In Memory of

Remington Kellogg

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REMINGTON K2&LLOGG
LIBRARY OF

MARINE MAMMALOGY
SMITHSONIAN INSTITUTION

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SKELETON AND THE TEETH.

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PRINCIPAL FORMS

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BY

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PROFESSOR R! OWEN, F.R.S., &.,

AUTHOR OF “‘ ODONTOGRAPHY ;” ** LECTURES ON COMPARATIVE ANATOMY;” ‘‘ ARCHETYPE OF
THE SKELETON ;” **ON THE NATURE OF LIMBS;” ‘HISTORY OF BRITISH
FOSSIL MAMMALIA,” ETC. ETC.

*

PHILA DE.L PHT A:

BLANCHARD ox Nek de Re
1854.

PHILADELPHIA:
7. K. AND P. G. COLLINS, PRINTERS.

PREFACE.

THE following work has just appeared in London as
a portion of a series entitled Orr’s Circle of the Sciences.
Believing that a treatise of so much value was worthy of
an independent position and a permanent form, the pub-
lishers issue it separately. Written by the most distin-
guished osteologist of the age, as an introduction to his
favorite science, it cannot fail to possess great interest
and value to all students of Zoology, Comparative Ana-
tomy, and Geology, of which departments of knowledge
Osteology may now be regarded as the foundation. As
indicative of the principles which have guided the author
in his labors, the following paragraphs are extracted from
the Preface to the Circle of the Sciences.

“Tn regard to the structure and conformation of that
great division of the Animal Kingdom called ‘the Verte-
brate,’ to which Man himself belongs, and which includes
the animals that most resemble Man, it has been deemed
sufficient for present purposes to restrict the Essay to the -
fundamental structures or framework of the body, with
the appendages of a like enduring material called the

1|*

*

vi PREFACE.

Teeth. The execution of this part of the ‘CrrcLe’ has
been confided to that great philosophical anatomist who
has so distinguished himself in working out the true
principles of Osteology—principles which will doubtless
soon be applied to the nomenclature and description of
every branch of Anatomical Science. Avoiding the com-
mon practice of intrusting the special essays to literary
compilers and abridgers, it has been part of the design
of the work—hitherto with success—to engage, in the
important task of teaching, those master-spirits who have
in their day effected the greatest improvements, and made
the most decided advances, in their respective depart-
ments of science. The result has been, as is especially
shown in the Essay on the Principal Forms of the Skeleton,
an original exposition of the principles of Anatomical
Science, and of the most important results that have been
attained by its latest cultivator; such exposition being
succinct without any important omission, and as clear
and comprehensible as is consistent with the inevitable
use of technical terms.

“New and clearly defined ideas must be expressed by
their appropriate signs. The explanation of the sign
teaches the nature of the idea. Without learning and
understanding the technical terms of a science, that sci-
ence cannot be comprehended. The terms seem ‘hard’
only while the ideas which they represent are not under-

| stood. We listen with pleasure and surprise to the glib
» facility with which the working classes, admitted in

PREFACE. Vil

homely attire at half price to the Zoological Gardens on |
Mondays, talk of the Elephant, the Rhinoceros, and the

Hippopotamus. These derivations from the Greek are

no harder to them than the Saxon monosyllabic names

of the bear, the seal, or the lion; and yet the four sylla-

bled and five-syllabled names above cited are longer than

the average of the technical terms derived from the same

learned and pliable language: for example, Alisphenoid

is not really harder than rhinoceros, nor Neurapophysis

than hippopotamus; and when the mind becomes as

familiar with the things of which these are the verbal |
signs, they fall naturally and easily into the circulating
medium for the currency of thought. To the intelligent
reader of every class, who may be blessed with the healthy
desire for the attainment of knowledge, let it then be
said: Be not dismayed with the array of ‘hard words’
which seems to bar your path in its acquisition. Where
such words are invented or adopted by the masters in |
science, be assured that your acquisition and retention of
their meaning will be the safest ‘first steps’ in the science
of your choice.

“Where plain and known words of Saxon or old Eng-
lish root could convey the meaning intended, the writers
have sedulously striven to use them instead of terms of
more exotic origin. But where the signification of a
thing, or group of things, would have demanded a round-
about explanation, or periphrase, as the alternative for
abandoning the single-worded and clearly defined tech-

Vill PREFACE.

nical term, they have not hesitated to use such term,
appending, either in the same page or in the Glossarial
Index, its derivation and meaning.

“Tn reference to the terms of Anatomy, a method has
been adopted further to facilitate their reception and
easy recognition by reference to the part itself so signi-
fied in the wood-cuts; the same or corresponding part
bearing the same numerals in all the cuts; thus the sca-
pula, or blade bone, is indicated by the No. 51 in the
fishes’ skeleton, Fig. 9, and in all the succeeding skele-
tons up to those of the Ape and Man, Fig. 46.”

CONTENTS.

ON THE PRINCIPAL FORMS OF THE SKELETON.

Principles of Osteology

Composition ef Bones .

Primary Classification of Bones

The Dermoskeleton

Growth ef Bones f
Structure of Bones in Different Clasede
The Neuroskeleton

The Vertebre

Archetype of the Siketéton

Skeleton of the Fish

The Sea-perch :

The Occipital Vertebra

The Parietal Vertebra .

The Frontal Vertebra .

The Nasal Vertebra

Names of Bones .

Bones of the Head

Jaws of Fishes

The Caudal Vertebra

The Fin-rays

Adaptation of the Fish’s Skull “a Skeleton. to pee Life

Action of the Fins

Principal Forms of the eee of Reptiles
Batrachian Illustrations

Skeleton of the Frog :

Osteology of the Serpent Tribe

Skeleton of the Serpent ‘
Structure of the Serpent’s Skull .

PAGE

24

29

x CONTENTS.

Structure of the Skull of the Python
The Maxillary Arch :
Skull of the Boa-Constrictor
The Mandibular Arch .

Skull of Poisonous Serpents

Vertebree of the Rattlesnake
Vertebra of Serpents .

Osteology of Lizards
Skeleton of the Crocodile

Vertebre and Skull of the Crocodile
Limbs of the Crocodile

-Osteology of Chelonian Reptiles
Carapace of the Turtle
Plastron of the Turtle

Vertebre, Skull, and Limbs of the Tortoise dial Tur tle

The Skeleton of Birds

Of the Swan

Of the Duck Tribe

Pelvis and Leg of Birds

Structure of the Foot in Birds

Mechanism of Flight in Birds

Forms of the Skeleton in the Class Merasin
Various Forms of Limbs in Mammals .
Skeleton of the Whale

Of the Dugong

Of the Seal

Of the Walrus E
Skeletons of Hoofed Cuuitavets :

Of the Horse

Of the Rhinoceros

Of the Giraffe :
Skeletons of Herbivorous Quidrupeds ;
Of the Camel :

Of the Hippopotamus .

Osteological Characters of even- sia Hoofed retin
The Nature of Limbs .

The Protopterus . ‘

Law of Simplification of Bact

The Amphiuma and the Proteus

The Tarsal Bones of the Horse and the Ox

PAGE
79
81
81
82
84
85
86
91

2D
96—-112
115
122
124
126
129
134
187
140
145
147
150
151
153
158
157
158
159
162
163
167
170
174
175
178
180
183
183
185
184
185

CONTENTS. X1

PAGE

The Tarsal Bones of the Rhinoceros, the Hippopotamus, and the
Elephant . : ; ‘ : f : : ‘ oot
Skeleton of the Sloth . ‘ : ‘ : 3 ‘ : : 1886
Of the Ant-eater . : : : : : 2 , : - 193
Of the Mole : : : : : : ; = : . 194
Of the Bat . : : F ; , 1) 193
Skeletons of the Carnivorous | iter aia : : ‘ t . 200
Of the Lion : : : : : ‘ : : . . | 202
Of the Kangaroo . : : 3 ‘ : P . 205
Conditions of Marsupial Siaraieteine . : : ; : J 2OF
Skeletons of the Orang, and of Man. ‘ : 200
Comparison of the Bony Structure of the Ape ‘ii Maiti ‘ 2 2a
Adaptation of the Human Skeleton to the erect Posture i 214
Modifications of the Human Skeleton, in relation to the pee 216
General and Special Terms in Osteology P ‘ : : s 228
The Facial Angle ‘i ‘ 222
Progressive Expansion of the Cnet ‘ ‘ : ; . 222
Crania of the Crocodile and the Albatross. ‘ : . - 222

Crania of the Dog and the Chimpanzee p F ‘ ait
Skulls of the Australian and the European . ; : ‘ . 224
Concluding Remarks . .. : ; : : : ; . 225

ON THE PRINCIPAL FORMS AND STRUCTURES OF

THE TEETH.
Intimate Relation of the Teeth to the Food and Habits of the Animal 229
Dental Tissues and Pulp Cavities . ; : : : - oe
Section of the Human Tooth ; : : : : ha 3.
Chemical and Structural Composition of Teeth : : : . 234
Complex and Compound Teeth : ‘ : : : - 285
Section of the Horse’s Incisor ; : .. 235
Transverse Section of Tooth of the Taya : : . 236
Transverse Section of the Orycteropus : . : : . 238
Grinders of an Elephant : : ‘ ‘ : : : . 289
Dental System of Fishes. : ; : : : : . 240
Skull and Teeth of the Pike - : ‘ : : ; . 240
Jaws and Teeth of the Sting-ray- . ; ‘ : : ‘ . 242
Teeth of the Wolf-fish . : ; : : : ‘ . 245, 246
Tissue of Teeth in Fishes. : : : : : ; - ee

Teeth of the Barracuda Fish : : : : : : ,* gas

xi CONTENTS.

Dental System of Repiiles

Teeth of the Iguanodon and the nd cdeleadatias
Skull and Teeth of the Dicynodon

Teeth of Crocodiles

Teeth of Poisonous Snakes .

The Dental System of Mammalia

Form, Fixation, and Structure of Middiadlian Teeth
Teeth of the Carnivora

Of the Lion

Of the Morse

Of the Porcupine

Teeth of the Rodent ee

Of the Horse

Of the Elephant .

Of the Siberian Mammoth

Succession of the Elephant’s Grinders
Development of the Elephant’s Grinders
Teeth of the Megatherium

Of the extinct Anoplotherium

Of Ruminants

Of the Seal Tribe

Of the Quadrumana

Of the Orang and the Ghinthanee

Of Monkeys and Lemurs

Homologies of the Teeth

Deciduous and Permanent Teeth of ite, cas
Homologies of the Human Teeth

Notation and Symbols of Teeth

PAGE

251
252
254
255
256
258
261
264
265
266
267
269
271
274
275
281
284
292
297
298
299
301
301
307
308
310
éll
313

FIG.

OONAHAP wo He

LIST OF ILLUSTRATIONS.

o

. Dermo and Neuro Skeletons of the Sturgeon :
. Portions of Dermo and Neuro Skeletons of the Armadillo

Typical Vertebra (Ideal)

. Parietal Segment, or Vertebra—Man

Thoracic Segment, or Vertebra—Raven

. Typical Vertebra
. Archetype Vertebrate Blk tis
. Section of Vertebra—Fish

Skeleton of the Perch

. Sections of the Caudal Vertebree of Fishes

. Vertebre of the Batrachians .

. Skeleton of the Frog

. Skeleton of the Cobra

. Skull of Bea-Constrictor

. Skull of a Poisonous Snake . .

. Vertebra of the Rattlesnake #

. Section of Skull, Boa-Constrictor

. Skeleton of the Crocodile ’
. Atlas and Axis Vertebre of the Crocodile ;
. Skeleton of the European Tortoise

. Carapace of Turtle

. Plastron of Turtle . :

. Segment of Carapace and Putco

. Skeleton of the Swan

. Foreshortened View of the skeivtet of n) Whale, ao iits its

Relative Size to Man

. Skeleton of the Dugong

. Skeleton of the Walrus .

. Skeleton of the Horse

. Skeleton of the Rhinoceros

2

PAGE
17
19
27
28
28
28
29
34
38
54
65
70
74
81
84
85
90
95
96

123
124
126
128
137

154
157
159
168
167

XIV LIST OF ILLUSTRATIONS.

30. Skeleton of the Giraffe .

31. Skeleton of the Hippopotamus

82. Segment of the Skeleton of Pr otopterdn:
33. Segment of the Skeleton of Amphiuma .
384. Segment of the Skeleton of Proteus

85. Tarsal Bones of the Horse

36. Tarsal Bones of the Ox.

87. Tarsal Bones of the Rhinoceros

88. Tarsal Bones of the Hippopotamus

39. Tarsal Bones of the Elephant

40. Skeleton of the Sloth

41. Skeleton of the Mole

42. Skeleton of the Bat

43. Skeleton of the Lion

44. Skeleton of the Kangaroo

45. Skeleton of Orang

46. Skeleton of Man

47. Facial Angle of Crocodile

48. Facial Angle of Albatross

49. Facial Angle of Dog :

50. Facial Angle of Chimpanzee .

51. Facial Angle of Australian

52. Facial Angle of European

53. Section of Human Incisor Tooth

54. Structure of Human Tooth

55. Section of Horse’s Incisor

56. Transverse Section of Tooth of aipaneeentiian

57. Transverse Section of part of Tooth of Orycteropus
58. Longitudinal Section of part of Grinder of Elephant

59. Skull of the Pike, showing the Teeth

60. Jaws and Teeth of the Sting-Ray

61. Teeth of the Wolf-fish

62. Tooth of the Megalosaurus :

63. New-Formed and Worn Teeth of the eustiatin
64. Skull and Tusks of Dicynodon lacerticeps

65. Tooth, with Germs of Successors, of the Garrhial .

66. Poison-Fang of Rattlesnake

67. Section of a Poison-Fang of Battloniuke
68. Skull of a Rattlesnake

69. Jaws and Teeth of the Lion

LISE OF ILLUSTRATIONS. XV

FIG. PAGE
70. Skull and Teeth of the Morse P : ; , ‘ so 266
71. Skull and Teeth of the Porcupine . : ie 267
72. Grinding Surfaces of the Upper and Lower Mains of Bows aie 2.
73. Section of Skull and Teeth of Elephant , F : . 274
74. Molar Teeth of Elephant and Siberian Mammoth . : oe Shp
75. Deciduous and Permanent Teeth of the Hog . 3 : J» 310

76. Deciduous and Permanent Teeth, Human, et.7 . ; <) $2

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THE

PRINCIPAL FORMS OF THE SKELETON.

PRINCIPLES OF OSTEOLOGY.

THE original substance of animals consists of a fluid
with granules and cells. In the course of development,
tubular tracts are formed, some of which become filled
with “neurine,” or nervous matter; others with “myo-
nine,” or muscular matter; other portions are converted
into glandular substance; and a great proportion of the
rest of the primordial matter forms “ cellular substance.”
This substance, in many animals, becomes hardened, in
certain parts of the, body, by earthy salts. When those
salts consist chiefly of:phosphate of lime, the tissues called
‘“‘osteine,” or bone, and “dentine,” are constituted, between
which the chief distinction lies in the mode of arrange-
ment of the earthy particles, in relation to the mainte-
nance of a more or less free circulation of the nutrient
juices through such hardened or calcified tissues. In
bone, certain canals are left, of a caliber sufficient for the
passage of capillary bloodvessels through the tissue. Still
more minute tubes, sometimes expanding into cell-like
cavities, are established for the slower percolation of the
colorless fluid of the blood, called “plasma,” or “liquor
sanguinis.” In true or hard dentine provision is made,

2

14 COMPOSITION OF BONES.

by fine tubes, for the passage of plasma through its sub-
stance; but the red particles of the blood are excluded.

True osteine and dentine are peculiar to the highest
division or province of the Animal Kingdom, which pro-
vince has been termed “ Vertebrata,” from the prevalent
disposition of the osseous matter in successive groups of
more or less confluent bones called “vertebre.” (From
verto, 1 turn; these being the parts on which the body
bends or rotates.)

Before entering upon the disposition of the bony mat-
ter, a few words may be premised as to the composition
of that matter in the different classes of vertebrata. These
classes are four: Fishes, Reptiles, Birds, and Mammals,
which latter class includes the hair-clad beasts, commonly
called quadrupeds, with the naked whales and human
kind. Fishes have the smallest proportion, birds the
largest proportion, of the earthy matter in their bones.
The animal part in all is chiefly a gelatinous substance.

PROPORTIONS OF EARTHY OR INORGANIC, AND OF ANIMAL OR ORGANIC,
MATTER IN THE BONES OF THE VERTEBRATE ANIMALS.

FISHES. .
Salmon. Carp. Cod.
Organic..>., ....60:62 40.40 34.30
Inorganic . . . 39.38 59.60 65.70
100.00 100.00 100.00
REPTILES.
Frog. Snake. Lizard.
Organise °° @*) 2." do.o) 31.04 7o.07 °
Inorganic . . . 64.50 69.96 53.33
100.00 100.00 100.00
MAMMALS.
Porpoise. Ox. Lion. Man.
Organic. . . . 35.90 31.00 27.70 31.03
Inorganic . . . 64.10 69.00 72.80 68.97

100.00 100.00 100.00 100.00

PRIMARY CLASSIFICATION OF BONES. 15

BIRDS.
Goose. Turkey. Hawk.
Orgasmic. . . ..d2.91 80.49 26.72
~ morganic . . . 67.09 69.51 73.28
100.00 100.00 100.00

From the above table, it will be seen that the bones of

the fresh-water fishes have more animal matter, and are, |

consequently, lighter than those of fishes from the denser

element of sea-water; and that the marine mammal called -

porpoise differs little from the sea-fish in this respect.
The batrachian frog has more animal matter in its bones
than the ophidian or saurian reptiles, and thereby, as in
other respects, more resembles the fish. Serpents almost

equal birds in the great proportion of the osseous salts, |

and hence the density and ivory-like whiteness of their
bones.

The chemical nature of the inorganic or hardening
particles, and of the organic basis of bone, is exemplified
in the subjoined table, including a species of each of the
four classes of vertebrata :—

CHEMICAL COMPOSITION OF BONES.

Hawk. Man. Tortoise. Cod.

Phosphate of lime with trace

of fluate of lime ; : 64.39 59.63 52.66 57.29
Carbonate of lime . “ ? 7.03 7.33 12.538 4.90
Phosphate of magnesia . . | 0.94 1.32 0.82 2.40
Sulphate, carbonate, and chlor-

ate of soda ; ‘ ’ 0.92 0.69 |. 0.90 1.10
Glutin and chondrin : ‘ 25.73 29.70 31.75 32.31
Oil : : : : é 0.99 1.33 1.34 2.00

100.00 | 100.00.| 100.00 | 100.00

Bony matter is very variously disposed in the bodies
of vertebrate animals. The sturgeon, the crocodile, and

16 COMPOSITION OF BONES. ;

the armadillo, are instances of its accumulation upon or
near the surface of the body; and hence the ball-proof
character of the skin of the largest of these mailed exam-
ples. The most constant position of bone is around the
central masses of the nervous and vascular systems, with
rays thence extending into the middle of the chief mus-
cular masses, forming the bases of the limbs. Portions
of bone are also developed to protect and otherwise sub-
serve the organs of the senses, and in some species are
found encasing mucus-ducts, and buried in the substance
of certain viscera; as, e. g., the heart in the bullock and
some other large quadrupeds. Strong membranes, called
‘“aponeurotic,” and certain leaders or tendons, become
bony in some animals; as, e. g., the “tentorium” in the
cat, the temporal fascia in the turtle, the leaders of the
leg-muscles in the turkey, the nuchal ligament in the
mole, Fig. 41, w, and certain tendons of the abdominal
muscles of the kangaroo, which, so ossified, are called the
“marsupial bones,” Fig. 44.

For a clear and intelligible view of the osseous system
in general, it has become requisite to make a primary
classification of its parts according to their prevalent
position, as in the cases above cited. The superficial or
skin-bones constitute the system of the “dermoskeleton”
(from the Greek derma, skin, and skeleton); the deep-seated
bones, in relation to the nervous axis and locomotion,
form the “neuroskeleton” (Gr. neuron, nerve, and skeleton);
the bones connected with the sense-organs and viscera
form the “splanchnoskeleton (Gr. splagchnon, viscus, or
inward part, and skeleton); those developed in tendons,
ligaments, and aponeuroses, the “scleroskeleton” (Gr.
scleros, hard, and skeleton). These technical terms may
seem harsh, and sound strange, to those commencing the

THE DERMOSKELETON. 17

study of the structure of animals, but the most complex
product of creation cannot be comprehended without
terms expressive of the results of the classification and
generalization of the manifold phenomena it offers to the
contemplative student.

In the arrangement of the parts of the dermo, splanchno,
and scleroskeleton, no common pattern is recognizable.
One can discern a definite end or purpose gained by the
positions those terms indicate of certain bony plates, cases,
or rods, and the special relation of such to the habits and
well-being of the creatures manifesting them; but the
diversity in the number, size, shape, and relative position
of such dermal bones and visceral bones seems in- |
terminable.

The head of the sturgeon, Fig. 1, is defended by a case
of superficial bony plates, d3,d 7, d11, &.; and the body,
by five longitudinal rows of similar plates—one extend-

Fig. 1.

DERMO AND NEURO SKELETONS—STURGEON (Acipenser Sturio).

ing along the mid-line of the back, ds, ds, one along each
side of the body, dp, dp, and two along the belly, dh, dh,
between the fins called “pectoral,” 57, and ventral. The
observations of the ichthyologist, or of those concerned
. =

18 THE DERMOSKELETON.

in the capture of the sturgeons for the sake of their air-
bladder, of which the most valuable isinglass consists,
show us how well the external defensive armor of these
fishes is adapted to their mode of life. The sturgeons
may be called the scavengers of the great rivers which
they frequent. They habitually swim, low, and grovel
along the bottom, turning up the mud and sand with their
pig-like snout, testing the disturbed matter with their
feelers, 6, and feeding in shoals, on the decomposing
animal and vegetable substances which are carried down
with the debris of the continents drained by those rapid.
currents; thus, they are ever busied reconverting the
substances, which otherwise would tend to corrupt the
ocean, into their own living organized matter. These
fishes are, therefore, duly weighted by a ballast of dense
dermal, osseous plates—not scattered at random over
their surface, but regularly arranged, as every seaman
knows how ballast should be, in orderly series along the
middle and sides of the body. The protection against
the logs and stones hurried along their feeding-grounds,
which the sturgeons derive from their plate armor, ren-
ders needless the ossification of the immediate case of the
brain and spinal marrow, and, consequently, all the parts
of the neuroskeleton, ch, pl, n, ns, remain in the flexible,
elastic, gristly state; the weight of the dermoskeleton
requiring that the other systems of the skeleton should
| be kept as light as might be compatible with its defensive
and sustaining functions. This view of the final purpose
of the dermal bony plates in the existing sturgeons affords
some insight into the habits and conditions of existence
of the similarly mailed extinct fishes which abounded in
the seas of the secondary periods of the geological history
of this planet. In most of these fishes, as in the stur-

THE DERMOSKELETON. 19

geons, the dermal bones are coated externally with a
much harder material, resembling enamel, and such fishes
have accordingly been termed “ ganoid,” from the Greek
word “ganos,” signifying brightness. The ganoid plates
in those extinct fishes are usually more close-set, over-
lapping each other, and being fastened together like tiles,
by a peg of one entering a socket in the next, and recip-
rocally. Only two genera of fishes are now known to
exhibit this beautiful arrangement of the dermal bones,
viz. the polypterus of the Nile, and the lepidosteus of the
Ohio, and other great rivers of North America.

In the armadillo, the dermal bones, Fig. 2, 0b, are small,

PORTIONS OF DERMO AND NEURO SKELETONS—ARMADILLO (Dasypus tricinctus).

polygonal, usually five or six-sided, smooth on their inner
surface, which rests on the soft subcutaneous layer of cel-
lular tissue, variously sculptured on the outer and ex-
posed side, but with a pattern constant in, and character-
istic of, each species. They are united together at their
thick margins by rough or “sutural” surfaces, and resem-
ble a tessellated pavement. The trunk is protected by a
large buckler of this bony armor; the head is defended

20 THE DERMOSKELETON.

by a casque of the same; and the tail is encased in a sheath
of similar interlocked ossicles. 'T'o allow of the requisite
movements of the trunk in the small existing armadillos,
which, when attacked, roll themselves into a ball, from
three to nine transverse rows of the dermal bones, 6 4,
are interposed, having a yielding elastic junction with
each other, and with the anterior, o 0, and posterior fixed,
and larger, parts of the trunk-armor; and by this modifi-
cation the head and limbs can be withdrawn beneath the
armor, when its parts are pulled together by the strong
cutaneous muscles into a hemispheric form. In South
America, to which continent the armadillos are peculiar,
remains of gigantic quadrupeds, similarly defended, have
been discovered in the more recent tertiary deposits; but
in these colossal armadillos (Glyptodon) the trunk-armor
was in one immovable piece, covering the back and sides,
and was not divided by bands. Besides the defence which
such a modification of the integuments would afford
against the attacks of predatory animals, the armadillos
and glyptodens habitually frequenting the great forests
of South America may have been protected by the same
hard, arched covering from falling timber.

Such are some of the instances of the structure and
uses of the dermoskeleton in the vertebrate province.
The development of this system of the skeleton is not
dependent on the grade of organization, for we find it in
the highest and in the lowest classes; nor does a great
amount of osseous matter in the skin necessarily involve
asmall amount or absence of the same matter in the
deeper-seated skeleton; for all the parts of this system of
bones, a, ¢, d, m, ns, are as well developed and as well
ossified in the armadillos as in the quadrupeds which are
_ covered by hair. The different states of the neuroskele-

GROWTH OF BONES. 21

ton, in the sturgeon and armadillo, are explicable only |
with reference to the different media and other conditions
under which the two vertebrates were destined to exist. —

In no species, and in no system of the skeleton, are
bones a primary formation of the animal: they are the
result of transmutations of pre-existing tissues, as sub-
stances composing antmal bodies—e. g. nerve, muscle,
membrane, &c.—are called. The inorganic salts, defined
in the tabular view of the composition of bone, pre-exist —
in the blood, in the albumen of the egg of the oviparous
vertebrates, and in the milk which nourishes the new-born |
mammal.

The primitive basis, or “blastema,” of bone is a sub-
transparent glairy matter, containing a multitude of
minute corpuscles. It progressively acquires increased
firmness—sometimes assumes a membranous or hgament-
ous state, sometimes a gristly state, before its conversion
into bone. Its assumption of the gristly state is attended
by the appearance in it of numerous minute nucleated
cells. As the gristle or “cartilage” hardens, these cells
increase in number and size, and are ageregated in rows at
the part where ossification is about to begin. These rows,
in the cartilaginous basis of long bones, are vertical to its
ends—in that of flat bones they are vertical to the peri-
pheral edge. The nucleated cells are the instruments by
which the earthy particles are arranged in order; and in |
bone, as in tooth, there may be discerned, in this prede-
termined arrangement, the same relation to the acquisi- |
tion of strength and power of resistance, with the greatest
economy of the building material, as in the disposition of |
the beams and columns of a work of human architec-/
ture. .

Osteine, so formed, is arranged in thin plates, concen-

22, GROWTH OF BONES.

trically around the vascular canals, around the entire cir-
cumference of the long bones, and in interrupted plates,
connecting together the walls of the vascular canals, so
as often to give rise to a reticular disposition of the bony
substance. .

In fishes, the bones continue to grow throughout life;
and their periphery, whether in the flat bones of the head
which overlap each other, or the thicker bones that inter-
lock, is cartilaginous or membranous, and the seat of pro-
gressive ossification. The long bones of most reptiles
retain a layer of ossifying cartilage beneath the terminal
articular cartilage; and growth continues at their ex-
tremities while life endures. Some of the long bones in
frogs, birds, and most of those in mammals, have their
ends distinct from the body or shaft of the growing bone,
these separately ossified ends being termed “ epiphyses.”
The seat of the active growth of the shaft is in a cartila-
ginous crust at the ends supporting the epiphyses; when
these coalesce with the shaft, growth in the direction of
the bones’ axis comes to an end; but there is a slower
growth going on over the entire periphery of the bone,
which is covered by a membrane called the “periosteum.”
In this membrane, the vascular system of a bone, except
the vessel supplying the marrow-cavity, undergoes the
amount of subdivision which reduces its capillaries to
dimensions suited for penetrating the pores leading to the
vascular canals.

Thus bone is a living and a vascular part, growing by
internal molecular addition and change, and having the
power of repairing fracture or other injury. The shells
and crusts of molluscous and crustaceous animals are un-
vascular; they grow by the addition of layers to their
circumference, may be cast off when too small for the

GROWTH OF BONES. 23

growing body, and be reproduced of a more conformable
size. When fractured, the broken parts may be cemented
together by newly superadded shell-substance from with-
out; but are not unitable by the action of the fractured
surfaces from within.

Extension of parts, however, is not the sole process
which takes place in the growth of bone; to adapt a bone
to its destined office, changes are wrought in it by the
removal of parts previously formed. In fishes, indeed,
we observe a simple unmodified increase. 'T'o whatever
extent the bone is ossified, that part remains, and, conse-
quently, most of the bones of fishes are solid or spongy
in their interior, except where the ossification has been
restricted to the surface of the primary gristly mould.
The bones of the heavy and sluggish turtles and sloths,
of the seals, and of the whale-tribe, are solid. But in the
active land quadrupeds, the shaft of the long bones of the
limbs is hollow, the first-formed osseous substance being
absorbed as new bone is being deposited from without.
The strength and lightness of the limb-bones are thus
increased after the well-known principle of the hollow
column, which Galileo, by means of a straw picked up
from his prison floor, exemplified, in refutation of a charge
of Atheism brought against him by the Inquisition. The
bones of birds, especially those of powerful flight, are re-
markable for their lightness. The osseous tissue itself is,
indeed, more compact than in other animals; but its quan-
tity in any given bone is much less, the most admirable
economy being traceable throughout the skeleton of birds,
in the advantageous arrangement of the weighty material.
Thus, in the long bones, the cavities analogous to those
called “medullary” in beasts, are more capacious, and
their walls are much thinner. A large aperture called

24 STRUCTURE OF BONES IN DIFFERENT CLASSES.

the “pneumatic foramen,” near one end of the bone, com-
municates with its interior, and an air-cell, or prolonga-
tion of the lung, is continued into and lines the cavity of |
the bone, which is thus filled with rarefied air instead of
marrow. ‘The extremities of such air-bones present a
light open network, slender columns shooting across in
different directions from wall to wall, and these little
columns are likewise hollow. ‘

The enormous beak of the hornbill, which seems at
first sight to constitute so grave an impediment to flight,
forms one enormous air-cell, with very thin bony walls;
and in this bird, in the swifts, and the humming-birds,
every bone of the skeleton, down to the last joints of the
toes, is permeated by hot air. The opposite extreme to
the above members of the feathered class is met with in
the terrestrial apteryx (wingless bird of New Zealand),
and in the aquatic penguin; in both of which, not any
bone of the skeleton receives air. Intermediate grada-
tions in the extent to which the skeleton is permeated by
air occur in different birds, and in relative proportion to
their different kinds and power of flight.

In the mammalian class, the air-cells of bone are con-
fined to the head, and are filled from the cavities of the
nose or ear, not from the lungs. Such cells are called
“frontal sinuses,” “antrum,” “sphenoidal” and “ethmoidal
sinuses” in man. The frontal sinuses extend backwards
over the top of the skull in the ruminant and some other
quadrupeds, and penetrate the cores of the horns in oxen,
sheep, and a few antelopes. The most remarkable de-
velopment of air-cells in the mammalian class is presented
by the elephant; the intellectual physiognomy of this
huge quadruped being caused, as in the owl, not by the

THE NEUROSKELETON. 25

actual capacity of the brain-case, but by the enormous
extent of the pneumatic cellular structure between the
outer and inner plates of the skull-walls.

In all these varied modifications of the osseous tissue,
the cavities therein, whether mere cancelli, or small me-
dullary cavities as in the crocodile, or large medullary
cavities as in the ox, or pneumatic cavities and sinuses
as in the owl, are the result of secondary changes by
absorption, and not of the primitive constitution of the
bones. These are solid at their commencement in all
classes, and the vacuities are established by the removal
of osseous matter previously formed, whilst increase pro-
ceeds by fresh bone being added to the exterior surface.
The thinnest-walled and widest air-bone of the bird of
flight was first solid, next a marrow-bone, and finally —
became the case of an air-cell. The solid bones of the
penguin, and the medullary femur of apteryx, exemplify
arrested stages of that course of development through
which the pneumatic wing-bone of the soaring eagle had
previously passed.

But these mechanical modifications do not exhaust all
the changes through which the parts of a skeleton, ulti-
mately becoming bone, have passed; they have been pre-
viously of a fibrous or of a cartilaginous tissue, or both.
Entire skeletons, and parts of skeletons, of vertebrate
animals exhibit arrests of these early stages of develop-
ment; and this quite irrespective of the grade of the
entire animal in the zoological scale. The capsule of the
eyeball, for example, in man, is a fibrous membrane; in
the turtle, it is gristle; in the tunny, and most other
fishes, it is bone. The skeletal framework of the little
lancelet-fish( Branchiostoma) does not go beyond the fibrous

5)

26 SEGMENTAL COMPOSITION.

stage of tissue change.’ In the sturgeon, skate, and shark,
it stops at the gristly stage, and hence these fishes are
called “cartilaginous.” In most fishes, and all air-breath-
ing vertebrates, it proceeds to the bony stage, with the
subsequent modifications and developments above recited.

The main part of the skeleton—what may be termed the
skeleton proper—consists of the neuro-skeleton; and it
is in the construction of this system that the most interest-
ing and beautiful evidences of unity of plan, as well as
of adaptation to end, have been discerned. The parts of
the neuroskeleton are arranged in a series of segments,
following and articulating with each other, in the direc-
tion of the axis of the body, from before backwards in
brutes, from above downwards in man.

Each complete segment, called “vertebra,” consists of
a series of osseous pieces, arranged according to one and
the same plan (Fig. 3), viz: so as to form a bony hoop, or
arch, above a central piece, for the protection of a seg-
ment of the nervous axis, and a bony hoop, or arch,
beneath the central piece, for the protection of a segment
of the vascular system. The upper hoop is called the
“neural arch,” N. (Gr. neuron, nerve); the lower one, the
‘“heemal arch,” H (Gr. havma, blood); their common centre
is termed the “centrum,” ¢ (Gr. kentron, centre). The
neural arch is formed by a pair of bones, called “neura-
pophyses,” 2 n (Gr. for nerve and apophysis, a projecting
part or process) ;* and by a bone, sometimes cleft or bifid,
called the “neural spine,” ns ; it also sometimes includes a
pair of bones, called “ diapophyses,” d d (Gr. dia, across,
or transverse, and apophysis). The hzmal arch is formed

1 The doctrine or study of this kind of development—the development
of substance and texture, as contradistinguished from that of size and
shape—is now termed “ Histology,” from the Greek his/os, net or tissue,
and logos, a doctrine or discourse.

TYPICAL SEGMENTS, OR VERTEBRS. NF

by a pair of bones called “pleurapophyses,” jl (Gr.
pleuron, rib, and apophysis); by

a second pair, called “ hemapo- Fig. 3.
phys es,” h (Gr. for blood, and Pw
apophysis; and by a bone some- Wy aN
times bifid, called the “hemal f} \
spine,” hs. It also sometimes of 2 y,

includes parts, or bones, called
“narapophyses” (Gr. para, trans- oa
verse, and apophysis). Bones,

: Ply So y
moreover, are developed, which
diverge as rays, from one or more A
parts of a vertebra.

The parts.of a vertebra which \ )
are developed from independent ® v4
centres of ossification are called ue

iS
“autogenous Si those parts that TYPICAL VERTEBRA.—(IDEAL.)

grow out from previously ossified

parts are called “ exogenous ;” the autogenous parts of a
vertebra are its elements,” the exogenous parts its “ pro-
cesses.” No part, however, is absolutely autogenous
throughout the vertebrate series, and some that are exo-
genous in most are autogenous in a few instances. The
line cannot be strictly drawn; and, in classifying the parts
of a vertebra, as of other parts of animals, or of entire
animals, the systematist must be guided by general rules,
to which there will ever be some exceptions.

