 373,
the thicker cranial walls of the Australian and the absence of
frontal sinuses. But, whilst the characters brought out by this
comparison are pretty constant in the Australian race, they are
far from being so in the European : and this difference depends
on the comparatively uniform low intelligence and sameness in the
mode of life of the savage as compared with the state of civilized
man. The cranium of the Australian may vary somewhat in the
degree of compression, of shehdng of the roof from the mid-line of
the vertex, of the convexity of the arch from before backward ; and
in the presence or absence of the suture between alisphenoid and
parietal : but besides the narrow cranium, with its contracted
and retreating forehead and the prognathic jaws common to the
Melanian races, the Australian skull is characterized by the thick

' XLiv. p. 823, no. 5;?04.
o o

564

ANATOMY OF VERTEBRATES.

and prominent superorbital ridge, which is continued across the
glabella and overhangs the deep-set, small, and slightly prominent
nasals : another well-marked characteristic is seen in the large
proportional size of the molars, premolars and canines, but more
especially of m i and m 2, and in the almost constant distinction
of the two external fangs of these teeth, in both jaws. In most
skulls the vertex is raised, and the sides of the calvarium slope
away from the sagittal elevation. The sutures are less dentated.
The malar bones are small, but moderately prominent and rugged.
The alisphenoid is narrow, and the squamosal is unusually closely
approximated to the frontal, if it does not directly articulate there-
with. The frontal sinuses are seldom developed.* Between the
extremes brought out by the above comparison lie subjects for
ethnological notice of cranial diversity, seemingly inexhaustible,
of which the following are selected examjiles.

In the diminutive Boschisman race of South Africa, by some
reckoned amono-st the lowest of the aborimnes of that continent,
the cranium, figs. 377-379, is flatter at the vertex and relatively
broader at the parietal protuberances than in the Australian race,
and the forehead, though low and narrow, is more prominent. A
larger proportion of the aHsphenoid joins the parietal. The border
of the orbit is thick and relieved, but the superorbital ridge is
not carried so strongly across the glabella as in the Australian
race, and the origin of the nasals is less sunk : the nasals are
narrower and flatter and the malar protuberances are more re-
gularly convex and prominent. (The prognathic character of
the jaws is afi'ected by the absorption of the alveoli due to age, in
the specimen figured.)^

377 378 379

Skull of Boschisman.

The cranium of the Hottentot ^ resembles that of the Boschis-

' Minor characters, such as the suborbital depression, siipra-niastoid ridge, &c.,
are cited in XLiv. pp. 805-830.

^ XLiv. no. 5357. ^ lb. no. 53-59.

SKELETON OF BIMANA.

565

mau, in the contracted but almost vertical forehead, continued,
^dtli a very slight prominence of the glabella, to the narroAv flat-
tened nasals, and in general shape : the malar bones are equally
prominent, and the facial parts of the maxillaries are similarly
depressed, but the superorbital ridges are less thickened and less
produced. The alisphenoid joins the parietal on both sides of the
head. The molars are small or average-sized. The upper border
of the squamosals is on a level mth the fronto-malar suture. The
superoccipital region rises immediately from the hinder margin of
the foramen magnum.

In a Negro from the Gold Coast, Africa,^ the cranium is large
at the parietal protuberances, though narrow at the forehead.
The nasal bones are broad and flat, but are continued from the
same vertical line as the glabella. The alisphenoids articulate
largely with the parietals. The jaws are produced. The molars
are not larger than in the White races. The cranial walls are
thick in most AYest-Coast Negroes. The uneducated African,
like the uneducated European, has a minor cranial capacity than

Skull of a Green

the educated African or European, but this becomes a race-
character only when, as in the Australians and Tasmanians, all
are sunk in barbarism, or none risen above that oldest known
state of man.

In the skull of a Greenlander, figs. 380-382,- the cranium
presents an elongate form, with the sides sloping from a median
sagittal eminence. The parietal protuberances are feebly de-
veloped. The glabella is not very prominent, scarcely produced
above the root of the nose : the superorbital ridge is thin and
well defined. The nasals are prominent : the upper jaw is pro-

X.L1V. no. 5364.

2 lb. no. 2479.

»66

ANATOMY OF VERTEBRATES.

duced ; but the chief characteristic of the skull is presented by
the large and prominent cheek-bones, the lower border of which
terminates a plane extending from the ectorbital process down-
ward, outward, and forward. The zygomata are long and strong.
The lower jaw is large, with a well-marked chin. These cha-
racters are repeated, mtli slight modifications, in the Esquimaux,
but with varying proportions of length to breadth in the cranium.
Among the Laplanders, with similar characters of zygomata and
jaws, and the sloping of the calvarium from the sagittal line, the
cranium is short, averaging 6*90 inches, mth a breadth of 5*78
inches. But the so-called 'pyramidal type,' as exemplified in
fig. 380, and in most races inhabiting high northern latitudes, and
extending southward in Asia, is associated with both long (doli-
chocephalic) and short (brachy cephalic) crania. Blumenbach's
^ Mongolian ' characters are, in the main, those of Pritchard's
' pyramidal type.' Where much uniformity of manner of life and
of degree of mental power prevails, as, e.g., in the Lapps and
the Esquimaux, a certain constancy of cranial character is asso-
ciated therewith : where difference of work and of social grade
creeps in, then cranial characters become inconstant. This is,
now, manifested instructively by extended comparison of the

skulls of the wide-spread Poly-
nesian peoples. Prognathism
is still the most constant feature
in them, concomitant probably
with late weaning of the infant.
It is a conspicuous character
in the skull of the native of
Tahiti, fig. 383,' in which the
forehead is narrow and sloping :
the parietal protuberances mo-
derately developed and the
cranium of moderate length ; it is narrower and flatter at the sides
than in the White races generally. The nasal bones are prominent.
Of the varieties exhibited by the aborigines of the two American
continents, the works of Dr. Morton ^ give ample evidence.

In the skull of a Macusi Indian, from Guiana, figs. 384, 385,^
the cranium is symmetrically formed, narrow at the forehead,
expanded at the parietal bosses, with the broad and rather low
nasals coming off in a line with the glabella ; the upper jaw is
produced, but the zygomata and the mandible have European
characters.

383

' XLiv. i)u. 5386.

XLiv. no. 5405.

SKELETON OF BIMANA.

367

384

385

Skull of Macusi Indian.

The cranium of a Peruvian of the modern or Inca race is short,
broad, and high, especially behind, owing to the habit of carrying
the infant with the back of the head resting upon a flat board,
the pressure usually producing a slight unsymmetrical distortion of
the occipital part of the skull. The forehead is narrow and receding.
The glabella slightly prominent. In the older race the cranium
was singularly and artificially distorted to the form, e.g., shown
in figs. 387 and 388 ; * in which, with a sudden slope and slight

Front. Side.

Skull of ain-ieut Peruvian, from Tlticaca,
with artificially constricted cranium.

Base.

convexity of the frontal, there is an annular constriction of the
cranium behind the coronal suture; the flattening, constriction,
and elongation having been produced by ligature at that part
during infancy. The nasal bones are large, moderately promi-
nent, and continued forward from the same sloping line with the
glabella. The jaws are much produced, but the chin is well de-
veloped. Notwithstanding the deformity and the low character
imparted artificially to tliis skull, the cranial cavity is as capacious

' XLiv. p. 844.

568 ANATOMY OF VERTEBRATES.

as in other American races : the brain was as large, but was dif-
ferently placed. The transverse line equally bisecting the lower
surface of the skull here crosses the middle, instead of the fore-
part, of the foramen magnum.

In the Indians of the Columbia River, called ' Flat-heads,' the
cranium is deformed by the application of flattened boards to the
frontal and superoccipital regions, occasioning a singularly de-
pressed, broad or side-bulging, subelongate figure. But they re-
semble most other Indians in the large and almost flattened nasals
being continued forward in a line with the glabella. The upper
jaw is produced, and the chin moderately prominent.

The skull of the Patagonian agrees in general shape with that
of the modern Peruvian, the occiput presenting the same height,
breadth, and slight unsymmetrical flattening, but it is distinguished
by its superior size, obviously belonging to a larger race of men.
The frontal sinuses are well developed. The nasal bones are nar-
row, but prominent. The malars are large and prominent. The
upper jaw is moderately produced. In a Fuegian I found the
cranium subelongate, moderately expanded at the parietal bosses,
with a narrow and protuberant superoccipital ; the forehead nar-
row and low. The glabella was i)r6minent, and the nasals pro-
duced. The malars were moderately prominent ; the jaws pro-
gnathic ; the chin well developed. The base of the skull presented
paroccipital protuberances, large styliform processes of the sphe-
noid, and small but distinct eustachian processes of the jjetrosal.
Traces of the maxillo-premaxillary suture remained on the palate.
The molar teeth were of moderate size, worn on the inner border
in the upper jaw and on the outer border in the lower jaw.