The elements, or autogenous parts, of a vertebra are
the centrum, c, the neurapophyses, n, the neural spine, ns,
the pleurapophyses, p/, the hzeemapophyses, h, and the
heemal spine, hs. The exogenous parts are the diapophy-
sis (Hig. 5), d, the parapophysis (¢b.) p, the zygapophysis
(Fig. 6), 2 (Gr. zugos, junction, and apophysis), the ana-

28 TYPICAL SEGMENTS, OR VERTEBR®.

pophysis (Fig. 2), a (Gr. ana, backwards, and apophysis),
the metapophysis (7b.), m (Gr. meta, between, and apophy-
sis), the hypapophysis (Fig. 5), y (Gr. hypo, below, and
apophysis), and the epapophysis (Fig. 4), e (Gr. epi, above,
and apophysis). Of the autogenous parts, the neural spine
is most commonly exogenous; of the exogenous parts, the
parapophyses, diapophyses, and hypapophyses are some-
times autogenous.

Vertebree are subject to many and great modifications
—e. g.,as to the number of the elements retained in their
composition, as to the form and proportion of the elements,
and even as to the relative position of the elements;
but the latter modification is never carried to such a
degree as to obscure the general pattern or type of the
segment.

ys

hs

PARIETAL SEGMENT, OR THORACIC SEGMENT, OR TYPICAL VERTEBRA.
VERTEBRA—MAN. VERTEBRA—
RAVEN.

Sometimes, as in the example (Fig. 4) of the third seg-
ment of the human skeleton, the neural arch, N, is much

expanded, the hzmal
one, H, is contracted ;
and, in the expanded
neural arch, the auto-
genous diapophyses, dd,
are wedged between the
neurapophyses, n, and
the enormously ex-

panded neural spine, .

ns. More commonly,
as in the example from
the raven’s thorax (Fig.
5), the heemal arch, H,
is much expanded, the
neural one, N, contract-
ed; and in the expanded
hemal arch, the para-
pophysis, p, here exo-
genous, is wedged be-
tween the centrum, C,
and the pleurapophysis,
pl. Sometimes, again,
as is exemplified in the
tail of the crocodile and
of many other animals,
both neural and hemal
arches, are alike con-
tracted; the pleurapo-
physes, pl, being ex-
cluded from the latter,
and standing out as con-
tinuations of the conflu-
ent diapophyses, d, and

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ARCHETYPE VERTEBRATE SKELETON.

30 ARCHETYPE OF THE SKELETON.

parapophyses, p. Such vertebre deviate but little from
the ideal type of the vertebra, under its less developed
condition, as in Fig. 6. The segments are commonly
simplified and made smaller as they approach the end of
the vertebral column or axis, one element or process after
another is removed, until the vertebra is reduced to its
centrum, asin the subjoined diagram (Fig. 7) of the arche-
type vertebrate skeleton. In this scheme, which gives a
side view of the series of segments or vertebree, the nature
of the principal modifications to which they are subject
are indicated, at the two extremes of the series.

As the four anterior divisions of the great trunk of the
nervous system are called, collectively, “brain,” so the
four corresponding segments of the osseous system are
called “skull.” The head, therefore, is not otherwise a
repetition of the trunk, than in so far as each segment of
the skull is a repetition or “homotype” of every other
segment of the body; each being subject to modifications
which may give it an individual character, without obli-
terating its typical features. So neither are the “arms”
and “legs” repeated in the head in any other sense than as
the cranial vertebra may retain their “diverging append-
ages,” 25, 37, 44, 53, a. The fore-limbs are actually
such appendages, 53, of the occipital vertebra, 1, 3, 2, 51,
52, 59, which appendages undergo modifications closely
analogous to those of the appendages of the pelvic seg-
ment, or “hind limbs,” 65. And inasmuch as in one
class the pelvic appendages, with their supporting hemal
arch, 68, hs, are detached from the rest of their segment,
and subject to changes of position (Fig. 9), 63, 69; so also
in other classes the appendages of the occipital segment
are liable to be detached, with their sustaining hemal .
arch, and to be transported to various distances from their

x

ARCHETYPE OF THE SKELETON. 31

proper centrum and neural arch, as in Fig, 21, Nos. 51,
53, 57.

The four anterior neurapophyses, 14, 10, 6, 2, give issue
to the nerves, the terminal modifications of which consti-
tute the organs of special sense.

The first or foremost of these is the organ of smell, 19,
always situated immediately in advance of its proper seg-
ment, which becomes variously and extensively modified
to.inclose and protect it.

The second is the organ of sight, 17, lodged in a cavity
or “orbit” between its own and the nasal segment, but
here indicated above that interspace.

The third is the organ of taste, the nerve of which

perforates the neurapophysis, 6, of its~proper segment,
ealled “parietal vertebra,” or passes by a notch between
this and the neurapophysis, 10, of the frontal vertebra,
to expand in the organ, which is always lodged below,
in the cavity called “mouth,” and is supported by the
heemal spine, 41, hs, of its own vertebra.
_ The fourth is the organ of hearing, 16, indicated above
the interspace between the neurapophysis of its own
(occipital) and that of the antecedent (parietal) vertebra,
in which it is always lodged; the surrounding vertebral
elements being modified to form the cavity for its recep-
tion, which is called “otocrane.” The jaws are the modi-
fied heemal arches of the first two segments.

The mouth opens at the interspace between these hzmal
arches; the position of the vent varies (in fishes), but
always opens behind the pelvic arch, 8, 62, 68, p, when
this is ossified.

Outlines of the chief developments of the dermoskeleton
in different vertebrates, which are usually more or less
ossified, are added to the neuroskeletal archetype; as,

82 ARCHETYPE OF THE SKELETON.

e.g. the median horn supported by the nasal spine, 15, in
the rhinoceros; the pair of lateral horns developed from
the frontal spine, 11, in most ruminants; the median folds,
D1, Du, above the neural spines, one or more in number,
constituting the “dorsal” fin or fins in fishes and cetaceans,
and the dorsal hump or humps in the buffaloes and camels;
similar folds are sometimes developed at the end of the
tail, forming a “caudal” fin, C, and beneath the heemal
spines, constituting the “anal” fin or fins, A, of fishes.
- The different elements of the primary segments are
distinguished by peculhar markings:—

The neurapophyses by diagonal lines, thus — Hi!
The diapophyses by vertical lines— |! | |

ll

The parapophyses by horizontal lines —-

The centrum by decussating horizontal and vertical lines — =

The pleurapophyses by diagonal lines— \\

The appendages by dots—* * °°

pi 6), 0, Kane

The neural spines and hemal spines are left blank.

In certain segments, the elements are also specified by
the initials of their names :—

ns is the neural spine.

n is the neurapophysis.

pl is the pleurapophysis.

c is the centrum.

his the hemapophysis, also indicated by the Nos. 21, 29, 44,
52, 58, 63, 64.

hs is the heemal spine.

a is the appendage.

The centrum is the most constant vertebral element as
to its existence, but not as to its ossification. There are
some living fishes—and formerly there were many, now

ARCHETYPE OF THE SKELETON. Go

extinct—in which, whilst the peripheral elements of the
vertebra become ossified, the central one remains unos-
sified; and here a few words are requisite as to the de-
velopment of vertebree.

The central basis of the neuro-skeleton is Jaid down in
the embryo of every vertebrate animal, as a more or less
cylindrical fibrous sheath, filled with simple cells con-
taining jelly. This fibro-cellulo-gelatinous column is
called “notochord,” Fig. 1, ch (Gr. notos, black; chorda,
cord; in Latin, “chorda dorsalis”). The centrums, or
“bodies of the vertebree,” as anthropotomists call them,
are developed in and from the notochord. The bases of
the other elements of the vertebra are laid down in fibrous
bands, diverging from the notochord, and giving the first
indication of the segmental character of the skeleton. At
this stage, the skeleton of the little fish called “lancelet”
(Amphwxus lanceolatus) is arrested. ‘These fibrous bands
are next converted into cartilage, and the cartilage is in
definite pieces in each segment, recognizable as “neura-
pophyses” (Fig. 1), n; “pleurapophyses” (¢d.), p/; “neural
spine” (7b), ns—the centrums still remaining in their
primitive state as the undivided notochord (7d), ch. At
this stage, the skeleton of the sturgeon is arrested. The
peripheral elements may be converted into bone, the cen-
tral ones remaining as notochord, as in the protopterus,
the lepidosiren, and many fossil fishes. But, more com-
monly, the next stage is the subdivision of the notochord
into a series of separate centrums, corresponding with the
pairs of neurapophyses and pleurapophyses—ossification
of all the parts being more or less imperfect, as in the
sharks and rays, which have thence been called “ cartila-
ginous fishes.” When the parts of the vertebrae have
become more completely ossified, as in the fishes called

34 DEVELOPMENT OF VERTEBRA.

“osseous,” ossification is rarely so advanced as in the
higher vertebrata. In most of these
fishes, e. g., a deep cavity is left at each
end of the centrum (Fig. 8), cc, which
cavity continues to be occupied by the
liquefied gelatinous remains of the
primitive notochord; and the charac-
teristic of such element in a fish’s
skeleton is, that it is “biconcave.” Of
the minor amount of the earthy mat-
ter in the ossified parts of the skeleton of fishes, mention
has been already made; and the consequent greater flexi-
bility and elasticity of such bones may be readily tested
by whoever will bend one of the long spines in the skele-
ton of a cod or turbot, and contrast its flexibility with
that of the similarly-shaped long and slender bone (pubis,
or fibula, e.g.) which he may find in the Christmas turkey
that follows in the feast.

Two or more contiguous vertebre are frequently sub-
jected to the same kind of modification, either by way of
excess or defect, and such groups of modified segments
have received special names; such, for example, as “skull”
(cranium), “neck” (cervix), “chest” (thorax), “pelvis,” and
“tail” (cauda); and these terms are reciprocally applied,
when modified as adjectives, to the individual vertebree
so grouped together, and which are called “cranial ver-
tebre,” “cervical vertebree,” “dorsal” or “thoracic ver-
tebree,” “sacral” or “pelvic vertebree,” and “caudal ver-
tebree.”

SECTION OF VERTEBRA
—FISH.

SKEQLETON OF THE FISH. 30

SKELETON OF THE FISH.

In all fishes, the extent of ossification is less than in
the higher vertebrate classes. Only in the skull do we
find all the elements of the typical segment represented
by bone. In the trunk, e.g., the hemapophyses and
heemal spines never advance beyond the fibrous stage of
tissue development.

Four segments enter into the composition of the skull
of fishes, answering to the first four in the archetype (Fig.
7), and they combine to constitute the bony framework
of a head, larger in proportion to the trunk than in any
other class of animals. The skull (Fig. 9), 5, 52, dr, forms
a cone, whose base is vertical, directed backwards, and
jomed to the trunk without an intervening neck, and
whose sides are commonly three in number, one superior,
and two lateral and inferior. The cone is shorter or
longer, more or less compressed or squeezed from side to
side, more or less depressed or flattened from above down-
wards, with a sharper or blunter apex, in different species
of fishes. The base of the skull is perforated by the hole,
called “foramen magnum,” for the exit of the spinal mar-
row; the apex is more or less widely and deeply cleft
transversely by the aperture of the mouth; the eye-sockets
or “orbits,” or, are lateral, large, and usually with a free
and wide intercommunication in the skeleton; the two
vertical fissures behind are called “ gill-slits,” or branchial
or opercular apertures, and there is a mechanism, like a
door, 84, 35, 36, for opening and closing them. The
mouth receives not only the food, but also the streams of
water for respiration (indicated by the arrow dr), which
escape by the gill-slits. The head contains not only the

36 SKELETON OF THE FJSH.

brain and organs of sense, but likewise the heart and
breathing organs. The inferior or “hemal” arches are
greatly developed accordingly, and their diverging append-
ages support membranes that can act upon the surround-
ing fluid, and are more or less employed in locomotion;
one pair of these appendages, P, 57, answers, in fact, to the
fore-limbs in higher animals, and their sustaining arch,
51, 52, in many fishes, also supports the homologues of
the hind-limbs, V, 69. Thus brain and sense-organs, jaws
and tongue, heart and gills, arms and legs, may all belong
to the head; and the disproportionate size of the skull, and
its firm attachment to the trunk, required by these func-
tions, are precisely the conditions most favorable for facili-
tating the course of the fish through its native element.
It may well be conceived, then, that more bones enter
into the formation of the skull in fishes than in any other
animals; and the composition of this skull has been
rightly deemed the most difficult problem in comparative
anatomy. “It is truly remarkable,” writes the gifted
Oken, to whom we owe the first clue to its solution,
“what it costs to solve any one problem in philosophical
anatomy. Without knowing the what, the how, and the
why, one may stand, not for hours or days, but weeks,
before a fish’s skull, and our contemplation will be little
more than a vacant stare at its complex stalactitic form.”
To show what the bones are that enter into the com-
position of the skull of the fish ; how, or according to what
law, they are there arranged; and why, or to what end,
they are modified, so as to deviate from that law or arche-
type, will next be our aim. These points, rightly under-
stood, yield the key to the composition of the skull in all
vertebrata, and they cannot be omitted without detriment
to the main end of the most elementary essay on the

COMPOSITION OF THE SKULL OF THE FISH. 87

skeletons of animals. The comprehension of the descrip-
tion will be facilitated by reference to Figs. 7 and 9; and
still more if the reader have at hand the skull of any
large fish.

In the cod (Gadus morrhua), e. g., it may be observed,
in the first place, that most of the bones are, more or less,
like large scales; have what, in anatomy, is called the
“squamous” character and mode of union, being flattened,
thinned off at the edge, and overlapping one another; and
one sees that, though the skull, as a whole, has less free-
dom of mdvement on the trunk, more of the component
bones enjoy independent movements. Before we proceed
to pull apart the bones, it may be well to remark that the
principal cavities, formed by their coadaptation, are the
“cranium,” lodging the brain and the organs of hearing;
the “orbital,” Fig. 9, or, and the “nasal,” n/, chambers; the
buccal and branchial canals, dr. Some of these cavities
are not well defined. The exterior of the skull is tra-
versed by five longitudinal crests, intercepting four chan-
nels which lodge the beginnings of the great muscles of
the upper half of the trunk. The median crest is de-
veloped to an extreme height in some fishes, as, e. g., the
dolphin and light-horseman fish (Hphippus). The flat-
fishes (turbot, sole, &c.) are remarkable for the unsym-
metrical character of the skull, in consequence of both
eyes being placed on one side of the head.

In the analysis of the cod’s skull it is best to begin at
the back part; for the segments of the skeleton deviate
most from the archetype as they recede in position to-
wards the two extremesof the body. After a little prac-
tice, one succeeds in detaching the bones which form the

' The skull of this fish, conveniently prepared for this examination,
may be had of Mr. Flower, No, 22 Lambeth Terrace, Lambeth Road.

4

OF THE PERCH.

N

SKELETO

38

*(s0yp'7) HOUNA-VaS

OCCIPITAL SEGMENT, OR VERTEBRA. 39

back part or base of the conical skull, and which immedi-
ately precede and join those of the trunk; we thus obtain
a “seoment” or “vertebra” of the skull. If we next pro-
ceed to separate a little the bones composing this segment,
we find those that were most closely interlocked to be in
number and arrangement as follows: T'wo single and
symmetrical bones, and two pairs of unsymmetrical bones,
forming a circle; or, if the lower symmetrical bone, which
is the largest, be regarded as the base, the other five form
an arch supported by it, of which the upper symmetrical
bone is the keystone.1. This answers to the “neural”
arch of the typical vertebra: the base-bone is the “ cen-
trum,” c; the pair of bones, which articulated with its
upper surface and protected the hind division of the brain,
form the “neurapophyses,” »; the smaller pair of bones,
projecting outwards, like transverse processes, are the
“ diapophyses,” d; the symmetrical bone completing the
arch, and terminating above in a long crest or spine, is
the “neural spine,” ns. It will be observed that the cen-
trum is concave at that surface which articulates with the
centrum of the first vertebra of the trunk; the opposite
surface is also concave, but expanded and very irregular,
in order to effect a much firmer union with the centrum
of the next cranial segment in advance—great strength
and fixity being required in this part of the skeleton,
instead of the mobility and elasticity which is needed in
the vertebral column of the trunk. It may be also ob-
served that the “ neurapophyses” are perforated, like most
of those in the trunk, for the passage of nerves; that the
diapophyses give attachment to the bones which form the
great inferior or hemal arch; and that the neural spine

1 See my work ‘‘On the Archetype of the Skeleton,” 8vo. 1848, p. 10,
Fig. 1.

40 OCCIPITAL SEGMENT, OR VERTEBRA.

retains much of the shape of the parts so called in the
trunk. Nevertheless, the elements of the neural arch of
this hindmost segment of the skull have undergone so
much development and modification of shape, that they
have received special names, and have been enumerated
as so many distinct and particular bones. The centrum,
No. 1, is called “ basioccipital;” the neurapophyses, No.
2, “exoccipitals ;” the neural spine, No. 8, “superoccipi-
tal;” the diapophyses, No. 4, “paroccipitals.” In the
human skeleton all those parts are blended together into
a mass, which is called the “ occipital bone.”

The entire segment, here disarticulated, in the cod-fish,
is called the “occipital vertebra,” and in it we have next
to notice the widely expanded inferior or heemal arch.
This consists of three pairs of bones. ‘The first pair are
bifurcate, and have two points of attachment to the neural
arch, the lower prong, answering to what is called the
“head of the rib,” abutting upon the neurapophysis; the
upper prong, answering to the “tubercle of the rib,”
articulating to the diapophysis. The second pair of bones
are long and slender, and represent the body of the rib.
The first and second piece together answer to the element
called “ pleurapophysis; the third pair of bones are the
“heemapophyses;” these support diverging appendages
consisting of many bones and rays. The special names
of the above elements of the hzmal arch of the occipital
vertebra are, from above downwards, “suprascapula,”
No. 50; “scapula,” No. 51; “coracoid,” No. 52. The in-
verted arch, so formed, encompasses, supports, and pro-
tects the heart or centre of the hemal system; it is called
the “scapular arch.” ‘There are animals—the gymnotho-
rax and slow-worm, e. g—in which this arch supports no
appendage; there are fishes—the protopterus, e.g. Fig. 832—

Ory

OCCIPITAL SEGMENT, OR VERTEBRA, 41

in which it supports an appendage in the form of a single
many-jointed ray, retaining the archetypal character, Vig.
7, No. 53. In other fishes, the number of rays progress-
ively increase, until, in those called “rays” par excellence,
they exceed a hundred in number, and are of great
length, forming the chief and most conspicuous parts of
the fish. The more common condition of the appendage
in*question is that exhibited in the species figured, Cut 9.
So developed, it is called in ichthyology the “ pectoral
fin:” otherwise and variously modified in higher animals,
the same part becomes a fore-leg, a wing, an arm, and
hand. Some of the special names, originally applied to
the parts of the scapular appendage in man, are retained
and applied to like parts in the pectoral fin of the fish.
Of the two flat bones connecting the fin with the coracoid,
the upper one is the “ulna,” No. 54; the lower one the
“radius,” No. 55; the row of short bones joined with
these are the “carpals,” No. 56; the longer and more
_ slender many-jointed rays answer to the parts called
“metacarpals” and “phalanges” in the human hand. In
the salmon there is a bone answering to the arm-bone or
humerus, which is articulated to the middle of the back
part of the coracoid by a transversely elongated ex-
tremity. It is also expanded at the distal end, where it
articulates by cartilage with the ulna and radius. The
ulna is a semicircular plate of bone perforated in the
centre, and, besides its articulation with the humerus, the
radius, and the ulnar carpals and metacarpal ray, it also
directly joins the broad coracoid. The radius, after ex-
panding to unite with the humerus, the ulna, and the
radial carpals, sends a long and broad process downwards
and inwards, which is united by ligament with its fellow
and with the lower termination of the coracoid. A basis
4*

“42 PARIETAL SEGMENT, OR VERTEBRA.

of adequate extent and firmness is thus insured for the
support of the pectoral fins. The carpal bones of these
fins are four in number, progressively increasing in length
from the ulnar to the radial side of the wrist. The meta-
carpo-phalangial rays are thirteen in number; the upper-
most or ulnar one being the strongest, and articulating
directly with the ulna.

Proceeding to the next segment, in advance, in the cod-
fish’s skull, we find that the bone which articulated with
the centrum of the occipital segment is continued forward
beneath a great proportion of the skull. In quadrupeds,
however, the corresponding part of the base of the skull
is occupied by two bones; and if the single long bone in
the fish be sawn across at the part where the natural
suture exists in the beast, we have then little difficulty in
disarticulating and bringing away with it a series of bones
similar in number and arrangement to those of the oc-
cipital segment.

In the skeletons of most animals the centrums of two
or more segments become, in certain parts of the body,
confluent, or they may be connate; they form, in fact, one
bone, like that, e. g., which human anatomists call “sa-
crum.” By the term “confluent” is meant the cohesion
or blending together of two bones which were originally
separate; by “connate,” that the ossification of the com-
mon fibrous or cartilaginous bases of two bones proceeds
from one point or centre, and so converts such bases into
one bone: this is the case, e. g., in the radius and ulna of
the frog, and in its tibia and fibula. In both instances
they are to the eye asingle bone; but the mind, trans-
cending the senses, recognizes such single bone as being
essentially two. In like manner, it recognizes the “oc-
cipital bone” of man as essentially four bones; but these

PARIETAL SEGMENT, OR VERTEBRA. 45

have become “confluent,” and were not “connate.” The
centrums of the two middle segments of the fish’s skull
are connate, and the little violence above recommended is
requisite to detach the penultimate segment of the skull.
When detached, the bones of it are seen to be so arranged
as to form a neural and a hemal arch. In the neural arch
the centrum, neurapophyses, diapophyses, and neural spine
are distinct: moreover, the neural spine in the cod, and
many other fishes, is bifid, or split at the median line.
The centrum is called “ basisphenoid,” No. 5; the neura-
pophysis, “alisphenoid,” No. 6; the neural spine, “pa-
rietal,’” No. 7; and the diapophysis, “mastoid,” No. 8.
The alisphenoids protect the sides of the optic lobes, and
the rest of the penultimate segment of the brain; the
mastoids project outwards and backwards as strong trans-
verse processes, and give attachment to the piers of the
great inverted hemal arch. Before noticing the structure
of this, I may remark that, in the recent cod-fish, the case,
partly gristly, partly bony, which contains the organ of
hearing, is wedged in between the last and penultimate
neural arches of the skull. The extent to which the ear-
case is ossified varies in different fishes, but the bone is
always developed in the outer wall of the case. In the
cod-fish it is unusually large, and is called “ petrosal,”
No. 16; it forms no part of the segmented neuroskeleton.
In the organ which it contributes to inclose, there is a
body as hard as shell, like half a split almond; it is the
‘otosteal,” No. 16, or proper ear-bone.

The hzemal arch consists of a pleurapophysis and a
heemapophysis on each side, and a hemal spine; but all
these elements are subdivided; the pleurapophysis into
two parts, the upper one called “epitympanic,” 28, a

' « Archetype Vert. Skel.,” p. 11, Fig. 2.

t+ PARIETAL SEGMENT, OR VERTEBRA.

(common to this and the next arch in advance); the lower
one “stylohyal,” No. 88. The hemapophysis is a broader,
slightly arched bone; the upper division is called “ epi-
hyal,” No. 89; the lower division, “ceratohyal,” No. 40.
The heemal spine is subdivided into four stumpy bones,
called collectively “basihyal,” No. 41; and which, in most
fishes, support a bone directed forwards, entering the sub-
stance of the tongue, called “glossohyal,” No. 42; and
another bone directed backwards, called “urohyal,” No. 48.

The ceratohyal part of the hamapophysis supports, in
the cod, seven long and slender bent bones, called “ bran-
chiostegal rays,” 44. The number of these rays differs
greatly in different fishes; the protopterus has but one
ray, the blenny has two rays, the carp three rays—a very
common number is seven; but the clops has thirty bran-
chiostegal rays. They are of great length in the angler-
fish (lophius), in which they serve to support a membrane,
developed to form a large receptacle on each side of the
head of this singular fish. Into these receptacles the
small fishes are transferred, which the angler attracts
within reach of its mouth, by the movable rod, line, and
bait attached to the top of its enormous head. In ordi-
nary fishes, the branchiostegal rays support a membrane
which helps to close the gill-slit, and by its movements
contributes to the direction of the branchial currents. It
is an appendage, or rudimental limb, answering to the
pectoral fin diverging from the hzmal arch, in the ad-
joining occipital segment.

The penultimate segment of the skull above described
is called the ‘‘parietal vertebra;” and the heemal arch is
called the “hyoidean arch,” in reference to its supporting
and subserving the movements of the tongue.

The next segment, or the second of the skull, counting

FRONTAL SEGMENT, OR VERTEBRA. 45.

backward, can be detached from the foremost segment
without dividing any bone. It is then seen to consist,
like the third and fourth segments, of two arches and a
common centre; but the constituent bones have been
subject to more extreme modifications. The centrum,
called “presphenoid,” No. 9, is produced far forwards,
shightly expanding; the neurapophyses, called ‘“orbito-
sphenoids,” No. 10, are small semioval plates, protecting
the sides of the cerebrum; the neural spine, or key-bone
of the arch, called “frontal,” No. 11, is enormously ex-
panded, but in the cod and most fishes is single; the
diapophyses, called “ post-frontals,’ No. 12, project out-
wards from the hinder angles of the frontal, and give
attachment to the piers of the inverted hemal arch. The
first bone of this arch is common in fishes to it and to
that of the last-described vertebra, being the bone called
“epitympanic,” No. 28 (Fig. 9); this modification is called
for by the necessity of consentaneous movements of the
two inverted arches, in connection with the deglutition
and course of the streams of water required for the bran-
chial respiration. The hzmal arch of the present seg-
ment—enormously developed—is plainly divided prima-
rily on each side into a pleurapophysis and hzemapophysis;
for these elements are joined together by a movable
articulation, whilst the bones into which they are sub-
divided are suturally interlocked together. The pleura-
pophysis is so subdivided into four pieces; the upper
one, articulating with the post-frontal and mastoid—the
diapophyses of the two middle segments of the skull—is
called “epitympanic,” No. 28, a; the hindmost of the two
middle pieces is the “mesotympanic,” No. 28, 0; the fore-
most of the two middle pieces is the “pretympanic,” No.
28, c; the lower piece is the hypotympanic, No. 28, d;

46 FRONTAL SEGMENT, OR VERTEBRA.

this presents a joint-surface, convex in one way, concave
in the other, called a “ginglymoid condyle,” for the heema-
pophysis, or lower division of the arch. In most air-
breathing vertebrates—the serpent, Cut 16, e. g—the
pleurapophysis resumes its normal simplicity, and is a
single bone, 28, which is called the “tympanic;” in the
eel-tribe it is in two pieces. ‘The greater subdivision, in
more actively breathing fishes, of the tympanic pedicle,
gives it additional elasticity, and, by their overlapping,
interlocking junction, greater resistance against fracture;
and these qualities seem to have been required in conse-
quence of the presence of a complex and largely-de-
veloped diverging appendage, which forms the framework
of the principal flap or door, called “operculum,” that
opens and closes the branchial fissure on each side. The
appendage in question consists of four bones; the one
articulated tothe tympanic pedicle is called “preopercular,”
No. 84; the other three are, counting downwards, the
“opercular,” No. 85; the “subopercular,” No. 86; the
“interopercular,” No. 87. The hamapophysis is sub-
divided into two, three, or more pieces, in different fishes,
suturally interlocked together; the most common division
is into two subequal parts, one presenting the concayo-
convex joint to the pleurapophysis, and called “articular,”
No. 29; the other, bifurcated behind to receive the point
of 29, and joining its fellow at the opposite end to com-.
plete the hemal arch, It is very singularly modified by |
supporting, and having more or less firmly attached to
it, a number of the hard bodies called “teeth,” and hence
it has been termed the “dentary,” No. 388. In the cod
there is a small separate bone, below the joint of the
articular, forming an angle there, and called the “angular
piece,” No. 81.

NASAL SEGMENT, OR VERTEBRA. 47

In consequence of this extreme modification, in rela-
tion to the offices of seizing and acting upon the food,
the pair of hemapophyses of the present segment of the
skull have received the name of “lower jaw,” or “man-
dible” (mandibula). The entire segment is called the
“frontal vertebra.” |

The first segment, forming the anterior extremity of
the neuroskeleton, like most peripheral parts, is that
which has undergone the most extreme modifications.
The obvious arrangement, nevertheless, of its constituent
bones, when viewed from behind, after its detachment
from the second segment, affords one of the most conclu-
sive proofs of the principle of adherence to common type
which governs all the segments of the neuroskeleton,
whatever offices they may be modified to fulfil. The
neural arch plainly exists, but is now reduced to its essen-
tial elements—viz: the centrum, the neurapophyses, and
the neural spine. The centrum is expanded anteriorly,
where it usually supports some teeth on its under surface
in fishes; it is called the “vomer,” No. 18. The neura-
pophyses are notched (in the cod) or perforated (in the
sword-fish), by the crura or prolongations of the brain,
which expand into its anterior divisions, called “olfactory
lobes;” the special name of such neurapophysis is “ pre-
frontal,’ No. 14. The neural spine is usually single,
sometimes cleft along the middle; it is the “nasal,” No. 19.

The hzemal arch is drawn forwards, so that its apex,
as well as its piers, are joined to the centrum (vomer) and
usually also to the neural spine (nasal), closing up ante-
riorly the neural canal. The pleurapophyses are simple,
short, sending backwards an expanded plate; they are
called “ palatines,” No. 20. The hemapophyses are sim-
ple, and their essential part, intervening between the

48 GENERAL AND SPECIAL NAMES OF BONES.

pleurapophysis and heemal spine, is short and thick; but
they send a long process backwards. This element is
called “maxillary,” No. 21. The heemal spine, cleft at
the middle line, sends one process upwards, of varying
length in different fishes, and a second downwards and
backwards; and its under surface is beset with teeth in
most fishes; it is called “premaxillary,” No. 22. Hach
pleurapophysis supports a “ diverging appendage,” con-
sisting commonly of two bones: the outer one, which fixes
the present hzmal arch to the succeeding one, is called
“pterygoid,” No. 24; the inner one is the “entopterygoid,”
No. 28. The entire segment is called the “nasal verte-
bra.” The heemal arch and its appendage form what is
termed the upper jaw (maxilla); the palatine and ptery-
goids forming the roof of the mouth, the maxillary and
premaxillary the proper upper jaw. On reviewing the
arrangement of the bones of the foregoing segments, one
cannot but be struck by the strength of the arches which
protect and encompass the brain, and by the beauty and
efficiency of that arrangement which provides such an _
arch for each primary division of the brain; and a senti-
ment of admiration naturally arises on examining the
firm interlocking of the extended sutural surfaces, and
especially of those uniting the proper elements of the
arch with the buttresses wedged in between the piers and
keystone, and to which buttresses (diapophyses) the
larger hamal arches are suspended.

Tn addition to the parts of the neuroskeleton, the bones
of the head include the ossified part of the ear-capsule,
“petrosal,” 16, already mentioned ; an ossified part of the
eye-capsule, commonly in two pieces, “sclerotals, No. 17;
and an ossified part of the capsule of the organ of smell,
“turbinal,” No. 19. Another assemblage of splanchno-

GENERAL AND SPECIAL NAMES OF BONES. 49

skeletal bones support the gills, and are in the form of
slender bony hoops, called “ branchiaLarches.” They are
articulated to and supported by the hyoidean arch.
Amongst the bones of the muco-dermal system, may be
noticed those that circumscribe the lower part of the orbit,
of which the anterior is pretty constant in the vertebrate
series, and is called “lachrymal,’ marked 20 in Cut 9.
In fishes, they are called “ suborbitals,” and are occasion-
ally present in great numbers, as e. g., in the tunny. A
similar series of bones sometimes overarches the temporal
fossze, and are called “ supertemporals.”

At the outset of the study of Osteology, it is essential to
know well the numerous bones in the head of a fish, and
to fix in the memory their arrangement and names. The
latter, as we have seen, are of two kinds, as regards the
bones of the neuroskeleton; the one kind is.“ general,”
indicative of the relation of the skull-bones to the typical
segment, and which names they bear in common with the
same elements in the segments of the trunk; the other
kind is “special,” and bestowed on account of the particular
development and shape of such elements, as they are modi-
fied in the head for particular functions. I would advise
any one earnestly desirous of comprehending this beau-
tiful department of Comparative Anatomy, to obtain a
prepared and partially disarticulated skull of a cod-fish
from Mr. Flower,’ in which every bone bears the initials
of its “general” name, and the numerals indicative of its
“special” name. A great proportion of the bones in the
head of a fish exist in a very similar state of connection
and arrangement in the heads of other vertebrata, up to
and including man himself. No method could be less {

' Ante, p. 37.

50 CLASSIFICATION OF BONES OF THE HEAD.

' conducive to a true and philosophical comprehension of
the vertebrate skeleton than the beginning its study in
_ man—the most modified of all vertebrate forms, and that
which recedes furthest from the common pattern.
‘Through an inevitable ignorance of that pattern, the
bones in anthropotomy are indicated only by special
names more or less relating to the particular forms these
bones happen to bear in man; such names, when applied
to the tallying bones in lower animals, losing that signi-
_ficance, and becoming arbitrary signs. Owing to the
frequent modification by confluence of the human bones,
collections of them, so united, have received a single
name, as e. g., “occipital,” “temporal,” &c.; whilst their
constituents, which are usually distinct vertebral elements,
have received no names, or are defined as processes, ¢. 7.,
“condyloid process of the occipital bone,” “ styloid process
of the temporal bone,” “ petrous portion of the temporal
bone,” &c. The classification, moreover, of the bones of
the head in Human Anatomy, viz: into those of the cra-
nium and those of the face, is artificial or special, and
consequently defective. Many bones which essentially
belong to the skull are wholly omitted in such classifica-
tion. ,

In regard to the archetype of the vertebrate skeleton,
fishes, which were the first forms of vertebrate life intro-
duced into this planet, deviate the least therefrom; and
according to the foregoing analysis of the bones of the
head, it follows that such bones are primarily divisible
into those of—

The Neuroskeleton ;

The Splanchnoskeleton ;
The Dermoskeleton.

The neuroskeletal bones are arranged in four segments,
called

CLASSIFICATION OF BONES OF THE HEAD. Dl

The Occipital segment ;
The Parietal segment ;
The Frontal segment ;
The Nasal segment.

Each segment consists of a “neural” and a “ hemal” arch.
The neural arches are—

N 1. Epencephalic arch (bones Nos. 1, 2, 3, 4):
N 11. Mesencephalic arch (5, 6, 7, 8);

N 1. Prosencephalic arch (9, 10, 11, 12);

N tv. Rhinencephalic arch (13, 14, 15).

The hzmal arches are—

H_ 1. Scapular arch (50-52) ;
H 1. Hyoidean arch (38-43) ;
H ut. Mandibular arch (28-82) ;
H iv. Maxillary arch (20-22).

The diverging appendages of the heemal arches are—

1. The Pectoral (54-57) ;
The Branchiostegal (44) ;
The Opercular (34-37) ;
The Pterygoid (23-24).

ed

agit

The bones or parts of the splanchnoskeleton which
are intercalated with or attached to pe arches of the true
vertebral segments, are—

The Petrosal (16) or ear-capsule, with the otolites, 16/7;
The Sclerotal (17) or eye-capsule ;

The Turbinal (19) or nose-capsule ;

The Branchial arches;

The Teeth.

The bones of the dermoskeleton are—

The Supratemporals ;

~ The Superorbitals ;
The Suborbitals ;
The Labials.

Such appears to be the natural classification of the
parts which constitute the complex skull of osseous fishes.

52 MODIFICATIONS OF THE JAWS OF FISHES.

The term “cranium” might well be applied to the four
neural arches collectively, but would exclude some bones
called “cranial,” and include some called “facial,” in Hu-
man Anatomy. In aside view of the naturally-connected
bones of the head of a fish, such as is shown in the figure
of the skeleton of the sea-perch, Cut 9, the upper part of
the head is formed by the neural spines called superocci-
pital, 3, frontal, 11, and nasal, 15; produced at the hinder
half into the median ridge. The right lateral ridge is
formed by the parietal, 7, and paroccipital, 4; the external
ridge by the post-frontal, 12, and the mastoid, 8. The
anterior termination of the series of centrums may be
partly seen through the widely-open orbits at 9 and 18,
indicating the presphenoid and vomer respectively. The
most conspicuous parts of the upper jaw are the pre-
maxillary, 22, and the maxillary, 21, the latter being
edentulous, as in most fishes; the salmon and trout are
examples where No. 21 bears teeth. The shape and
slight attachment of those bones relate to the necessity of
a movable mouth that can be protruded and retracted, in
a class of animals that derive no aid in the prehension of
their food from their limbs, which are reduced to fins.
The upper bent back part of the premaxillary is called
its “nasal branch,” and is of unusual length in fishes with
protractile snouts, as, e. g., the dories (Zeus), certain wrasses
(Coricus), and especially the sly-bream (Sparus insidvator
of Pallas). In this fish, the nasal branch of the premaxil-
lary plays in a groove on the upper surface of the skull,
and reaches as far back as the occiput, when the mouth
is shut and retracted. The descending branch of the
premaxillary is attached by a ligament to the maxillary,
and, as this is similarly attached to the mandible, both
are protruded, when the long nasal branch of the pre-

MODIFICATIONS OF THE JAWS OF FISHES. 53

maxillary is drawn forwards out of its epicranial groove.
This action is aided by the hypotympanic, which is of
great length, and has a movable articulation at both ends;
the lower end joining the mandible is pulled forward,
simultaneously with the protrusion of the premaxillary,
and co-operates therewith in the sudden projection of the
mouth, by which the sly-bream seizes, or shoots with a
suddenly-propelled drop of water, the small agile aquatic
insects that constitute its prey.

An opposite extreme of modification of the maxillary
and premaxillary bones, where unusual fixity and strength
are needed, is that presented by the “sword-fishes,” in
which the premaxillaries constitute, by an unusual pro-
longation and density of tissue, the sword-shaped weapon
characteristic of the genera Xiphias and Istiophorus.

In Cut 9 the divisions 28 a, c, and d, of the tympanic
pedicle, and the two chief divisions, 29 and 33, of the
mandible, are shown, together with the four bones of the
opercular appendage; the preopercular, 34, being serrated
and spined, as in most perches.

Of the hyoidean arch may be seen the glossohyal, 42,
the ceratohyal, 40, with its branchiostegal rays, 44, and
the urohyal, 45. Of the scapular arch, the scapula, 51,
and the coracoid, 52, this supports not only the bones of
the “pectoral fin,” P, viz: ulna, radius, with the small
carpal bones intervening between them and the metacar-
pophalanges, 57, but also the lower elements of the pelvic
arch, 68, and their diverging appendage, 69, called the
rs cen Bn) Vi.

In the segments of the trunk the ere noie es save
in the first vertebra, 58, and the pelvic vertebra, 68, are
not ossified; but they are represented by aponeurotic
fascia continued downwards from the ossified elements of

~ Ae

ey on

54 MODIFICATIONS OF THE CAUDAL VERTEBR&.

Fig. 10.

the segments; these elements
consist of the centrum, the neu-
rapophyses, and neural spines,
the pleurapophyses, and the
parapophyses. In most fishes
the neural spines are connate
with the neurapophyses, and
these become confluent with
the centrums in most of the
segments; the neurapophyses
are perforated directly by the
spinal nerves in many fishes,
as at nn (Fig. 8); they usually
develop anterior zygapophyses, —
Z (¥ig. 9). The centrums are
biconcave in all fishes, save the
lepidosteus, in which they are
convex in front, and concave
behind. The pleurapophyses,
pl (Fig. 9), form what are called
“ false ribs,” or free or “ floating
ribs,” in Anthropotomy; they
articulate with the centrums in
the anterior trunk-vertebre,
and then with the parapophy-
ses, p, which are usually con-
fluent with the centrum. The
parapophyses elongate, bend
down, and unite together at or
near to the end of the abdo-
men, and so form the contract-
ed hzemal canal, for the caudal
vessels, in the long and mus-

STRUCTURE AND FORMUL# OF FIN-RAYS. 5d

cular tail of the fish. The trunk-vertebre of a fish are
divisible into those which have free pleurapophyses, called
“abdominal vertebre,” and those without, and which
terminate below by narrow hzmal arches and long
spines, called “caudal vertebre.” These hamal arches
are formed by different parts in different fishes; com-
monly by the bent-down and terminally confluent para-
pophyses (Fig. 10), I, py, cod ; sometimes, as in the tunny
(¢b.) II, by parapophyses, p, lengthened out by pleurapo-
physes, pl ; sometimes, as in lepidosteus (vb.), IT, by pleu-
rapophyses, p/; but never, as in air-breathing vertebrates
(zb.), V, by ossified heemapophyses, h, hs. These elements,
in the first vertebra of the trunk of a fish, are indeed
ossified, and form the long and slender bone called “clav-
icle,” 58 (Fig. 9), usually attached to the inner side of the
scapular arch. The hemapophyses of, probably, the last
abdominal vertebra, called “‘ischia,” No. 68, are detached
from the rest of their segment, and are either loosely
suspended in the flesh, beneath or near it, as in the fishes
called “abdominal ;” or they are advanced, much elon-
gated, and attached to the scapular arch, as in the fishes
called “thoracic” (Fig. 9); or they are more advanced,
shortened, and similarly attached, as in the fishes called
“jugular ;” or they are wholly wanting, as in the fishes
called “apodal.” The fins called “ ventral,” V, supported
by the pelvic hamapophyses, indicate by their position
the orders of fishes called “abdominal,” “ thoracic,” and
“jugular,” by Linnezeus.

The only proper fins in pairs are the “ pectoral,” P, |
answering to the fore-limbs of quadrupeds, and the “ven- |

tral,” V, answering to the hind-limbs. The rest of the
fins are single and median in position, and are due to

folds of the skin, in which certain dermal bones are |

56 STRUCTURE AND FORMULE OF FIN-RAYS.

_ developed for their support. These bones are of two
kinds; one, dagger-shaped, are plunged, so to speak, up
to the hilt, in the flesh between the neural spines, and
between the hzmal spines; those along the upper surface
of the fish are called “interneural spines,” zn, Cut 9; those
on the under surface are the “interhzemal spines,” ch.
The interneural spines support the “ dermoneural spines,
dn, forming the rays of the dorsal fin or fins, D1, D2, and
the upper rays of the caudal fin. The interhzemal spines
support the dermohzmal spines, dh, which form the rays
of the anal fin, A, and the lower rays of the caudal fin,
dh, ©.

Both dermoneural and dermohzemal spines may pmesent
two structures; they may be simple, unjointed, firm, bony
spines; or they may be flexible, jointed, and iearichied
rays. Those fishes which have one or more of the hard
spines at the beginning of the pectoral, ventral, dorsal,
and anal fins are called “acanthopterygian,” or spiny-
finned fishes (Gr. acanthos, spine; pterux, fin); those in
which the vertical fins are supported by soft spines are
called ‘“malacopterygian,” or soft-finned fishes (Gr. ma-
lakos, soft; and pterux). Ichthyologists avail themselves
of the number and kind of rays in the fins to characterize
the species of fishes, and adopt an abbreviated formula
and symbols to express these characters.

In regard to the sea-perch (Fig. 9), the fin-formula
would be as follows :—

D7,1+12: P12: Tile A3+8: C18,
which signifies that D, the dorsal fin, has, in its first divi-
sion, 7 rays, all spinous; in its second division, 1 spinous
+ (plus) 12 rays that are soft. P, the pectoral fin, has
12 rays, all soft. V, the ventral fin, has one spinous+5

ADAPTATION OF THE FISH’S SKULL, ETC. 57

soft rays. A, the anal fin, has 3 spinous+8 soft rays.
C, the caudal fin, has 18 rays.

When the piscine modification of the vertebrate skele-
ton is contemplated in relation to the life and movements
of a fish in its native element, every departure from the
archetype is seen to be in direct relation to the habits
and well-being of the species.

The large head has been compared to the embryonic
disproportion of that part in higher vertebrates; but the
head of a fish should be of the size and shape best fitted
to overcome the resistance of water, and to facilitate rapid
progression through that element; the head must, there-
fore, grow with the growth of the body. Accordingly,
the large skull-bones always show the radiating bony
filaments in their clear circumference, which is the seat
of growth; and hence the number of overlapping squa-
mous sutures which least oppose the progressive exten-
sion of the bones. The cranial cavity expands with the
expansion of the skull, but the brain undergoes no cor-
responding increase; it lies at the bottom of its capacious
chamber, which is principally occupied by a loose cellular
tissue, situated, like the “arachnoid” membrane in man,
between the brain-tunics, called “pia mater” and “dura
mater,” and having its cells filled by a light, oily fluid;
thus the head is rendered specifically lighter than if
erowth only, and not the modelling absorption also, had
gone on. ‘The loose connection of the hemal arches and
‘ their parts, including most of what are called “bones of
the face,” seems like the retention of a condition observ-
able in the partially-developed skull of the embryos of
higher animals; but this condition is subservient to the
peculiar and extensive movements of the jaws, and of the
bony supports of the breathing machinery. Not any of

58 ADAPTATION OF THE FISH’S SKULL

the limbs of fishes are prehensible; the mouth may be

propelled by them to the food, but the act of taking it
~ must be performed by the jaws; these can, accordingly,
be not only opened and shut, but can be protruded and
retracted. The division of the long tympanic pedicle into
several partly-overlapping pieces adds to its strength,
and by a slight elastic yielding diminishes the liability to
fracture. The tongue, to judge by its structure, seems to
serve little as an organ of taste, but the arch sustaining it
has much to effect in the way of swallowing; for this
action relates not merely to food; the mechanical part of
breathing is a modified, habitual, and frequent act of deglu-
tition. The hyoid arch is the chief support of the bran-
chial arches and gills; and the branchiostegal membranes,
stretched out upon the diverging rays of the hyoid arch,
regulate the course and exit of the respiratory currents.

By the retraction of the hyoid arch the opercular doors
are forced open, and the branchial cavity is widened,
whilst all entry from bebind is prevented by the branchi-
ostegal flaps, which close the external gill-openings. The
water, therefore, enters by the gaping mouth, and rushes
through the sieve-like interspaces of the branchial arches
into the branchial cavity; the mouth then shuts, the
opercular doors close upon the branchial and hyoid
arches, which again swing forwards; and the branchio-
stegal membranes being withdrawn, the currents rush out
at the gill-openings. Thus the mechanical functions of
the heemal arches of the thorax of the higher air-breath- .
ing classes are transferred to the hemal arches and ap-
pendages of the skull in fishes.

The persistent gills and gill-arches in fishes have been
compared with the same parts which are transitory in
frogs, and with some traces of branchial organization in

TO AQUATIC LIFE. 59

the embryos of higher vertebrates; and fishes have been
called, in the language of the transmutation-of-species
hypothesis, “arrested gigantic tadpoles.” It will be
found, however, that so far from there having been any
stoppage of development, the branchial arches have been
adapted to the exigencies of the fish by advancing to a
grade of structure which they never reach in the frog.
This is shown by their firm ossification, and their numer-
ous elastic joints; the sieve-like valves developed from
the side next the mouth have been pre-arranged, with the
utmost complexity and nicety of adjustment, to prevent
the entry of any particles of food, or other irritating mat-
ters, into the interspaces of the tender, vascular, and
sensitive gills. It is interesting, also, further to observe,
that the last pair of these arches, which, when the em-
bryo-fish is as yet edentulous, usually support gills, are
reduced, when the supply of yollk-food is exhausted, and
the jaws get their prehensile organs, to the capacity of
the gullet, become thickened, in order to support teeth
for tearing in pieces, mincing, or crushing the food, and
are converted into an accessory pair of jaws, and this
pair the most important of the two, as it would seem; for
the carp-tribe—e. g., tench, barbel, roach—which have no
teeth on their proper jaws, have teeth on the pharyngeal
jaws. In no other vertebrate animals, save the osseous
fishes, is the mouth provided with maxillary instruments
at both the fore and hind apertures; and in no other part
of the piscine structure is the direct divergence from any
conceivable progressive scale of ascending organisms,
culminating in man, so plainly marked as in this.

The general form of the fish is admirably adapted to
the element in which it lives and moves. The viscera
are packed in a moderate compass, in a cavity brought

60 ADAPTATION OF THE FISH’S SKELETON.

forwards close to the head. The absence of any neck
gives the advantage of a more extensive and resisting
attachment of the head to the trunk, and a greater pro-
portion of the trunk is left free for the allocation of the
muscular masses which move the tail. In the “ caudal”
division of the vertebral column, the parapophyses cease
to extend outwards; they bend downwards, unite and
elongate in that direction, proportionally with the elon-
gation of the spines above, whilst dermal and intercalated
spines shoot forth from the middle line above and below,
giving the vertically extended, compressed form to the
hinder half of the body, by the alternating lateral strokes
of which the fish is propelled forwards in the diagonal
between the direction of those forces. The advantage of
the biconcave form of vertebra, with intervening elastic
capsules of gelatinous fluid, in producing a combination
of the resilient with the muscular power, is as obvious as
it is beautiful to contemplate.

The fixation and coalescence of any of the vertebra in
this locomotive part of the fishes’ body, analogous to the
part called “sacrum” and “ pelvis” in land quadrupeds,
would be a great hindrance to the alternate and vigorous
inflections of that part, by which mainly the fish swims.
A “sacrum” is a consolidation of part of the vertebral
axis of the body, for the transference of more or less of
the weight of that body upon limbs organized for its sup-
port on dry land; such a modification would have been
not merely useless, but a hinderance to a fish. The pec-
toral fins are the prototypes of the fore-limbs of the higher
vertebrates. With their terminal segment, or “hand,”
alone projecting freely from the trunk, and swathed in a
common sheath of skin, they present an interesting ana-
logy to the embryonal buds of the answerable members

TO AQUATIC LIFE. 61

in man. But what would have been the result if both
arm and forearm had extended freely from the side of the
fish, and dangled as a long many-jointed appendage in
the water! This “higher development,” as it is termed,
in relation to the prehensile or cursorial limb of the deni-
zen of dry land, would have been a defect in the structure
of a creature destined to cleave the liquid element. In
the fish, therefore, the fore-limb is left as short as was
compatible with its required functions; the broad many-
fingered hand alone projects, but can be applied prone
and flat, by flexion of the wrist, to the side of the trunk;
or it may be extended with its flat surfaces turned forwards
and backwards, so as to check and arrest, more or less
suddenly, the progress of the fish; its breadth can also
be diminished by closing up or stretching out the digital
rays. In the act of flexion, the pectoral fin slightly ro-
tates, and gives an oblique stroke to the water. The
requisite breadth of the modified hand is gained by the
addition of ten, twenty, or it may be a hundred fingers
over and above the number to which they are restricted
in the forefoot or hand of the higher classes of vertebrata.
The pike maintains a stationary position in a stream by
vibrations of the pectoral fins ; the nature of the bottom of
the fish’s habitat is ascertained by a tactile application of
the same fins. In the hard-faced gurnards, certain rays
of the pectorals are liberated from the web, and have a
special endowment of nerves, in order to act as feelers.
In the siluroid fishes, the pectorals wield a formidable
weapon of offence. A tropical species of perch (Anabas)
uses a smaller analogous pectoral spine for climbing up
the mangrove stems in quest of insects.

Certain lophioid fishes, that live on sand-banks left dry
at low water, are enabled to hop after the retreating tide

6

62 ACTION OF THE FINS IN FISHES.

by a special prolongation of the carpal joint of the pec-
toral fin, which projects in these “frog fishes,” as they
have been termed, like the limb of a land quadruped, and
presents two distinct segments clear of the trunk.

The sharks, whose form of body and strength of tail
enable them to swim near the surface of the ocean, are
further adapted for this sphere of activity, and compen-
sated, for the absence of an air-bladder, by the large pro-
portional size of their pectoral fins, which take a greater
share in their active and varied évolutions than in ordi-
nary fishes; more especially in producing that half turn
or roll of the body required to bring the mouth, which is
on the under part of the head, in contact with their prey.
The maximum of development of the many-fingered
hands is attained in the rays, and in ‘those fishes—e. 9.,
Exocetus and Dactylopterus—called “flying fishes,” in con-
sequence of the pectorals being long enough, and their
webs broad enough to sustain them in the air, in their
long “flying leaps” out of the water.

With regard to the ventral fins—the rudiments of hind-
limbs—these combine merely with the pectorals in raising
the fish, and in preventing, as outriggers, the rolling of
the body during progression. In the long-bodied and
small-headed abdominal fishes the ventrals are situated
near the vent, where they best subserve the office of ac-
cessory balancers; in the large-headed thoracic and jugu-
lar fishes they are transferred forwards, to aid the pectorals
in supporting and raising the head. If the pectoral and
ventral fins in one of these fishes be ent off, the head
sinks to the bottom; if the right pectoral fin only be cut
off, the fish leans to that side; if the ventral fin on the
same side be cut away, then it loses its equilibrium en-

tirely ; if the dorsal and anal fins be cut off, the fish reels

ACTION OF THE FINS IN FISHES. 63

to the right and left; when the caudal fin is cut off, the —
fish loses the power of progressive motion ; when the fish
dies, and the fins cease to play, the belly turns upwards.

Paley thus sums up the actions of the fins of fishes:
“The pectoral, and more particularly the ventral, fins
serve to raise and depress the fish; when the fish desires
to have a retrograde motion, a stroke forward with the
pectoral fin effectually produces it; if the fish desire to
turn either way, a single blow with the tail the opposite
way sends it round at once; if the tail strike both ways,
the motion produced by the double lash is progressive,
and enables the fish to dart forwards with an astonishing
velocity. The result is not only in some cases the most
rapid, but in all cases the most gentle, pliant, easy ani-
mal motion with which we are acquainted.” “In their
mechanical use, the anal fin may be reckoned the keel;
the ventral fins, the outriggers; the pectoral fins, the
oars ;” and we may now add “the caudal fin, the screw-
propeller.” And if there be such similitude between
those parts of a boat and a fish, “observe,” adds Paley,
“that it is not the resemblance of imitation, but the like-
ness which arises from applying similar mechanical means
to the same purposes.”!

! «Nat. Theology,” 8vo., 1805, p. 257.

64 BATRACHIAN ILLUSTRATIONS OF THE

PRINCIPAL FORMS OF THE SKELETON IN THE
CLASS REPTILIA.

The transition from fishes to reptiles is easy, and the
signs thereof very manifest in the skeleton. In the
thorn-back and allied fishes the skull articulates with
the trunk by two condyles, and the part answering to the
basioccipital is a depressed plate. The Batrachia, or low-
est order of reptiles—including the siren, proteus, frog,
toad—have a similar double articulation of the skull
with the trunk, the two condyles being developed from
the two exoccipitals. _Heemapophyses are not present as
bones in the abdominal part of the trunk of Batrachia,
but they are so developed in the tail. This structure,
with the detachment of the scapular arch from the oeci-
put, and the absence of dermoneural and dermohzmal
spines, serves to distinguish the most fish-like batrachian
from the protopterus and lepidosiren, which are the
most reptile-like of fishes.

In commencing the study of the skeletons of reptiles
in the most fish-like of the class, we find a much less
complex condition of the osseous framework of the body
than in the bony fishes; this will be immediately mani-
fest by a comparison of the skeleton of the menopome
(which may be seen in the Museum, Royal College of
Surgeons, No. 583), as an example of the perennibran-
chiate batrachia, with the skeleton of the trout (No. 45)
or of the haddock (No. 176, in the same Museum).

The difference tends greatly to elucidate the true nature
of the complexities of the fish’s skeleton, since it chiefly
consists in the simplification of that of the batrachian, by
the non-development of the parts of the dermal skeleton
which characterize that of the fish. The suborbital, super-

NATURE OF LIMBS. 65

orbital, and supratemporal scale-bones are removed, to-
gether with the opercular bones, from the head; and the
interneural and dermoneural spines, with the interhemal
and dermohzmal spines, are removed from the trunk.
The endoskeleton is also reduced to a very simple condi-
tion; the advance characteristic of the higher class being
appreciable only by a comparison of it with the skeleton
of the most batrachoid of fishes—e. g. the protopterus
(No. 380).

We then perceive that the bodies of the vertebre, in
the true batrachian, are distinctly ossified, though pre-
serving, in the perennibranchiate species, a deep, conical,
jelly-filled cavity both before and behind (Cut 11), C; they

SACRAL VERTEBRA AND CONTIGUOUS VERTEBR.E—MENOPOME.

have also coalesced with the neural arches, as these have
with their spines, which are, however, scarcely prominent,
except in the tail. The transverse processes are developed
not only from the centrum but from the base of the neural
arch, and are formed by both parapophyses and diapo-
physes; and they coexist with distinct hamapophyses in
the tail (¢b.), H. With these, likewise, coexist cartilagin-
ous pleurapophyses (7d.), pl, in the second, third, and
6*

66 BATRACGHIAN ILLUSTRATIONS OF LIMBS.

fourth caudal vertebre; short ossified pleurapophyses
being developed from the ends of the diapophyses in the
first caudal to the vertebra dentata inclusive.

By this instructive condition of the skeleton of the me-
nopome, we perceive at once that the heemapophyses (:0.),
H, are neither transverse processes, nor ribs bent down or
displaced, but are elements of vertebree, as distinct as the
neurapophyses above. The neural arches are now articu-
lated together by well-developed zygapophyses with syno-
vial articulations, which are absent in the protopterus, as
in most fishes.

In the protopterus, as in the squatina and some other
cartilaginous fishes, the neural arch of the atlas rests
upon a backward production of the basioccipital; in the
batrachians it is confluent with its own proper centrum,
which developes two articular surfaces for the two oc-
cipital condyles. The hemal arch of the occipital seg-
ment, which is attached to its proper vertebra in the pro-
topterus (Fig. 32), A, 51, 52, as im osseous fishes, is
detached and displaced backwards in the batrachians
(Fig. 83), 51, 52. In the completion of the hemal arch
of the sacral vertebra in the menopome, by the enlarge-
ment of its transverse procesg (Fig. 11), D, and by its
pleurapophysis (72.), pl, extended to join a hemapophysis
(‘b.), H, below, we have the key to the essential nature of
the pelvis in all air-breathing animals. The progressive
development of the appendages of the scapular and pelvie
arches, which are to become the four limbs of air-breath-
ing vertebrates, should be traced from their condition in
the protopterus. Here (Fig. 82) they are reduced toa
single ray, which is soft and many-jointed. In the Am-
phiuma didactyla (Fig. 38) the ray is ossified ; its first joint
(b,), 58, is long, its second (7d.), 54, 55, is bifid, and a car-

METAMORPHOSES OF THE FROG’S SKELETON. 67

tilage at the end of this supports two short terminal rays.
This is the pattern of the subdivision of the appendage
both of the scapular and pelvic arches, in all the higher
vertebrates; hence, in consequence of the vast modifica-
tions of the several segments, the necessity for their
special names. ‘In the fore-limb the first segment (Fig.
38), 58, is the “arm,” and its bone, the “humerus,” No.
538; the second segment is the forearm—its two bones
are the “radius,” No. 55, and “ulna,” No. 54; the third
segment is the “hand”’—its rays are the “fingers;” and
its bones are subdivided into “carpals,” No. 56, “ meta-
carpals,” and “phalanges,” No. 57. In the hind-limb
(Fig. 34), the first segment is the “thigh,” and its bone,
the “femur,” No. 65; the second segment is the “leg,”
and its two bones are the “tibia,” No. 66, and “ fibula,”
No. 67; the third segment is the “ foot” —its rays are the
“toes;” its bones are subdivided into “tarsals,” “ meta-
tarsals,” and “ phalanges.”

In the siren, the pelvic arch and limbs are not de-
veloped; but they coexist with the scapular arch and
limbs in all other batrachia. In the proteus, the last seg-
ment of the fore-limb divides into three rays, that of the
hind-limb into two rays; in other words, it has three
fingers and two toes. The menobranchus has four fingers
and four toes. The axolotl has four fingers and five toes.
The menopome has five fingers and five toes.

The ultimate subdivisions of the radiated or diverging
appendages of the scapular and pelvic arches do not ex-
ceed five in any existing air-breathing animal, and their
further complexity is due to the specialization of each
digit, so as to combine in associated action, instead of
their indefinite multiplication, which causes the seeming
complexity of the same appendages in fishes.

68 METAMORPHOSES OF THE FROG’S SKELETON.

In all the fish-like batrachia, called, from a retention of
more or less of the branchial apparatus, “ perenni-
branchia,” the limbs are short, and the rays of the
terminal segments of each limb are, more or less, united
by a web; the body is long, and the tail long and com-
pressed. But a great ascent in the scale of life is made
in the batrachian order: all the species when hatched
have the fish-like form, and gills for breathing water;
most of them exist for some time, under this form, in
water; and these undergo so strange a modification of
form and structure before arriving at maturity, that it has
been called a “metamorphosis.” They change their
aquatic for a terrestrial life; they breathe air instead of
water; and from being omniverous become carnivorous.
The tadpoles of our common toad and frog afford ready
and abundant instances for tracing these stages. The
following is an outline of the main phenomena of the
change observable in regard to the osseous system :—

In the development of the skeleton of the common
frog, a fibrous and cartilaginous framework is originally
laid down conformably with the aquatic habits and life
of the larva. A large cartilaginous cranium with four
heemal arches, and one of these supporting the framework
of the branchial apparatus—a short series of fibro-carti-
laginous vertebra, minus the hzmal arches, in the trunk,
and a series of fibrous septa diverging from the fibrous
capsule of the notochord, and defining and giving attach-
ment to the muscular segments along the tail—constitute
the skeleton of the newly-hatched tadpole. As it grows,
ossification begins; but only in those parts of the skele-
ton which are to be retained in the future frog. Thus,
the centrums and neurapophyses of the head and trunk
are ossified, but not those of the tail. In the trunk, ossi-

METAMORPHOSES OF THE FROG’S SKULL. 69

fication of the vertebral body proceeds centripetally by
layers, successively diminishing in extent, and conical
interspaces are left, consisting of the changed fibrous
capsule of the notochord with the inclosed gelatinous cells,
their liquefied contents forming the balls of fluid, between
the biconcave vertebre, as in fishes. But ossification
proceeds to fill up the hinder cavity of the centrum, and
to project into the front cavity of the succeeding vertebra,
with which it is finally connected by a synovial ball-and-
socket joint. Thus, the firmer intervertebral articulations
are established, which adapt the vertebral column to the
support of a body which is to be suspended upon limbs,
and transported by them along the surface of the dry
ground. Whilst this change is proceeding, the tail is
undergoing rapid absorption, the retained fibro-cartilagin-
ous condition of its vertebree rendering them more ready
for removal. In the last fused rudiments of the caudal
vertebrae, ossification extends continuously, and the
peculiar style (Fig. 12), c, at the end of the vertebral
series in the frog and other tailless batrachians, is thus
established.

In the conversion of the biconcave into cup-and-ball
vertebree in batrachian larvee, ossification commonly, but
not always, proceeds to obliterate the hinder cavity. In
the land salamanders, however, it extends from the front
cavity; so that in the adult vertebree the ball is anterior,
and the cup posterior, as in certain salamandroid fishes
—-e. g., lepidosteus. In those batrachians that retain more
or less of the branchial apparatus, with the outward form
and natatory tail adapted to aquatic life, the vertebrz of
the tail are ossified like those of the trunk, but the bicon-
cave structure and intervening gelatinous joints are re-
tained throughout life. |

70 SKELETON OF THE FROG.

The chief changes which take place in the conversion
of the cartilaginous skull of the larva to the ossified one

Fig. 12.

SKELETON OF THE FROG (ana esculenta).

of the imago, or perfect frog, are seen in the shape and
relative position of the hzmal arches and their append-
ages—. e., of the maxillary, mandibular, hyoid, and sca-
pular arches. The maxillary arch expands in breadth,

“SKELETON OF THE FROG. ya |

the mouth widens, and the horny mandibles are shed.
As the mouth advances forwards, the tympanic pedicles
are elongated, and are placed more obliquely; their
proximal end retrograding from the post-frontal to the
mastoid region of the skull, and their distal end inclining
forwards with the attached lower jaw, Nos. 29, 33, on
which the denticles now begin to be developed. Yor the
still more extraordinary changes of the hyoid arch, No.
41, and its branchial appendages, No. 46, the student is
referred to Dugé’s Recherches sur 0 Ostéologie des Batra-
ciens, 4to., 1835; and to the writer’s Archetype of the Ver-
tebrate Skeleton, pp. 70, 71.

The scapular arch, which was close to the occiput,
whilst protecting and supporting the branchial heart—
its primary function—begins, as the rudiments of the
fore-limbs bud out, to recede backwards, like the mandi-
bular and branchial arches, but to a greater extent, the
attachment to the occipital segment being wholly lost.
The scapular and coracoid portions of the arch become
first ossified ; the suprascapular plate remains long carti-
laginous, and always partly so; the sternum is developed
in proportion as the hyoid arch is reduced, and the bran-
chial arches are removed; thus a strong fulcrum is com-
pleted for the articulation of the shoulder-joints. The
pelvic arch had previously been completed, and the iliac
bones and sides of the sacrum become coelongated: then
the ila continue to extend backwards as the tail is being
absorbed, and the hind-limbs are lengthened out and
finished,

Thus metamorphosed, the skeleton of the frog pre-
sents the following structure (Fig. 12): The number of
vertebree of the trunk, exclusive of the coxygeal style, ¢,
is nine; the first, or atlas, has no diapophyses, but these

72 SKELETON OF THE FROG.

are present and long on the rest, especially on the third,
d, and ninth, s, vertebree; in the latter they are thick,
stand outwards, and support two other long, curved, rib-
like bones, 62, which expand at their distal ends, and
unite to two bony plates, 63, completing the hzemal arch
of the ninth segment of the trunk. The bones of the
hinder extremities are attached to the point of union of
the above costal and hzemal pieces, one of which answers
to the ilium, 62, and the other to the ischium, 638. The
superior development of this arch relates to the great
size and strength of the hinder extremities in the tailless
tribe. The bodies of the vertebra are articulated by
ball-and-socket joints, the cup being anterior, the ball
posterior, a modification which relates to the more ter-
restrial habits and locomotion of these higher-organized
batrachia. The caudal vertebre are represented by a
single, elongated, cylindrical style, c, having an anchy-
losed neural canal. In the seven vertebrae, between the
atlas and the sacrum, two zygapopophyses, looking up-
wards, two zygapophyses, z, looking downwards, and a
short spine, are developed from each neural arch.

The suprascapula, 50, is very broad, and in great part
ossified; the scapula, 51, divides at its humeral end into
an acromial and coracoid process; the latter articulates
with the true coracoid bone, 52, the acromion with the
expanded ‘extremity of the clavicle, 58: the glenoid
cavity is formed by both the scapula and the coracoid.
An episternal bone, 59, supporting a broad cartilage, is
articulated to the mesial union of the clavicles, from
which a bony bar is continued backwards between the
expanded and partially conjoined ends of the coracoids.
The sternum, 60, is articulated to the posterior part of

SKELETON OF THE FROG. 73

the same extremities of the coracoids, and ors a
broad “ xiphoid” cartilage.

The proximal end of the humerus, 58, is an epiphysis ;
the distal end presents a hemispherical ball between a
small external ridge, and a large internal condyloid pro-
cess. The antibrachial bones have coalesced, but an
anterior and posterior indentation at the distal half indi-
cates the radius, 55, and ulna, 54; their distal articular
extremities are represented by a single epiphysis. The
ulnar portion of the bone develops a short and broad
olecranon, 0. ‘The bones of the carpal series now receive
definite names, and are as follows: (Fig. 12), s, sca-
phoid; 7, lunare; ¢ and p, cuneopisiforme; ¢, trapezium ;
ir, trapezoides; m, magnum; uw, unciforme—here two
distinct bones. The first digit, I, has one bone, a meta-
carpal; the second digit, II, has a metacarpal and two
phalanges; the third, ITI, the same; the fourth, IV, has
a metacarpal and three phalanges; and the fifth, V, the
same.

Both the proximal and the distal extremities of the
femur, 65, are in the condition of epiphyses. The tibia
and fibula are connate, 66: a longitudinal impression on
the front and back part of the expanded distal end indi-
cates their division, but a single epiphysis, partially an-
chylosed, forms the proximal extremity, and a similar
one the distal extremity, of the connate bones; they are
perforated near their middle, from before backwards, by
a vascular canal. The tarsal bones are now distinguished
by names.

The astragalus, a, and caleaneum, cl, are much elongated;
the former is slightly bent, the latter straight; they have
coalesced at their proximal and also at their distal ex-
tremities with each other, and with the scaphoid, s, and

7

74

SKELETON OF THE SERPENT.

SKELETON OF THE COBRA (Naija tripudians).

:
:

———

SKELETON OF THE SERPENT. 75

cuboid, 0, bones. Three cuneiform bones, ¢, ci, remain
detached, and immediately support the three inner toes
and a cartilaginous appendage. ‘The first toe, 2, and
second toe, 77, have each a metatarsal and two phalanges;
the third toe, 77, has a metatarsal and three phalanges;
the fourth toe, 7v, has a metatarsal and four phalanges;
the fifth toe, v, a metatarsal and three phalanges. The
great length and strengh of the pelvic arch, and its ap-
pendages, the hind-limbs, give the frog the power of exe-
cuting the long leaps for which it is proverbial.

All the batrachia present this structure in common with
fishes, viz., that the ribs of the trunk, when present, are
free, consist only of “pleurapophyses,” and do not en-
compass the thoracic-abdominal cavity. The absence of
unyielding osseous girdles at this part seems to relate to
a peculharity of their generation, viz: the almost simul-
taneous ripening of the sperm-cells and ova, causing a
great and sudden distension of the abdomen at the breed-
ing period.

OSTEOLOGY OF THE OPHIDIA, OR SERPENT
TRIBQ.

There are certain tropical land batrachia—the Cecilia,
eé.g.—in which the body is as long and slender as in ser-
pents, includes almost as numerous vertebre, and is
devoid of all trace of limbs. But the osteology of the
typical Ophidian reptiles differs from that of the batra-
chians in the more elongated ribs; in the distinct basi-
and superoccipitals; in the superoccipitals forming part
of the ear-chamber; in the basioccipital combining with
the exoccipital to form a single articular condyle for the
atlas; in the ossification of the membranous space be-

76 STRUCTURE OF THE SKULL IN SERPENTS.

tween the elongated parietals and the sphenoid; in the

constant coalescence of the parietals with one another; in
the constant confluence of the orbitosphenoids with the
frontals, and in the meeting of the orbitosphenoids below
the prosencephalon, upon the upper surface of the pre-
sphenoid; in the presence of distinct postfrontals, and the
attachment thereto of the ectopterygoids, whereby they
form an anterior point of suspension of the lower jaw,
through the medium of the pterygoid and tympanic
bones; lastly, in the connation of the prefrontals and lach-
rymals.

In studying the osteology of the head of the python,
as the type of the Ophidian Order, by the aid of the fol-
lowing description, the student may compare the disar-
ticulated skull, No. 628, with that of the large skeleton,
No. 602, in the Museum, Royal College of Surgeons: the
bones are numbered as here referred to.

The basioccipital, 1, is subdepressed, broadest ante-
riorly, subhexagonal; smooth and concave at the middle
above, with a rough sutural tract on each side, and a
hypapophysis below, produced into a recurved point. The
hinder facet of the basioccipital 1s convex, forming the
lower half of the occipital condyle, which is supported on
a short peduncular prolongation. The basioccipital unites
above and laterally with the exoccipitals and alisphe-
noids, and in front with the basisphenoid, upon which it
rests obliquely, and it supports the medulla oblongata on
its upper smooth surface.