In the Indians of the Pampas the head is generally rounded,
nearly ellipsoid, contracted in length and but little compressed
laterally, with a forehead moderately prominent and not falling
back. In the Chiquitos the same character is exaggerated and
the head is nearly circular, while in the Moxos it is more oblong :
this last form is very nearly that of the Guarani, or Paraguay
Indians. The heads of the Caribs, as well of the Antilles as
of Terra Firma, are naturally rounded. The skulls of the
individuals of the continental Caribs are ovate, viewed from
above : the occiput is not flattened as in the Peruvian and
Californian Indians, but is moderately prominent, rounded and
rather narrow. The forehead is narrow and slopes Avith a gentle
curve directly from the interorbital space, which is more pro-
minent than the supraciliary ridges and has no median vertical
impression. The alisphenoid presents a margin of half an inch in

SKELETON OF BIMANA. 569

length to join the iiarietal on both sides of the head. The cheek-
bones and lower border of the orbit are moderately prominent :
the nasal bones are continued with a very slight depression from
the glabellar prominence: the superior maxillary bones are pro-
duced : the lower border of the malar process of the maxillary
bone is slightly concave. The lower border of the orbit is a little
more concave than the upper one : the spheno-orbital fissure is
widely open anteriorly. The cranium of the Macusi Indian, fig.
384, is more oblong and ellipsoid, viewed from above : the fore-
head is broader, the parietal region narrower, or at least not
broader, than it is in the shorter crania of the Carib tribe. The
frontal sinuses cause the superorbital ridges to project beyond the
interorbital space : the malar bones are equally prominent ; the
outer angle of the malar processes of the maxillary bones over-
hangs the concave line leading thence to the alveolar processes.
The general character of the facial part of the skull resembles
that of the Patagoniau Indian, but the prominent convex occiput
and general form of the cranium approach nearer to the Carib
form. The Carib, Guianian, and Columbian skulls all agree in
the roundness or convexity of the occipital region, and differ in
this respect, as well as their more symmetrical figure, from the
skulls of the Peruvians, Chilians, and Patagonians. All the
American skulls manifest the same inferiority in the size of the
true molar teeth as compared with the skulls of the Australians :
the incisors, canines, and premolars, or bicuspides, are not smaller
than in the Black races.

In the average skull of the Chinese the cranium presents the
moderate or medium proportions of length, height, and breadth.
The sagittal region is not unusually elevated. The plane of the
glabella is slightly affected by the frontal sinuses, and the large
and prominent nasals are continued therefrom with a very slight
depression. The malars are large and slightly prominent. The
upper jaw is not produced. The chin is Avell developed. The
paroccipital tubercles are well marked. The chief distinction
which such skull presents from the average form of those of
European races is in the size and prominence of the malar bones.

Most well-formed skulls of educated Whites present the charac-
teristics ascribed by Blumenbach to his Caucasian race. The
contour of the cranium, as well as that of the face, is oval : the
forehead is moderately vertical, high, and broad : the nasal bones
are prominent and well developed : the malars are vertical, and
the orbital boundaries are neatly defined. The upper jaw is not
produced : the lower jaw has the chin well marked.

570

ANATOMY OF VERTEBRATES

The range of variety is, however, considerable. From an old
and well-filled European graveyard may be selected specimens
of ' klinocephalic ' (slope- or saddle-skull), ' conocephalic ' (cone-
skull), ' br achy cephalic ' (short-skull), * dolichocephalic ' (long-

389

390

391

Front. l^i'lf-

Elliiitical cranium of European.

skull), * platycephalic ' (flat-skull), ' leptoce})halic ' (slim-skull),
and other forms of cranium equally worthy of penta- or hexa-
syllabic Greek epithets. There are varieties in the degree of
projection of the supranasal and superorbital ridge, but never at-
taining that exhibited as a constant and specific character in the
Gorilla, fig. 395. There are varieties in the sutures, in the time
and degree of their obliteration,' and in* their intercalated ^ wormian'
bones, &c. &c.

' Rokitanski '^ appears first to have conceived, in relation to the skull of a young
person in which the lower ends, for rather more than an inch, of the coronal suture
were obliterated," that it was the cause of a transverse contraction of the cranium at
that part.

What this skull actually shows is the coincidence of partial confluence of parietals and
frontals with a least transverse diameter at the temporal fossa3, a high and rather
short ci-anium, with a general inferior capacity of the brain-case. But the relation of
cause and eifect in this instance is not reasoned out by the great pathologist. The
ultimate or adult size of the cerebrum is due to inherent, or inherited, capacity of
brain-developement, with the accident of such culture, or of the absence thereof, through
which that developement might be influenced. The growth of the brain governs
the capacity of the cranium, and, in a general Avay, is anterior in the order of the
phenomena : it influences its bony case, moreover, not by mechanical expansion,
but by exciting the modelling action of the absorbents in co-operation with the
arterial depositors of the bony matter. The coronal, sagittal, and lambdoid sutures
are, as a rule, and in the cranium in question, too intricately interwoven to admit of
any forcible drawing asunder. On what facts it is assumed that the obliteration of

* CXi'. Bd. ii. p. 148: — ' Durch seitliche Synostose der Scheitel- und Stirn-beine,
d. h. Verknocherung des seitlichen unteren Theiles der Kranznaht, wird eine quere
Verengerung des Schadels bedingt.'

^ Figured in Lucae, Tafel VIIT.

SKELETON OF BIMANA.

571

392

the proportion of the cranial

The progressive superiority of the cranial over the facial
division of the skull is best illustrated in the Mammalian class ;
but, to show the full gradational extent of diversity, two exam-
ples, in this retrospective summary, are borrowed from lower
vertebrate classes.

In the cold-blooded Crocodile, %. 392, theca\4ty for the brain,
in a skull three feet long, will
scarcely contain a man's
thumb. Almost all the
skull is made up of the
instruments for gratifying
an insatiable propensity to

slay and devour ; it is the material symbol of the lowest animal
passion. ^^.^

In the Bird, fig. 393, the
brain-case has expanded
vertically and laterally, but
is confined to the back part
of the skull. In the small
singing-birds, with shorter beak^
cavity becomes much greater.

In the Dog, fig. 394, the brain-case, Avith more capacity, begins
to advance further forward.
In the Gorilla, fig. 395, the
capacities of the cranium
and face are about equal.
In Man, fig. 396, the cra-
nial area vastly surpasses
that of the face.

A difference in this re-
spect is noticeable between the savage and civilised races of
mankind ; but it is immaterial as compared Avith the contrast in
this respect presented by the lowest form of the human head, fig.
396, and the highest of the brute species. Such as it is, how-
ever, the more contracted cranium is commonly accompanied by
more produced premaxillaries and thicker walls of the cranial
cavity, as is exemplified in the negro or Papuan skull.

the parts named of the coronal suture caused or conditioned (' bedingt ') the trans-
verse contraction of the cranial cavity is not stated. If the mechanical idea prevailed
that obliteration of a suture prevented the previously distinct bones being pulled
apart, so as to allow, or stimulate, disproportionate growth at the margins of the
stretched bones, then we should have expected that the elongation of the cranial box
would have been prevented in the direction at right angles to the obliterated suture,
producing contraction in the longitudinal instead of in the transverse direction.

394

Dog.

572

ANATOMY OF VERTEBRATES.

If a line be drawn from the occipital condyle along the floor of
the nostrils, and be intersected by a second touching the most
prominent parts of the forehead and upper jaw, the intercepted
angle gives, in a general way, the proportions of the cranial
cavity and the grade of intelligence ; it is called the ' facial

395

396

^feo^;^^

angle.'* In the Dog this angle is 20°; in the Gorilla it is 40°,
but the prominent superorbital ridge occasions some exaggeration ;
in the Australian it is 85° ; in the educated White it averages 95°.
The ancient Greek artists adopted, in their beau ideal of the beau-
tiful and intellectual, an angle of 100.

C. Bones of the Limbs. — The Human clavicle, fig. 18vH, 58,
is more slender in proportion to its length, and its curves are
always better marked than in the great Apes : the tubercle for
the conoid ligament is usually more developed. The peculi-
arities of the Human scapula, as brought out by the same com-
parisons, are its great breadth in proportion to its length, the
more transverse direction of the spine and acromion, and the
disproportionate extent of the subspinal as compared with the
supraspinal tract. The upj)er angle is less rounded ; tlie extent
of the upper border between that angle and the superscapular
notch is relatively greater, and is more nearly straight ; the notch
itself is smaller and deeper. The smooth triangular surface near
the origin of the spine, upon which the trapezius muscle glides,
is relatively greater. The surface for the teres minor muscle, on
the outer side of the bone, near the lower border, is broader ; as
is that for the teres major, nearer the lower angle. The deep
part of the subscapular bed, being parallel with the attachment of

• For illustration of other 'angles,' e.g. tlie ' pulato-facial' and ' basi-facial,'
reference may be made to ciii". and ex-, p. 21, pis. x. xi. and xii.