The exoccipitals, 2, 2, are very irregular subtriangular
bones; each is produced backwards into a peduncular
process, supporting a moiety of the upper half of the oc-
cipital condyle. The outer and fore part of the exoc-
cipital expands into the irregular base of the triangle:

¢

STRUCTURE OF THE SKULL IN SERPENTS. 77

it is perforated by a slit for the eighth pair of nerves; it
articulates below with the basioccipital; it is excavated
in front to lodge the petrosal cartilage, where it articulates
with the alisphenoid ; it unites above with the superoc-
cipital. The superoccipital, 5, is of a subrhomboidal form,
sends a spine from its upper and hinder surface, expands
laterally into oblong processes, is notched anteriorly, and
sends down two thin plates from its under surface, bound-
ing on the mesial side the surface for the cerebellum, and
by the outer side forming the inner and upper parts of
the acoustic cavities. The superoccipital articulates below
with the exoccipitals and alisphenoids, and in front with
the parietal, by which it is overlapped in its whole extent.
The occipital vertebra is as if it were sheathed in the ex-
panded posterior outlet of the parietal one (Fig. 17), the
centrum resting on the oblique surface of that in front,
and the-anterior base of the neural spine entering a cavity
in and being overlapped by that of the preceding neural
spine: the analogy of this kind of “emboitement” of the
occipital in the parietal vertebra with the firm interlock-
ing of the ordinary vertebree of the trunk is very inte-
resting: the end gained seems to be, chiefly, an extra
protection of the epencephalon—the most important seg-
ment to life of all the primary divisions of the cerebro-
spinal axis. The thickness of its immediately protecting
walls (formed by the basi, ex, and superoccipitals) is
equal to that of the same vertebral elements in the human
skull; but they are, moreover, composed of very firm and
dense tissue throughout, having no diploé: the epencepha-
lon also derives a further and equally thick bony covering
from the basisphenoid and the parietals, the latter being
overlapped by the mastoids, which form a third covering
to the cerebellum.
T%

78 STRUCTURE OF ‘THE SKULL OF THE PYTHON.

The basisphenoid, 5, and presphenoid, 9, form a single
bone, and the chief keel of the cranial superstructure.
The posterior articular surface looks obliquely upwards
and backwards, and supports that of the vertebral centrum
behind, as the posterior ball of the ordinary vertebree
supports the oblique cup of the succeeding vertebre ;
here, however, all motion is abrogated between the two
vertebrae, and the coadapted surfaces are rough and
sutural. The basisphenoid presents a smooth cerebral
channel above for the mesencephalon, in front of which a
deep depression (sella) sinks abruptly into the expanded
part of the bone, and there bifurcates, each fork forming
a short cul-de-sac in the substance of the bone. ~

The alisphenoids, 6, form the anterior half of the fe-
nestra ovalis, which is completed by the exoccipitals ; and
in their two large perforations for the posterior divisions
of the fifth pair of nerves, as well as in their relative size
and position, the alisphenoids agree with those of the frog.
Kach alisphenoid is a thick suboval piece, with a tuber-
cular process on its under and lateral part; it rests upon
the basisphenoid and basioccipital, supports the posterior
part of the parietal and a portion of the mastoid, 8, and
unites anteriorly with the descending lateral plate of the
parietal bone.

The parietal, 7, is a large and long, symmetrical, roof-
shaped bone, with a median longitudinal crest along its
upper surface, where the two originally distinct moieties
have coalesced. It is narrowest posteriorly, where it
overlaps the superoccipital, and is itself overlapped by
the mastoid: it is convex at its middle part on each side
of the sagittal spine, and is continued downwards and in-
wards, to rest immediately upon the basisphenoid. ‘This
part of the parietal seems to be formed by an extension

STRUCTURE OF THE SKULL OF-THE PYTIION. 79

of ossification along a membranous space, like that which
permanently remains so in the frog, between the alisphe-
noid and orbitosphenoid : the mesencephalon and the chief
part of the cerebral lobes are protected by this unusually
developed spine of the mesencephalic vertebra. The
optic foramina are conjugational ones, between the ante-
rior border of the lateral plate of the parietal and the
posterior border of the corresponding plate of the frontal.

The frontals, 11, rest by descending lateral plates, re-
presenting connate orbitosphenoids, 12, upon the attenu-
ated, pointed prolongation of the basisphenoid : the upper
surface of each frontal is flat, subquadrate, broader than
long in the boa, and the reverse in the python, where the
roof of the orbit is continued outwards by a detached super-
orbital bone: there is a distinct, oval, articular surface near
the anterior median angle of each frontal to which the
prefrontal is attached : the angle itself is slightly produced,
to form the articular process for the nasal bones. The
smooth orbitosphenoid plate of the frontal joins the outer
margin of the upper surface of the frontal at an acute
angle; the inner side of each frontal is deeply excavated
for the prolongation of the cerebral lobes, and the cavity
is converted into a canal by a median vertical plate of
bone at the inner and anterior end of the frontal. The
frontals join the parietals and postfrontals behind, and,
by the anchylosed orbital plates, the presphenoid below,
the prefrontals and nasals before, and the superorbitals at
their lateral margins. The orbitosphenoids have their
bases extended inwards, and meet below the prosence-
phalon and above the presphenoid, as the neurapophyses
of the atlas meet each other above the centrum. The
anterior third part of such inwardly-produced base is met
by a downward production of the mesial margin of the

80 STRUCTURE OF THE SKULL OF THE PYTHON.

frontal, forming a septum between the olfactory prolonga-
tions of the brain, but is not confluent with the frontal
bone: the outer portion of the orbitosphenoids ascends
obliquely outwards, and is confluent with the under part
of the frontal; it is smooth externally, and deeply notched
posteriorly fot the optic foramen.

The post-frontal, 12, is a moderately long trihedral ais
articulated by its expanded cranial end to the frontal and
parietal, and bent down to rest upon the outer and fore
angle of the ectopterygoid. It does not reach that bone
in the boa, nor in poisonous serpents. In both the boa
and python, it receives the anterior sharp angle of the
parietal in a notch.

The natural segment which terminates the cranium an-
teriorly, and is formed by the vomerine, prefrontal, and
nasal bones, is very distinct in the ophidians.

The vomer, 13, is divided, as in salamandroid fishes
and batrachians, but is edentulous: each half is a long,
narrow plate, smooth and convex below, concave above,
with the inner margin slightly raised; pointed anteriorly,
and with two processes, and an intervening notch above
the base of the pointed end. The prefrontals, 14, are
connate with the lachrymals, 73. The two bones which
intervene between the vomerine and nasal bones are the
turbinals, 19; they are bent longitudinally outwards in
the form of a semicylinder about the termination of the
olfactory nerves.

The spine of the nasal vertebra is divided symmetri-
cally, as in the frog, forming the nasal bones, 15; they are
elongated, bent plates, with the shorter upper part arching
outwards and downwards, completing the olfactory canal
above, and with a longer median plate, forming a vertical
wall, applied closely to its fellow, except in front, where

— |

SKULL OF THE BOA CONSTRICTOR. 81

the nasal process of the premaxillary is received in the
interspace of the nasals.

The acoustic capsule remains in great part cartilaginous;
there is no detached centre of ossification in it; to what-
ever extent, this capsule is ossified, it. is by a, continuous
extension from the alisphenoid. The sclerotic capsule of
the eye is chiefly fibrous, with a thin inner layer of car-
tilage; the olfactory capsule is in a great measure ossified,
as above described.

MAXILLARY ARCH.

The palatine, 20, or first piece of this arch, is a strong,
oblong bone, having the inner side of its obtuse anterior
end applied to the sides of the prefontals and turbinals,
and, near its posterior end, sending a short, thick process
upwards and inwards for ligamentous attachment to the
lachrymal, and a second similar process outwards as the
point of suspension of the maxillary bone. Between these
processes the palatine is perforated, and behind them it
terminates in a point. The
chief part of the maxillary, 21
(Fig. 14), is continued forwards
from its point of suspension,
increasing in depth, and termi-
nating obtusely; ashorter pro- al
cess is also, as usual, continued SKULL OF BOA CONSTRICTOR.
backwards, and terminates in
a point. ‘The point of suspension of the maxillary forms
a short, narrow, palatine process. A space occupied by
elastic ligament intervenes between the maxillary and the
premaxillary, 22, which is single and symmetrical, and

82 SKULL OF THE BOA CONSTRICTOR.

firmly wedged into the nasal interspace ; the anterior ex-
panded part of this small triangular bone supports two
teeth. Thus, the bony maxillary arch is interrupted by
two ligamentous intervals at the sides of the premaxillary
key-bone, in functional relation to the peculiar independ-
ent movements of the maxillary and palatine bones re-
quired by serpents during the act of engulfing their usually
large prey. ‘Two bones extend backwards as appendages
to the maxillary arch: one is the “ pterygoid,” 24, from
the palatine; the other the ectopterygoid, 25, from the
maxillary. The pterygoid is continued from the posterior
extremity of the palatine to abut against the end of the
tympanic pedicle; the under part of the anterior half of
the pterygoid is beset with teeth. The ectopterygoid, 25,
overlaps the posterior end of the maxillary, and is arti-
culated by its posterior-obliquely cut end to the outer
surface of the middle expanded part of the pterygoid.

MANDIBULAR ARCH.

The tympanic bone, 28 (Iigs. 14 and 15), is a strong
trihedral pedicle, articulated by an oblique upper surface
to the end of the mastoid, and expanded transversely
below to form the antero-posteriorly convex, transversely
concave, condyle for the lower jaw. This consists chiefly
of an articular and a dentary, with a small coronoid and
splenial, piece. The articular piece ends obtusely, imme-
diately behind the condyle; it is a little contracted in
front of it, and gradually expands to its middle part,
sends up two short processes, then suddenly contracts
and terminates in a point wedged into the posterior and
outer notch of the dentary piece. The articular is deeply

SKULL OF THE BOA CONSTRICTOR. 83

grooved above, and produced into a ridge below. The
coronoid is a short compressed plate; the splenial is a
longer, slender plate, applied to the inner side of the
articular and dentary, and closing the groove on the
inner side of the latter. The outer side of the dentary
offers a single perforation near its anterior end, which is
united to that of the opposite ramus by elastic ligament.

By the above-described mode of union of the extremi-
ties of the maxillary and mandibular bones, those on the
right side can be drawn apart from those on the left, and
the mouth can be opened not only vertically, as in other
vertebrate animals, but also transversely, as in insects.
Viewing the bones of the mouth that support teeth in
the great constricting serpents, they offer the appearance
of six jaws—four above and two below; the inner pair
of jaws above are formed by the palatine and pterygoid
bones, the outer pair by the maxillaries, the under pair
by the mandibles, or “rami,” as they are termed, of the
lower jaw. ;

Kach of these six jaws, moreover, besides the move-
ments vertically and laterally, can be protruded and re-
tracted, independently of the other: by these movements
the boa is enabled to retain and slowly engulf its prey,
which may be much larger than its own body. At the
first seizure, the head of the prey is held firmly by the
long and sharp recurved teeth of all the jaws, whilst the
body is crushed by the overlapping coils of the serpent;
the death-struggles having ceased, the constrictor slowly
uncoils, and the head of the prey is bedewed with an
abundant slimy mucus: one jaw is then unfixed, and its
teeth withdrawn by being pushed forward, when they
are again infixed, further back upon the prey; the next
jaw is then unfixed, protruded, and reattached; and so

84 SKULL OF POISONOUS SERPENTS.

with the rest in succession—this movement of protrac-
tion being almost the only one of which they are suscep-
tible whilst stretched apart to the utmost by the bulk
of the animal encompassed by
them; thus, by their successive
movements, it is slowly and
spirally introduced into the
wide gullet.
any The bones of the mouth, in
SKULL oF A Poisoxous sxixe. fhe poisonous serpents, have
characters distinct from those
-of the constricting serpents. These characters consist
chiefly in the modification of form and attachments of
the superior maxillary bone (Fig. 15), 21, which is mov-
ably articulated to the palatine, eatdptery oid: and Jachry-
mal bones; but chiefly supported by the latter; which
presents the form of a short, strong, three-sided pedicle, :
extending from the anterior external angle of the frontal
to the anterior and upper part of the maxillary. The
articular surface of the maxillary is slightly concave, of
an oval shape; the surface articulating with the ectopte-
rygoid on the posterior and upper part of the maxillary
is smaller and convex. The maxillary bone is pushed
forward and rotated upon the lachrymal joint by the ad-
vance of the ectopterygoids, which are associated with
the movements of the tympanic pedicle of the lower jaw
by means of the true pterygoid bones. The premaxil-
lary bone (Fig. 13), 22, is edentulous. A single, long,
perforated poison-fang is anchylosed to the right maxil-
lary, and sometimes two similar fangs, as in the cobra
fivured in Cut 18. The palatine bones have four or five,
and the pterygoids from eight to ten small, imperforate,
pointed, and recurved teeth. The frontal bones are

VERTEBRA OF THE RATTLESNAKE. 85

*

broader than they are long; there are no superorbitals.
A strong ridge is developed from the under surface of
the basisphenoid, and a long and strong recurved hypa-
pophysis from that of the basioccipital; these give inser-
tion to the powerful “longi-colli” muscles, by which the
downward stroke of the head is performed in the inflic-
tion of the wound by the poison-fangs.

The characteristics of the trunk-vertebre of the ophi-
dian reptiles are as follows: The autogenous elements,
except the pleurapophyses (Fig. 16), pl, coalesce with
one another in the vertebree of the trunk; and the pleu-
rapophyses also become anchylosed to the diapophyses
in those of the tail. There is no trace of suture between
the neural arch (7b.), n, and centrum, c. The outer sub-
stance of the vertebra is compact, with a smooth or
polished surface. The vertebre are
“proccelian ;” that is, they are articu-
lated together by ball-and-socket joints,
the socket being on the fore part of the
centrum, where it forms a deep cup
with its rim sharply defined; the cavity
looking not directly forwards, but a
little downwards, from the greater pro-
minence of the upper border; the well- — V#"7=BRA oF THE
turned prominent ball terminates the cael Seis
back part of the centrum rather more
obliquely, its aspect being backwards and upwards.
The hypapophysis, hy, is developed in different propor-
tions from different vertebra, but throughout the greater
part of the trunk presents a considerable size in the
cobra and crotalus (Figs. 15 and 16), hy; it is shorter in
the python~and boa. A vascular canal perforates the
under surface of the centrum, and there are sometimes

8

86 VERTEBRZ& OF SERPENTS.

two or even three smaller foramina. In the python, a
large, vertically oblong, but short diapophysis extends
from the fore part of the side of the centrum obliquely
backwards: it is covered by the articular surface for the
rib, convex lengthwise, and convex vertically at its
upper half, but slightly concave at its lower half. In
the rattlesnake, the diapophysis develops a small, cir-
cuniscribed, articular tubercle, d, for the free vertebral
rib or pleurapophysis, p/; a parapophysis, p, extends
downwards and forwards below the level of the centrum;
the anterior zygapophysis, z, seems to be supported by a
similar process from the upper end of the diapophysis.
The base of the neural arch swells outward from its con-
fluence with the centrum, and develops from each angle
a transversely-elongated zygapophysis; that from the
anterior angle looking upwards, that from the posterior
angle downwards, both surfaces being flat, and almost
horizontal, as in the batrachians. The neural canal is
narrow; the neural spine, ns, is of moderate height,
about equal to its antero-posterior extent; it is com-
pressed and truncate. A wedge-shaped process (the
“zygosphene”), zs, is developed from the fore part of the
base of the spine; the lower apex of the wedge being, as
it were, cut off, and its sloping sides presenting two
smooth, flat, articular surfaces. This wedge is received
into a cavity (the “zygantrum”) excavated in the poste-
rior expansion of the neural arch, and having two
smooth articular surfaces to which the zygosphenal sur-
faces are adapted.

Thus the vertebre of serpents articulate with each
other by eight joints in addition to those of the cup and
ball on the centrum; and interlock by parts reciprocally
receiving and entering one another, like the joints called

VERTEBRZ OF SERPENTS. 87

tenon-and-mortise in carpentry. In the caudal vertebra,
the hypapophysis is double, the transition being effectea
by its progressive bifurcation in the posterior abdominal
vertebrae. The diapophyses become much longer in the
caudal vertebrae; and support in the anterior ones short
ribs which usually become anchylosed to their extremi-
ties.

The pleurapophyses or vertebral ribs in serpents have
an oblong articular surface, concave above and almost flat
below in the python, with a tubercle developed from the
upper part, and a rough surface excavated on the fore
part of the expanded head for the insertion of the pre-
costal hgament. They have a large medullary cavity,
with dense but thin walls, and a fine cancellous structure
at their articular ends. Their lower end supports a short
cartilaginous hemapophysis, which is attached to the
broad and stiff abdominal scute. These scutes, alternately
raised and depressed by muscles attached to the ribs and
integument, aid in the gliding movements of serpents;
and the ribs, like the legs in the centipede, subserve loco-
motion ; but they have also accessory functions in relation
to breathing and constriction. The anterior ribs in the
cobra (Fig. 13), pl, are unusually long, and are slightly
bent; they can be folded back one upon another, and can
be drawn forward, or erected, when they sustain a fold of
integument, peculiarly colored in some species—e. g. the
spectacled cobra—and which has the effect of making
this venomous snake more conspicuous at the moment
when it is about to inflict its deadly bite. The ribs com-
mence in the cobra, as in other serpents, at the third ver-
tebra from the head.

The centrum of the first vertebra coalesces with that
of the second, and its place is taken by an autogenous

88 VERTEBRZ OF SERPENTS.

hypapophysis: this, in the python, is articulated by suture
to the neurapophyses; it also presents a concave articular
surface anteriorly for the-lower part of the basioccipital
tubercle, and a similar surface behind for the detached
central part of the body of the atlas, or “odontoid pro-
cess of the axis.” The base of each neurapophysis has
an antero-internal articular surface for the exoccipital
tubercle, the middle one for the hyapophysis, and a
postero-internal surface for the upper and lateral parts of
the odontoid; they thus rest on both the separated parts
of their proper centrum. The neurapophyses expand
and arch over the neural canal, but meet without coalese-
ing. There is no neural spine. Hach neurapophysis de-
velops from its upper and hinder border a short zyga-
pophysis, and from its side a still shorter diapophysis.
In the second vertebra, the odontoid presents a convex
tubercle anteriorly, which fills up the articular cavity in
the atlas for the occipital tubercle; below this is the sur-
face for the hypapophysial part of the atlas, and above
and behind it are the two surfaces for the atlantal neura-
pophyses. The whole posterior surface of the odontoid
is anchylosed to the proper centrum of the axis, and in
part to its hypapophysis. The neural arch of the axis
develops a short ribless diapophysis from each side of
its base; a thick sub-bifid zygapophysis from each side of
the posterior margin; and a moderately long bent-back
spine from its upper part. The centrum terminates in a
ball behind, and below this sends downwards and back-
wards a long hyapophysis.

At the opposite extreme of the elongated body, two or
three much simplified vertebrze are usually found blended
together. In true serpents there are no scapular arch and
appendages, no sternum, no sacrum; but a pair of slender

VERTEBR® OF SERPENTS. 89

bones, often supporting a second bone, armed with a claw,
are found suspended on the flesh near the vent. The ex-
posed parts of these appendages are called “anal hooks;”
the parts themselves, like the similarly suspended ventral
fins of the pike, are rudiments of hind limbs.

Serpents have been regarded as animals degraded from
a higher type; but their whole organization, and especially —
their bony structure, demonstrate that their parts are
as exquisitely adjusted to the form of their whole, and to
their habits and sphere of life, as is the organization of
any animal which we call superior to them. It is true
that the serpent has no limbs, yet it can outclimb the
monkey, outswim the fish, outleap the jerboa, and, sud-—
denly loosing the close coils of its crouching spiral, it
can spring into the air and seize the bird upon the wing:
‘all these creatures have been observed to fall its prey.
The serpent has neither hands nor talons, yet it can out-
wrestle the athlete and crush the tiger in the embrace of
its ponderous overlapping folds. Instead of licking up
its food as it glides along, the serpent uplifts its crushed
prey, and presents it, grasped in the death-coil as ina
hand, to its slimy gaping mouth.

It is truly wonderful to see the work of hands, feet,
and fins performed by a modification of the vertebral
column—by a multiplication of its segments with mobility
of its ribs. But the vertebrae are specially modified, as
we have seen, to compensate, by the strength of their
numerous articulations, for the weakness of their mani-
fold repetition, and the consequent elongation of the |
slender column. As serpents move chiefly on the surface
of the earth, their danger is greatest from pressure and
blows from above; all the joints are fashioned accordingly
to resist yielding, and sustain pressure in a vertical direc-

8* 7

90 SECTION OF THE BOA CONSTRICTOR’S SKULL.

tion; there is no natural undulation of the body upwards
and downwards—it is permitted only from side to side.
So closely and compactly do the ten pairs of joints be-
_ tween each of the two hundred or three hundred vertebre
| fit together, that even in the relaxed and dead state the
' body cannot be twisted except in a series of side coils.
In the construction of the skull, which has merited a de-
scription in some detail, and well deserves a close study,
the thickness and density of the cranial bones must strike
the mind as a special provision against fracture and injury
to the brain. When we contemplate the still more re-
markable manner in which these bones are applied, one
over another, the superoccipital (Fig. 17), 8, overlapping

Fig. 17.

SECTION OF SKULL, BOA CONSTRICTOR.

the exoccipital, 4, and the parietal, 7, overlapping the
superoccipital—the natural segments or vertebre of the
cranium being sheathed, one within the other, like the
corresponding segments in the trunk—we cannot but
discern a special adaptation in the structure of serpents
to their commonly prone position, and a provision, ex-
emplified in such structure, of the dangers to which they
would be subject from falling bodies and the tread of .
heavy beasts. Many other equally beautiful instances of
design might be cited from the organization of serpents,
in relation to the necessities of their apodal vermiform

VERTEBRA AND SKULL OF THE LIZARD. 91

“character; just as the snake-like eel is compensated by
analogous modifications amongst fishes, and the snake-
like centipede among insects.

OSTEOLOGY OF LIZARDS.

The transition from the ophidian, or snake-like, to the
lacertian, or lizard-like reptiles, is very gradual and easy,
if we pass from the serpents with fixed jaws and a scapu-
lar arch—as, e. g. the slow-worms (anguis)—to the ser-
pentiform lizards with mere rudiments of limbs—as, e. 9.
the pseudopus. The distinction is effected through the
establishment of a costal arck in the trunk, completed by
the addition of a heemal spine (sternum) and heemapophy-
ses (sternal ribs) to the pleurapophyses or vertebral ribs,
which are alone ossified in ophidia.

The vertebrae of the trunk have the same proccelian
character, z. e. with the cup anterior and the ball behind;
the latter being usually less prominent, more oblique, and
more transversely oval than in serpents. The vertebree
also are commonly larger, and always fewer in number
than in the typical ophidia. The ribs do not begin to be
developed so near the head in lizards. Not only the atlas
and dentata, but sometimes, as in the monitor (varanus),
the four following vertebree are devoid of pleurapophyses;
and when these first appear they are short, and sometimes
(as in cyclodus) expanded at their extremities. They ra-
pidly elongate in succeeding vertebree, and usually at the
ninth from the head (cyclodus, iguana), or tenth (varanus),
they are joined through the medium of ossified hamopo-
physes to the sternum; two (varanus), three (chameleo,
iguana), or four (cyclodus), following vertebre are simi-

92 VERTEBRZ AND SKULL OF THE LIZARD.

larly completed; and then the hemapophyses are either
united below without intervening sternum (chameleo), or
two or three of them are joined by a common cartilage to
the cartilaginous end of the sternum. The hemapophyses
afterwards project freely, and are reduced to short ap-
pendages to the pleurapophyses. These also shorten, and
sometimes suddenly, as, e.g. after the eighteenth vertebra
in the monitors (varanus), in which they end at the twen-
ty-eighth vertebra, as they began, viz: in the form of
short straight appendages to the diapophyses.

The flying lizard (Draco volans), is so called on account
of the wing-like expansions from the side of its body, sup-
ported, like the hood of the cobra, by slender elongated
ribs. In this little lizard there are twenty vertebrz sup-
porting movable ribs, which commence apparently at the
fifth. Those of the eighth vertebra first join the sternum,
as do those of the ninth and tenth; the pleurapophyses of
the eleventh vertebra suddenly acquire extreme length;
those of the five following vertebrz are also long and
slender; they extend outwards and backwards and sup-
port the parachute formed by the broad lateral fold of
the abdominal integuments. The pleurapophyses of the
seventeenth vertebra become suddenly shorter, and these
elements progressively diminish to the sacrum; this con-
sists of two vertebrae, modified as in other lizards. There
are about fifty caudal vertebre.

The semi-ossified sternum in the iguana has a median
eroove and fissure, and readily separates into two lateral
moieties. The long stem of the episternum covers the
outer part of the groove, where it represents the keel of
the sternum in birds.

In the skull of the lizard order we first meet with a
second bony bar, diverging from the maxillary arch back-

a

VERTEBRA AND SKULL OF THE LIZARD. 98

wards, and abutting against the mastoid, and sometimes
also against the tympanic and postfrontal. This bar is

-ealled the “zygomatic arch;” it usually consists of two

bones—the one next the maxillary is the “malar,” 26,
the one next the mastoid is the “squamosal,” 27; it
assumes a form meriting that name in the tortoise, and
first received it, as “pars squamosa,” in man, where it is
not only like a great scale, but becomes confluent with
both the mastoid and tympanic. But, as has been before
remarked, we must use the terms invented by anthropo-
tomists as arbitrary signs of the corresponding bones in
the lower creation.

The scapula in the monitor (varanus) is a triangular
plate with a convex base, a concave hind border, and a
nearly straight front border; the apex is thick and trun-
cate, with an oval surface divided into two facets. The
hind border forms a part of the glenoid cavity; the front
one is a rough epiphysial surface, continuous with a
similar but narrower tract, extending upon the anterior
border, and by which the scapula articulates with the
coracoid. In the iguanians and scincoids this synchon-
drosis is obliterated, and the two bones are confluent.
The hind border of the scapula is nearly straight—the
front one sends forwards a process dividing it into two
deep marginations.

The coracoid in both the varanus and iguana is short
and broad; its main body, which articulates with the
sternum, is shaped like an axe-blade; and two strong,
straight, compressed processes extend forwards from its
neck, which is perforated between the origins of these
processes and the part forming the glenoid articulations.

The clavicles are simple sigmoid styles in the varanus
and iguana; are bent upon themselves, like the Australian

94 VERTEBRZ AND SKULL OF THE LIZARD.

boomerang, in the cyclodus; and have the median part of
the bend expanded and perforated in lacerta and scincus.
They are absent in the chameleon.

The sacral vertebre retain, in some lacertians, the cup-
and-ball joints; and in these, e. g. the scincoids—in which
the centrums coalesce, the hind end of the second presents
a ball to the first caudal—not a cup, as in the crocodile.
In the cyclodus, the thick, short, straight pleurapophyses
are distinct at their origins from the two coalesced cen-
trums, but coalesce at their ends, that of the first sacral
being the thickest. In varanus and iguana, the pleurapo-
physes as well as the centrums, retain their distinctness,
but the hinder ribs incline forwards and touch the ex-
panded ends of the fore pair. These ends are very thick,
and are scooped out obliquely behind, so as to present a
curved border to the ium, which Cuvier compares to a
horseshoe.

In the varanus and iguana, the pleurapophyses of the
first caudal incline backwards as much as those of the
second sacral do forwards. In the cyclodus they extend
outwards, parallel with those of the sacral vertebra, and
are longitudinally grooved beneath. Hzemapophyses are
‘wanting in the first caudal, are developed in the second,
and are displaced to the interval between this and the
third; they are confluent at their distal end, and pro-
duced into a long spine. At the twelfth tail-vertebra, the
line is obvious that indicates the extent of the anterior
detached piece, or epyphysis, of the centrum, immediately
in front of the origin of the diapophyses; it continuese
marking off the anterior third of the centrum in all the
other caudals. At this line the tail snaps off, when a
lizard escapes by the common ruse of leaving the part of
the tail by which it had been seized in the hands of the

a as

SKELETON OF THE CROCODILE. 95

baffled pursuer. It is a very curious character, and quite
peculiar to the lacertians—this ossification of the centrum
from two points and their incomplete coalescence: it adds
nothing to the power of bending, or to any other action
of the tail, but indicates a prevision of the lability to
their being caught by their long tail, and may be inter-
preted as a provision for their escape. The neural arch
has coalesced with the centrum throughout the tail; the
epiphysial line does not extend through that arch; but
its thin and brittle walls soon break, when the two parts
of the centrum are forcibly separated.

Lizards, as is well known, have the power of reproduc-
ing the tail, but the vertebral axis is never ossified in the
new-formed part. |

3

OSTEOLOGY OF CROCODILES.

The numerous and varied forms of fossil bones of ex-
tinct reptiles derive most elucidation from the skeleton
of the higher organized sauria of Cuvier, which now are
rightly held to constitute a distinct order, called Zoricata,
or Crocodilia ; a more complete description, therefore, will
be given of the skeleton of a member of this order, than
was deemed needful in regard to the lacertian group of
sauria.

Hi (fil
NSS o
LSS
SSS Tr
BS 7
Vw

SKELETON OF THE CROCODILE (Crocodilus niloticus).

96 VERTEBRZ OF THE CROCODILE.

Commencing with the trunk, the first and second ver-
tebrze of the neck are peculiarly modified in most air-
breathing vertebrata, and have ac;
cordingly received the special names,
the one of “atlas,” the other of “axis.”
In comparative anatomy these be-
_ come arbitrary terms, the properties
being soon lost which suggested
those names to the human anato-
PE le bres harkens, POE the “atlas,” e. g., has no power
Faas cl of rotation upon the “axis,” in the
crocodile, and it is only in the up-
right skeleton of man that the large globular head is
sustained upon the shoulder-like processes of the “ atlas.”
In the crocodile, these vertebrz are concealed by the pe-
culiarly prolonged angle of the lower jaw in the side view
of the skeleton (Fig. 18), and a figure of the two vertebree
is therefore subjoined (Fig. 19). The pleurapophyses, pi,
are retained in both segments, as in all the other vertebrz
of the trunk. That of the atlas, pl, a, is a simple slender
style, articulated by the head only, to the “ hypapophysis,”
ahy. The neurapophyses, na, of the atlas retain their
primitive distinctness ; each rests in part upon the proper
body of the atlas, ca, in part upon the hypapophysis. The
neural spine, ns, a, is also here an independent part, and
rests upon the upper extremities of the neurapophyses.
It is broad and flat, and prepares us for the further me-
tamorphosis of the corresponding element in the cranial
vertebree.

The centrum of the atlas, ca, called the “ odontoid pro-
cess of the axis” in human anatomy, here supports the
abnormally-advanced rib of the axis vertebra, pl,x. ‘The
proper centrum of the axis vertebra, cx, is the only one

Fig. 19.

VERTEBRE OF THE CROCODILE. 97

in the cervical series which does not support a rib; it
articulates by suture with its neurapophyses na, and is
characterized by having its anterior surface flat, and its
posterior one convex.

With the exception of the two sacral vertebrz, the
bodies of which have one articular surface flat and the
other concave, and of the first caudal vertebra, the body
of which has both articular surfaces convex, the bodies of
all the vertebree beyond the axis have the anterior articular
surface concave, and the posterior one convex, and arti-
culate with one another by ball-and-socket joints. This
type of vertebra, which I have termed “proccelian” (pos,
before, xovaos, concave), characterizes all the existing genera
and species of the order Crocodilia with all the extinct
species of the tertiary periods, and also two extinct species
of the greensand formation in New Jersey.’ Here, so
far as our present knowledge extends, the type was lost,
and other dispositions of the articular surfaces of the
centrum occur in the vertebree of the crocodilia of the
older secondary formations. The only known crocodilian
genus of the periods antecedent to the chalk and green-
sand deposits with vertebree articulated together by ball-
and-socket joints, have the position of the cup and the
ball the reverse of that in the modern crocodiles; and one
genus, thus characterized by vertebree of the “ opistho-
coelian” type (ontoG0s, behind, xoa0s, concave), has accord-
ingly been termed streptospondylus, signifying “ vertebree
reversed.” But the most prevalent type of vertebra
amongst the crocodilia of the secondary periods was that
in which both articular surfaces of the centrum were con-
cave, but in a less degree than in the single concave sur-

1 «Quarterly Journal of the Geological Society,” November, 1849.
9

98 VERTEBR& OF THE CROCODILE.

face of the vertebre united by ball and socket. Vertebree
of this “amphiccelian” type (au¢, both, zoos, concave)
existed in the teleosaurus and steneosaurus. In the ich-
thyosaurus, the concave surfaces are usually deepened to
the extent and in the form shown in those of the fish
(Cut 8). Some of the most gigantic of the crocodilia of
the secondary strata had one end of the vertebral centrum
flattened, and the other (hinder) end concave; this “ pla-
tyccelian” type (aarvs, flat, xocaos, concave) we find in the
dorsal and caudal vertebrze of the gigantic cetiosaurus.

With a few exceptions, all the modern reptiles of the
order lacertilia have the same proccelian type of vertebrze
as the modern crocodilia, and the same structure pre-
vailed as far back as the period of the mosasaurus, and
in some smaller members of the lacertilian order in the
cretaceous and wealden epochs.

Resuming the special description of the osteology of the
modern crocodilia, we find the proccelian type of centrum
established in the third cervical, which is shorter but
broader than the second; a parapophysis is developed
from the side of the centrum, and a diapophysis from the
base of the neural arch; the pleurapophysis is shorter, its
fixed extremity is bifid, articulating to the two above-
named processes; its free extremity expands, and its ante-
rior angle is directed forwards to abut against the inner
surface of the extremity of the rib of both the axis and
atlas, whilst its posterior prolongation overlaps the rib of
the fourth vertebra. The same general characters and
imbricated coadaptation of the ribs (Fig. 18), pl, charac-
terize the succeeding cervical vertebre to the seventh
inclusive, the hypapophysis progressively though slightly
increasing in size. In the eighth cervical the rib becomes
elongated and slender; the anterior angle is almost or

ee GALLE LELAND: El CDE

VERTEBRA OF THE CROCODILE. 99

quite suppressed, and the posterior one more developed
and produced more downwards, so as to form the body of
the rib, which terminates, however, in a free point. In
the ninth cervical, the rib is increased in length, but is
still what would be termed a “false” or “floating rib” in
anthropotomy.

In the succeeding vertebra the pleurapophysis articulates
with a hemapophysis, and the hemal arch is completed
by a hemal spine; and by this completion of the typical
segment we distinguish the commencement of the series
of dorsal vertebree (7b.), D. With regard to the so-called
“perforation of the transverse process” this equally exists
in the present vertebra, as in the cervicals; on the other
hand, the cervical vertebrze equally show surfaces for the
articulation of ribs. The typical characters of the seg-
ment, due to the completion of both neural and hzemal
arches, are continued in some species of crocodilia to the
sixteenth, in some (crocodilus acutus) to the eighteenth
vertebra. In the crocodilus acutus and the alligator luctus
the hemapophysis of the eighth dorsal rib (seventeenth
segment from the head) joins that of the antecedent ver-
tebra. The pleurapophyses project freely outwards, and
become “ floating ribs” in the eighteenth, nineteenth, and
twentieth vertebree, in which they become rapidly shorter,
and in the last appear as mere appendages to the end of
the long and broad diapophyses: but the hemapophyses
by no means disappear after the solution of their union
with their pleurapophyses; they are essentially independ-
ent elements of the segment, and they are continued,
therefore, in pairs along the ventral surface of the abdo-
men of the crocodilia, as far as their modified homotypes
the pubic bones. They are more or less ossified, and are

generally divided into two or three picces.

100 VERTEBRA OF THE CROCODILE.

The lumbar vertebree are those in which the diapophy-
ses cease to support the movable pleurapophyses, although
they are elongated by the coalesced rudiments of such
which are distinct in the young crocodilia. The length
and persistent individuality of more or fewer of these
rudimental ribs determines the number of the dorsal and
lumbar vertebre respectively, and exemplifies the purely
artificial character of the distinction, The number of
vertebra or segments between the skull and the sacrum,
in all the crocodilia I have yet examined, is twenty-four.
In the skeleton of a gavial, I have seen thirteen dorsal
and two lumbar; in that of a crocodilus cataphractus,
twelve dorsal and three lumbar; in those of a crocodilus
acutus and alligator lucius, eleven dorsal and four lumbar,
and this is the most common number; but in the skeleton
of the crocodile, probably the species called croc. bipor-
catus, described by Cuvier, he gives five as the number
of the lumbar vertebre. But these varieties in the de-
velopment or coalescence of the stunted pleurapophysis
are of little essential moment; and only serve to show
the artificial character of the “dorsal” and “lumbar”
vertebrae. The coalescence of the rib with the diapophy-
sis obliterates of course the character of the “costal
articular surfaces,” which we have seen to be common to
both dorsal and cervical vertebree. The lumbar zygapo-
physes have their articular surfaces almost horizontal,
and the diapophyses, if not longer, have their antero-
posterior extent somewhat increased; they are much de-
pressed, or flattened horizontally.

The sacral vertebrze are very distinctly marked by. the
flatness of the coadapted ends of their centrums; there
are never more than two such vertebree in the crocodila
recent or extinct: in the first, the anterior surface of the

~»

VERTEBRA OF THE CROCODILE. 101

centrum is concave; in the second, it is the posterior sur-
face; the zygapophyses are not obliterated in either of
these sacral vertebre, so that the aspects of their articular
surface—upwards in the anterior pair, downwards in the
posterior pair—determines at once the corresponding ex-
tremity of a detached sacral vertebra. The thick and
strong transverse processes form another characteristic of
these vertebrae; for a long period the suture near their
base remains to show how large a proportion is formed
by the pleurapophysis. This element articulates more
with the centrum than with the diapophysis developed
from the neural arch; it terminates by a rough, truncate,
expanded extremity, which almost or quite joins that of
the similarly but more expanded rib of the other sacral
vertebre. Against these extremities is applied a sup-
plementary costal piece, serially homologous with the
appendage to the proper pleurapophysis in the dorsal
vertebrae, but here interposing itself between the pleura-
pophyses and hemapophyses of both sacral vertebra,
not of one only. This intermediate pleurapophysial
appendage is called the “ilium;” it is short, thick,
very broad, and subtriangular, the lower truncated apex
forming with the connected extremities of the heemapo-
physis an articular cavity for the diverging appendage,
called the “hind leg.” The hemapophysis of the an-
terior sacral vertebra is called “pubis,” 64; it is mode-
rately long and slender, but expanded and flattened at
its lower extremity, which is directed forwards towards
that of its fellow, and joined to it through the inter-
medium of a broad, cartilaginous, hemal spine, com-
pleting fhe heemal canal. The posterior hemopophysis,
63, is broader, subdepressed, and subtriangular, expand-
ing as it approaches its fellow to complete the second
Q%*

102 VERTEBRA OF THE CROCODILE.

haemal arch; it is termed “ischium.” The great develop-
ment of all the elements of these hzmal arches, and the
peculiar and distinctive forms of those that have thereby
acquired, from the earliest dawn of anatomical science,
special names, relates physiologically to the functions of
the diverging appendage which is developed into a potent
locomotive member. ‘This limb appertains properly, as
the proportion contributed by the ischium to the articular
socket and the greater breadth of the pleurapophysis show,
to the second sacral vertebra; to which the ilium chiefly
belongs.

The first caudal vertebra, which presents a ball for
articulating with a cup on the back part of the last sacral,
retains, nevertheless, the typical position of the ball on
the back part of the centrum; it is thus biconvex, and
the only vertebra of the series which presents that
structure.

The first caudal vertebra, moreover, is distinguished
from the rest by having no articular surfaces for the hee-
mapophyses, which in the succeeding caudals form a
heemal arch, like the neurapophyses above, by articulat-
ing directly with the centrum. The arch so formed has
its base not applied over the middle of a single centrum,
but, like the neural arch in the back of the tortoise and
sacrum of the bird, across the interspace between two
centrums. The first heemal arch of the tail belongs, how-
ever, to the second caudal vertebra, but it is displaced a
little backwards from its typical position.

The caudal heemapophyses, hh, coalesce at their lower
or distal ends, from which a spinous process is prolonged
downwards and backwards; this grows shorter towards
the end of the tail, but is compressed and somewhat ex-
panded antero-posteriorly. The hemal arch so constituted
has received the name of “chevron bone.”

VERTEBRA OF THE CROCODILE. 105

It is very true, as Cuvier said in the last lecture he de-
livered, “if we were agreed as to the crocodile’s head, we
should be so as to that of other animals; because the
crocodile is intermediate between mammals, birds, and
fishes.” Accordingly, the following description of the
crocodile’s skull is coextensive with that of the fish; if
the answerable bones are rightly determined between
these, their correspondence with those of other verte-
brates will be facilitated. The difficulties in comprehend-
ing the nature of some of the bones of the crocodile’s
head have arisen through passing to its comparison from
that of the mammal’s skull—by descending instead of
ascending to it.

The segments composing the skull are more modified
than those of the pelvis; but just as the vertebral pattern
is best preserved in the neural arches of the pelvis, which
are called collectively “sacrum,” so, also, is it in the same
arches of the skull, which are called collectively “cra-
nium.” The elements of which these cranial arches are
composed, preserve, moreover, their primitive or normal
individuality more completely than in any of the vertebree
of the trunk, except the atlas, and consequently the arche-
typal character can be more completely demonstrated.’

If, after separating the atlas from the occiput, we pro-
ceed to detach the occipital segment of the cranium from
the next segment in advance, we find the detached seg-
ment presenting the form and structure of the neural arch.
The “centrum” presents, like those of the trunk, a con-
vexity or ball at its posterior articular surface, but its
anterior one, like the hindmost centrum of the sacrum,

1 The skull of the crocodile, partially disarticulated, and with the
bones numbered as in the following description, may be had of Mr.
Flower, No. 22 Lambeth Terrace, Lambeth Road.

*

104 SKULL OF THE CROCODILE.

unites with the next centrum in advance by a flat rough
“sutural” surface. Like most of the centrums in the neck
and beginning of the back, that of the occiput develops
a hypapophysis, but this descending process is longer
and larger, its base extending over the whole of the under
surface of the centrum. It is a character whereby the
occipital centrum of a crocodilian reptile may be dis-
tinguished from that of a lacertian one; for in the latter
a pair of diverging hypapophyses project from the under
surface, as is shown in most recent lizards and in the
great extinct mosasaurus.

The upper and lateral parts of No. 1 present rough
sutural surfaces, like those in the centrums of the trunk,
for articulating with the “neurapophyses,” Nos. 2, 2,
which develop short, thick, obtuse, transverse processes,
4,4. The modified or specialized character of the ele-
ments of the cranial vertebrze has gained for them special
names. The centrum, 1, is called, as in fishes and all
other vertebrates, the “ basioccipital;” the neurapophy-
ses, 2, 2, are the “exoccipitals;” the neural spine, 3, is
the “superoccipital.” The transverse processes, 4, 4,
which may combine both diapophyses and paropophyses,
are called the “paroccipitals;” they are never detached
bones in the crocodilia, as they are in the chelonia and
in most fishes. The exoccipitals perform the usual func-
tions of neurapophyses, and, like those of the atlas, meet
above the neural canal; they are perforated to give exit
to the vagal and hypoglossal nerves, and protect the
sides of the medulla oblongata and cerebellum—the two
divisions of the epencephalon. The superoccipital, 8, is
broad and flat, like the similarly detached neural spine
of the atlas; it advances a little forwards, beyond its sus-
taining neurapophyses, to protect the upper surface of

ee EE AO

SKULL OF THE CROCODILE. 105

the cerebellum ; it is traversed by tympanic air-cells, and
assists with the exoccipitals, 2, 2, in the formation of the
chamber for the internal ear.

The chief modification of the occipital segment of the
skull, as compared with that of the osseous fish, or with
the typical vertebra, is the absence of an attached heemal
arch. We shall afterwards see that this arch is present
in the crocodile, although displaced backwards. .

Proceeding with the neural arches of the crocodile’s
skull, if we dislocate the segment in advance of the occi-
put, we bring away, in connection with the long base-
bone, 5, the bone, 9, which in the figure of the section of
the serpent’s skull (Cut 17) is shown similarly united to
5. In fact, the centrums of the vertebrze have here co-
alesced, as we find to happen in the neck of the siluroid
fishes, and in the sacrum of birds and mammals. The
two connate cranial centrums must be artificially divided,
in order to obtain the segments distinct to which they
belong. The hinder portion, 5, of the great base-bone,
which is the centrum of the parietal vertebra, is called
“basisphenoid.” It supports that part of the “mesence-
phalon,” which is formed by the lobe of the third ven-
tricle, and its upper surface is excavated for the pituitary
prolongation of that cavity. The basisphenoid develops
from its under surface a “hypapophysis,” which is sutu-
rally united with the fore part of that of the basioccipital,
but extends further down, and is similarly united in
front to the “ pterygoids,” 24. These rough sutural sur-
faces of the long descending process of the basisphenoid
are very characteristic of that centrum, when detached,
in a fossil state. The neurapophyses of the parietal ver-
tebra, 6, 6, or the “alisphenoids,” protect the sides of the
mesencephalon, and are notched at their anterior margin,

106 SKULL OF THE CROCODILE.

for a conjugational foramen transmitting the trigeminal
nerve. As accessory functions they contribute, like the
corresponding bones in fishes, to the formation of the
ear-chamber. They have, however, a little retrograded
in position, resting below in part upon the occipital cen-
trum, and supporting more of tke spine of that segment,
5, than of their own, 7. The spine of the parietal verte-
bra is a permanently distinct, single, depressed bone, like
that of the occipital vertebra; it is called the “ parietal,”
and completes the neural arch, as its crown or key-bone;
it is partially excavated by the tympanic air-cells, and
overlaps the superoccipital. The bones, 8, 8, wedged
between 6 and 7, manifest more of their diapophysial
character than their homotypes, 4, 4, do in the occipital
segment, since they support modified ribs, are developed
from independent centres, and preserve their individu-
ality. They form no part of the inner walls of the cra-
nium, but send outwards and backwards a strong trans-
verse process for muscular attachment. They afford a
ligamentous attachment to the hemal arch of their own
segment, and articulate largely with the pleurapophyses,
28, of the antecedent heemal arch, whose more backward
displacement, in comparison with its position in the fish’s
skull, is well illustrated in the metamorphosis of the toad
and frog.

On removing the neural arch of the parietal vertebra,
after the section of its confluent centrum, the elements
of the corresponding arch of the frontal vertebra present
the same arrangement. The compressed produced cen-
trum has its form modified lke that of the vertebral cen-
trums at the opposite extreme of the body in many
birds; it is called the “presphenoid.” The neurapophy-
ses, 10, 10, articulate with the upper part of 9; they are

ee

SKULL OF THE CROCODILE. 107

expanded, and smoothly excavated on their inner surface
to support the sides of the large prosencephalon; they
dismiss the great optic nerves by a notch. ‘They show
the same tendency to a retrograde change of position as
the neighboring neurapophyses, 6; for though they sup-
port a greater proportion of their proper spine, 11, they
also support part of the parietal spine, 7, and rest, in
part, below upon the parietal centrum, 5: the neurapo-
physes, 10, 10, are called “ orbitosphenoids.” The neural
spine, 11, of the frontal vertebra retains its normal cha-
racter as a single symmetrical bone, like the parietal
spine which it partly overlaps; it also completes the
neural arch of its own segment, but is remarkably ex-
tended longitudinally forwards, where it is much thick-
ened, and assists in forming the cavities for the eyeballs;
it is called the “ frontal” bone.

In contemplating in the skull itself, or such side view
as is given in Fig. 9, p. 22, of my work on the Archetype
Skeleton, the relative position of the frontal, 11, to the
parietal, 7, and of this to the superoccipital, 8, which is
overlapped by the parietal, just as itself overlaps the flat-
tened spine of the atlas, we gain a conviction which can-
not be shaken by any difference in their mode of ossifi-
cation, by their median bipartition, or by their extreme
expansion in other animals, that the above-named single,
median, imbricated bones, each completing its neural
arch, and permanently distinct from the piers of such
arch, must repeat the same element in those successive
arches—in other words, must be ‘“ homotypes,” or seri-
ally homologous. In like manner the serial homology
of those piers, called “neurapophyses,” viz: the laminze
of the atlas, the exoccipitals, the alisphenoids, and the
orbitosphenoids, is equally unmistakable. Nor can we

108 SKULL OF THE GROCODILE.

shut out of view the same serial relationship of the
paroccipitals, as coalesced diapophyses of the occipital
vertebra, with the mastoids 8, and the postfrontals, 12,
as permanently detached diapophyses of their respective
vertebrae. All stand out from the sides of the cranium,
as transverse processes for muscular attachment; all are
alike autogenous in the turtles; and all of them, in fishes,
offer articular surfaces for the ribs or hzmal arches of
their respective vertebrae; and these characters are re-
tained in the postfrontals as well as in the mastoids of
the crocodiles.

The frontal diapophysis, 12, is wedged between the
back part of the spine, 11, and the neurapophysis, 10;
its outwardly projecting process extends also backwards,
and joins that of the succeeding diapophysis, 8; but, not-
withstanding the retrogradation of the inferior arch, it
still articulates with part of its own pleurapophysial
element, 28, which forms the proximal element of that
arch.

There finally remain in the cranium of the crocodile,
after the successive detachment of the foregoing arches,
the bones terminating the forepart of the skull; but, not-
withstanding the extreme degree of modification to which
their extreme position subjects them, we ean still trace
in their arrangement a correspondence with the vertebrate
type. ,

A long and slender symmetrical grooved bone, 13,
between 24 and 24, like the ossified inferior half of the
capsule of the notochord, is continued forwards from the
inferior part of the centrum, 9, of the frontal vertebra, and
stands in the relation of a centrum to the vertical plates
of bone, 14, which expand as they rise into a broad, thick,
triangular plate, with an exposed horizontal superior sur-

SKULL OF THE CROCODILE. 109

face. ‘These bones, which are called “prefontals,” stand
in the relation of “neurapophyses” to the rhinencephalic
prolongations of the brain commonly but erroneously
called “olfactory nerves;” and they form the piers or
haunches of a neural arch, which is completed above by
a pair of symmetrical bones, 15, called “ nasals,” which I
regard as a divided or bifid neural spine.

The centrum of this arch is established by ossification
in the expanded anterior prolongation of the fibrous cap-
sule of the notochord, beyond the termination of its gela-
tinous axis. The median portion above specified retains
most of the formal characters of the centrum; but there
is a pair of long, slender, symmetrical ossicles, which,
from the seat of their original development, and their
relative position to the neural arch, must be regarded as
also parts of its centrum. And this ossification of the
element in question from different centres will be-no new
or strange character to those who recollect that the ver-
tebral body in man and mammalia is developed from three
centres. The term “vomer” is appled to the pair of
bones, 13, because their special homology with the single
median bone, so called in fishes and mammals, is indis-
putable; but a portion of the same element of the skull
retains its single symmetrical character in the crocodile,
and is connate with the enormous pterygoids, 24, between
which it is wedged. In some alligators (all. niger) the
divided anterior vomer extends far forwards, expands
anteriorly, and appears upon the bony palate.

Almost all the other bones of the head of the crocodile
are adjusted so as to constitute four inverted arches.
These are the hzemal arches of the four segments or ver-
tebree, of which the neural arches have been just described.
But they have been the seat of much greater modifica-

10 é

110 SKULL OF THE CROCODILE.

tions, by which they are made subservient to a variety of
functions unknown in the heemal arches of the rest of the
body. Thus, the two anterior heemal arches of the head
perform the office of seizing and bruising the food; are
armed for that purpose with teeth: and, whilst one arch
is firmly fixed, the other works upon it like the hammer
upon the anvil. The elements of the fixed arch, called
“ maxillary arch,” have accordingly undergone the great-
est amount of morphological change, in order to adapt
that arch toits share in mastication, as Well as for forming
part of the passage for the respiratory medium, which is
perpetually traversing this hemal canal in its way to
purify the blood. Almost the whole of the upper surface
of the maxillary arch is firmly united to contiguous parts
of the skull by rough or sutural surfaces, and its strength
is increased by bony appendages, which diverge from it
to abut against other parts of the skull. Comparative
anatomy teaches that, of the numerous places of attach-
ment, the one which connects the maxillary arch by its
element, 20, with the centrum, 13, and the descending
plates of the neurapophyses, 14, of the nasal segment, is
the normal or the most constant point of its suspension,
the bone, 20, being the pleurapophysial element of the
maxillary arch: it is called the “palatine,” because the
under surface forms a portion of the bony roof of the
mouth, called the “palate.” It is articulated at its fore
part with the bone, 21, in the same plates, which bone is
the hemapophysial element of the maxillary arch: it is
called the “maxillary,” and is greatly developed both in
length and breadth; it is connected not only with 20 be-
hind, and 22 in front, which are parts of the same arch,
and with the diverging appendages of the arch, viz., 26,
the malar bone, and 24, the pterygoid, but also with the

SKULL OF THE CROCODILE. lil

nasals, 15, and the lachrymal, 16, as well as with its fellow
of the opposite side of the arch. The smooth, expanded
horizontal plate, which effects the latter junction, is called
the palatal plate of the maxillary ; the thickened external
border, where this plate meets the external rough surface
of the bone, and which is perforated for the lodgment of
the teeth, is the “alveolar border” or “process” of the
maxillary. ‘he hemal spine or key-bone of the arch, 22,
is bifid, and the arch is completed by the symphysial
junction of the two symmetrical halves; these halves are
called “premaxillary bones:” these bones, like the maxil-
laries, have a rough facial plate, and a smooth palatal
plate, with the connecting alveolar border. The median
symphysis is perforated vertically through both plates;
the outer or upper hole being the external nostril, the
under or palatal one being the prepalatal or naso-palatal
aperture.

Both the palatine and the maxillary bones send outwards
and backwards parts or processes which diverge from the
line of the hemal arch, of which they are the chief ele-
ments; and these parts give attachment to distinct bones
which form the “diverging appendages” of the arch, and
serve to attach it, as do the diverging appendages of the
thoracic heemal arches in the bird, to the succeeding arch.

The appendage 24, called “ pterygoid,” effects a more
extensive attachment, and is peculiarly developed in the
crocodilia. As it extends backwards it expands, unites
with its fellow below the nasal canal, and encompassing
that canal, coalesces above it with the vomer, and is firmly
attached by suture to the presphenoid and basisphenoid :
it surrounds the hinder or palatal nostril, and, extending
outwards, it gives attachment to a second bone, 25, called
“ ectopterygoid,” which is firmly connected with the max-

112 SKULL OF THE CROCODILE.

illary, 25, the malar, 26, and the postfrontal, 12. The
second diverging ray is of great strength; it extends from
the maxillary, 21 (“hamapophysis” of the maxillary arch),
to the tympanic, 28 (“ pleurapophyses” of the mandibular
arch), and is divided into two pieces, the malar, 26, and
the squamosal, 27. Such are the chief crocodilian modi-
fications of the hemal arch, and appendages of the ante-
rior or nasal vertebra of the skull.

The hzemal arch of the frontal vertebra is somewhat less
metamorphosed, and has no diverging appendage. It is
slightly displaced backwards, and is articulated by only a
small proportion of its pleurapophysis, 28, to the parapo-
physis, 12, of its own segment; the major part of that
short and strong rib articulating with the parapophysis,
8, of the succeeding segment. ‘The bone, 28, called “tym-
panic,” because it serves to support the “drum of the ear”
in air-breathing vertebrates, is short, strong, and immovy-
ably wedged, in the crocodilia, between the paroccipital,
4, mastoid, 8, postfrontal, 12, and squamosal, 27; and the
conditions of this fixation of the pleurapophysis are ex-
emplified in the great development of the heemapophysis
(mandible), which is here unusually long, supports numer-
ous teeth, and requires, therefore, a firm point of suspen-
sion, in the violent actions to which the jaws are put in
retaining and overcoming the struggles of a powerful
living prey. The movable articulation between the pleu-
rapophysis, 28, and the rest of the hzemal arch is analogous
to that which we find between the thoracic pleurapophysis
and hemapophysis in the ostrich and many other birds.
But the hzemopophysis of the mandibular arch in the
crocodiles is subdivided into several pieces, in order to
combine the greatest elasticity and strength with a not
excessive weight of bone. The different pieces of this

SKELETON OF THE CROCODILE. FFs

purposely subdivided element have received definite
names. That numbered 29, which offers the articular
concavity to the convex condyle of the tympanic, 28, is
called the “articular” piece; that beneath it, 80, which
develops the angle of the jaw, when this projects, is the
“anoular” piece; the piece above, 29’, is the “surangular;”
the thin, broad, flat piece, 31, applied, like a splint, to the
inner side of the other parts of the mandible, is the
“splenial ;” the small accessory ossicle, 31’, is the “coro-
noid,” because it develops the process, so called, in lizards;
the anterior piece, 82, which supports the teeth, is called
the “dentary.” This latter is the homotype of the pre-
maxillary, or it represents that bone in the mandibular
arch, of which it may be regarded as the hemal spine;
the other pieces are subdivisions of the heemapophysial
element. The purport of this subdivision of the lower
jaw-bone has been well explained by Conybeare’ and
Buckland,” by the analogy of its structure to that adopted
in binding together several parallel plates of elastic wood
or steel to make a crossbow, and also in setting together
thin plates of steel in the springs of carriages. Dr. Buck-
land adds: “Those who have witnessed the shock given
to the head of a crocodile by the act of snapping together
its thin long jaws, must have seen how liable to fracture
the lower jaw would be, were it composed of one bone only
on each side.” The same reasoning applies to the com-
posite structure of the long tympanic pedicle in fishes.
In each ease the splicing and bracing together of thin flat
bones of unequal length and of varying thickness, affords
compensation for the weakness and risk of fracture that

1 «Geol. Trans.,” 1821, p. 565.
2 «« Bridgewater Treatise,’ 1836, vol. i. p. 176,

hi

114 SKELETON OF THE CROCODILE.

would otherwise have attended the elongation of the parts.
In the abdomen of the crocodile, the analogous subdivision
of the hzeemapophyses, there called abdominal ribs, allows
of a slight change of their length, in the expansion and
contraction of the walls of that cavity ; and since amphi-
bious reptiles, when on land, rest the whole weight of the
abdomen directly upon the ground, the necessity of the
modification for diminished lability to fracture further
appears. These analogies are important, as demonstrating
that the general homology of the elements of a natural
segment of the skeleton is not affected or obscured by
their subdivision for a special end. Now this purposive
modification of the hemapophyses of the frontal vertebra,
is but a repetition of that which affects the same elements
in the abdominal vertebree.

Passing next to the hzmal arch of the parietal verte-
bra, we are first struck by its small relative size. Its
restricted functions have not required it to grow in pro-
portion with the other arches, and it consequently retains |
much of its embryonic dimensions. It consists of a
ligamentous “stylohyal,” its pleurapophysis retaining the
same primitive histological condition which obstructs the
ordinary recognition of the same elements of the lumbar
heemal arches. A cartilaginous “epihyal,” 39, intervenes
between this and the ossified “ hemapophysis,” 40, which
bears the special name of ceratohyal. The hzemal spine,
41, retains its cartilaginous state, like its homotypes, in
the abdomen; there they get the special name of “abdo-
minal sternum,” here of “basihyal.’ The basihyal has,
however, coalesced with the thyrohyals to form a broad
cartilaginous plate, the anterior border rising like a valve
to close the fauces, and the posterior angles extending
beyond and sustaining the thyroid and other parts of the

LIMBS OF THE CROCODILE. 115

larynx. The long, bony ‘“ceratohyal,” and the commonly
cartilaginous “epihyal,” are suspended by the ligament-
ous “stylohyal” to the paroccipital process; the whole
arch having, like the mandibular one, retrograded from
the connection it presents in fishes.

This retrogradation is still more considerable in the
succeeding hemal arch. In comparing the occipital seg-
ment of the crocodile’s skeleton with that of the fish, the
chief modification that distinguishes that segment in the
crocodile is the apparent absence of its hamal arch. We
recognize, however, the special homologues of the con-
stituents of that arch of the fish’s skeleton in the bones
51 and 52 of the crocodile’s skeleton (Fig. 18); but the
upper or suprascapular piece, 00, retains, in connection
with the loss of its proximal or cranial articulations, its
cartilaginous state; the scapula, 51, is ossified, as is like-
wise the coracoid, 52, the lower end of which is separated
from its fellow by the interposition of a median, symme-
trical, partially-ossified piece called “episternum.” ‘The
power of recognizing the special homologies of 50, 51,
and 52 in the crocodile, with the similarly-numbered
constituents of the same arch in fishes—though masked,
not only by modifications of form and proportion, but
even of very substance, as in the case of ,o00—depends
upon the circumstance of these bones constituting the
same essential element of the archetypal skeleton, viz,
the fourth heemal arch, numbered pi, 52, in Fig. 7: for
although in the present instance there is superadded, to
the adaptive modifications above cited, the rarer one of
altered connections, Cuvier does not hesitate to give the
same names, “suprascapulaire” to 50, and “scapulaire”
to 51, in both fish and crocodile; but he did not perceive
or admit that the narrower relations of special homology

116 LIMBS OF THE CROCODILE.

were a result of, and necessarily included in, the wider
law of general homology. According to the latter law,
we discern in 50 and 51 a compound “ pleurapophysis,”
in 52 a “hemapophysis,” and in hs, the “heemal spine,”
completing the hzemal arch.

The scapulo-coracoid arch, both elements, 51, 52, of
which retain the form of strong and thick vertebral and
sternal ribs in the crocodile, is applied in the skeleton of
that animal over the anterior thoracic hemal arches.
Viewed as a more robust heemal arch, it is obviously out
of place in reference to the rest of its vertebral segment.”
If we seek to determine that segment by the mode in
which we restore to their centrums the less displaced
neural arches of the antecedent vertebree of the cranium
or in the sacrum of the bird,’ we proceed to examine the
vertebrze before and behind the displaced arch, with the
view to discover the one which needs it, in order to be
made typically complete. Finding no centrum and neu-
ral arch without its pleurapophyses from the scapula to
the pelvis, we give up our search in that direction; and
in the opposite direction we find no vertebra without its
ribs, until we reach the occiput; there we have centrum
and neural arch, with coalesced parapophyses, but with-
out the hemal arch, which arch can only be supplied by
a restoration of the bones 50-52 to the place which they
naturally occupy in the skeleton of the fish. And since
anatomists are generally agreed to regard the bones
50-52 in the crocodile (Fig. 18) as specially homologous
with those so numbered in the fish (Fig. 9), we must con-
clude that they are likewise homologous in a higher

1 See ‘On the Archetype and Homologies of the Vertebrate Skeleton,”
pp- 117 and 159.

LIMBS OF THE CROCODILE. Le

sense; that in the fish the scapula-coracoid arch is in its
natural or typical position, whereas in the crocodile it
has been displaced for a special purpose. ‘Thus, agree-
ably with a general principle, we perceive that, as the
lower vertebrate animal illustrates the closer adhesion to
the archetype by the natural articulation of the scapulo-
coracoid arch to the occiput, so the higher vertebrate
manifests the superior influence of the antagonizing
power of adaptive modification by the removal of that
arch from its proper segment.

The anthropotomist, by this mode of counting and de-
fining the dorsal vertebree and ribs, admits, unconsciously
perhaps, the important principle in general homology
which is here exemplified; and which, pursued to its
legitimate consequences, and further applied, demon-
strates that the scapula is the modified rib of that
centrum and neural arch, which he calls the “ occipital
bone ;” and that the change of place which chiefly masks
that relation (for a very elementary acquaintance with
comparative anatomy shows how little mere form and
proportion affect the homological characters of bones),
differs only in extent, and not in kind, from the modifica-
tion which makes a minor amount of comparative obser-
vation requisite, in order to determine the relation of the
shifted dorsal rib to its proper centrum in the human
skeleton.

With reference, therefore, to the occipital vertebra of
the crocodile, if the comparatively well-developed and
permanently-distinct ribs of all the cervical vertebre
prove the scapular arch to belong to none of those seg-
ments, and if that hemal arch be required to complete
the occipital segment, which it actually does complete in

118 FORE-LIMB OF THE CROCODILE.

fishes, then the same conclusion must apply to the same
arch in other animals, up to man himself.

The anterior locomotive extremity is the diverging ap-
pendage of the arch, under one of its numerous modes
and grades of development. The proximal element of
this appendage, or that nearest the arch, is called the
“humerus,” 58 (Fig. 18). The second segment of the
limb consists of two bones; the larger one, 54, is called
the “ulna:” it articulates with the outer condyle of the
humerus by an oval facet, the thick convex border of
which swells a little out behind, and forms a kind of
rudimental “olecranon ;” the distal end is much less than
the proximal one, and is most produced at the radial side.

The radius, 55, has an oval head; its shaft is cylin-
drical ; its distal end oblong and subcompressed.

The small bones, 56, which intervene between these
and the row of five longer bones, are called “ carpals ;”
they are four in number in the crocodilia. One seems to
be a continuation of the radius, another of the ulna; these
two are the principal carpals; they are compressed in the
middle, and expanded at their two extremities: that on
the radial side of the wrist is the largest. A third small
ossicle projects slightly backwards from the proximal end
of the ulnar metacarpal; it answers to the bone “pisi-
forme” in the human wrist. The fourth ossicle is inter-
posed between the ulnar carpal and the metacarpals of
the three ulnar digits.

These five terminal-jointed rays of the appendage are
counted from the radial to the ulnar side, and have re-
ceived special names; the first is called “pollex,” the
second “index,” the third “medius,” the fourth “annu-
laris,” and the fifth “minimus.” The first joint of each
digit is called “metacarpal ;” the others are termed “ pha-

PELVIS AND HIND-LIMB OF THE CROCODILE. 119

lanx.” In the crocodilia, the pollex has two phalanges,

the index three, the medius four, the annularis four, and
the minimus three. The terminal phalanges, which are
modified to support claws, are called “ ungual” phalanges.

As the above-described bones of the scapular extremity
are developments of the appendage of the scapular arch,
which is the hzmal arch of the occipital vertebra, it
follows, that, like the branchiostegal rays and opercular
bones in fishes, they are essentially bones of the head.
But the enumeration of the bones of the crocodile’s skull
is not completed by these; there is a bone anterior to the
orbit, which is perforated at its orbital border by the duct
of the lachrymal gland, whence it is termed the “lach-
rymal bone,” and its facial part extends forwards between
the bones marked 14, 15, 21, and 26. In many croco-
dilia there is a bone at the upper border of the orbit,
which extends into the substance of the upper eyelid; it
is called “superorbital.” In the crocodilus palpebrosus
there are two of these ossicles.

Both the lachrymal and superorbital bones answer to a
series. of bones found commonly in: fishes, and called
“ suborbitals” and “ superorbitals.” The lachrymal is the
most anterior of the suborbital series, and is the largest
in fishes; it is also the most constant in the vertebrate
series, and is grooved or perforated by a mucous duct.
These ossicles appertain to the dermal or muco-dermal
system or “exoskeleton,” not to the vertebral system or
‘‘endoskeleton.”

There remains, to complete this sketch of the osteology
of the crocodile, a brief notice of the bones composing
the diverging appendage of the pelvic arch: these being
a repetition of the same element as the appendage of the
scapular arch, modified and developed for a similar office,

120 PELVIS AND HIND-LIMB OF THE CROCODILE.

manifest a very close resemblance to it. The first bone,
called the “femur,” is longer than the humerus, and, like
it, presents an enlargement of both extremities, with a
double curvature of the intervening shaft, but the direc-
tions are the reverse of those of the humerus, as may be
seen in Fig. 18, where the upper or proximal half of the
femur is concave, and the distal half convex, anteriorly.
The head of the femur is compressed from side to side,
not from before backwards, as in the humerus; a pyra-
midal protuberance from the inner surface of its upper
fourth represents a “trochanter;” the distal end is ex-
panded transversely, and divided at its back part into two
condyles. The next segment of the hind-limb or “leg,”
includes, like the corresponding segment of the fore-limb
called “fore-arm,” two bones. The largest of these is the
“tibia,” 66, and answers to the radius. It presents a large,
triangular head to the femur; it terminates below by an
oblique crescent with a convex surface. The “fibula” is
much compressed above; its shaft is slender and cylin-
drical, its lower end is enlarged and triangular. The
eroup of small bones which succeed those of the leg are
the tarsals; they are four in number, and have each a
special name. The “astragalus” articulates with the tibia,
and supports the first and part of the second toe. The
calcaneum intervenes between the fibula and the ossicle
supporting the two outer toes; it has a short but strong
posterior tuberosity. The ossicle referred to represents
the bone called “cuboid” in the human tarsus. A smaller
ossicle, wedged between the astragalus and the metatar-
sals of the second and third toes is the “ ectocuneiform.”

Four toes only are normally developed in the hind-foot
of the crocodilia; the fifth is represented by a stunted
rudiment: of its metatarsal, which is articulated to the

PELVIS AND HIND-LIMB OF THE CROCODILE. 121

cuboid and to the base of the fourth metatarsal. The four
normal metatarsals are much longer than the correspond-
ing metacarpals. That of the first or innermost toe is the
shortest and strongest; it supports two phalanges. The
other three metatarsals are of nearly equal length, but
progressively diminish in thickness from the second to
the fourth. The second metatarsal supports three pha-
langes; the third four; and the fourth also has four pha-
langes, but does not support aclaw. The fifth digit is
represented by a rudiment of its metatarsal in the form of
a flattened triangular plate of bone, attached to the outer
side of the cuboid, and slightly curved at its pointed and
prominent end.

The forms and proportions of the entire skeleton of the
crocodile are adapted to the necessities of an amphibious
animal, but minister to much more rapid and energetic
movements in water than on land. The short limbs pre-
clude the possibility of very quick course along shore;
and the overlapping of the ribs of the neck, whilst en-
abling the head the better to cleave the water during the
acts of diving or swimming, makes the bending of that
part from side to side an act of difficulty and time; this,
it is said, may avail any one pursued by a crocodile on
dry land to escape by turning out of the straight course.
But the crocodile usually seizes his prey by stratagem or
concealment when in or close to the water; and it is there
that he shows himself master of his position, and chiefly
by the powerful strokes of his long, large, vertically-
flattened tail.

A

122 OSTEOLOGY OF CHELONIAN REPTILES.

OSTEOLOGY OF CHELONIAN REPTILES—
TORTOISES AND TURTLES.

Those animals to which, in the manifold modifications
of the organic framework, a portable dwelling or place
of refuge has been given, in compensation for inferior
powers of lomocotion or other means of escape or defence,
have always attracted especial attention; and of them the
most remarkable, both for the complex construction of
their abode as well as for their comparatively high orga-
nization, are the reptiles of the chelonian order. The
expanded thoracic-abdominal case, into which, in most
chelonians, the head, the tail, and the four extremities
can be withdrawn, and in some of the species be there
shut up by movable doors closely fitting both the ante-
rior and posterior apertures, as e.g. in the box-tortoises
(cinosternon, cistudo), has been the subject of many -and
excellent investigations; and not the least interesting
result has been the discovery that this seemingly special
and anomalous superaddition to the ordinary vertebrate
structure is due, in a great degree, to the modification of
form and size, and, in a less degree, to a change of relative
position, of ordinary elements of the vertebrate skeleton.

The natural dwelling-chamber of the chelonia consists
chiefly, and in the marine species (chelone) and mud-turtles
(trionyx) solely, of the floor and the roof; side-walls of
variable extent are added in the fresh-water species (emy-
dians) and land-tortoises (testudinians). The whole consists
chiefly of osseous “plates” with superincumbent horny
plates or “scutes,” except in the soft or mud-tortoises
(trionyx and sphargis), in which these latter are wanting.

Fig. 20 shows the manner in which the head and tail

OSTEOQLOGY OF CHELONIAN REPTILES. 123

can be retracted within the thoracic-abdominal box; the
four limbs are figured as extended in the act of walking,
to show their structure. The only movable vertebre are
those of the neck and tail, and the former enjoy a great
degree of flexibility. The vertebree answering to the dor-
sal, lumbar, and sacral series are firmly fixed together ;
but the dorsal ones, 1 to 8, are chiefly concerned in the
formation of the osseous dwelling-chamber. The com-
position of this will be first described as it exists in the
turtle (chelone), the species called “loggerhead” being here
selected for its illustration.