SKELETON OF BIMANA. 573

the spine of the scapula, is situated nearer the upper border
than in the Gorilla or Chimpanzee. The surface for the upper
origin of the serratus magnus is relatively less than in the
Gorilla. The long narrow surface between the obtuse lower
boundary of the subscapular fossa and the lower border of the
scapula is flat, or is less concave than in either the Gorilla or
Chimpanzee.

The humerus of the male Australian, ib. 53, is more slender
than that of the average-sized male European; both show the
inferior developement of the condyloid processes as compared with
the Gorilla ; and the same difference in relation to muscular
attachments is exemplified by the lower tuberosities at the upper
end of the bone. The intercondyloid perforation is occasionally
seen in the Human humerus. The characteristics of the Human
radius, ib. 54, are its greater relative shortness to the humerus
(seldom noted in anthropotomical descriptions of the bone) ; its
more slender and less bent shaft ; the better definition and greater
depth of the grooves for the three tendons acting on the tliumb
at the back part of the distal expansion, and the more produced
styloid process ; whilst the tuberosity above it for the attachment
of the supinator longus is much less developed than in either the
Gorilla or Chimpanzee. The chief distinctions presented, in the
same comparison, by the ulna, ib. 55, are its minor length com-
pared with the humerus ; its greater relative slenderness ; the less
proportional expansion of the proximal end ; the somewhat minor
production of the coronoid process ; and the greater straightness
of the shaft, especially on the side view.

In the Gorilla the hand is an instrument of great power of
grasp, capable of easily sustaining the weight of the body sus-
pended by the fingers : the length and strength of the whole
pectoral limb accord with the mechanical adjustments of the
hand as a hook, and as a crutch in moving along the ground.
In Man the framework of the hand, ib. 56, 57, bespeaks an
organ of varied and delicate prehension ; and the form and 2>i'o-
portions of the whole upper limb relate to the free motions and
complex functions of the instrument. In Man the length of the
three bones of the thumb, i, nearly equals one third the length
of the humerus : in the Gorilla it is little more than a fifth of that
length. The metacarpal of the index digit in the Gorilla is twice
the length of that of the pollex : in Man it is little more than
one fourth larger. Tlie shafts of the proximal and middle pha-
langes of the fingers are less expanded than in the Gorilla ; their
distal ends are broader than the shaft instead of being narrower :

574 ANA.TOJMY OF VEETEBRATES.

the terminal portions of the ungual phalanges are longer, broader,
and flatter than in the Gorilla, considerably so in relation to the
size of the whole hand,' having reference to sustaining the deve-
loped surface for a refined sense of touch.

The ilium, fig. 367, A, 62, ischium, ib. 64, and pubis, ib. 63,
coalescing, the two latter at the sixth year, and both with the
ilium at about the twenty-fifth year, have been described, accord-
ing to the usage of anthropotomy in such instances, as a single
bone, under the designation of ' os innominatum.' The Human
characteristics are strongly marked in this part of the skeleton.^
The ilium is broader than it is long, and is more concave ante-
riorly, fig. 398, 4, than in the Gorilla ; it is also more concave
posteriorly, fig. 397, especially in the vertical direction, in which
it is slightly convex in the Chimpanzee. The sacro-iliac symphysis,
fig. 398,2, 3, n, />, is subquadrate, instead of being long and narrow
as in the Chimpanzee. The ' crest,' a, Z», c, is much thicker and
much more curved ; and both angles or ' spines,' but especially
the posterior one, b, are more produced. These modifications,
and especially the developement of the ' external labrum,' fig.
397, c, relate chiefly to the needful increased surface of attachment
for the large muscles which sustain the trunk upright u])on the
hinder, now become the lower, limbs. The anterior border of the
innominatum, figs. 397, 398, «, e,^, especially that part formed by
the ilium, a, u, r/, is much shorter and thicker, and the ' anterior
inferior spine,' J, is better developed. The acetabulum, fig. 397,
4, is turned more toward the back of the os innominatum. The
great ischiatic notch, m, is shorter, but much deeper ; the spine of
the ischium, Z, is more produced ; the lesser ischiatic notch, k, is
deeper, more concave, but of the same length. The tuberosity of
the ischium, i, is convex, and is continued upon the outer part of
the bone to near the acetabulum ; in the Gorilla and Chimpanzee
it is more flattened, is carried further down from the acetabulum,
and its outer margin is produced or everted. The pubis, q, s, is
shorter and much thicker than in the Chimpanzee. The symphysial
boundary of the obturator foramen, o, is much narrower and less
curved. The oblique groove, t, beneath the pubic boundary of
the foramen in Man is not present in either the Chimpanzee or
Orang-utan. The cotyloid notch, 5, is broader, and the .sym-
physis pubis, fig. 398, ^, is much shorter than in the Anthropoid
apes.

The backward developement of the ilium, b, n, for the ecto-
glutaeus, and the ant. inf.-spine, d, for the rectus femoris, relate to
» ciir. vol. V. pi. 10. 2 II, vqI y pi^ Q

OSTEOLOGY OF BIMANA.

575

the important share taken by both muscles in maintaining the
erect position.

With the outer surface
of the ilium turned to the
observer, as in fig. 397, is
seen the same surface of
both ischium and pubis,
together with the aceta-
bulum; but, in the Gorilla,
the twist of the innomina-
tum is such as to present
only the outer margin of
the ischium, with a side
view of the acetabulum ;
and, in the Chimpanzee,
the o-reater twist brin2:s
the iniier surface of the
pubis into view and almost
excludes the acetabulum.

The sacro-iliac surface
is divided into a ' syndes-
motic,' fig. 398, i, 7, and
a ' synchondrosal,' ib. n, 2, part : the latter is more especially termed
the ' articular,' and some-
times, from its shaj^e, the
' auricular ' part ; it is
united by ' fibro-cartilage '
to the first and second,
and a small part of the
third, sacral vertebrae. The
concavity, 4, is the ' inter-
nal iliac fossa.' The ridore,
5, transmits, like a but-
tress, the weight sustained
by the articular surface, 2,
to the back wall of the
acetabulum : the ridge, 6,
thence continued to the
spine of the pubis, /, is
termed 'ilio-pectineal.'

The human pelvis, formed
by the sacrum, coccyx, and

OSSa innominata, offers mtemal view or the os iunumiuatu.u.

External view of the innominate bone.

398

576 ANATOMY OF VEKTEBRATES.

characters of sex and race. The male pelvis is shown in fig. 183,
62, 63, 64 : the female pelvis in ^g. 399. In the latter the sacrum
is relatively wider, and, anteriorly, it is less concave transversely
above, a, more concave vertically below, b. The ilia are broader
and shorter, with more capacious fossae : the ' obturator foramen ' is
triangular ; the ischial tuberosities are wider apart, and the sym-
physis pubis less deep. An-
^^^ thropotomists call the part

which is above the linea ilio-
pectinea, o, f, and promon-
tory of the sacrum, «, the
' false pelvis ;' that beneath,
the ' true pelvis." Of this
the ' brim,' or * superior cir-
cumference ' e, f, h, incloses
the ' inlet ' ; the ' inferior
circumference,' boumled by
the ischial tuberosities, pu-
bic symphysis, and tip of
the coccyx, incloses the
* outlet' of the ' true pelvis.' The diameter from the sacral pro-
montory, «, to the pubic symphysis, h, is called the ' conjugate ' or
' antero-posterior ' one ; that between the ilia taken at e, jT, or
half way between the sacro-iliac joint and the pectineal eminence,
is the ' transverse ' diameter ; the ' oblique ' diameter is between
the point of the brim nearest the pectineal eminence, c, and the
sacro-iliac joint of the opposite side, d. Of the pehdc outlet two
diameters are noted — the ' antero-posterior ' from the tip of the
coccyx to the lower part of the pubic symphysis, and the ' trans-
verse ' taken between posterior parts of the ischial tuberosities.
The following may be regarded as the normal extent of the
above diameters in the two sexes : —

Auterior view of the female pelvis.

' BRIM.'

MALE.

FEMALE.

In.

Linos,

In.

Lines.

Transverse ,

4

6

5

1

Oblique

4

6

5

0

Antero-posterior .

4

0

4

5

' OUTLET.'

Transverse .

3

3

4

5

Antero-pnsterior .