In the marine species of the chelonian order, of which

m= GEISCS we Se

ti X >
WO) St FQ

eT

SKELETON OF THE EUROPEAN TORTOISE.

this may be regarded as the type, the ossification of the
carapace and plastron is less extensive, and the whole
skeleton is lighter than in the box-tortoise (Fig. 20),
or any of those species that live on dry land. The
head is proportionally larger—a character common to

124 CARAPACE OF THE TURTLE.

aquatic animals; and, being incapable of retraction
within the carapace, ossification extends in the direc-
tion of the fascia covering the temporal muscles, and
forms a second bony covering of the cranial cavity; this
accessory defence is not due to the intercalation of any
new bones, but to exogenous growths from the frontals,
11, postfrontals, 12, parietals, 7, and mastoids, 8.

The carapace (Fig. 21) is composed of a series of median
and symmetrical pieces ch, sl to s11, and of two series
of unsymmetrical pieces on each side. The median pieces
have been regarded as lateral expansions of the summits
of the neural spines; the medio-lateral pieces as similar
developments of the ribs; and the marginal pieces as the
homologues of the sternal ribs. But the development
of the carapace shows that ossification begins independ-

CARAPACE OF TURTLE (Chelone imbricata).

ently in a fibro-cartilaginous matrix of the corium in the
first, ch, and some of the last, s9 to s11, median plates,

CARAPACE OF THE TURTLE. 195

and extends from the summits of the neural spines into
only eight of the intervening plates, s1 to s8; ossification
also extends into the contiguous lateral plates, p/1 to p/8,
in some chelonia, not from the corresponding part of the
subjacent ribs, but from points alternately nearer and
further from their heads, showing that such extension of
ossification into the corium is not a development of the
tubercle of the rib, as has been supposed. Ossification
commences independently in the corium in all the margi-
nal plates, m1 to py, which never coalesce with the bones
uniting the sternum with the vertebral ribs, and which
are often more numerous, and sometimes less numerous
than those ribs, and in a few species are wanting.
Whence it is to be inferred that the expanded bones of
the carapace, which are supported and impressed by the
thick epidermal scutes called “tortoise-shell,” are dermal
— ossifications, homologous with those which support the
nuchal and dorsal epidermal scutes in the crocodile.
Most of the pieces of the carapace being directly con-
tinuous or connate with the obvious elements of the ver-
tebree, which have been supposed exclusively to form
them by their unusual expansion, the median ones, s1 to
s11, have been called “neural plates,” and the medio-
lateral pieces, p/1 to pl8, “costal-plates;” but the exter-
nal lateral pieces, m1 to m12, have retained the name of
“marginal plates.” The first or anterior of the median
plates (ch, “nuchal plate”) is remarkable for its great
breadth in the turtles, and usually sends down a ridge
from the middle line of its under surface, which articu-
lates more or less directly with the summit of the neural
arch of the first dorsal vertebra; the second neural plate
is much narrower, and is connate with the summit of the
neural spine of the second dorsal vertebra; the seven suc-

tl

126 PLASTRON OF THE TURTLE.

ceeding neural plates have the same relations with the
succeeding neural spines; the rest are independent der-
mal bones. The costal plates of the carapace are super-
additions to eight pairs of the pleurapophyses or ver-
tebral portions of the second to the ninth ribs inclusive.
The slender or proper portions of these ribs project
freely for some distance beyond the connate dermal
portions, along the under surface of which the rib may
be traced, of its ordinary breadth to near the head, which
liberates itself from the costal plate to articulate to the
interspace of the two contiguous vertebrz, to the pos-
terior of which such rib properly belongs.

The plastron, or floor of the bony house, consists in
the genus Chelone, as in the rest of the order, of nine

Fig. 22.

PLASTRON OF CHELONE CAOUANNA.

pieces—one median and symmetrical, and the rest in
pairs. With regard to the homology of these bones,

VERTEBRA OF THE TORTOISE. 127

three explanations may be given: one in conformity
with the structure of the thoracic-abdominal cage in the
crocodile; the other based upon the analogy of that part
in the bird; and the third agreeably with the phenomena
of development. According to the first, the median
piece of the plastron, called “entosternal,’ S, answers to
the sternum of the crocodile, or “sternum proper,” and
the four pairs of plastron-pieces, es, hs, ps, xs, answer to
the “hzmapophyses” forming the so-called sternal and
abdominal ribs of the crocodile. Most comparative ana-
tomists have, however, adopted the views of Geoffroy St.
Hilaire, who was guided in his determination of the
pieces of the plastron by the analogy of the skeleton of
the bird; according to which"all the parts of the plas-
tron are referred to a complex and greatly developed
sternum, and the marginal plates are viewed as sternal
ribs (hemapophyses). The third ground of determina-
tion refers the parts of the plastron, like those of the
carapace, to a combination of parts of the endoskeleton
with those of the exoskeleton,

In Fig. 21, the marginal plates m 1 to m 12, are
twenty-four in number, or twenty-six if the first (nuchal,
ch) and last (pygal, py) vertebral plates be included.
Omitting these in the enumeration, three marginal pieces
intervene on each side at the angles between the first
median plate and the point of the first costal plate formed
by the end of the second dorsal rib, which point enters a
depression in the fourth marginal piece, m 4; the fifth,
sixth, seventh, eighth, ninth, and tenth marginal plates
are similarly articulated by gomphosis to the six suc-
ceeding ribs; the eleventh marginal plate has no corre-
sponding rib; the twelfth is articulated with the point of
the ninth dorsal rib supporting the eighth costal plate.

128 VERTEBRZX OF THE TORTOISE.

The want of concordance with the vertebral ribs, or
“ nleurapophyses,” arising from the increased number of
the marginal pieces, favors the idea of their being dermal
ossifications, such peripheral elements being more sub-
ject to vegetative division and multiplication than the
hemapophyses: the absence of the marginal pieces in
the trionyx gives additional support to the same view.
The median piece, 8, is here regarded as a heemal spine:
it is called “entosternum.” The parial pieces of the plas-

tron are the “hemapophyses” connate with expanded
dermal ossifications, and have received the following spe-
cial names: es, “episternal;” hs, “ hyosternal;” ps, “ hy-
posternal ;” ws, “ xiphisternal.”

In some extinct chelonia, the number of these lateral
elements of the plastron is increased by an intercalated
pair which I have called “mesosternals.” In the figure
of the segment, as modified to form the carapace and
plastron (Cut 28), the nature of the bones is indicated by
the letters according to the explanation given of the
archetype vertebrae (Fig. 5, p. 29), the dermal superad-
ditions being marked sc.

VERTEBR# OF THE TORTOISE, 129 |

In the figure of the skeleton of the box-tortoise (Fig.
20) a section of the carapace and plastron has been re-
moved from the right side to expose the dorsal and
sacral vertebre, and the disposition of the scapular and
pelvic arches. The eight cervical vertebrz are free,
movable, and ribless; the fourth of these vertebre has
a much elongated centrum, which is convex at both
ends; the eighth is short and broad, with the anterior
surface of the body divided into two transversély elon-
gated convexities, and the posterior part of the body
forming a single convex surface divided into two lateral
facets; the under part of the centrum is carinate. ‘The
neural arch, which is anchylosed to this centrum, is
short, broad, obtuse, and overarched by the broad ex-
panded nuchal plate, ch. The first dorsal vertebra, d 1,
is also short and broad, with two short and thick pleura-
pophyses, articulated by one end to the expanded ante-
rior part of the centrum, and united by suture at the
other end to the succeeding pair of ribs. The head of
each rib of the second pair is supported upon a strong
trihedral neck, and articulated to the interspace of the
first and second dorsal vertebree: it is connate, at the
part corresponding to the tubercle, with the first broad
costal plate, which articulates by suture to the lateral
margin ‘of the first neural plate, and to portions of the
nuchal and third neural plates: the connate rib, which is
almost lost in the substance of the costal plate, is con-
tinued with it to the anterior and outer part of the cara-
pace, where it resumes its subcylindrical form, and arti-
culates with the second and third marginal pieces of the
carapace. The neural arch of the second dorsal vertebra
is shifted forwards to the interspace between its own cen-
trum and that of the first dorsal vertebra. A similar
disposition of the neural arch and spine, and of the ribs,

130 VERTEBRA OF THE TORTOISE.

prevails in the third to the ninth dorsal vertebree inclu-
sive. The corresponding seven neural plates are connate
with the spines of those vertebre, and form the major part
of the median pieces of the carapace; the corresponding |
costal plates, anchyclosed to the ribs, form the medio-
lateral pieces ; the ninth, tenth, and pygal plates, with the
marginal plates of the carapace, do not coalesce with any
parts of the endoskeleton. The bony floor of the great
abdominal box, or “ plastron,” is formed by the hemapo-
physes and sternum eonnate with dermal osseous plates,
forming, as in the turtle, nine pieces, one median and sym-
metrical, answering to the proper sternum, and eight in
pairs: but they are more ossified, and the hyo and hypo-
sternals unite suturally with the fourth, fifth, and sixth
marginal plates, formigg the side-walls of the bony cham-
ber. The junction between the hyo- and hyposternals
admits of some yielding movement. ‘The iliac bones, 62,
abut against the pleurapophyses of the tenth, eleventh,
and twelfth vertebrze, counting from the first dorsal ver-
tebra. ‘These three vertebree form the sacrum: their pleu-
rapophyses are unanchylosed, converge, and unite at their
distal extremities to form the articular surface for the
ilium. Beyond these the vertebre, thirty-five in number,
are free, with short, straight, and thick pleurapophyses,
articulated to the sides of the anterior expanded portions
of the centrums. ‘They diminish to mere tubercles in the
first caudal vertebra, and disappear in the remainder. The
neural arches of the caudal vertebre are flat above, and
without spines. The strong columnar scapula, 51, is
attached by ligament to the first costal plate, and, retain-
ing its primitive rib-like form, it descends almost vertically
to the shoulder-joint, of which it forms, in common with
the coracoid, 52, the glenoid cavity. .A strong subcylin-
drical process or continuation of the scapula, representing

SKULL OF THE TORTOISE. 131

the acromion, bends inwards to meet its fellow at the
middle line. The coracoid continues distinct from the
scapula, expands, and becomes flattened at its median
extremity, which does not meet its fellow or articulate
with the sternum. ‘The iliac bones, 62, are vertical and
columnar, lke the scapula, but are shorter and more com-
pressed: they articulate, but do not coalesce, with the
pubis, 64, and ischium, 68. The acetabulum is formed
by contiguous parts of all the three bones. The pubis
arches inwards, and expands to join its fellow at the me-
dian symphysis and the ischium posteriorly. It sends
outwards and downwards a long, thick, obtuse process from
its anterior margin. ‘The ischia, in like manner, expand
where they unite together to prolong the symphysis back-
wards.

In the skull, the parietal crista is continued into the
occipital one without being extended over the temporal
fossee, as in the turtle; the fascia covering the muscular
masses in these fossee undergoing no ossification. The
bony hoop for the membrana tympani is incomplete
behind, and the columelliform stapes passes through a
notch instead of a foramen to attain the tympanic mem-
brane. The mastoid is excavated to form a tympanic air-
cell. In the Australian long-necked terrapene (hydraspis
longicollis) the head is much depressed, the mastoids are
excavated by large tympanic cells, and prolonged back-
wards: the frontal is produced forwards as far as the an-
terior nostril, where it terminates in a point between the
two nasals, which are here distinct from the prefrontals.
The margins of the upper and lower jaws are trenchant:
the hypapophysis of the atlas has the form of a diminutive
wedge-bone, forming as usyal the lower part of the arti-
cular cup for the occipital condyle: the rest of the body

1382 SKULL OF THE TORTOISE.

of the atlas, or “odontoid,” has coalesced with its proper
neural arch, which develops two transverse and two long
posterior oblique processes, as in the chelys.

In the true or land tortoises the temporal depressions
are exposed, as in the box-tortoises and fresh-water ter-
rapenes: the head is proportionally -small, and can be
withdrawn beneath the protective roof of the carapace.
The skull is rounder and less depressed than in the terra-
penes: the frontals enter into the formation of the orbital
border. The tympanic hoop is notched behind, but the
columelliform stapes passes through a small foramen. The
palatine processes of the maxillaries are on a plane much
below that of the continuation of the basis cranii, formed
by the vomer and palatines. In most of the chelonia, the
nasal bone is connate with the prefrontal; and, in all, the
tympanic pedicle is firmly wedged between the broad
appendage of the maxillary arch, formed by the malar,
26, and squamosal, 27, in front, and the mastoid, 8, behind.
The broad-headed terrapene (podocnemys expansa) differs
from other fresh-water tortoises, and approaches the ma-
rine tortoises (turtles), by the vaulted bony roof arching
over the temporal depressions. This roof is chiefly formed
by the parietals, but differs from that in the turtles in
being completed laterally by a larger proportion of the
squamosal than of the postfrontal, which does not exceed
its relative size in other terrapenes. The present species
further differs from the marine turtles in the nonossifica-
tion of the vomer, and the consequent absence of a septum
in the posterior nostrils; in the greater breadth of the
pterygoids, which send out a compressed rounded process
into the temporal depressions: the orbits also are much
smaller, and are bounded behind by orbital processes of
the postfrontal and malar bones: the mastoids and paroc-

LIMBS OF THE TORTOISE AND TURTLE. 1383

cipitals are more produced backwards, and the entire skull
is more depressed than in the turtles.

The ordinary position of the scapular extremity is a
state of extreme pronation, as shown in Fig. 20, with the
olecranon, or top of 54, thrown forwards and outwards,
and the radial side of the hand, or thumb, 7, directed to
the ground. The humerus, 53, is strongly bent in a sig-
moid form, with the anconal surface convex and directed
upwards and outwards: the two tuberosities at the proxi-
mal end are much developed and bent towards the palmar
aspect, bounding a deep and wide groove: that which
answers to the external tuberosity is the smallest, and by
the rotation of the humerus it becomes the most internal
in position. The proximal row of the’ carpus consists of
four bones—viz: a large scaphoides, a small lunare,
wedged into the interspace of the radius and ulna, a large
cuneiforme, and a small pisiforme. The second row con-
sists of five distinct bones, corresponding with the five
digits ; those supporting the fourth and fifth answering to
the os unciforme, the remaining three to the trapezium,
trapezoides, and magnum. ‘The first and fifth of the digits
have each one metacarpal and two phalanges; the rest,
i2, 111, wv, have each a metacarpal and three phalanges. - A
sesamoid bone is placed beneath the metacarpo-phalangeal
joint of the three middle digits.

In the pelvic extremity, the femur, 65, is sigmoidally
bent, but in a less degree than the humerus, and is a
shorter bone. The patella is hgamentous: the synovial
- joint between it and the femur is distinct from the proper
capsule of the knee-joint; the fibula, 66, is longer and more
slender than the tibia, 66; a small “ fabella” is articulated
to its upper end. The proximal row of the tarsus consists
of two bones, astragalus and caleaneum, which sometimes

12

134 SKELETON OF BIRDS.

become confluent. The distal row consists of five bones,
four of which support the four normal toes, and the fifth,
a rudiment of the fifth toe without a claw: the fourth and
fifth of the second row of tarsals answer to the os cuboides
of higher animals; the other three bones to the three ossa
cuneiformia. The astragalar part of the single proximal
bone would seem to include the scaphoid as well as the
calcaneum.

In the marine chelonia, the digits of both limbs are
elongated, flattened, and united by a web; the hands and
feet having the form of fins. :

In all the chelonia, the long bones of the limbs are solid,
without medullary cavities.

THE SKELETON OF BIRDS.

From the massive frame of the cold-blooded, heavy,
and proverbially slow tortoise, to the light, hot-blooded,
flying bird, the transition seems to be abrupt, and the
discrepancy between creatures so differently endowed ex-
treme; nevertheless, at the confines of the feathered class,
we find some aquatic species, such as the penguin, in-
capable of flight, having the wings modified to act as fins,
and much resembling those of the turtle; with the bones
solid, and the feathers resembling scales. All birds, like
tortoises, lay eggs, are devoid of teeth, and have their
jaws sheathed with horn, and forming a bill or beak.
Most birds, however, enjoy the faculty of flight.

If the student of comparative osteology will procure
the skull of a rook, a hawk, a swan, or a sea-gull, and
vertically bisect it, he will have a ready instance illus-
trative of some of the characteristics of the osteology of

+
(ees

4

~ =>
we a=
‘2

SKELETON OF BIRDS. 135

the feathered class. Such a section will, show the ivory-
like whiteness and compactness of the osseous tissue, and
the loose, open, cancellous structure of the bones. He
will see that air is admitted into these cancelli partly from
the nasal passages, and partly from the tympanic cavity
which receives it from the Eustachian tube; from the latter
source, the proper bones of the cranium receive their air.
Some of the characteristic features in the composition of
the skull of birds may also be noticed: as, for example,
the obliteration ofall the ordinary sutures of the cranium,
except those which unite the tympanic bone, 28, to the
mastoid, 8; and that which unites the pterygoid, 23, to
the basisphenoid, 5; which sutures are speedily obliterated
in the human subject. The premaxillary is confluent
with the nasal and with the maxillary; the nasal being
confluent with the frontal and the maxillary with the
jugal. The jugal and squamosal are also confluent, and
form a long zygomatic style in all birds, connected at the
hinder extremity by a movable glenoid joint to the
outer and lower part of the tympanic. The pterygoid
articulates, in like manner, with the inner and lower part
of the tympanic, the movements of which are thus com-
municated to the upper mandible, so far as the junction
of the nasal with the frontal admits of such independent
motion. ‘The upper jaw, or mandible, which includes the
vomer and nasals with the maxillary arch and appendages,
is movable in a bird through the junction of the nasals
and nasal branch of the premaxillary. with the frontal, by
means of a movable articulation, or by elastic plates.

If the student will next separate one of the vertebree
of the trunk from the rest, and cut out that portion of the
long and broad breast-bone to which its pair of ribs are

136 SKELETON OF BIRDS.

attached, he will have a segment of the skeleton, answer-
ing to that figured in Fig. 5, p. 28.

The cut surfaces will demonstrate the light cellulosity
of the divided bones. The following letters indicate the
elements of such modified vertebree of the thorax: y, cen-
trum, with its hyapophysis; p, parapophysis; d, diapo-
physis; m, neural arch and rudimental spine; p/, pleura-
pophysis ; 2, heemapophysis; hs, heemal spine. The tend-
ency of individual elements and bones to coalesce in birds
has already been illustrated in the cranium; it is shown,
in most birds of flight, not only by the sAtnaenen of the
centrum with the neural arch, but by that of several con-
secutive centrums and arches into a single bone, in the
ample chest. In lke manner the hzmal spines, which
continue distinct in many vertebrata, have here coalesced
into a single bone, which articulates on each side with
the hemapophyses of several vertebrae. These coalesced
spines are also much developed in breadth, and send
down, from the middle of their under surface, a longi-
tudinal crest or keel. This modification relates to the
extension of the surface for the origin of the great mus-
cles of flight, and renders the “ sternum,” as the coalesced
series of heemal spines is called, one of the most charac-
teristic parts of the skeleton of the bird. Ossification
extends from the neural arches into the tendons of the
vertebral muscles, and: such bone-tendons, both here and
in other parts of the body, as the legs, are also character-
istic of birds. The scapula (Fig. 24), 51, is long and
slender, as in the chelonia, but is more compressed and
sabre-shaped. The coracoid, 52, as a general rule, is a
distinct bone, movably articulated to the scapula at one
end and to the sternum at the other. Its broad sternal
end here articulates by a kind of gomphosis with a deep

SKELETON OF THE SWAN. 137

Fig. 24.

SKELETON OF THE SWAN (Cygnus ferus).

12*

138 SKELETON OF THE SWAN.

groove on the fore part of the sternum. The clavicle (7d.),
58, articulates with the coracoid above, but is confluent
with its fellow and with the keel of the sternum below.
The iliac bones, 62, are remarkable for their length, and
for the number of the vertebre, or the great extent of the
confluent spinal column, to which they are anchylosed.
They reach in the swan, and in most other birds, from
the tail forwards to the vertebrae with movable ribs.
Thus the artificial characters of a “lumbar vertebra” are
wanting. The pubis and ischium on each side have
coalesced with the ilium to form the lower boundary of
the widely-perforated acetabulum. The pubis is long and
slender, joins the ischium of its own side near its lower
extremity, but does not join its fellow; thus the foramen
ovale is defined, but there is no symphysis pubis: the
absence of this symphysis facilitates the expulsion of the
large ovum with its unyielding calcareous shell. The
ischium coalesces posteriorly with the ilium, and converts
the ischiadic notch into a foramen. The caudal vertebre,
Cd, are few in number, with broad transverse processes
formed by confluent pleurapophyses, the limits of which
may still be traced. A heemapophysis is articulated to
the lower interspace, between the fourth and fifth caudal,
and is anchylosed to the sixth. The humerus of some of
the larger birds of flight—e.g. the pelican or adjutant
crane—is remarkable for its lightness, as compared with
its bulk and seeming solidity; it is, in fact, a mere shell
of compact osseous tissue. The orifice admitting air to
its large cavity is beneath the great tuberosity at the
proximal end.

The keel is excavated, not only for the reception of an
air-cell, but likewise for a fold of the windpipe, which
fold expands with age, and lies horizontally in the sub-

SKELETON OF THE SWAN. 139

stance of the back part of the sternum. Small pneumatic
foramina are situated at the anterior and inner surface of
the bone, and perforate the articular surfaces for the ster-
nal ribs.

In the skeleton of the wild swan (Cygnus ferus) (Fig.
24), here selected as an illustration of the ornithic modi-
fication of the vertebrate type, there are not fewer than
twenty-eight vertebre, CSD, between the skull and the
sacrum, the last six of which, DD, support movable ribs;
of these, the first and second pairs are free; the next four
are articulated to the sternum by bony hemapophyses ;
the last five pairs of ribs are attached to the sacrum, and
also to the sternum; but the tenth, or last rib on the left
side, is very rudimentary, being only about one inch in
length. There are eight caudal vertebr, Cd. The trachea,
or windpipe, penetrates the sternum, and bends and winds
in the interior of the bone before returning to enter the
chest. The apex of the furculum, 58, bends upwards,
and forms a hoop over the windpipe as it enters into the
keel of the breast-bone. The furculum, sometimes called
“merrythought,” consists of the two clavicles confluent
at their lower free ends. If a portion of the one side of
the sternum be removed, the tortuous trachea which it
incloses will be exposed. To the great length and pecu-
liar course of the windpipe in this species is to be attri-
buted its remarkably loud and harsh voice; whence the
name hooper, or whistling swan, has been derived; and
is applied in contradistinction to the domestic or mute
swan, in which, as in most other birds, the trachea pro-
ceeds at once to the lungs, without entering the sternum.
In the female of the wild species, the course of the tra-
chea is much more limited than in the male, seldom

140 SKELETON OF THE DUCK TRIBE.

penetrating the sternum to a greater extent than from
three to four inches.

The breadth of the sternum, and the strong ridge or
keel that descends from the midline of its under surface,
relate to the increased extent of surface required for the
attachment of the “pectoral” muscles, which are the ac-
tive organs of flight. In the land-birds devoid of the
power of flight, such as the ostrich and apteryx, the keel
is wanting and the sternum is short. Its various propor-
tions, processes, notches, and perforations render it a very
characteristic bone in birds.

In no order, founded upon modifications of the feet, is
the sternum more diversified in character than in the
palmipedes or web-footed order; for in none are the .
powers of flight enjoyed in such different degrees, or ex-
ercised in such various ways, from the frigate-bird down
to the penguins, where the power of flight is abrogated,
and the rudimental wings used as fins,

In the goose and duck tribes, as well as the swans
(anseres, Linn.), the sternum is long and broad, and presents
two moderately wide and deep hind notches; the costal
processes are usually subquadrate; the coracoid grooves
are continued into one another at the median line; the
costal tract forms about half of the lateral margin in the
ducks and geese, and two-thirds or more in the swans;
the interpectoral ridge extends from the prominent part
of the coracoid margin backwards, nearly parallel to the
lateral margin, to the inner side of the lateral grooves;
the back part of the sternum between the grooves is quad-
rate, with the angles slightly produced in most; there is
a short manubrial process below the coracoid groove.
The form of the sternum, its long keel, and the backward
production of the long and slender ribs, give a boatlike

SKELETON OF THE DUCK TRIBE. 141

figure to the trunk of these swimming-birds, which is
well adapted to their favorite medium and mode of loco-
motion. The bones of the wing or anterior extremity do
not present that extraordinary development which might
be expected from the powers of the member of which
they form the basis. The great expanse of the wing is
gained at the expense of the epidermoid system (quills
and feathers, like hairs and scales, are thickened epiderm),
and is not exclusively produced by folds of the skin re-
quiring elongated bones to support them, as in the flying-
fish, flying-lizards, and bats. The wing-bones of birds
are, however, both in their forms and modes of articula-
tion, highly characteristic of the powers and applications
of the muscular apparatus requisite for the due actions
of flight. The bones of the shoulder consist on each side
of a scapula, 51, a coracoid, 52, and a clavicle, 58, the
clavicles being, as a general rule in birds, confluent at
their median ends, and so forming a single bone called
‘“‘furculum,” or “os furcatorium;” this further modification
of the hemal arch in birds, repeating that of the pubis
and lower jaw in some other animals, having occasioned
an additional specific term in ornithotomy. The scapula,
51, isa long, narrow, flat sabre-shaped plate, expanded at
the humeral end, where it forms externally part of the
joint for the arm-bone called “glenoid cavity,” and ex-
tended backwards nearly parallel with the vertebra, as
far as the ilium, 62, in the swan,.and reaching to the last
rib in the swift; but it is much shorter in the birds in-
_eapable of fight. The coracoid is the strongest of the
bones of the scapular arch: it forms the anterior half of
the glenoid cavity, extends above this part to abut upon
the furculum, and is continued downwards below the
joint, expanding, to be fixed in the transverse groove at

142 SKELETON OF THE DUCK TRIBE.

the fore part of the sternum; it thus forms the chief
support of the wing, and the main point of resistance
during its downward stroke. In the hawks and other
birds of prey, and in the crows and most passerine birds,
a small bone (os humero-capsulare) extends between the
scapula and coracoid along the upper part of the glenoid
cavity; this is absent in the swan and other swimmers,
as well as in the gallinaceous and wading birds. The
humerus, 58, is, usually a long and slender bone, but is
not always developed in length in proportion to the pow-
ers of flight; for, although it is shortest in the struthious
birds and penguins, it is also. very short, but much thicker
and stronger in the swift and humming birds. The head
of the humerus is transversely oblong and convex; it is
further enlarged by two lateral crests; of these the supe-
rior is. the longest, and is bent outwards; the inferior is
thickened and incurved, and beneath it is situated the
orifice by which the air penetrates the cavity of the bone.
The articular surface at the opposite or “distal” end is
divided into two parts, one internal, for the ulna, of a
hemispheric form, the other also convex, but more elong-
ated and oblique, extending some way upon the anterior
surface of the humerus. The extremity of a long bone of
a limb which is next the trunk is called the “proximal”
one; the extremity furthest from the trunk, the “distal”
one; they are not always “upper” and “lower.” The
ulna, 55, glides upon the inner hemispheric tubercle, upon
the trochlear canal, and on the back part of the outer con-
vexity. A ligament, extending from the outer part of

the head of the radius to the outer part of the olecranon, —
above the posterior margin of the outer division of the
articular surface of the ulna, plays upon the back part of
the radial convexity of the humerus and completes the

BONES OF THE WING. 148

cavity receiving it. The ulna is always stronger than the
radius; but both are long, slender, and nearly straight
bones, so articulated together as to admit of scarcely any
rotation which adds to the resisting power of the wing
in the action of flight. The upper part of the ulna, or
‘“‘olecranon,” is short. In the tendon attached to it, a
separate ossicle is developed in the swift,and two such
bones in the penguin, The ulna is often impressed by
the insertions of the great quill-feathers of the wing.
The bones of the hand are very long and narrow, with
the exception of the two distinct or unanchylosed carpal
bones; these are so wedged in between the antibrachium,
54, 55, and the metacarpus, 57, as to limit the motions of
the hand to abduction and adduction, or those necessary
for folding up and spreading out the wing. The hand is
thus fixed in a state of pronation; all power of flexion,
extension, and rotation is removed from the wrist-joint;
so that the wing strikes firmly, and with the full force of
_the depressed muscles, upon the resisting air. The part
of the hand numbered 57 in Fig. 24 includes the meta-
carpal bones of the digits answering to the second, third,
and fourth of the pentadactyle members, which are con-
fluent at their proximal ends with each other, and with
the “os magnum,” one of the carpal bones, now forming
the convex base of the middle metacarpal. This meta-
carpal, and that answering to the “fourth” digit, are of
equal length, and are also confluent at their distal ends;
but the middle or “third” metacarpal is much the strong-
est. That answering to the “second” digit, 2, is very
short, and like a mere process from the third; it supports
two short phalanges in the swan. The third metacarpal
supports three phalanges, 22, the fourth a single phalanx,
w. All these are wrapped:up in a sheath of integument,

144 BONES OF THE WING. -

and are strongly bound together; so that the wing loses
nothing of its power, whilst so much of the typical struc-
ture of the member is retained, that every bone can be
referred to its corresponding bone in the most completely
developed hand.

In ornithology, the large quill-feathers that are attached
to the ulnar side of the hand are termed “ primarize,” or
primary feathers; those that are attached to the forearm
are the “secundarix,” or secondaries, and “tectrices,” or
wing-coverts; those which lie over the humerus are called
“ scapularie,” or scapularies; and those which are attached
to the short outer digit, 7, erroneously called the “thumb,”
are the “spurie,” or bastard feathers. The bones of the
leg do not present the same number of segments as those
of the wing, that corresponding with the carpus being ~
wholly blended with the one that succeeds. :

The pelvic bones offer this contrast with those of the
shoulder, that they are always anchylosed on either side
into one piece, ‘os innominatum,” and not at the median.
line, whilst this is the only place where the elements of
the scapular apparatus are united by bone. In the young
bird, the os innominatum is composed of three bones.
The ilium, 62, is flattened, elongated, usually. anchylosed
to a very long sacrum; it forms the upper half of the
joint for the thigh-bone, called “cotyloid cavity.” The
pubis, 64, is very long and slender; it does not meet its
fellow at the middle line in any bird save the ostrich, but
is directed backwards, with its free extremity bent down-
wards. The pelvis of the ostrich is so vast, that the pubic
junction completing it does not impede the exit of the
egg; in other birds the open pelvis facilitates the passage
of that large and brittle generative product. The ischium,
63, is a simple elongated bone, extending from the coty-

PELVIS AND BONES OF THE LEGS OF BIRDS. 145

loid cavity backwards, parallel with the ilium; it some-
times coalesces, as in the swan, with both the ilium and
pubis at its distal end.

The cotyloid cavity is incomplete behind, and is closed
there by ligament. The femur, 65, is a short, cylindrical,
almost straight bone; the head is a small hemisphere,
presenting at its upper part a depression for the “round
ligament.” The single large “trochanter” generally rises
above-the articular eminence, and is continuous with the -
outer side of the shaft. The orifice for the admission of
air is situated in the depression between the trochanter
and head. The distal end presents two condyles, the
inner one for the inner condyloid cavity of the tibia; the
outer one for the outer cavity of the tibia and for the
fibula; the outer condyle is produced into a semicircular
ridge, which passes between the tibia and fibula; this
ridge puts the outer elastic ligament on the stretch, when
the fibula is passing over the condyle, and the fibula is
pulled into a groove at the back of the condyle, with a
jerk, when in extreme flexion; this spring-joint is well
exemplified in both the swan and water-hen.

The proximal end of the tibia is divided into the two
shallow condyloid cavities above noticed: two ridges:are
extended from its upper and anterior surface: the
strongest of these is the “procnemial” ridge, and is
slightly bent outwards; the shorter one on the outside of
this is the “ ectocnemial” ridge; they are usually united
above by a transverse ridge, called “epicnemial” ridge;
this is developed into a long process in the divers, grebes,
and cuillemots: a fibular ridge projects slightly from the
upper third of the tibia for junction with the fibula. The
distal end of the tibia forms a transverse pulley or troch-
lea, with the anterior borders produced. Above the fore

13

146 PELVIS AND BONES OF THE LEGS OF BIRDS.

part of the trochlea is a deep depression, and in many
birds an osseous bridge extends across it.

The third segment of the leg, 69, is a compound bone,
consisting originally of one proximal piece, short and
broad, presenting two articular concavities to the two thick
and round borders of the tibial trochlea, of three meta-
tarsals which coalesce with each other and with the above
tarsal piece, and of one or more bony processes which are
ossified from the back part of the proximal piece, or from
the proximal ends of the metatarsals, and which, from
their relations to the extensor tendons, are called “cal-
caneal” processes. In most birds, a small rudimental
metatarsal, supporting the innermost toe, or “hallux,” 2,
is articulated by ligament with the innermost of the
coalesced metatarsals, and is properly included in the
same segment of the limb. The three principal metatar-
sals are interlocked together before they become anchy-
losed, the middle one being wedged into the back part of
the interspace of the two lateral ones above, and into the
fore part below, passing obliquely between them. The
period at which these several constituents of the “ tarso-
metatarse” coalesce is shorter in the birds that can fly
than in those that cannot; and the extent of the coales-
cence is least in the penguins, in which the true nature of
the compound bone is best seen.

The modifications of the tarso-metatarse are chiefly
manifested in its relative length and thickness, in the
relative length of the three metatarsals, and in the number
and complexity of the calcaneal processes.

The inner of the two cavities for the condyles at the
proximal end of the bone is the “entocondyloid” cavity
or surface, the outer one the “ ectocondyloid” surface; they
are separated by an “intercondyloid” tract, from the fore-

STRUCTURE OF THE FOOT IN BIRDS. 147

part of which there usually rises an intercondyloid tuber-
osity. The entocondyloid cavity is usually the largest
and deepest: it is so in the raven, in which the base of the
intercondyloid tubercle extends over the whole of the in-
tercondyloid space. There are three calcaneal processes:
one, called the “entocalcaneal,” projects from below the
entocondyloid cavity, and from the back part of the upper
end of the entometatarse; a second, called the “ mesocal-
caneal,” from the intercondyloid tract and the mesometa-
tarse, and the third called “ ectocalcaneal,” from behind
the ectocondyloid cavity and the ectometatarse. These
three processes are united together by two transverse
plates circumscribing four canals, two smaller canals being
further carried between the ento and meso-calcaneal pro-
cesses. ‘The primitive interosseous spaces are indicated
by two small foramina at the upper and back part of the
shaft, which converge as they pass forward, and terminate
by a single foramen at the fourth part of the anterior con-
cavity. A similar minute canal is retained between the
outer and middle metatarsals, near their distal ends; each
metatarsal then becomes distinct, and develops a convex
condyle for the proximal phalanx. The middle one is
the largest, and extends a little lower than the other two:
it is also impressed by a median groove; the more com-
pressed lateral condyles are simply convex, and are of
equal length. A rough surface, a little way above the
inner condyle, indicates the place of attachment of the
small metatarsal of the hallux.

In the swan and other anserine birds the calcaneal
prominence presents four longitudingl ridges, divided by
three open grooves, the innermost ridge being the largest;
the shaft is subquadrate, with the angles rounded, and
none of the surfaces are channelled. The inner condyle

148 STRUCTURE OF THE FOOT IN BIRDS.

scarcely extends before the base of the middle one; the
canal perforating the outer intercondyloid space is
bounded below by two small bars passing from the mid-
dle to the outer condyle, and which bars define the groove
for the abductor muscle of the outer toe.

The tarso-metatarse of the diver (colymbus) is remark-
ably modified by its extreme lateral compression. The
ento and ecto-caleanea are prominent, oblong, subqua-
drate plates, inclining towards each other, but not quite
circumscribing a wide intermediate space. The broad
outer and inner surfaces of the shaft are nearly flat; the
narrow fore and back surfaces are channelled; the ante-
rior groove leads to the wide canal, perforating obliquely
the shaft above the outer intercondyloid space, from
which a narrower canal conducts to that interspace. The
middle and outer trochlez are nearly equally developed ;
the inner one stops short at the base of the middle one.

The number of toes varies in different birds; if the spur

of the cock be regarded as a rudimental toe (which is not,
however, my view of it), it may be held to have five toes,
while in the ostrich the toes are reduced to two. Birds,
moreover, are the only class of animals in which the
toes, whatever bg their number or relative size, always
differ from one another in the number of their joints or
phalanges, yet at the same time present a constancy in
that variation.

The innermost or back toe, ¢ (Fig. 24), answering, as I
believe, to the “hallux,” or innermost digit of the pen-
tadactyle foot, has two phalanges; the second toe, 7, has
three, the third toe, 7:7, four, and the fourth toe, 7, five
phalanges. I believe the toe answering to the fifth in
lizards and other pentadactyle animals to be wanting in
the bird’s foot; and the spur, sometimes single, sometimes

MECHANISM OF FLIGHT IN BIRDS. 149

double, as in Pavo bicalearatus, to be a superadded weapon
to the metatarse. As the toes in the tridactyle emeu,
eassowary, and bustard, have respectively three phalanges,
four phalanges, and five phalanges, we recognize them as
answering to the second, third, and fourth in other birds;
the toes in the didactyle ostrich have respectively four
and five phalanges, and what is here truly suggestive, the
outermost, which is much the smallest and shortest toe,
has the greater number of joints, viz: five, thus retaining
its ornithic type, as the fourth, or outermost, toe.

The entire form of the body, and consequently that of |
its bony framework, in a bird, has special reference to |
the power of flight. The trunk is an oval with the large —
end forwards. The vertebral column of this part is short |
and almost inflexible, so that the muscles act to great ad-
vantage ; the spine of the neck being long and flexible,
the centre of gravity is readily changed from above the
feet—as when standing or walking—-to between and be-
neath the wings during flight; when suspended in the air
the bird’s body naturally falls into that position, which
throws the centre of gravity beneath the wings. The axis.
of motion being situated in a different place in the line of
the body when walking from that which is used when flying,
the discrepancy requires to be compensated by some means
in all birds, in order to enable them to perform flight
with ease. Raptorial birds take a horizontal position
when suspended in the air, and the compensating power |
consists in their taking a more or less erect position when
at rest. Another class, including the woodpeckers, wag-
tails, &., take an oblique position in the air; with these —
the compensating power consists in their cleaving and
passing through the air at an angle coincident with the
position of the body, and performing flight by a series of »

£3?

150 MECHANISM OF FLIGHT IN BIRDS.

curves or saltations. Natatorial birds sometimes need
very extended flight; they take a very oblique position
in the air, stretch out their legs behind and their neck in
front; they have the ribs greatly lengthened, the integu-
ments of the abdomen are long and flexible, which enables
them greatly to enlarge the abdominal portion of their
bodies by inflating it with air; this causes a decrease in
the specific gravity of that part, and raises it to a hori-
zontal position; the compensating power consists in the
posterior half of the body becoming specifically lighter,
while the specific gravity of the anterior half remains un-
altered. When they alight they drop the legs, throw back
the trunk by bending the knee-joint, and bring the head
over the trunk by a graceful sigmoid curve of the long
neck, as in Fig. 24. The act of swimming is rendered
easy by the specific gravity of the body, by the boatlike
shape of the trunk, and by the conversion of the hinder
extremities into oars, in consequence of the membranes
uniting the toes together. ‘The effect of these web-feet in
water is further assisted by the toes having their mem-
branes lying close together when carried forwards ; whilst,
on the contrary, they are expanded in striking backwards.
The oarlike action of the legs is still further favored by
their backward position—an arrangement, however, which
- is unfavorable for walking.

Borelli was the first who, by comparison of the ana-
tomical peculiarities of the human frame and the structure
of birds, demonstrated, to a certain extent, the impossi-
bility of the realization of the cherished project of flying
by man. He arrived at this conclusion from a compari-
son of the form and strength of the muscles of the wings

_ of birds with the corresponding muscles of the human
body,

VARIOUS FORMS OF LIMBS IN MAMMALS. l15l1

PRINCIPAL FORMS OF THE SKELETON IN
THE CLASS MAMMALIA.

In the class Mammalia, which includes the hairy quad-
rupeds with the naked apodal whales and biped man, the
form of the animal is modified for a great diversity of
kinds and spheres of locomotion. Some live exclusively
in the ocean, and cleave the liquid element under the form
and with the locomotive powers of fishes; some frequent
the fresh waters ; some pass a subterraneous existence, and
work their way through the solid earth; some mount aloft,
to seek and seize their prey in the air; some pass their
lives in trees; most, however, dwell on the earth, with
various powers of walking, running, and leaping. Lastly,
man is modified to sustain his frame erect on the hinder,
now become in him the lower, limbs.

In the Mammalian class, accordingly, we find the limbs
progressively endowed with more varied and complicated
powers. They retain in the Cetacea (whale and porpoise
tribe) their primitive form of flattened fins; in the Un-
gulata (hoofed beasts) one or more of the digits acquire
the full complement of joints, but have the extremity en-
veloped in a dense hoof; in the Unguiculata (quadrupeds
with claws), the limbs, with ampler proportions, have the
digits liberated, and armed with claws confined to the
upper surface, leaving the under surface of the toes free
for the exercise of touch; in the mole, the hand is
shortened, thickened, expanded, and converted into a
sort of spade; in the bat, the fingers are lengthened,
attenuated, and made outstretchers and supporters of a
pair of wings; in the Quadrumana (ape and monkey

152 VARIOUS FORMS OF LIMBS IN MAMMALS.

tribes), certain digits are endowed with special offices, and
by a particular position enabled to oppose the others, so
as to seize, retain, and grasp. Lastly, in Man, the offices
of support and locomotion are assigned to a single pair
of members; the anterior, and now the upper, limbs being
left free to execute the various purposes of the will, and
terminated by a hand, which, in the matchless harmony
and adjustment of its organization, is made the suitable
instrument of a rational being.

In contemplating and comparing the skeletons of a
series of mammals, the most striking modifications are
observable in the structure and proportions of the limbs.

There are a few osteological characters in which all
mammalia agree, and by which they differ from the lower
vertebrata; and some have been supposed to be peculiar
to them that are not so. The pair of occipital condyles,
e. g., developed from the exoccipitals, are a repetition of
what we saw in the batrachia. The flat surfaces of the
bodies of the trunk-vertebree were a character of many
extinct reptiles; but these surfaces in mammals are de-
veloped on separate epiphysial plates, which coalesce in
the course of growth with the rest of the centrum. Moy-
able ribs, projecting freely (pleurapophyses) in the cervical
region, may be found in a few exceptional cases (sloths,
monotremes); bony sternal ribs (hemapophyses) exist in
most Hdentata; a coracoid extending, as in birds and
lizards, from the scapula to the sternum, with an “epi-
coracoid,” as in lizards, is present in the monotremes
(platypus or duck-mole, and echidna or spiny ant-eater,
of Australia); the cotyloid cavity may be perforated in
the same low mammals as in birds; the digits may have
the phalanges in varying number in the same hand, and
exceeding three in the same finger, e. g.,in the whale

SKELETON OF THE WHALE. 158

tribe. But the following osteological characters are both
common and peculiar to the mammalia. ‘The squamosal,
27, or second bone of the bar continued backwards from
the maxillary arch, is not only expanded as in the che-
lonia, but develops the articular surface for the mandible,
and this surface is either concave at some part or is flat.
Kach half or ramus of the mandible is ossified from a
single centre, and consists of one piece; and the condyle
is either convex or is flat, never concave. The presphe-
noid (centrum of the parietal vertebra) is developed dis-
tinctly from the basisphenoid; it may become confluent,
but is not connate, therewith.

One known mammal (the three-toed sloth) has more,
and one (the manatee, or sea-cow) has less than seven
vertebree of the neck. In the rest of the class these
vertebree, which have the pleurapophyses short and
usually anchylosed, are seven in number. |

SKELETON IN THE CETACEA, OR WITALE TRIBE.

In the skeleton of the whale (Fig. 25), which to out-
ward appearance seems to have as little neck as a fish,
there are as many cervical vertebree as in the long-necked
giraffe: this is a very striking instance of adherence to
type within the limits of a class: the adaptation to form
and function is effected by a change of proportion in the
bones; the cervical vertebree in the whale are flattened
from before backwards into broad thin plates; in the
giraffe (Fig. 80) they are produced into long sub-
cylindrical bones. In the whales, the movements of these
vertebrae upon one another are abrogated; and in the
grampus and porpoise, the seven vertebra are blended

e

154 SKELETON OF THE WHALE.

together into a single bone; they thus give a firm and
unyielding support to the large head, which has to over:
come the resistance of the water when the rapid swimmer
is cleaving its course through that element. The dorsal

FORESHORTENED VIEW OF THE SKELETON OF A WHALE (Balcnoptera boops),
SHOWING ITS RELATIVE SIZE TO MAN.

vertebre are characterized in all mammalia by the sudden
increase in the length and size of the ribs, which, in a
certain number of these vertebre, including the first, are
joined to a breast-bone by a commonly cartilaginous,
rarely osseous, part. The first rib is remarkable for its
great breadth in the whale; this and a few following ribs
are joined to a short and broad and often perforated ster-
num (Fig. 25), No. 60; the remaining ribs are free, or, as
they would be called in Human Anatomy, “false.” They
are articulated to the ends of diapophyses, which pro-
gressively increase in length to the last of the dorsal
series. ‘Then follow vertebre without ribs, answering to
those called “lumbar.” The whole hinder part of the
trunk of whales being needed to effect the strokes by
which they are propelled, its vertebree are as free from
anchylosis as in fishes; there is consequently no “sacrum,”
and the caudal vertebree are counted from the first of

SKELETON OF THE WHALE. 155

those that have “chevron bones” articulated to their
under part. ‘This special name is given to the vertebral
elements called “hamapomophyses” (see Fig. 26, h),
which are articulated in cetacea as in crocodilia, directly
to the under surface of the centrum, and, coalescing at
their opposite ends, develop thence a “ haemal spine,” and
form a “heemal” canal analogous to, but not homologous
with, that in fishes (compare No. V, h, with No. I, p, in
Cut 10, p. 182). The caudal vertebree of whales further
differ from those in fishes in retaining the transverse pro-
cesses, and in becoming flattened from above downwards,
without coalescing. These modifications relate to the
support of a caudal fin, which is extended horizontally
instead of vertically.

Whales and porpoises progress ig bounding move-
ments or undulations in‘a vertical plane, and their neces-
sity of coming to the surface to inhale the air directly, as
warm-blooded mammals, calls for a modification in the
form of the main swimming instrument, such as may best
adapt it to effect an easy and rapid ascent of the head.

The course of the whale is stopped and modified by
the action of the pectoral limbs, which are the same
parts as those in fishes, but constructed more after the
higher vertebrate type. The digital rays do not exceed
five in number; but they consist of many flattened pha-
langes, and are enveloped in a common sheath of integu-
ment. A radius, 55, and an ulna, 54 (Fig. 25), support
the carpal series; but, instead of being directly articulated
to the scapular arch, they are suspended to a humerus,
538: this is a short, thick bone, with a rounded head.
The scapula, 51, is detached from the occiput, has a short,
stunted, coracoid anchylosed to it, and is thus freely sus-
pended in the flesh ; it develops an acromial process: the

CO ce. Dee

156 SKELETON OF THE DUGONG.

ulna, 54, is produced upwards into an olecranon. With
all those marks, however, of adhesion to the mammalian
type of forearm, the outward aspect of the limb is as
simple as is that of the fish’s fin; it moves, as by one
joint, upon the trunk, and is restricted to the functions of
a pectoral fin. :

In the huge skull of the whale, the broad vertical oc-
ciput may be noticed, by which the head is connected,
through the medium of a short, consolidated neck, with
the trunk; the whole cranium seems to have been com-
pressed «above, from before backwards, so that the small
nasal bones, 15, articulating with the short and very broad
frontals, form the highest part of the skull. The long
maxillaries, 21, and premaxillaries, 22, extend backwards
and upwards, to articulate with the nasals, and complete
with them the bony entry to the air-passages, situated so
favorably at the summit of the cranium. The nostrils,
formed by the soft parts guarding that entry, are called
“blow-holes;” they are double in the whales—single in
the smaller cetacea. In the whales, the “baleen,” or
“whalebone” plates are attached to the palatal surface
of the maxillary and premaxillary bones; the expanded
toothless mandible supports an enormous under lip,
which covers the whalebone plates when the mouth is
shut. The skeleton of the great finner whale (Bale-
noptera boops), from which the foreshortened view (Cut
25) is taken, was ninety-six feet in length; the relative
dimensions of man is given by the outlines of the skele-
ton at its side. No known extinct animal of any class
equalled this ihving Leviathan in bulk.

There are a few whalelike mammals, equally devoid of
rudiments of hinder limbs, which obtain their sustenance
from sea-weeds or seaside herbage. ‘They have teeth

SKELETON OF THE DUGONG. - WoT

adapted for bruising such substances, and the movements
of the head in grazing require the cervical vertebree to be
unanchylosed; these are, however, short, and in the ma-
natee but six in number. In the dugong (Fig. 26), one
of these herbivorous sea-mammals frequenting the Ma-
Jayan and Australian shores, the upper and lower jaws
are singularly bent down, and the upper jaw is armed
with a pair of short tusks. The bones of all these cetacea
are singularly massive and compact. Three or four of
the anterior thoracic ribs are joined to a sternum—the
rest are free. One of the vertebree intervening between
the costal and caudal series has connected with it a simple
pelvic arch, in which the ilium and ischium may be re-
cognized, anda still more rudimental condition of such
arch is suspended in the inguinal muscles of the true
cetacea. Most of the caudal vertebree (Fig. 26), cd, of the

Fig. 26.

SKELETON OF THE DUGONG (Halicore Australis).

manatee and dugong, have long diapophyses, and hzemal
arches (Fig. 26), h. The terminal vertebree are flattened
horizontally.

The lacteal organs of the dugong are placed on the

breast, and the pectoral fins, in the female at least, are
14

158 SKELETON OF THE SEAL.

applied to clasp the young; and the animal so observed,
with its own head and that of its young above water, has
given rise to the fable of the siren and mermaid. The
bones and joints of the pectoral fin are accordingly better
developed than in the ordinary whales. The first row of
carpal bones, 56, consists of two—one articulated to the
radius, 55, the other to the ulna, 54, and fifth digit, 57, v,
and both to the single bone representing the second row.
The first digit, 7, consists of a short metacarpal; the me-
tacarpals of the others support each three phalanges.

SKELETON OF THE SEAL.

In the seal tribe (Phocide), another and well-marked
stage is gained in the development of the terrestrial in-
struments of locomotion. Hind limbs are now added—
the marine mammal has become a quadruped. The
sphere of life of the seals is near the shores; they often
come on land; they sleep and bring forth among the
rocks and littoral caves: hence the necessity for a better
development of the pectoral limbs, although these, like
the pelvic ones, still retain the general form of fins. The
fish-hunting seals make more use of the head in inde-
pendent movements of sudden extension, retraction, and
quick turns to the right and left, than do the cetacea of
like diet ; and the walrus (Fig. 27) works the head, as the
place of attachment of its long, vertical, down-growing
tusks, in various movements required in climbing over
floes and bergs of ice. Accordingly, in the seal tribe, we
find the seven neck-vertebree (zd.) c, longer, and with more
finished and free-playing joints than in the whales and
dugongs. The sigmoid curve, in which they can be

SKELETON OF THE WALRUS. 159

thrown during retraction of the head, exceeds that in most
other mammals, and almost reminds one of the extent of
flexion of this part of the spine in birds.

Fig. 27.

SKELETON OF THE WALRUS (Zrichecus rosmarus).

In the walrus, the skeleton of which is here selected to
exemplify the phocal modification of the mammalian skele-
ton, the vertebral formula is: 7 cervical, C, 11 dorsal, D,
5 lumbar, L, 3 sacral, S, and 9 caudal, cd. As, in conse-
quence of the presence of hind-lmbs, a sacrum is now
established, the characters of the above five kinds of
body-vertebrz, as defined in man and other mammals,
may here be given: the cervical or neck-vertebree “ have
perforated transverse processes,” the dorsal vertebrze
“bear ribs;” the lumbar vertebree “have imperforate
transverse processes and no ribs;” the sacral vertebree
“are anchylosed together ;” the rest are caudal vertebrae,
whatever their modifications. In the above characters,
the term “rib” is given to the vertebral element called
‘““»leurapophysis,” when this is long and movable; that

—

160 SKELETONS OF THE SEAL AND WALRUS.

element may be, and often is, present, but short and fixed,
in both cervical, lumbar, sacral, and caudal vertebrze; in
some mammals, e.g. monotremes, the pleurapophysis may
remain unanchylosed in some of the neck-vertebree, but
it is short, like a transverse process; and the so-called
“nerforated transverse process” in all mammals consists
of the diapophysis, parapophysis, and pleurapophysis;
the hole being the interval between those parts; in the
lumbar vertebre the pleurapophysis is short, and con-
fluent or connate with the diapophysis.

Returning to the skeleton of the walrus, we find that
nine pairs of ribs directly join the sternum, which con-
sists of eight bones. The transverse processes of the last
cervical are imperforate, consisting of the diapophysis
only. The neural arches of the middle dorsal vertebrae
are without spines and very narrow, leaving wide unpro-
tected 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 constituent parts. Inferior ridges
and tuberous processes, called “ hypapophyses,” are de-
veloped from some dorsal and lumbar vertebree. These
processes indicate the great development of the anterior
vertebral muscles, e.g. the “longi colli” and “psoz,” and
relate to the important share which the vertebre and
muscles of the trunk take in the locomotion of the sea-
tribe, especially when on dry land, where they may be
called “‘ gastropods,” in respect of their peculiar mode of

| progression. The walrus alone seems to have the power

of supporting itself on the fore fins, so as to raise the

| belly from the ground. There is no trace of clavicle in

‘any seal. The upper part of the scapula exceeds the

SKELETONS OF THE SEAL AND WALRUS. 161

lower one in breadth. 'The spine terminates by a short
and simple acromion. The humerus is short and thick,
and is remarkable for the great development of the inner
tuberosity and of the deltoid ridge, which is deeply ex-
eavated on its outer side. The inner condyle is per-
forated. The scaphoid and lunar bones are connate.
Although the pollex or the first digit exceeds the third,
fourth, and fifth in length, it presents its characteristic
inferior number of phalanges, by which the front 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 femur is
equally peculiar for its shortness and breadth. The tibia
and fibula present the more usual proportions, and are
anchylosed at their proximal ends. The bones of the
foot are strong, long, and are modified to form the basis
ofa large and powerful fin: the middle toe is the shortest,
and the rest increase in length to the margins of the foot;
the inner toe has, nevertheless, but two phalanges, the
rest having three phalanges, whatever their length; and
this is the typical character, both as to the number of the
digits and their joints, in both fore and hind feet of the
mammalia.

In-the living walrus and on the digits of each ex-
tremity are not only bound together by a common broad
web of skin, but those of the hind-limbs are closely con-
nected with the short tail: being stretched out back-
wards, they seem to form with it one great horizontal
caudal fin, and they constitute the chief locomotive organ
when the animal is swimming rapidly in the open sea.
The long bones of seals, like those of whales, are solid.

With regard to the skull in the seal-tribe, it may be
remarked that an occipitosphenoidal bone is formed, as

14*

162 SKELETON OF THE HORSE.

in man, by the coalescence of the basioccipital with the
basisphenoid; the parts of the dura mater or outer mem-
brane of the brain, called “tentorium,” with the posterior
part of the “falx,” are ossified. The sella turcica is shal-
low, but well defined behind by the overhanging poste-
rior clinoid processes: the petrosal shows a deep, trans-
verse, cerebellar fossa, and is perforated by the carotid
canal. The frontal forms a small rhinencephalic fossa,
and contributes a very large proportion to the formation
of the orbital and olfactory chambers. .

In Fig. 27, 62 is the ilium, 68 the ischium, and 64 the
pubes, 65 is the femur or thigh-bone, 66 the tibia, 66’ the
patella or kneepan, 67 the fibula, 68 the tarsus, and 69
the metatarsus and phalanges of the hind-foot; the num-
bers on the other bones correspond with those in the
skeleton of the dugong.

SKELETONS OF HOOFED QUADRUPEDS—
THE HORSE.

The contrast, as regards the sphere of life and kind of
movement between the seal and the horse is very great;
the instruments of locomotion, and indeed the whole
frame, need to be very different in an animal that can
only shuffle on its belly along the ground, and one that
can traverse the surface of the earth at the rate of four
miles in six minutes and a half, as was achieved by the
noted racer “ Flying Childers.” The modifications in the
form and proportions of the locomotive members are
accordingly extreme. The limbs in the horse are as
remarkable for their length and slenderness, as in the
seal for their brevity and breadth. Both fore and hind
limbs in the horse terminate each in a single hoof; the

SKELETON OF THE HORSE. 163

trunk is raised high above the ground, and is more re-
markable for its depth than breadth, especially at the
fore part; the neck is long and arched; the jaws long
and slender, being produced so as to facilitate the act of
cropping the grass, and leaving so much space between

Fig. 28.

HORSE (Lquus cabailus).

the front teeth, 7, and the grinders, m, as permits man to
insert the instrument called “ bit” into the mouth, where-
by he masters and guides his noble and valuable four-
footed ally, as the ship is steered by the helm.

Were every animal constructed expressly and exclu-
sively for its own peculiar habits of life, and irrespective
of any common pattern, it could scarcely be expected,

?

164 SKELETON OF THE HORSE.

beforehand, that the same bones would be found in the
horse as in the seal; yet a comparison of their skeletons,
Cuts 27 and 28, will demonstrate that this is, to a very
great degree, the case.

The vertebral formula of the horse is: 7 cervical, C,
19 dorsal, D, 5 lumbar, L, 5 sacral, S, and 17 caudal.
Hight pairs of ribs directly join the sternum, 60, which
consists of seven bones and an ensiform cartilage. The
neural arches of the last five cervical vertebrae expand
above into flattened, subquadrate, horizontal plates of
bone, with a rough tubercle in place of a spine: the zyga-
pophyses, z, are unusually large. The perforated trans-
verse process sends a pleurapophysis, p/, downwards and
forwards, and a diapophysis, d, backwards and outwards,
in the third to the sixth cervicals inclusive: in the seventh
the diapophysial part alone is developed, and is imper-
forate. ‘The spinous processes suddenly and considerably
increase in length in the first three dorsals, and attain
their greatest length in the fifth and sixth, after which
they gradually shorten to the thirteenth, and continue of
the same length to the last lumbar. The lumbar diapo-
physes are long, broad, and in close juxtaposition; the
last presents an articular concavity adapted to a corre-
sponding convexity on the fore part of the diapophysis of
the first sacral. The scapula, 51, is long and narrow, and
according to its length and obliquity of position the mus-
cles attached to it, which act upon the humerus, operate
with more vigor, and to this bone the attention of the
buyer should be directed, as indicative of one of the good
points in a horse. The coracoid is reduced to a mere
confluent knob. The spine of the scapula, 51, has no
acromion. The humerus, 53, is remarkable for the size
and strength of the proximal tuberosities in which the

SKELETON OF THE HORSE. 165

scapular muscles are implanted. The joint between it
and the scapula is not fettered by any bony bar connect-
ing the bladebone with the breastbone; in other words,
there is noclavicle. The ulna, represented by its olecranal
extremity, 04, is confluent with the radius, 55. The os
magnum in the second series of carpal bones, 56, is re-
markable for its great breadth, corresponding to the
enormous development of the metacarpal bone of the
middle toe, which forms the chief part of the foot. Splint-
shaped rudiments of the metacarpals, answering to the
second, 7, and fourth, w, of the pentadactyle foot, are
articulated respectively to the trapezoides and the reduced
homologue of the unciforme. The mid-digit, 2, consists
of the metacarpal called “cannon-bone,” and of the three
phalanges, which have likewise received special names in
Veterinary Anatomy, for the same reason as other bones
have received them in Human Anatomy. ‘“ Phalanges” is
the “ general” term of these bones, as being indicative of
the class to which they belong, and “ heemapophyses” is
the “ general” term of parts of the inferior arches of the
head-segments; and justas, from the modifications of these
heemapophyses, they have come to be called “ maxilla,”
“mandibula,” “ceratohyal,” &c., so the phalanges of the
horse’s foot are called—the first, “great pastern bone,”
the second, “small pastern bone,” and the third, which
supports the hoof, the “coffin bone;” a sesamoid ossicle
between this and the second is called the “coronary.”
The ilium, 52, is long, oblique, and narrow, like its homo-
type, the scapula; the ischium, 68, is unusually produced
backwards. The extreme points of these two bones show
the extent to which the bending muscles and extending
muscles of the leg are attached; and according to the
distance of these points from the thigh-bone the angle at

166 SKELETON OF THE RHINOCEROS.

which they are therein inserted becomes more favorable
for their force; the longer, therefore, and the more hori-
zontal the pelvis, the better the hind-quarter of the horse,
and its qualities for swiftness and maintenance of speed
depend much on the “good point” due to the development
of this part of the skeleton. The femur, 65, is character-
ized by a third trochanter springing from the outer part
of the shaft before the great trochanter. There isa splint-
shaped rudiment of the proximal end of the fibula, 67,
but not any rudiment of the distal end. The tibia, 66, is
the chief bone of the leg. The heel-bone, “calcaneum,”
is much produced, and forms what is called the “ hock.”
The astragalus is characterized by the depth and obliquity
of the superior trochlea, and by the extensive and undi-
vided anterior surface, which is almost entirely appro-
priated by the naviculare. The external cuneiforme is
the largest of the second series of tarsals, being in pro-
portion to the metatarsal of the large middle digit, 777,
which it mainly supports. The diminished cuboides arti-
ceulates partly with this, partly with the rudiment of the
metatarsal corresponding with that of the fourth toe, zv.
A similar rudiment of the metatarsal of the toe, corre-
sponding with that of the second, 7, articulates with a
cuneiforme medium-—here, however, the innermost of the
second series of tarsal bones.

Of all the other known existing hoofed quadrupeds, it
would hardly be anticipated that the rhinoceros presented
the nearest affinity to the horse; one might rather look to
the light camel or dromedary; but a different modification
of the entire skeleton may be traced in the animals with
toes in even number, as compared with the horse and other
odd-toed hoofed quadrupeds. In an extinct kind of horse
(ippopotherium), the two splint-bones are more developed,

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SKELETON OF THE RHINOCEROS. 167

and each supports three phalanges, the last being provided
with a diminutive hoof. In the extinct Paleotheria, the
outer and inner digits acquired stronger proportions, and

SKELETON OF THE RHINOCEROS (Lh. bicornis).
.

the entire foot was shortened. The transition from the
Paleotheria, by the extinct hornless rhinoceros (Acerothe-
rium), to the existing forms of rhinoceros, is completed.
In the skeleton of the rhinoceros, we find resemblances to
the horse in the number of the dorsal vertebra, in the
third trochanter of the femur, and in the number of digits
on each foot, albeit the two that are hidden and rudi-
mental in the swifter quadruped are here made manife8t in
their full development: the concomitant shortening of the
whole foot, and strengthening of the entire limbs, agcord
with the greater weight of the body to be supported, clad
as it is with a coat-armor of thickened tuberculated hide:
the broader feet, terminated each by three hoofs, afford a
better basis of support in the swampy localities affected

ed

168 SKELETON OF THE RHINOCEROS.

by the rhinoceros. Both scapulee and iliac bones are of
ereater breadth, and less length. The ulna is fully de-
veloped in the fore-limb, and the fibula in the hind-leg;
but there is no power of rotation of the fore-limb in any
hoofed quadruped. The upper surface of the skull is
roughened for the attachment of the horn, and in two
distinct places where the species has two horns.

If the equine skull be compared with that of the rhi-
noceros, the basioccipital will be seen to be narrow and
more convex. The true mastoid intervenes, as a tuberous
process, between the post-tympanic and paroccipital pro-
cess, clearly indicating the true nature of the post-tym-
panic in the rhinoceros; the tapir shows an intermediate
condition of the mastoid between the rhinoceros and
horse. The latter differs from both the tapir and rhi-
noceros in the outward production of the sharp roof of
the orbit and the completion of the bony frame of that
cavity behind by the junction of the postorbital process
with the zygoma. The temporal fossa, so defined, is small
in proportion to the length of the skull: the base of the
postorbital process is perforated by a superorbital fora-
men. The lachrymal canal begins by a single foramen.
The premaxillaries extend to the nasals, and shut out
the maxillaries from the anterior aperture of the nos-
trils. The chief marks of affinity to other odd-toed
hoofed beasts (Perissodactyles) are seen in the shape, size,
and formation of the posterior aperture of the nostrils,
the major part of which is bounded by the palatine bones,
of which only a small portion enters into the formation
of the bony palace, 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 ex-

{

CHARACTERS OF ODD-TOED HOOFED BEASTS. 169

tent: its base is perforated by the ectocarotid canal. The
entopterygoids are thin plates, applied lke splints over
the inner side of the squamous suture between the ptery-
goid processes of the palatines and alisphenoids. The
postglenoid process in the horse is less developed than in
the tapir. The Eustachian process is long and styliform.
There is an anterior condyloid foramen, and a wide
“fissura lacera.” The broad and convex bases of the
nasals articulate with the frontals a little behind the an-
terior boundary of the orbits. The space between the
incisors and molars is of greater extent than in the tapir;
along diastema is not, however, peculiar to the horse;
and, although it allows the application of the bit, that
application depends rather upon the general pature of the
horse, and its consequent susceptibility to be broken in,
than upon a particular structure which it possesses in
common with the ruminants and some other herbivora.
The tapir and the rock cony have four digits on each
fore-foot, and three digits on each hind-foot; but they
resemble more the horse and rhinoceros than any other
Ungulata. If the osteological characters of the hoofed
animals with the hind digits in uneven number be com-
pared together, they will be found to present, notwith-
standing the differences of form, proportion, and size
presented by the rhinoceros, hyrax, tapir, and horse, the
following points of agreement, which are the more sig-
nificative of natural affinity when contrasted with the
skeletons of the hoofed animals with digits in even num-
ber. Thus, in the odd-toed or “ perissodactyle” ungulates,
the dorso-lumbar vertebre differ in different species, but
are never fewer than twenty-two; the femur has a third
trochanter, and the medullary artery does not penetrate
the fore part of its shaft. The fore part of the astragalus
15

170 SKELETON OF THE GIRAFFE.

is divided into two very unequal facets. The os magnum
and the digitus medius which it supports is large, in some
disproportionately, and the digit is symmetrical; the

Fig. 30.

ee
SKELETON OF THE GIRAFFE (Camelopardalis giraffa).

same applies to the ectocuneiform and the digit it sup-
ports in the hind foot. Ifthe species be horned, the horn
is single; or if there be two, they are placed-on the me-

SKELETON OF THE GIRAFFE, 171

dian line of the head, one behind the other, each being
thus a single or odd horn. There is a well-developed
post-tympanic process, 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, of
the palatines enters into the formation of the posterior
nares, the oblique aperture of which commences in ad-
vance of the last molar, and, in most, of the penultimate
one. The pterygoid process has a broad and thick base,
and is perforated lengthwise by the ectocarotid. The
crowns of the antepenultimate, as well as the penultimate
and last premolars, are as complex as those of the molars;
that of the last lower milk-molar is bilobed. To these
osteological and dental characters may be added some
important modifications of internal structure, as, e. g., the
simple form of the stomach, and the capacious and saccu-
lated caecum, equally indicating the mutual affinities of
the odd-toed or perissodactyle hoofed quadrupeds, and
their claims to be regarded as a natural group of the
Ungulata. Many extinct genera, e. g., lophiodon, tapio-
therium, paleéotherium, hippotherium, acerotherium, ma-
crauchenia, elasmotherium, coryphodon, have been dis-
covered, which once linked together the now broken
series of Perissodactyla, represented by the existing
genera rhinoceros, hyrax, tapyrus, and equus.

Another series of hoofed quadrupeds is characterized
by having their hoofs and digits in even number in both
fore and hind feet. The majority of these have a pair, so
developed as to serve as feet, and terminated by a pair of
hoofs so shaped as to look like one split hoof, whence the
name “cloven-footed,” given to this predominant family of

172 CHARACTERS OF EVEN-TOED HOOFED BEASTS.

“artiodactyle,” or even-toed beasts; the synonym “ rumi-
nant,” indicative of the same great family, is deduced from
the characteristic complexity of their act of digestion.

No food is more remote or distinct from flesh than oTass.
Extremities enveloped in hoofs are incapacitated from
seizing and retaining a living prey, hence all hoofed
mammals are necessarily herbivorous: hence the com-
plexity of their grinding teeth, the concomitant strength
of their grinding muscles, and weakness of the biting
muscles; the length of the neck, to enable the head to
reach the verdant earth, and the length and slenderness
of the jaws. The absence of a clavicle, and of any power
of rotating the bones of fore-leg and fore-foot, are also con-
stant characteristics of both great divisions of the Ungulata
or hoofed quadrupeds.

The ox, the hog, and the hippopotamus are examples
of even-toed hoofed quadrupeds. In the ox, besides the
two large and normally developed hoofs, two small sup-
plementary hoofs dangle behind, in each foot; in the hog
these are brought down to the level of the midpair, but
are smaller; in the hippopotamus the four digits and hoofs
are subequal on each foot. From this type of extremity
to that of the giraffe, or camel, where the digits are abso-
lutely restricted to two on each foot, there is a close series
of gradational shortcomings affecting the outer and the
inner toes, until they wholly disappear. The giraffe (Fig.
30) is a ruminant dwelling in climes where herbage dis-
appears from the parched soil soon after the rainy season
has terminated, and where sustenance for a herbivore of
its bulk could hardly be afforded, except by trees: it is
therefore modified to browse on the tender branches, and
chiefly of the light and lofty acacias. Its trunk is accord-
ingly short, and raised high upon long and slender limbs,

CHARACTERS OF EVEN-TOED HOOFED BEASTS. 173

especially at the forepart; a small and delicate head is
supported on an unusually long neck. The number of
vertebree here, however, accords with that characteristic
of the mammalian class, viz: seven. They are peculiar
for the length of their bodies. There are fourteen dorsal
vertebree with very long spinous processes, and support-
ing long and slender ribs, especially the anterior ones,
seven pairs of which join the sternum, which consists of
six bones; the lumbar vertebre are five in number, the
sacral four, and the caudal twenty; this series is term1-
nated in the living animal by a tuft of long, wavy, stiff
black hair, forming an admirable whisk to drive off insect
tormentors. The bladebone, 51, is remarkably long and
slender; its spine or ridge forms a very low angle, and
gradually subsides as it approaches the neck of the sca-
pula; the coalesced coracoid is a large tuberosity. The
humerus, 538, forms the shortest of the three segments of
the limb; it is remarkable for the strength of the proximal
processes ; the second segment is chiefly constituted, as in
all ruminants, by the radius, 55; the slender shaft of the
ulna, 56, which supports a long olecranon, becomes blended
with the radius, and lost at its lower third, but its distal
end reappears as a distinct part. The metacarpals of the
retained digits, answering to the third and fourth in the
human and other five-fingered (pentadactyle) hands, are
blended together to form a single “cannon-bone” of the
veterinarians; but the nature of this is different from that
in the horse; it divides at its distal end into two well-
formed trochlez, or pulley-joints, and to these are articu-
lated the digits 77 and iv, which each consist of three joints
or phalanges. Thus the main extent of this singularly
elongated limb is gained by the excessive development of
the hand-segment, restricted, however, to those elements
15*

174 CHARACTERS OF IERBIVOROUS QUADRUPEDS.

that answer to the middle and ring-fingers of the human
hand.

The pelvis, of which the sacral, 5, iliac, 62, and ischial,
64, elements are shown in Cut 381, is small in proportign
to the animal’s bulk. The femur, 65, is short like the
humerus, and chiefly remarkable for the great expanse of
this distal end. ‘The tibia, 66, forms the main basis of the
leg, as its homotype the radius does in the forearm, but
the fibula is more reduced than in the ulna; rarely in any
ruminant is more of it visible than its distal end, 67,
wedged in between the tibia and the calcaneum. The
series of tarsal bones, 68, is peculiar in all ruminants for
a coalescence of the two bones answering to the “ scaphoid
and cuboid” in the human tarsus. In all ruminants the
astragalus is unusually symmetrical in shape, with a deep
trochlear articular surface for the tibia, and two equal
convex surfaces for succeeding tarsal bones; the calca-
neum is produced into a long “hock.” ‘The rest of the
bones of the hind-foot conform closely with those of the
fore-foot.