3

4

4

2

In Man alone are the boundaries of the superior outlet on one
plane : the section through the ilium, in fig. 400, shows this to be
due to the direction of the body of the pubis, which is on the same

OSTEOLOGY OF BIMANA.

577

plane with that of the cotylo-sacral tract of the ilium. In this
section, « «' is the line oi fulcrum falling in the transverse vertical
plane of the trunk ; c c' is the line of iveiglit passing through the
centre of the sacro-iliac joint ; b b' is the line of power, or pubic
projection, giving attachment to the extensor muscles of the thio-h ;
d d' is the line of sacral projection ; e f gives the ' cotylo-sacral

400 401

Section through cotylo-sacral arch : Human
pelvis, cv.

Angles of inclination and axes : Female pelvis, cv,

curve; ' a' Z*' is the pubic arm of the lever; a' c^ is the cotylo-
sacral arm ; a' d' gives the length of the gluteal arm ; c' d' that
of the posterior spinal arm. In the diagram, fig. 401, the lines
a e, e c, mark the angle of inclination of the pelvis, or the ' pelvi-
vertebral angle ; ' f g d gives the inferior angle of inclination of
the pelvis, which is about 10° with the horizon, y d. The two
lines of the superior and inferior planes, when prolonged ante-
riorly, cut each other at c, and include an angle of about 50°,
e cf. The ' sacro-vertebral angle ' is shown at « <? i, which is
about 117° in the male and 130° in the female. The angle abk,
VOL. rr. r r

578 ANATOMY OF VERTEBRATES.

taken through the long diameter of the pubic symphysis, is the
complementary angle of the sacro-vertebral one in the female,
owing to the general parallelism of the pubic with the sacral
wall of the ^true pelvis.' The ' axis of the brim ' is the line I m,
drawn from the centre of the superior plane at right angles
thereto. The ^ axis of the inferior outlet,' n p, is drawn at
right angles to the centre of the inferior plane. The axis of the
pelvic cavity, I o r p,is an irregular parabolic curve, passing from
the fixed axis of the brim and moveable forward, through the
flexibility of the coccyx at its inferior extremity, with the move-
able axis of the inferior outlet, with which it coincides below. ^

The observed range of variety in the Human pelvis is restricted
to some slight difference in the breadth and curve of the sacrum,
in the contour of the iliac crest (fig. 397, a, c, b), in the interspace
between the ant. -superior, a, and ant. -inferior, d, spines,^ and in
proportions that modify the shape of the upper aperture of the
* true pelvis,' w^hereby it might be approximately defined as ' oval,'
' oblong,' ' round,' or even approaching to ' quadrate.' Accord-
ing to my experience, these are not characteristic of race, nor
uniformly concomitant with cranial varieties, as, e. g. the ' round '
pelvis with the ' brachycephalic,' the ' oblong ' mth the * dolicho-
cephalic,' or the * square ' with the ' pyramidal ' form of skulL^
Vrolik^ has noted a more vertical direction of the ilia, and the
proximity of the highest part of the crest to the posterior superior
spine, in the pifelvis of a Negro : I have noted the smaller and nar-
rower iliac bones of an Australian female as compared with an
European ;^ but the size accorded with a general dwarfishness of
stature, and the difference of proportion was too slight to affect
the characteristic human confio-uration of the bone. Save in

o

regard to Europeans, the requisite number of observations of the
pelvis in the same races or tribes of mankind is yet a desideratum.
In the typical Mammalian foot the digits decrease from the
middle to the two extremes of the series of five toes ; and in the
modifications of this type, as traced through the gradations (p. 308,
fig. 193), the innermost, i, is the first to disappear. In Man it is
the seat of excessive developement, and receives the name of ' hal-
lux,' or ' great toe ;' it retains, how ever, its characteristic inferior
number of phalanges. The tendons of a powerful muscle, which
in the Orangs and Chimpanzees are inserted into the three middle
toes, are blended in Man into one, and this is inserted into the
hallux, upon which the force of the muscle now called ^ flexor
longus hallucis ' is exclusively concentrated.

' cv. pp. 133-135. ' XLiv. p 839 (Polynesian). ^ cvi'.

* cvir. •■* XLiv. p. 806.

OSTEOLOGY OF BIMANA. 579

The arrangement of other muscles, in subordination to the
peculiar developement of this toe, makes it the chief fulcrum when
the weight of the body is raised by the power acting upon the
heel, the whole foot of Man exemplifying the lever of the second
kind. The strength and backward production of the heel-bone
relate to the augmentation of the power. The tarsal and meta-
tarsal bones are coadjusted so as to form arches both lengthwise
and across, and receive the superincumbent weight from the tibia
on the summit of a bony vault, which has the advantage of a cer-
tain elasticity combined with adequate strength. In proportion to
the trunk, the pelvic limbs, fig. 183, 65-68, are longer than in any
other animal; they even exceed those of the Kangaroo, fig. 211,
and are peculiar for the superior length of the femur, fig. 183, 65,
and for the capacity of this bone to be brought, when the leg is
extended, into the same line with the tibia, ib. 66. The inner
condyle of the femur is longer than the outer one, so that the shaft
inclines a little outward to its upper end, and joins a neck longer
than in other animals, and set on at a very open angle. The
weight of the body, received by the round heads of the thigh-
bones, is thus transferred to a broader base, and its support in the
upright posture facilitated. The pelvis is modified so as to receive
and sustain better the abdominal \dscera, and to give increased
attachment to the muscles, especially the ^ glutei,' which, com-
paratively small in other Mammals, are in Man vastly developed,
to balance the trunk upon the legs, and reciprocally to move these
upon the trunk. In comparison with that of the Apes the Hu-
man femur is distinguished by its greater length, both absolute
and relative to the trunk, by the more angular and less cylindrical
shape of the shaft ; by its forward bend, and the buttress-like deve-
lopement of the ' linea aspera ; ' by the greater proportional expanse
of the distal end, especially at and above the inner condyle, and
by the greater backward production of both condyles, especially of
the inner one. Only in the Chimpanzee and Gorilla is the ^ cer-
vix femoris ' relatively as long as in Man ; but it stands out at a
different angle, and the femora are parallel, fig. 340, 65, not con-
verging to the knee-joints, through the double obliquity of ^ neck '
and * shaft ' which characterises the human femur, fig. 183, 65. The
great trochanter does not rise so high as the head of the bone in
Man : the small trochanter is more prominent and circumscribed.
The terminal expansion of the shaft is chiefly toward the inner or
tibial side. The major part of the rotular surface is on the outer
condyle.

After the femur, the tibia, 66, is the longest bone of the skeleton

P P 2

580 ANATOMY OF VERTEBRATES.

in Man : in the Gorilla it is the shortest of all the long bones of
the limbs : the Human tibia also differs from that of the Gorilla in
the more equable diameter of the shaft and more parallel contour
of the outer and inner sides, with a considerable reduction of the
interosseous space between it and the fibula. The crest descends
in Man near the middle of the anterior surface of the shaft, with
a slightly sigmoid or wavy course. The lower articular surface
is uniformly concave from before backward, and is continued at
a less open angle and to a greater extent upon the articular sur-
face of the inner malleolus, the articulation with the astragalus
being deeper and firmer than in the Gorilla and other apes. The
outer or fibular malleolus descends in Man lower and more verti-
cally than the inner malleolus, interposing a greater obstacle to
lateral inflections of the foot upon the leg than in the Gorilla. The
foot is shorter in proportion to the leg, in Man, than in any Qua-
drumane, and is so articulated that the sole is directed downward :
the tarsus is longer and narrower. The entocuneiform presents a
flat, reniform surface, anteriorly, to the base of the hallux. The
four outer toes are very slender compared with the innermost ;
and their proximal and middle phalanges are very feeble compared
with those of the Gorilla : all the five toes have the same direction,
forward.^

The osseous texture of the Human bones is remarkable for its
delicacy and finish : it is exemplified in fig. 402 by longitudinal
sections of parts of the three chief bones of the pehdc limb. In
the section of the upper end of the femur. A, the outer, compact
tissue, a, is extremely thin upon the head of the bone, begins to
gain thickness at its under part, and at the corresponding part of
the great trochanter, and increases until it forms the wall of the
medullary cavity. In the cancellous or reticular tissue forming
the substance of the head and neck, a tendency to a radiating dis-
position, diverging from the under part of the neck, and favour-
able to strength, may be discerned in the principal laminae. In
the head of the tibia, B, the compact tissue is also very thin,
where it encloses the reticular structure occupying the proximal
end, and becomes thicker as that structure is absorbed. In both
the tibia and fibula is shown the line indicative of the union of
the upper ' epiphysis ' with the ' shaft : ' and in the femur there
is a similar indication of the epiphysial condition of the great
trochanter.

The more constant sesamoid bones of the Human skeleton,

' For the details of a compari&on of the limb-bones of Man with those of the Apes,
bee cin". vol v. p. 1, pl^. i.-xiii.

SKELETON OF BIMANA. 581

wliich liave an articular facet playing upon a joint, are the
*• patella,' fig. 183, 66^, the pair beneath the metatarso-phalangial
joint of the great toe, and the pair at the corresponding part of
the thumb. Of those playing on surfaces of bone, there is one in
the tendon of the peroneus longus which glides on the groove of

40-2

Sections of A femur, B tibia, and fibula.

the cuboid ; one in the tendon of the tibialis anticus opposite the
smooth facet on the entocuneiform ; one in the tendon of the
tibialis posticus opposite the inner side of the astragalus; and
one (fabella) in the outer head of the gastrocnemius behind the
outer condyle of the femur. The os penis, common in Quadru-
mana, is never developed in Man.

D. Relations to Archetype. — Finally, in regard to the skeleton
of Bimaiia, there remain a few observations on its relations to the
general vertebrate archetype (vol. i. fig. 21), from which it de-
parts so widely.

The skull shows the following extreme modifications. In the
occipital segment the hajmal arch is detached and displaced, as in
all Vertebrates above fish ; its pleurapophysis (scapula, fig. 403,
pi, 5i) has exchanged the long and slender for the broad and fiat
form ; the h^mapophysis (coracoid, o2) is rudimental, and coalesces
Avith 51 : the diverging appendage, 53-57, of this arch becomes the
' pectoral limb.' The nenrapophyses (exoccipitals, 2) coalesce with

582

ANATOMY OF VERTEBRATES.

the neural spine (superoccipital, 3), and next with the centrum
(basioccipital). This afterwards coalesces with the centrum (basi-
sphenoid, 5, c) of the parietal segment. With this centrum also the

403

1' ' ia

Vertebral segments shown In the Human foetal skeleton. CXL.

neurapophyses, called ' alisphenoids,' n, the centrum of the frontal
vertebra, called ^ presphenoid/ and its neurapophyses (orbito-
sphenoids, 10), become anchylosed. The neural spine (parietal, 7)
retains its primitive distinctness, but is enormously expanded, and
is bifid, in relation to the vast size of the brain in Man. The
parapophysis (mastoid, fig. 404, c) becomes confluent mth the
otic capsule (petrosal), the tympanic, d, squamosal, «, and with
the pleurapophysis, called ' stylo-hyal,' fig. 403, 38, of the haemal
(hyoidian) arch. The h^emapophysis is ligamentous, save at its
junction with the haemal spine when it forms the ossicle called
^ lesser cornu of the hyoid bone,' ib. 40, the spine itself being the
basi-hyal, 41. The whole of this inverted arch is much reduced
in size, its functions being limited to those of the tongue and
larynx, in regard to taste, speech, and deglutition. The neur-
apophyses (orbitosphenoids, 10) becoming confluent with the cen-
trum (presphenoid, 9) of the frontal vertebra, and the latter
coalescing with that of the parietal vertebra, the compound bone
called ' sphenoid ' in Anthropotomy results, which combines the
centrums and neurapophyses of two cranial vertebra?, together
with a diverging appendage (pterygoid) of the maxillary arch.

The knowledge of the essential nature or ' general homology *
of such a compound bone gives a clue to the phenomena of its
developement from so many separate points, which neither em-

SKELETON OF BIMANA.

583

Elements of Human ' temporal bone,' outside
view : the confluent ear-capsule, called ' pe-
trous portion,' is not here seen.

bryology nor teleology could have afforded. As the centrum, 5,
becomes confluent with 1, a still more complex whole results,
which has accordingly been described as a single bone, under the
name of ^ os spheno-occipitale ' in some anthropotomies. Such a
bone has not few^er than twelve 404

distinct centres of ossification,
correspondiag with as many dis-
tinct bones in the cold-blooded
animals that depart less from the
vertebrate archetype. The spine
of the frontal vertebra (frontal
bone) is much expanded and
bifid, fig. 405, dy d, like the
parietal bone ; but the two
halves more frequently coalesce
into a single bone, with which
the parapophysis (postfrontal, b)
is connate. Much of the haemal arch is consumed by the rapidly-
growing " ossicles of the ear,' and the proper pleurapophysis (tym-
panic bone, fig. 404, d) is reduced to the function of supporting
the ear-drum, b ; and becomes anchylosed to the squamosal, a, and
mastoid, c. The h^mapophysis, fig. 403, 29, hs, is modified to form
the dentigerous lower jaw, but articulates, as in other Mammals,
with a diverging appendage (squamosal, 27), of the antecedent
h^mal arch, now interposed between it and its proper pleur-
apophysis ; the two hsemapophyses, originally separate, as in fig.
405, become confluent at their distal ends, forming the sym-
physis mandibul^e.

The centrum of the first or nasal vertebra, like that of the last
vertebra in Birds, is shaped like a ploughshare, and is called
* vomer,' fig. 403, 13 ; the neurapophyses have been subject to
similar compression, and are reduced to a pair of vertical plates,
which coalesce together, ib. 14, and mth parts of the olfactory
capsules (upper and middle turbinals), forming the compound
bone called ' ethmoid.' The prefrontals assume this confluence
and concealed position even in some fishes — Xij)hias, e. g. — and
repeat the character in all Mammalia and in most Birds ; but
they become partially exposed in the Ostrich and Batrachia.
The spine of the nasal vertebra (nasal bones, ib. is) is usually
bifid, like those of the two succeeding segments ; but it is much
less expanded. The haimal arch, called ^maxillary,' is formed by
the pleurapophyses (palatines, 20) and by the haemapophyses
(maxillaries, 21), with which the halves of the bifid haemal spine
(premaxillaries, 22) are partly connate, and become completely

584 ANATOMY OF VERTEBRATES.

confluent. Each moiety, or premaxillary, is reduced to the size
required for the lodgment of two vertical incisors. As the canines
in Man do not exceed the adjoining teeth in length, and the pre-
molars are reduced to two in number, the alveolar extent of the
maxillary is short, and the whole upper jaw is very slightly
prominent.

Of the diverging appendages of the maxillary arch, the more
constant one, called ' pterygoid,' 24, articulates with the palatine,
but coalesces with the sphenoid ; the second pair, formed by the
malar, 26, and squamosal, 27, has been subject to a greater degree of
modification : this appendage still performs the function assigned to
it in Lizards and Birds, where it has its typical,
405 ray -like figure, of connecting the maxillary with

the tympanic, or one rib with the next ; but the
second division of the appendage (squamosal),
which began to expand in the lower Mammalia,
and to strengthen, without actually forming part
of, the walls of the brain-case, as in fig. 140, 27,
now attains its maximum of developement, and
forms an integral constituent of the cranial pari-
Frontview^^^Human total ^^^g^ filling up a Very large cavity between the
neural arches of the occipital and parietal seg-
ments. It coalesces, moreover, with the tympanic, mastoid, and
petrosal, and forms, with the subsequently anchylosed stylo-hyal, a
compound bone called ' temporal ' in human anatomy. Embryology
shows, empirically, the facts of developement: the key to the
complex beginning of this •■ cranial bone ' is given by the dis-
covery of the general pattern on which the skulls of the verte-
brate animals have been constructed. In relation to that pattern,
or to the archetype vertebrate skeleton, the Human temporal bone
includes two pleurapophyses, 38 and 28, a parapophysis, 8, part of
a diverging appendage, 27, and a sense-capsule, I6.

In the Human embryo the cartilaginous follows the fibrous stage
of the brain-case in all the neurapophyses, viz. : exoccipitals, ali-
sphenoids, orbitosphenoids, prefrontals. The latter already show
their lateral confluence, closing the cranium anterior to the multi-
perforate part for the divisions of the olfactory nerve, called ' cribri-
form plate of the ethmoid,' and forming the ' crista galli ' above,
and the ' lamina perpendicularis ' below, that plate ; in connection
with which are the ^ turbinal ' capsules, or supporters of the ^ sense-
organ,' which are also cartilaginous. The chondrified bases of
the alisphenoids descend into the basisphenoid. The exoccipital
cartilage ascends into the lower half of the superoccipital. The
cartilaginous capsule of the ear-organ also sends a thin plate to

SKELETON OF BIMANA. 585

the superoccipital, and a thicker process behind which becomes the
basis of the mastoid. All the above cartilaginous parts are more
or less continuous or confluent, and when separate from the un-
chondrified extensions of the brain-capsule have been, illogically,
termed ' primordial cranium ' (Primordialschadel). But the actual
embryonal or primordial skull is originally wholly membranous,
and at the stage above described includes parts unchondrified, as
well as those showing the intermediate histological conversion into
cartilage. The bones, ossification of which begins in membrane,
are the basioccipital, vomer, upper half of superoccipital, parietals,
frontals, nasals, lacrymals, malars, squamosals, palatines, ptery-
goids. A pair of cartilaginous buds from the prefrontals form the
piers of the yet unclosed anterior haemal, or ' maxillary,' arch. A
pair of cylindrical cartilages, called ' Meckel's,' are developed in
the blastemal basis of the tympano-mandibular arch. The body
and the stylo-hyal parts of the cornua of the hyoid are gristly
before they ossify : much of the cerato-hyal parts of this thin haemal
arch retain their primitive fibrous condition. The capsule of the
essential parts of the organ of vision is in the same ^ sclerous ' pre-
dicament in Man and Mammals : that of the organ of hearing
becomes cartilaginous before it ossifies : the perfection of this
organ in the well-brained Mammals calls for accessory parts, which
show their true nature by their rapid groAvth.^ The true com-
prehension of the developemental phenomena of the Human and
Mammalian skull is afforded by that of its vertebral archetype :
the artificial nature of the classification of the ossified parts into
' primordial skull-bones ' and ^ lid-bones ' (' Deckknochen ') is
hereby plainly manifested : it is akin to that which divides them
into 'eight bones of the cranium' and ' fourteen bones of the face.'
The first seven segments of the trunk consist each of ' centrum,'
' neurapophyses,' fig. 403, n, and ' pleurapophyses,' pi, the ultimate
confluence of which forms the bone called ' cervical vertebra : '
the centrum of the first of these coalesces with that of the second,
and forms the ' odontoid process :' its place in the ' atlas ' is taken
by a ' hypaphophysis.' The pleurapophyses of the seventh cer-
vical are occasionally elongated as 'ribs,' fig. 185, A, h. In the
seven segments which svicceed the cervicals, the pleurapophyses,
pi, are elongated, and retain their freedom ; and after the first they
are shifted to the interspace between their own centrum and the

* The precocious developement of the ear-organ and its complex appendages in
Mammals sorely perplex the devotees of developemental phenomena: the superadded
bones of the ear-drum, growing straightway to full size, and appropriating much
of the blastema of the pleurapophysial or tympanic part of the haemal arch, have
been veritable ' will-o'-thc-wisps ' to hunters of homologies on embryological ground.

586

ANATOMY OF VERTEBRATES.

next in advance (or above). The hsemapopliyses, A, are gristly and
interposed between the pleurapophyses and the hsemal spines, the
conversion of which into the 'sternum' has been already explained.
The fact of this short and slender bone in Man being ossified
from a longitudinal series of centres (fig. 364, h) is learnt from
embryology, the reason from general homology. The haemal
spine here repeats the variability of its homotype, the neural one,
being sometimes entire, sometimes bifid (ib. c, d). In the three
succeeding segments the pleurapophyses become shorter and the
haemapophyses are attached by their attenuated ends each to that
in advance. In the next two segments the still shorter pleur-
apophyses resume the exclusive articulation with their proper cen-
trum and terminate freely. The centrum and neurapophyses of
each of the segments, with free and elongate pleurapophyses, con-
stitute by their coalescence the ' dorsal vertebrae,' which are
' twelve ' in number. Each of the five succeeding^ seorments is
represented by the centrum, neural arch, and short confluent
pleurapophyses, forming the * lumbar vertebrae : ' the hjemapo-
physes of these segments are represented by the ' inscriptiones
tendineae musculi recti,' h', which are the homologues of the gristly
or bony * abdominal ribs ' of reptiles. The constitution of the
Human 'os sacrum' has already been given. Part of a sacral
pleurapophysis expands to form the * ilium,' fig. 403, 62, pi. Two
haemapophyses called " ischium,' 63, and pubis, 64, coalesce with
62 to constitute the ' innominatum : ' the inverted arch, supporting
the appendage which becomes developed into 'pelvic limb,' is
completed by the ischio-pubic symphysis.

406

Kestoration ot Arrhro/itert/.r, n iiiesozoic

*¥V*'V* . '

TABLE I.— SYNONYMS OF THE BONES OF THE HEAD, ACCORDING TO THEIR GENERAL HOMOLOGIES. iTofacepagerm,Vai..-D..

KopmvmuEL oder Kopfsinnkswirbel.

!Tot recognised a

diverging a

TJiidetcrmined .

; transrers! oder Orper nebst den Sei

Scapulffi capitia (in birds) .... Oder Schnlterblatt des Kopfra . .

diverging appendage .

neurapophyses .

Corpus vertebrale. .

KOPSTlDMPFSINNESWmBEL.

Oder Korper der Nasenwirbel .. .
1(18) fUr das auGefassen

B Kopfrippe .. . . ,
>• EUenbogenbein des Kopfes .
f Hand des Kopfes* ,

Badlus capitis .

. oJct- Speiche des Kopfes

. o(faTOberamide8Kopfe8{iubird8);8capnlacepiti3(inn

.. Unwidersprechliche Bronohien nnd Lungen.. ,

ad are indicated throughout the present work,

' Report on the Archetype Skeleton," in 'Trans. (

' This vertebra is not formally admitted in the Pr«

Corpus vertebKB pr
Processus tranavcrs
t Pars superior pro

Oaaa extremitatiB tl

Ossa esrtremitatia o

s faciei scapulare

Phalanges pedis faciei .

Os secundum hyoideo-faciale

Undetermined .

Ob clavicularc faciei ..

Ohr-QnindstUck .

Domforteatz

Undetermined

Not recognised as e

I of"

Schmeck-GnuidBtUck. .

BogenstUcke

Domfortsatz

Undetermined .
Seh-BogenstUcki

Undetermined .

Undetermined .

Undetermined .

Undetermined .

Undetermined .

fepiaux de la Vneme vert^bre UuUre Deckplatien deal. 6. Wirbela....
Not re^^gnlscd as Cements of , ! j ^^^^^J^^^^^}^. " I der HalErioncn

i^2S

de la V&me verttbre'"

Wirbelkijtperdesll. Sch'ddelwirbels ..

Deckjiluttendesn. S. Wirbels

P6riaux de la V6me vert^bre .

Undetermined .

Undetermined

, 36! 1 Vneme vertfibre."

fepial de

de la Ude vert^bre "

Yordertheil des antem Eopfgli
Oberehlntere EopfgUedmaasse

des or. Zwischei

Cataaux de la niSmevertdbre

P^riaux et Paraaux

I IVftme vertfibre

Deckplattcn des IV. i

Unterer StemaltheU d

maxillary he regards as more particularly i

PoiESons t 1 r ) a- iH. I. II li;,t which Oeoffroy
pabliahed, and of the date of December 1825. It dUXera

is recognised as essentially a part c

^■ii

wbioh, by extending biu^vards t

TABLE II.— SYNONYMS OF THE BONES OF THE HEAD OF VERTEBRATES, ACCORDING TO THEIR SPECIAL HOMOLOGIES. [r.

/oc<j«i<K586, Vol.U.o/fcrl

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WORKS

REFERRED TO BY ROMAN NUMERALS AND DOT IN THE SECOND VOLUME.
(Those referred to by Roman Numerals without Dot are in the First Volume.)

I-. Becquerel and Breschet. Recherches sur la Chaleur animale au moyen

des appareils thermo-electriques, in Archives du Museum, t. i.

II*. Martin. Description des eflFets du Sommeil sur la Chaleur du corps

humain, in Journal de Physique, 1773, t. ii.
III'. Brown-Sequard. Experimental Researches (on the Normal Degree of

the Temperature of 5lan),
IV'. Martins. Sur la Temperature des Oiseaux palmipedes du Kord de
I'Europe, in Memoires de I'Academie des Sciences et Lettres de Mont-
pellier, 1856, t. iii.
V'. Chossat. Influence du Systeme nerveux sur la Chaleur animale. 8vo.

1820.
VI'. Budge. De I'lnfluence de la Moelle epiniere siir la Chaleur de la Tete,
in Coraptes Rendus de I'Academie des Sciences. 1853.
VII'. Owen. Art. Aves, Cyclopsedia of Anatomy, vol. i. 1836.
VIII'. NiTZSCH. Osteographische Beitrage zur Naturgeschichte d. Vcigel. 8vo.
1811.
IX'. Vigors. Observations on the Natural Affinities that connect the Oi-ders
and Families of Birds. Transactions of the Linnsean Society, vol. xiv.
1827.
X-. Owen. On the Megatherium, Philosophical Transactions, 1851.
Xr. Owen. On the Anatomy of the Southern Apteryx {Apteryx australis),
Transactions of the Zoological Society, vol. ii. 1838, and vol. iii. 1842.
XII'. 0-«t;n. On the Osteology of the Great Awk {AIca impennis). Transac-
tions of the Zoological Society, vol. v. 1864, and
CuviER, Legons d' Anatomic Comparee.
XIII'. Blythe, in Orr's edition of Cuvier's Animal Kingdom. 8vo. 1840.
XIV'. Eyton. Osteologia Avium. 4to. 1861-4.

XV'. Owen. On the Archeopteryx, Philosophical Transactions, 1863.
XVI'. Owen. On Dinornis, Transactions of the Zoological Society of London,

1839-1864.
XVII'. OwTEN. Palseontology. 8vo. 2nd ed. 1861.

XVIII'. Ot\ten. On Notornis, Transactions of the Zoological Society, vol. iii.
1848.
XIX'. O'^'EN. On the Affinities of Gastornis parisicnsis. Quarterly Journal
of the Geological Society. 1856.
XX'. Owen. Catalogue of the Physiological Series in tlie Museum of the
Royal College of Surgeons.
XXI'. Owen. On the Anatomy of the Flamingo {Phixnicopfcrus), Proceedings
of the Zoological Society, vol. ii. 1835.

WORKS REFERRED TO BY ROMAN NUMERALS AND DOT.

589

XXII-.
XXIII-.
XXIV-.

XXV-.

XXVI-.

XXVII-.

XXVIII-.

XXIX- .
XXX-.

XXXI-.

XXXII- .
XXXIII-.

XXXIV-.
XXXV-.

XXXVI-

XXXVII-

xxxvin-

XXXIX-

XL-

XLI-

XLII-
XLIII-
XLIV-

XLV-

XLVI-

XLVII-

XLVIII-

XLIX-

LI-

Owen. On the Anatomy of the Oannet (Sicla), Proceedings of the
Zoological Society, vol. i. 1833.

0\A"EN. On the Anatomy of the Red-backed Pelican (Pelecanus rufus),
Proceedings of the Zoological Society, toI. iii. 1836.

Owen. Memoir on the Apteryx, Proceedings of the Zoological Society,
vol. X. 1842 ; and

Yarrell, Wm., On the Xiphoid Bone, &c., of the Cormorant.

Owen, E. On the Anatomy of the Hornbill {Buceros cavatus), Trans-
actions of the Zoological Society, vol. i. 1836.

O^SNTEN, R. On the Dodo, Transactions of the Zoological Society, vol. iii.

Strickland and Melville. The Dodo and its Kindred. 4to. 1848.

Yarrell, Wm. On the Structure of the Beak and its Muscles in Loxia
curvirostra, Zoological Journal, vol. iv.

Mayer. Analekten fiir Vergleichende Anatomic. 4to. 1839,

MiJLLER, J. Physiologic des Gesicht-Sinnes, 8vo. 1826 ; and

Bishop. Art. Voice, in Cyclopaedia of Anatomy, vol. iv. (CCCXX. vol. i.).

Owen, R. On the Olfactory and Trigeminal Nerves of the Vulture, Tur-
key, and Goose, Proceedings of the Zoological Society, Part v. 1837.

Audubon, J. J. Ornithological Biography. 8vo. 5 vols. 1831-1839.

Edwards, Gt. A Natural History of Uncommon Birds, &c. 4to. 1743-
1751.

Crampton, Sir P. Description of an Organ by which the eyes of Birds
are accommodated to the dijGferent distances of objects, Annals of
Philosophy, 1813. 8vo.

Valentin. Fortgesetzte Untersuchungen iiber die Flimmerbewegung,
in Repertorium d'Anatomie ; and

PuRKiNjE. Commentatio Physiologica de Phenomeno motus vibratorii
continui. 4to. 183o.^

GrEOFFROY St.-Hilatre, Et. Systcmc Dentaire des Mammiferes et des
Oiseaux. 8vo. 1824.

NiTzscH, in Meckel's Archiv fiir Physiologic, 1826.

Newton, Alfred. On the supposed Gular Pouch of the Male Bustard,
in the 'Ibis,' April 1862.

Lund. De Oenere Euphones. Hafn. 1829.

Perault. Memoires de 1' Academic Royale des Sciences, Paris, t. iii.

Lauth. Memoire sur les Vaisseaux Lymphatiques des Oiseaux, Annales
des Sciences Nat., vol. iii. 1825.

Panizza. Osservazione Antropo-zootomico-fisiologiche. Pol. 1830.

Macartney. Art. Birds, in Rees' Cyclopaedia.

Owen. Catalogue of the Osteology, Royal College of Surgeons ; and

Barkow. Untersuchimgen iiber das Schlagadersystem d. Vogel, Meckel's
Archiv fiir Physiologie. 1828.

Rainey. Memoir on the Minute Structure of the Lungs, and on the
Minute Anatomy of the Lung of the Bird, Medico-Chirurgical Trans-
actions, vols. xxii. and xxiii.

Yarrell, Wm. On the Organs of Voice in Birds, Transactions of the
Linnsean Society, vol. xvi. ; and

Meckel. Vergleich. Anatomic.

Yarrell, AVm. Observations on the Tracheae of Birds, Transactions of
the Linnaean Society, vol. xv.

Yarrell, AVm. On a new species of Wild Swan, &c., in Transactions
of the Linnaean Society, vol. xvi.

MiJLLER, J. Ueber Compensation der physischen Krafte am menschlichen
Stimmorgane ; mit Bemerkungen iiber die Stimme der Saugethiere,
der Vogel und der Amphibien, 8vo. 1835. Vergleichende Anatomic
der Stimmorgane bei Vogeln, Berlin. Akad. 1845.

Geoffroy St.-Hilaire. Memoire sur les Appareils sexuels et urinaires
de I'Ornithorhynque, in Memoires du Museum, t. xv. ; and Composi-
tion des Appareils genitaux, urinaires et intestinaux dans I'Autruche,
etc., in Memoires du Museum, t. xx.

CuviER, P. Sur le Developpement des Plumes, in Memoires du
Museum, t. xiii.

)90

WORKS REFERRED TO BY ROMAN NUMERALS AND DOT

LII-. Yaeeell, W, On the Laws that regulate the Changes of Plumage in
Birds, Transactions of the Zoological Society, vol. i.
LIII*. Jaegbb, Gustav. Das Os humeroscapulare der Vogel, Sitzungsherichte
der Mathem.-naturwissensch. Classe, Kaiserl. Akad. der Wissensch.
inWien. 2tes Heft. ]857.
LIV". NiTZscH, C- L. System der Pterylographie. 4to. 1840.
LV'. Owen. John Hunter's Observations on Animal Development, edited,
and his Illustrations of that Process in the Bird described. Pol. 1841.
LVI*. GoLXD, John, F.R.S. On the Brush Turkey ( TalegaUa Lathami), and
On the Habits and Characters of Lei-poa ocellata, Proceedings of the
Zoological Society, vol. viii.
LYII'. GrOULD, John, F.R.S. On the 'Run' or Playing-house constructed by
the Satin-bird {FtiJojiorhynchus holosericeus), &c., of Australia, Pro-
ceedings of the Zoological Society, vol. viii.
LVIII-. Gould, John, F.R.S. The Birds of Australia. 7 vols. fol. 1840-48.
LIX-. Schwann. De necessitate Aeris Atmospheric! ad evolutionem Pulli in

Ovo incubito. 4to. 1834.
LX-. SoEMMEERiNG, S. M. Dc Sectiouc Oculorum.

LXI*. Sappey. Recherches STir I'Appareil respiratoire des Oiseaux. 4to. 1847.
LXII". Owen, R. On Thylacotherium and Phascolotherium, Transactions of the
Geological Society, 2nd series, vol. vi. 1839.
LXIII'. Owen, R. Description of the Foetal Membranes and Placenta of the

Elephant, Philosophical Transactions, 1857.
LXIV*. Ow^EN, R. On the Characters, Principles of Division, and Primary Groups
of the Class Mammalia, Proceedings of tlie Linnsean Society, February
and April, 1857. 'Rede's Lecture' on the same subject. 8vo. 1858.
LXV*. EscHRiCHT and Reinhaedt. Om Nordhvalen. 4to. 1861.
LXVr. Paley. Natural Theology. 10th ed. 8vo. 1805.
LXVII". Mt'LLEE, J. Ueber zwei verschiedene Typen in dem Ban der erectilen
mannlichen Geschlechtsorgane bei den straussartigen Yogelu. 4to.
1838.
LXVIII-. OwTEN, R. Hunterian Lectures on the Nervous System, in Medical
Times, 1840.
LXIX-. Veglik. Art. Quadrumana, Cyclopaedia of Anatomy, vol. iv.
LXX*. Owen. On the Structure of the Brain in Marsupial Animals, Philo-
sophical Transactions, 1837.
LXXI-. TuENER, H. N. On the Evidences of Affinity affi)rded by the Skull in
the Ungulate Mammalia. Ann. and Mag. of Nat. History, Dec.
1850, ser. 2, vol. iii.
LXXII'. Milne-Edwards, Alf Recherches sur la Famille des Chevrotains, in

Annales des Sciences, 5th ser. vol. ii. 1864.
LXXIIP. Pander and D' Alton. Die Vergleichende Osteologie. Fol. 1821-7.
*LXXIV*. OwrEN, R. Outlines of a Classification of the Marsupialia, Zoological
Transactions, vol. ii. 1839.
LXXV". OwTSN, R. On the Generation of the Marsupial Animals, with a descrip-
tion of the Impregnated Uterus of the Kangaroo, Philosophical Trans-
actions, 1834 ; and on the Osteology of the Marsupialia, Zoological
Transactions, Part 1, vol. ii. 1841 ; Part 2, vol. iii. 1845.
LXXVI*. Ow^N, R. On the Mammary Glands of the Ornithorhynchiis 'paradoxus,

Philosophical Transactions, 1832, p. 517.
LXXVII'. Owen, R. On the Ova of the Ornithorhynchus 'paradoxus, Philosophical

Transactions, 1834.
LXXVIII-. Owen, R. On the Young of the Ornithorhynchus paradoxus, Zoological
Transactions, vol. i. 1834.
LXXTX*. Owen, R. Art. Monotremata, Cyclopaedia of Anatomy, vol. iii. 1841.
LXXX-. O^^EN, R. Art. Marsupialia, Cyclopaedia of Anatomy, vol. iii. 1841.
LXXXI*. Meckel. Ornithorkyoichi par ad oxi J) e&cr'r^xXo AmXonnca.. Fol. 1826.
LXXXII*. Owen, R. Anatomy of Capromys Fournieri, Proceedings of the Com-
mittee of Science of the Zoological Society of London. 8vo. 1832.
LXXXIII'. O-^'EN, R. On some Outline-drawings and Photographs of the Skull of
the Zygoonaturus trilohus, Macl., Notothcrium, Owen, Quarterly Jour-
nal of the Geological Society, vol. xv. 1858.,

IX THE SECOND VOLUME.

591

LXXXIV*. Peters. Naturw, Reise nach Mosambique : Saugthiere. 4to.
LXXXV'. Peters. Ueber das normale Vorkommen von nur sechs Halswirbeln bei
Choloepus Hoffmamii, Monatsberieht der Konigl. Akad. der Wis-
senschaften zu Berlin, Dec. 1864.
LXXXVI'. Owen. On the Cervical and Lumbar Vertebrge of the Mole {Talpa
europcea, L.), Transactions of the British Association, 1858.
LXXXVII'. MiRAiN, Ed. Ueber einen eigenthiimlichen Bau des Grehororganes bei

den Nagem. Svo. 1840.
LXXXVIII-. Yahrell, Wm. On the Osteology of the Chlamyphorus truncatus, in
the ZoologicalJournal, vol. iii. 1830,
LXXXIX-. Owen, On the Glyptodon. Transactions of the Geological Society,
2nd ser. vol. vi., and Catalogue of the Fossil Mammalia in the Royal
College of Surgeons. 4to. 1845.
XC-. Owen, R. Description of the Skeleton of the Mylodon. 4to. 1842.
XCI-. Owen, R. Memoir on the Megatherium. 4to. 1860.
XCII". Owen, R. Catalogue of Eossil Organic Remains (Mammalia and Aves)
in the Museum of the Royal College of Surgeons of England. 4to.
1845.
XCIII-. Macleat, W. S. History and Description of the Skeleton of a New

Sperm-whale, «fcc. 8vo. Sydney: 1851,
XCIV-, Brandt, J. F, Symholce Sirenologicce. 4to. 1846.
XCY-. Otven, R. Fossil Mammalia of the Voyage of the Beagle. 4to. 1840.
XCVI-. CoBBOLD, T. S. Art. i?z^;n«mw2^m, Cyclopaedia of Anatomy, Supplement,
1859.
XCVII-, O^^N, R. Memoir on the Anatomy of the Nubian Giraffe, Zool. Trans.,

vol. ii.
CXVIII-. Stannius, H, Beitrage zur Kenntniss der Amerikanischen Manati.
4to, 1845.
XCLX-. Owen, R. On Indian Cetacea, Transactions of the Zoological Society,
vol. V. (1866),
C", Rapp, W. V. Die Cetaceen zoologisch-anatomisch dargestellt. 8vo.

1837.
CI'. Murray, A, On the genus Galago, Edinb. New Philosophical Journal.

New ser., Oct. 1859.
CII". Ow^N, R, Monograph on the Aye-aye {Cheiro/nys madagascariensis,

Cuv.). 4to. 1863.
CIII'. Otnt;n, R. Osteological Contributions to the Natural History of the
Orangs (Pifhecus) and Chimpanzees (Troglodytes), Transactions of
Zoological Society, vols, ii., iii., and {Troglodytes Gorilla) vols. iv. and
V. Parts I.-VIII.
CIV-. De Blainville, H. D. Osteographie, &c. 4to, andfol. (plates). 1841.

CV'. Wood, Jno, Art. Pelvis, Cyclopaedia of Anatomy, Supplement.
CVI-. Weber, M. J. Die Lehre von dem Ur- und Raceu-formen der Schadel
und Becken des Menschen. 1830.
CVII*. Vrolik, W. Platen behoorende tot deBeschowing van het Verschel der
Bekkens in onderscheidene Volkstammen. 1826.
CVIII', Breschet. Recherches sur difFerentes Pieces du Squelette des Animaux
Vertebres, etc., in Anuales des Sciences Naturelles. 2e serie, t. x.
(Zoologie).
CIX-. Morton, Dr. Crania Americana. 1839.

CX-. Owen, R. Memoir on the Gorilla (Troglodytes Gorilla, S.). 4to. 1865.
CXI-, RoKiTANSKi. Lehrlmch der Pathologische Anatomic,
CXII-, Zawarykin, Th, Ueber die Aufbewahrung von Blutkrystallen mittelst
Aether, in Kais. Akad, der Wissenschaften in Wien, Sitzungsberichte,
8vo, Nr. IV, p. 14.
CXIII*. TscHERiNOFF, M. Ueber die Abhangigkeit des Glykogengehaltes der
Leber von der Ernahrung, in Kais. Akad. der Wissenschaften in Wien,
Nr. XL pp. 64-65.
CXIV'. ToROK, Aurel. Beitrage zur Kenntniss der ersten Anlagen der Sinnes-
organe und der primiiren Schadelformation bei den Batrachiern, in
Kais. Akad. der Wissenschaften in Wien, 3. Nr. XXIX. pp. 206
bis 207.

592 WOKKS EEFERRED TO BY ROMAN NUMERALS AND DOT.

CXV'. Steicker, S, Ueber den Bau und das Leben der capillaren Blutgefasse,
in Kais. Akad. der Wissenschaften in Wien, H). Nr. XXII., pp. 164-
165. Ueber die Histologic der Gehirnentzilndung, in Kais. Akad.
der Wissenschaften in Wien, Sitzungsberichte, 8to. Nr. XXYI.
pp. 186-187.
CXVI-. Hyrtl, J. Ueber einenfreien Korperim Herzbeutel, in Kais. Akad. der
Wissenschaften in Wien, lb. Nr. IX. p. 48.
CXVII*. Hyrtl, J. Ein Pancreas accessorium und Pancreas divisum, in Kais.

Akad. der Wissenschaften in Wien, lb. Nr. XXI. p. 148.
CXVIir. Hyrtl, J. Eine quere Schleimhautfalte in der Kehlkopf hohle, in Kais.
Akad. der Wissenschaften in Wien, lb. Nr. XXI. p. 148.
CXIX-. Goethe. Zur Natnrwissenschaft iiberhaupt, besonders zur Morphologie.

4 Bde. M. Kupf. 8vo. 1817-23.
CXX*. Hartwig, G. Gott in der Natur, oder die Einheit der Schopfung. Mit

Abbild. Svo. 1864.
CXXI-. EuDOLPHi, K. A. Zur Anthropologic u. allgem. Naturgesch, 8vo. 1812.
CXXII-. BuFFON et Daubenton. Histoire naturelle generale et particuliere.
14 vols. 4to. 1766.
CXXIII-. Hutchinson. Art. Thorax, Cyclopaedia of Anatomy, vol. iv.
CXXIV*. L'Herminier. Eecherches sur I'Appareil sternal des Oiseaux. Me-
moires de la Soc. Linn, de Paris, torn. iii. 1827.
CXXV-. Blanchard, Em. Osteologie des Oiseaux. Annales des Sciences Nat.,
ser. iv. torn. ix. 1859.

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