A few remarks, although interesting chiefly to the pro-
fessed anatomist, appear called for in reference to the bony
structure of the head of the giraffe.

The exoccipitals form a marked protuberance above
the foramen magnum, and below a deep fossa, for the im-
plantation of the ligamentum nuchze—the length of the
dorsal spines being related, in all ruminants, to a due
surface for the attachment of this strong elastic support
of the head and neck. ‘The parietals are chiefly situated
on the upper surface of the skull; the osseous horn-cores,
which are originally distinct, become anchylosed in old
giraffes, across the coronal suture, equally to the parietals
and frontals: if one of these be divided longitudinally, it.

SKELETON OF THE CAMEL, 175

will show the extension of the frontal and parietal sinuses
into its lower fourth, the rest of the horncore being a solid
and dense bone. The protuberance upon the frontal and
contiguous parts of the nasal bones is entirely due to an
enlargement of those bones, and not to any distinct osse-
ous part: its surface is roughened by vascular impressions.
The lachrymal is separated from the nasal by a large va-
cuity intervening between those bones, the frontal and
the maxillary. The premaxillaries, which are of unusual
length, articulate with the nasals. The petrotympanic is
a separate bone, as in all ruminants. The symphysis of
the lower jaw is unusually long and slender in the giraffe.

In the skeleton of the Camel (Camelus bactrianus) the
vertebral formula is—seven cervical, twelve dorsal, seven
lumbar, four sacral, eighteen caudal. Seven pairs of ribs
articulate directly with the sternum, which consists of six
bones, the last being greatly expanded and protuberant
below, where it supports the pectoral callosity in the living
animal. ‘The cervical region, though less remarkable for .
its length than in the giraffe, is longer than in ordinary
ruminants, and is remarkable for its flexuosity ; the ver-
tebree are peculiar for the absence of the perforation for
the vertebral artery in the transverse process, with the
exception of the atlas; that artery, in the succeeding cer-
vicals, enters the back part of the neural canal, and per-
forates obliquely the forepart of the base of the neurapo-
physis. The costal part of the transverse process is large
and lamelliform in the fourth to the sixth cervical vertebree
inclusive: in the seventh it isa short protuberance. The
spinous process of 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 sum-
mits of the spines are on almost the same horizontal line,

176 SKELETON OF THE CAMEL.

and are expanded and obtuse above, sustaining the sub-
stance of the two humps of this species; they afford,
however, no other indication of those risings, which are
as independent of the osseous system as is the dorsal fin
in the grampus or porpoise. The spines of the lumbar
vertebree progressively decrease in length. The spine of
the scapula is produced into a short-pointed acromion:
the coracoid tubercle is large, and grooved below. The
ridge upon the outer condyle of the humerus is much less
marked than in the normal ruminants. The ulna has
coalesced more completely with the radius, and appears
to be represented only by its proximal and distal extre-
mities. 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 metacarpals of those answering to the third and
fourth have coalesced to near their distal extremities,
which diverge more than in the ordinary ruminants,
giving a greater spread to the foot, which is supported by
the ordinary three phalanges of each of those digits. The
last phalanx deviates most from the form of that in the
ordinary ruminants by its smaller proportional size,
rougher surface, and less regular form: it supports, in
fact, a modified claw rather than a hoof. In the femur
the chief deviation from the ordinary ruminant type is
seen in the position of the orifice of the canal for the me-
dullary artery, which, as in the human skeleton, enters
the back part of the middle of the shaft, and inclines
obliquely upwards. The fibula is represented by the
irregularly-shaped ossicle interlocked between the outer
side of the distal end of the tibia and the caleaneum.. The
scaphoid is not confluent with the cuboid as in the normal

SKELETON OF THE CAMEL. hi

ruminant: the rest of the hind-foot deviates in the same
manner and degree from the ordinary ruminant type, as
does the fore-foot.

The camel tribe have no horns; some small deer of
the musk-family are compensated for the want of horns
by very long and sharp upper canine teeth; the rest of
the ruminants, either in the male sex or in both sexes,
are endowed with the weapons of offence and defence,
developed from and supported by the head, called “horns”
and “antlers.” The term “ horn” is technically restricted
to the weapon which is composed of a bony base, covered
by a sheath of true horny matter. Such horns are never
shed; and as, in order to diminish the weight of the head, —
the horn-core is made as hollow as is consistent with
strength, the ruminants with such horns are called hollow-
horned ; the ox, the sheep, and the antelope are examples.
Antlers consist of bone only. During the period of their
growth they are covered by a vascular, short-haired skin
like velvet; but when their growth is completed, this
skin dries and peels off, leaving the antler a solid, naked, ©
and insensible weapon.’ Being deprived, however, of its
vascular support it dies, and, after a certain period of ser-
vice, is undermined by the absorbents and cast off. The
process of growth and decadence of the antlers is re-
peated each year; and in the fallow-deer the antlers pro-
gressively acquire greater size and more branches to the
sixth year, when the animal is in its prime. Good evi-
dence has been obtained that the same law of growth,
shedding, and annual renewal prevailed in the gigantic
fossil deer of Ireland, in which upwards of eighty pounds
of osseous matter must have been developed from the
frontal bones every year in the full-grown animal. The.
ruminants of the deer and elk tribes are those which have

178 SKELETON OF THE HIPPOPOTAMUS.

antlers, or are “solid-horned.” The horns of the giraffe
are peculiar; they are short and simple, are always
covered by a hairy integument, and are never shed.
They relate in position to both the frontal and parietal

bones. _ In all other ruminants, the horns are developed

from the frontals exclusively, although they sometimes,
as in the ox, project from the back part of the cranium;

but the frontals; in such cases, extend to that part. The
_ horn of the rhinoceros consists wholly of fibrous horny
/ matter.

The even-toed hoofed animals that do not ruminate
have no horns. The osteology of this division is here
illustrated in the hippopotamus (Fig. 31). The skeleton,

SKELETON OF THE HIPPOPOTAMUS AMPHIBIUS.

in its strength and massiveness, presents a greater con-
trast with that of the giraffe than the rhinoceros’s skeleton
does with that of the horse; there are, nevertheless, as
will be shown in the concluding summary, more essential
points of resemblance to the giraffe’s skeleton than to

SKULL OF THE HIPPOPOTAMUS. 179

that of the rhinoceros. In points of minor importance,
we find the hippopotamus resembling the rhinoceros; as
e.g. in the shortness and strength of its neck; but it has
only fifteen dorsal, d, and four lumbar, /, vertebrae. The
spines of these vertebrze are shorter and less unequal
than in the ruminants; and they have an almost uniform ,
direction, as in all quadrupeds that do not move by leaps ©
or bounds. The tail is short, and, in the living animal,
compressed, acting lhke a rudder. The bones of the
limbs are short and thick. In the scapula, 51, the acro-
mion is slightly produced, and the coracoid recurved.
The great tuberosity of the humerus, 58, is divided into
two subequal processes. ‘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 holes. In the carpal series of bones, the
trapezium is present, but does not support any digit; the
innermost, answering to the thumb or pollex, therefore,
is the one which is absent; of the remaining four digits,
the two middle ones, answering to the third and fourth,
are most developed. The femur has no third trochanter.
The fibula is distinct from the radius, and extends from
its proximal end to the caleaneum. The entocuneiform
bone is present in the tarsus, but there is no rudiment of
the innermost toe or hallux; the proportions of the other
four toes resemble those on the fore-foot.

The skull is remarkable for the prominence and high
position of the orbits, which allow the eye to be projected
above the surface of the water, and a survey to be made
by the suspicious animal without the exposure of any
other part of the head. The upper jaw is peculiar for
the development of the sockets of the great canine teeth,

180 CHARACTERS OF EVEN-TOED BEASTS.

=

and the lower jaw combines with the like character an
unusual production and curvature of the angle.

With regard to the osteology of the hog tribe, our
_ limits compel us to restrict ourselves to the notice of the
still more singular development of the sockets of the up-
per canines or tusks in the babyroussa, in which those
teeth curve upwards and pierce the skin of the face, like
horns, whence the name “horned hog” sometimes im-
posed upon it. |

If the hoofed animals with the digits in even number
be compared together, in regard to their osteological cha-
racters, they will be found, notwithstanding the difference
of form, proportion, and size presented by the hippopo-
tamus, wild boar, vicugna, and chevrotain, to agree in
the following points, which are the more significative of
natural affinity when contrasted with the skeletons of the
hoofed animals with digits in uneven number. ‘Thus, in
the even-toed or “artiodactyle” ungulates, the dorso-lum-
bar vertebree are the same in number, as a general rule,
in all the species, being nineteen. The rare exceptions
appear to be due to the development, rarely to the sup-
pression, of an accessory vertebra as an individual vari-
ety, the number in such cases not exceeding twenty, or
falling below eighteen, and the supernumerary vertebra
being most usually manifested in the domesticated and
highly-fed breeds of the common hog. The recognition
of this important character appears to have been impeded
by the variable number of movable ribs in different spe-
cies of the artiodactyles, the dorsal vertebrae, which these
ribs characterize, being fifteen in the hippopotamus and
twelve in the camel; and the value of this distinction has
been exaggerated owing to the common conception of
the ribs as special bones, distinct from the vertebrae, and

ar

CHARACTERS OF EVEN-TOED BEASTS. 181

their non-recognition as parts of vertebra equivalent
to the neurapophyses and other autogenous elements.
The discovery of the pleurapophyses under the condition
of rudimental ribs attached to the ends of the lumbar dia-
pophyses, which afterwards become suturally attached or
anchylosed, and the pleurapophysial nature of a part of
the so-called perforated transverse process of the cervical
vertebra, show that the anthropotomical definition of a
dorsal vertebra, as one that supports ribs, is inapplicable
to the mammalia generally, and is essentially incorrect.
It is convenient, in comparative tables of vertebral form-
ulee, to denote the number of those vertebre of the trunk
in which the pleurapophyses remain free and movable, con-
stituting the “ribs” of anthropotomy; but the differences
sometimes occurring in this respect, in individuals of the
same species, have their unimportance manifested when the
true nature of a rib is recognized. The vertebral form-
ulze of the artiodactyle skeletons show that the difference
in the number of the so-called dorsal and lumbar verte-
bree does not affect the number of the entire dorso-lumbar
series: thus, the Indian wild boar has d, 138, 7, 6=19;
z.¢€. 13 dorsal, and 6 lumbar, making a total of 19 trunk-
vertebrae; the domestic hog and the peccari have d, 14,
1,5, = 19; the hippopotamus has d, 15, 7,4, = 19; the gnu
and aurochs have d, 14, J, 5,= 19; the ox, and most of
the true ruminants, have d, 18, J, 6, = 19; the camel and
lamas have d, 12,7, 7,= 19. These facts illustrate the
natural character and true affinities of the artiodactyle
group. They are further shown by the absence of the
third trochanter in the femur, and by the place of perfo-
ration of the medullary artery at the fore and upper part
of the shaft, as in the hippopotamus, the hog, and most
of the ruminants. ‘The fore part of the astragalus is di-
16

182 CHARACTERS OF EVEN-TOED BEASTS.

vided into two equal or subequal facets; the os mag-
num does not exceed, or is less than, the unciforme in
size, in the carpus; and the ectocuneiforme is less, or
not larger, than the cuboid, in the tarsus. The digit
answering to the third in the pentadactyle foot is un-
symmetrical, and forms, with that answering to the
fourth, a symmetrical pair. If the species be horned,
_ the horns form one pair or two pairs; they are never de-
veloped singly and symmetrically 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 in length. The
bony palate extends further back than in the perissodac-
tyles; 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 crowns of the premolars are
smaller and less complex than those of the true molars,
usually representing half of such crown. The last milk-
molar is trilobed.

Tio these osteological and dental characters may be
added some important modifications of internal structure,
as e.g. the complex form of the stomach in the hippopo-
tamus, peccari, and ruminants, the comparatively small
and simple czcum, and the spirally folded colon, which
equally indicate the mutual affinities of the even-toed or
artiodactyle hoofed quadrupeds, and their claims to be
regarded as a natural group of the Ungulata. Many ex-
tinct genera, e.g. cheeropotamus, anthracotherium, hyopo-
tamus, dichodon, merycopotamus, xiphodon, dichobune,
anoplotherium, have been discovered, which once linked
together the now broken series of Artiodactyla, repre-
sented by the existing genera hippopotamus, sus, dico-

— sr OO

THE NATURE OF LIMBS. 188

tyles, camelus, moschus, camelopardalis, cervus, antelope,
ovis, and bos.

As we have now traced both the fore and hind foot to
the five-toed or pentadactyle structure, with the definite
number of joints or phalanges in each toe, characteristic
of the highest class of vertebrate animals, a few remarks
will be offered in illustration of the plan of structure
which prevails in such extremities, and of the law that
governs the departure from the pentadactyle type in the
mammalha.

The essential nature of the limbs is best illustrated by
the fish called protopterus, and by some of the lower
reptiles that retain gills with lungs.

If the segment of the skeleton supporting the rudi-
ments of the fore-limbs in the protopterus (Fig. 82), be

Fig. 82.

PROTOPTERUS.

compared with the modification of the typical vertebra,
exemplified in Fig. 6, p. 28, it will be seen to be con-
structed on the same type. The hzmal arch is most ex-
panded, and it is composed of a pleurapophysis or verte-
bral rib, pl, and a hemapophysis or sternal rib, 2, on
each side; the hemal spine, or sternum, is not here de-
veloped; the long, many-jointed ray, a, answers to the
more simple diverging appendage, a, in Vig. 5.

184 THE NATURE OF LIMBS.

The segment supporting these appendages, or first
rudiments of the fore-limb in the fish, is the occipital
one, or the last vertebra of the skull. The pleurapo-
physis of this segment is the seat of all those modifica-
tions which have earned for it the special name of
“scapula,” 51; the haemapophysis is the seat of those
that have led to its being called “coracoid,” 52.

The corresponding segment of the batrachian amphi-
uma (Fig. 83) yields the next important modification of
these parts. The scapule, pl, 51, are detached from the
occiput, or neutral arch; the coracoids, h, 52, are much
expanded; three segments of the diverging appendage, a,
are ossified, and two of these segments are bifid, showing

Fig. 83. Fig. 34
A Cc
ns
“sv
ae
a
a n 6s &
5
2
Chas CYS 4a <2
ae —
AMPHIUMA. PROTEUS.

the beginning of the radiating multiplication of its parts.
The first segment is the seat of those modifications which
have obtained for it the special name of “humerus,” 58 ;
the two divisions of the next segment of the appendage are
called “ulna,” 58, and “radius,” 54; the remainder of the
limb is called “manus,” or hand; 56 is the gristly carpus,
and the two bony divisions are the digits or fingers, 57.
The segment supporting the hind-lmbs retains most
of its typical character in the subterranean reptile called
the Proteus; one sees, e.g. in Fig. 84, that the centrum
has coalesced with the neurapophyses, n, and neural
spine, vs, forming the neural arch from which the dia-

LAW OF SIMPLIFICATION OF FEET. 185

pophyses, d, are developed: the more expanded hemal
arch consists of the pleurapophyses, p/, and the heemapo-
physes, 2; the former is called the “ilium,” 62, the latter
the “ischium,” 63; and, as the hamapophyses of another
segment are usually added to the scapular arch, when
they receive the name of “clavicles,” so also the hema-
pophyses of a contiguous segment are usually added to
the pelvic arch, when they are called “ pubic bones.”

The pelvic diverging appendage, aa, has advanced to
the same stage of complexity in the proteus, as the scapu-
lar one in the amphiuma; the first ossified segment is
ealled “femur,” 65; the divisions of the next segment
are respectively termed “ tibia,” 66, and “ fibula,” 67 ; the
first set of short bones in the “pes,” or foot, are called
“tarsals,” 68; those of the two toes are called “ meta-
tarsals” and “ phalanges,” 69.

The tarsal bones, from the degree of constancy of their
forms and relative positions, have re-
ceived distinct names. In Fig. 85 of Fig. 35. Fig 36.
the bones of the hind-foot in the horse, jy),
a marks the “astragalus,” cl, the “cal-
caneum,” or heel-bone, the prominent
part of which forms the “hock ;” s is the
‘“scaphoides,” or naviculare, 6, the “cu-
boid,” ce, “ ectocuneiform,” and cm, the
““mesocuneiform.” Now, the ectocunei-
form in all mammaha supports the third
or middle of the five toes when they
are all present, the mesocuneiform sup-
ports the second toe, and the cuboides
the fourth and fifth. We see, therefore,
in the horse, that the very large bone
articulated to the ectocuneiform, ce, is Horse. Ox.

16%

186 LAW OF SIMPLIFICATION OF FEET.

the metatarsal of the third toe, to which are articulated the
three phalanges of the same toe, 777, the last phalanx being
expanded to sustain the hoof. The small bone called
“split-bone,” by veterinarians, articulated to the “ meso-
cuneiform,” is the stunted metatarsal of the second toe, w ;
the outer “splint-bone,” articulated to the “ cuboides,” is
the similarly stunted metatarsal of the fourth toe, 2.

In the foot of the ox (Fig. 36), the cuboides, b, presents
a marked increase of size, equalling the ectocuneiform, cc,
which is proportionally diminished. The single bone,
called “ cannon-bone,” which articulates with both these
carpal bones, does not answer to the single “ cannon-
bone” in the horse, but to the metatarsals of both the
third and the fourth digits; it is accordingly found to
consist of those two distinct bones in the fcetal rumin-
ant, and there are a few species in which that distinction
is retained. Marks of the primitive division are always
perceptible, especially at its lower end, where there
are two distinct joints or condyles, for the phalanges
of the third, 27, and fourth, 7, toes. In the horse, the
rudiments of the two stunted toes were their upper ends
or metatarsal bones; in the ox, they consist of their lower
ends or phalanges; these form the “ spurious hoofs,” and
are parts of the second, 2, and fifth, v, toes (Hig. 36). The
rhinoceros more closely resembles the horse in the bony
structure of its hind-foot (Fig. 87); the ectocuneiform is
still the largest of the three lowest tarsal bones, although
the mesocuneiform, em, and the cuboids, 0, have gained
increased dimensions in accordance with the completely
developed toes which they support; these toes we there-
fore recognize as being answerable to the rudiments of
the second, 7, and fourth, ¢v, in the horse, the principal
toe being still the third, 2. The hippopotamus (Fig. 38)

chiefly differs from the ox, as the rhinoceros differs from

twits Sipe es |

LAW OF SIMPLIFICATION OF FEET. 187

the horse, viz: by manifesting the two toes fully de-
veloped, which were rudimental in the more simple foot;
the cuboides, b, being proportionally extended to support
the fifth toe, v, as well as the fourth, 7; the second toe,
27, articulates, as usual, with a distinct tarsal bone. In
the elephant (Fig. 89), where a fifth digit is added,

RHINOCEROS. HIPPOPOTAMUS. ELEPHANT,

answering to our first or great toe, I, there is also a dis-
tinct carpal bone, called the “ entocuneiform,” cz, and the
tarsus presents, as in other pentadactyle mammals, all the
bones which are seen in the human tarsus, viz: the
astragalus, a, the caleaneum, c, the scaphoides, s, the ento-
cuneiform, c7, the mesocuneiform, cm, the ectocuneiform,
cc, and the cuboides, 0.

The course of the simplification of the pentadactyle
foot or hand is first a diminution and removal of the
innermost digit, 7; next of the outermost, v ; then of the
second, 7; and lastly of the fourth, iv; the third or middle
toe, wi, being the most constant and important of the five
toes. ‘The same law or progress of simplification prevails
in the fore-foot or hand. The thumb is the first to dis-
appear, then the little finger, and the middle finger is the

188 SKELETON OF THE SLOTH.

most constant, and forms the single-hoofed fore-foot of
the horse.

The scapula, 51, in the fore-limb repeats or answers to
the ilium, 62, in the hind-lmb; the coracoid, 52, to the
ischium, 63; the clavicle, 58, to the pubis, 64; the hu-
merus, 53, to the femur, 65; the radius, 55, to the tibia,
66; the ulna, 54, to the fibula, 67; the carpus, 56, repeats
the tarsus, 68; and the metacarpus and phalanges of the
fore-foot repeat the metatarsus and phalanges of the hind-
foot: they are technically called “serial homologues,” or
“homotypes,” and each bone in the carpus can be shown
to have its homotype in the tarsus. (See Archetype of the -
Vertebrate Skeleton,” p. 167.)

SKELETON OF THE SLOTH.

The transition from the quadrupeds with hoofs to those
with claws seems in the present series to be abrupt; but
it was made gradual by a group of animals, now extinct,
which combined hoofs and claws in the same foot. Some
of the outer toes, at least, were stunted and buried ina
thick callosity, for the ordinary purpose of walking,
whilst the other toes were provided with very long and
strong claws for uprooting or tearing off the branches of
trees. These singular beasts were of great bulk, and ap-
pear to have been peculiar to America. As restored by
anatomical science, they have received the names of Me-
gatherium, Megalonyx, Mylodon, &. They were huge ter-
restrial sloths; the present remnants of the family consist
of very few species enabled by their restricted bulk to
climb the trees in quest of their leafy food, and peculiarly
organized for arboreal life. The toes, which were modi-

SKELETON OF THE SLOTH. 189

fied in their huge predecessors to tread the ground, are
reduced to rudiments, or are undeveloped; and those only
areretained which support the claws, now rendered by their
length and curvature admirable instruments for clinging
to the branches. The whole structure of the hind and
fore limbs is modified to give full effect to these instru-
ments as movers and suspenders of the body in the bosky
retreats for which the sloths are destined; and, in the
same degree, the power of the limbs to support and carry
the animal along the bare ground is abrogated. Accord-
ingly, when a sloth is placed on level ground, it presents
the aspect of the most helpless and crippled of creatures.
It is less able to raise its trunk above its limbs than the |
seal, and can only progress by availing itself of some in-
equality in the soil offering a holdfast to its claws, and!
enabling it to drag itself along. But to judge of the
creative dispensations towards such an animal by ob-
servation of it, or reports of its procedure, under these
unnatural circumstances, would be as reasonable as a spe-
culation on the natural powers of a tailor suddenly trans-
ferred from his shopboard to the rigging of a ship under
way, or of a thorough-bred seaman mounted for the first
time on a full-blood horse at Ascot. Rouse the prostrate
sloth, and let it hook on to the lower bough of a tree, and
the comparative agility with which it mounts to the top-
most branches will surprise the spectator. In its native
South American woods its agility is still more remarkable,
when the trees areagitated bya storm. At that time, the
instinct of the sloth teaches it that the migration from tree
to tree will be most facilitated. Swinging to and fro,
back downwards, as is its habitual position, at the end of
a branch just strong enough to support the animal, it
takes advantage of the first branch of the adjoining tree

190 SKELETON OF THE SLOTH.

that may be swayed by the blast within its reach, and
stretching out its fore-limb, it hooks itself on, and at once
transfers itself to what is equivalent to a fresh pasture.
' The story of the sloth voluntarily dropping to the ground,
' and crawling under pressure of starvation to another tree,
is one of the fabulous excrescences of a credulous and
gossiping zoology.
In the sloth, accordingly (Fig. 40), the fore-limbs are
much elongated, and that less at the expense of the hand
than of the arm and forearm. The humerus, 58, is of

Fig. 40.

SKELETON OF THE SLOTH,.

unwonted leneth—is slender and straight; the radius, 55,
and ulna, 54, are of similar proportions—the former
straight, the latter so bent as to leave a wide interosseous

APTITUDES OF THE SLOTH. 191

space. Now, moreover, these bones, instead of being
firmly united as one bone, are so articulated with each
other as to permit a reciprocal rotatory movement, chiefly
performed, however, by the radius; and since to this bone
the carpal segment of the hand is mainly articulated, that
prehensile member can be turned prone or supine, as in
the human arm and hand. Six bones are preserved in
the carpus of three-toed sloth (Bradypus tridactylus), an-
swering to those called “lunare,” “cuneiforme,” “ unci-
forme,” and “pisiforme,” also to the “scaphoides and
trapezium” united, and to the “trapezoides and magnum”
united. The scapho-trapezium is characteristic of the
sloth-tribe, and is found in the extinct as well as existing
species. The articulation of the carpus with the radius,
and with the metacarpus, is such as to turn the palm of
the long hand inwards, and bring its outer edge to the
ground. ‘The three fully-developed metacarpals are con-
fluent at their base, which is also anchylosed to the rudi-
ments of the first and fifth metacarpals; the proximal
confluent with their metacarpals, and those digits appear
therefore to have only two joints. The last phalanx is
remarkably modified for the attachment of the very long
and strong claw.

With regard to the bladebone of the sloth, 51, it is
much broader in proportion to its length than in the swift
cloven-footed herbivores; the spinous process is unusu-
ally short; the acromion is of moderate length, and unex-
panded at its extremity; the supraspinal fossa is the
broadest, and has a perforation instead of the usual “su-
praspinal” notch. There is a short clavicular bone
attached to the acromion, but not attaining to the ster-
num.

192 LIMBS OF THE SLOTH.

The iliac bones, 62, repeat the modifications of their
homotypes the scapule, and are of unusual breadth as
compared with those of other quadrupeds; they soon be-
come anchylosed to the broad sacrum, 8, the ischia, 68,
and pubes, 64, are long and slender, and circumscribe
unusually large “thyroid” and “ischial” foramina, the
latter being completed by the coalescence of the tuberosi-
ties of the ischia with the transverse processes of the last
two sacral vertebre. The head of the femur, 65, has no
impression of a ligamentum teres. The patella, 66’, is
ossified; there is a fabella behind the external condyle.
The tibia, 66, and fibula, 67, are bent in opposite direc-
tions, intercepting a very wide interosseous space. The
anchylosis of their two extremities, which has been found
in older specimens, has not taken place here. The inner
malleolus projects backwards and supports a grooved
process. The outer malleolus projects downwards, and
fits like a pivot into a socket in the astragalus, turning
the sole of the foot inwards—a position like that of the
hand—best adapted for grasping boughs. The caleaneum,
68, is remarkably long and compressed. The scaphoid,
cuboid, and cuneiform bones have become confluent with
each other and the metatarsals, of which the first and fifth
exist only in rudiment. The other three have lkewise
coalesced with the proximal phalanges of the toes which
they support: these toes answer to the second, third, and
fourth, in the human foot.

The short and small head of the sloth is supported on
a long and flexible neck presenting the very unusual cha-
racter in the Mammalian class of nine vertebrae, C—the
superadded two, however, appearing to have been im-
pressed from the dorsal series, D, by their short, pointed,
and usually movable ribs. The head and mouth can

SKULL OF THE SLOTH. 193

be turned round every part of a branch in quest of the \
leafy food by this mechanism of the neck. As the trunk —
is commonly suspended from the limbs with the back
downwards, the muscles destined for the movements of
the back and support of the head are feebly-developed,
and the vertebral processes for their attachment are pro-
portionally short. The spines of the neck-vertebree are
of more equal length than in most mammals—that of the
dentata being little larger than the rest: the spines gra-
dually subside in the posterior dorsals, and become
obsolete in the lumbar vertebree. The first pair of fully-
- developed ribs, marking the beginning of the true “dorsal”
series of vertebra, are anchylosed to the breast-bone
which consists of eight ossicles. In the two-toed sloth,
however, which has twenty-three dorsal vertebra, there
are aS many as seventeen subcubical sternal bones in one
long row, with their angles truncated for the terminal
articulations of the sternal ribs, which are ossified.

The skull of the sloth is chiefly remarkable for the
size, Shape, and connections of the malar bone, which is
freely suspended by its anterior attachment to the maxil-
lary and frontal, and bifurcates behind; one division ex-
tending downwards, outside the lower jaw, the other
ascending above the free termination of the zygomatic
process of the squamosal. The premaxillary bone is
single and edentulous, being represented only by its
palatal portion completing the maxillary arch, but not
sending any processes upwards to the nasals.

The skull in the toothless ant-eater chiefly forms a
long, slender, slightly-bent bony sheath for its still longer
and more slender tongue, the main instrument for ob-
taining its insect food. The mouth in the living animal
is a small orifice at the end of the tubular muzzle, just

17

194 SKELETON OF THE MOLE.

big enough to let the vermiform tongue glide easily in
and out. The fore-limbs are remarkable for the great
size and strength of the claw developed from the middle
digit: this is the instrument by which the ant-eater mainly
effects the breach in the walls of the termite fortresses,
which it habitually besieges in order to prey upon their
inhabitants and constructors. As in the sloths, both fore
and hind feet have an inclination inwards, whereby the
sharp ends of the long claws are prevented from being
worn by that constant application to the ground which
must have resulted from the ordinary position of the foot.
The trunk-vertebree of the ant-eater are chiefly remark-
able for the number of accessory joints by which they
are articulated together. This complex structure is also
met with in the armadillos, in which the anterior zygapo-
physes of the dorsal vertebrze send processes—the meta-
pophyses (Fig. 2, p. 165), m, m—upwards, outwards, and
forwards, which processes, progressively increasing in the
hinder vertebrz, attain, in the lumbar region, a length
equal to that of the spinous processes, ns, and have the
same relation to them, in the support of the osseous cara-
~ pace, as the “tie-bearers” have to the “king-post” in the
architecture of a roof.

SKELETON OF THE MOLE.

The mole is hardly less fitted for the actions of an or-
dinary land-quadruped than the sloth; but the one is as
admirably constructed for subterraneous as the other
for arboreal life. The fore-limbs are remarkably short,
broad, and massive in the mole, as they are long and
slender in the sloth; yet the same osseous elements,

® bey!

SKELETON OF THE MOLE. 195

similarly disposed, occur in the skeleton of each. The
head of the mole is long and cone-shaped; its broad base
joins on the trunk without any outward appearance of a
neck. The forepart of the trunk, to which the principal
muscular masses working the fore-limbs are attached, is

SKELETON OF THE MOLE.

the thickest, and thence the body tapers to the hind-
quarters, which are supported by limbs as slender as they
are short.

The neck-bones, nevertheless, are not wanting; they
even exist in the same number as in the giraffe; the ver-
tebral formula of the mole being—7 cervical, 13 dorsal,
6 lumbar, 5 sacral, and 10 caudal. The spine of the
second vertebra or dentata is large, and extended back
over the third vertebra: the neural arches of this and the
succeeding neck-vertebree form thin simple arches with-
out spines: the entire vertebree have been described as
mere rings of bone; but the transverse processes of the
fourth, fifth, and sixth cervicals are produced forwards
and backwards, and overlap each other: in the seventh
vertebra those processes are reduced to tubercular diapo-
physes which are not perforated: the bodies of the verte-

196 SKELETON OF THE MOLE.

¥

br are depressed and quadrate. The part answering to
the nuchal ligament in the giraffe is bony in the mole, w.

The first sternal bone, or manubrium, is of unusual
length, being much produced forwards, and its under
surface downwards in. the shape of a deep keel for ex-
tending the origin of the pectoral muscles. Seven pairs
of ribs directly join the sternum, which consists of four
bones, in addition to the manubrium and an ossified ensi-
form appendage. ‘The neural spines, which are almost
obsolete in the first eight dorsals, rapidly gain length in
the rest, and are antroverted in the last two dorsal verte-
bree. The diapophyses, being developed in the posterior
dorsals, determine the nature of the longer homologous
processes in the lumbar vertebree.

The lumbar spines are low, but of considerable antero-
posterior extent: the diapophyses are bent forward in the
last four vertebra: a small, detached, wedge-shaped hy-
papophysis is fixed into the lower interspace of the bodies
of the lumbar vertebree.

The scapula, 51, is very long and narrow, but thick,
and almost three-sided: the common rib-shape is resumed
in this cranial pleurapophysis, as we have seen in the
bird and tortoise. The clavicle, on the other hand, in-
stead of the usual long and slender figure, presents the
form of a cube, being very short and broad, articulated
firmly to the anteriorly projecting breast-bone, and more
loosely with the acromion and head of the humerus.

This bone, 53, would be classified amongst the “flat”
bones. It is almost as broad as it is long, especially at
_ its proximal end, which presents two articular surfaces
—one for the scapula, the other for the clavicle: the
expanse of the bone beyond these surfaces relates to the
formation of an adequate extent of attachment for the

SKELETON OF THE MOLE. 197
.

deltoid, pectoral, and other great burrowing muscles.
All the other bones of the fore-limb are as extremely
modified for fossorial actions. The olecranon expands
transversely at its extremity, and the back part of the
ulna is produced into a strong ridge of bone.

The shaft of the radius is divided by a wide inter-
osseous space from the ulna, and the head of the radius
is produced into a hook-shaped process like a second
“olecranon.” ‘The carpal series consists of five bones
in each row—the scaphoid being divided in the first, and
asesamoid being added to the second row; moreover,
there is a large supplementary sickle shaped bone, ex-
tending from the radius to the metacarpal of the pollex,
giving increased breadth and a convex margin to the
radial side of the very powerful hand, and chiefly com-
pleting its adaptation to the act of rapidly displacing the
soil. The phalanges of the fingers are short and very
strong: the last are bifid at their ends for a firmer attach-
ment of the strong claws. Little more of the hand than
these claws, and the digging or scraping edge, projects
beyond the sheath of skin enveloping the other joints,
and connecting the hand with the trunk.

The common position of the arm-bone is with its distal
end most raised. The fore-arm, with the elbow raised, is
in the state between pronation and supination, the radial
side of the hand being downwards, and the palm directed
outwards. The whole limb, in its position and structure,
is unequalled in the vertebrate series as a fossorial instru-
ment, and only paralleled by the corresponding limb in
the mole-cricket (Gryllotalpa) amongst the insect-tribes.

No impediment is offered by the hinder parts of the
body or limbs when the thickest part of the animated
wedge has worked its way through the soil. The pelvis

ae

198 SKELETON OF THE BAT. «
is remarkably narrow. The ossa innominata have coa-
lesced with the sacrum, but not with each other, the
pubic arch remaining open. ‘The bodies of the sacral
vertebra are blended together, and are carinate below;
their neural spines have coalesced to form a high ridge. -
The acetabula look almost directly outwards. The head
of the femur has no pit for a round ligament. A fabella
is preserved behind the outer condyle. A hamular pro-
cess is sent off from the head of the tibia and fibula; the
lower moieties of the shafts of these bones are blended
together. The toes are five in number on the hind-feet as
in the fore, but are much more feebly developed. They
serve to throw back the loose earth detached by the
spade-shaped hands.

SKELETON OF THE BAT.

The form of limb presented by the arm and hand of
the bat, offers the most striking contrast to the burrowing
trowel of the mole. Viewed in the living animal, it is a
thin, widely expanded sheet of membrane, sustained lke
an umbrella by slender rays, and flapped by means of
these up and down in the air, and with such force and
rapidity, as, combined with its extensive surface, to react
upon the rare element more powerfully than gravitation
can attract the weight to which the fore-limbs are attached;
consequently, the body is raised aloft, and borne swiftly
through the air. The mammal now rivals the bird in its
faculty of progressive motion; it flies, and the instru-
ments of its aerial course are called “wings.” The whole
frame of the bat is in harmony with this faculty, but the
mammalian type of skeleton is in nowise departed from.

The vertebral formula of the common bat ( Vespertilio

SKELETON OF THE BAT. 199

£
murinus) (Fig. 42), is: 7 cervical, 12 dorsal, 7 lumbar, 3
sacral, and 8 caudal vertebre. The chief characteristics
of the skeleton are: the gradual diminution of size of the
spinal column from the cervical to the sacral regions; the
absence of neural spines in the vertebree beyond the den-
tata; a keeled sternum; long and strong, bent clavicles,

“iy

SKELETON OF THE BAT (Vespertilio murinus).

58; broad scapule, 51; elongated humeri, 53; more
elongated and slender radius, 55; and still longer and
more slender metacarpals and phalanges of the four fin-
gers, @, wi, iv, v, Which are without claws, the thumb, 7@,
being short, and provided with a claw; the pelvis, 62, is
small, slender, and open at the pubis, 638; the fibula, 67,
is rudimental, like the ulna, 54,in the fore-arm. The
common bat has a long and slender stilliform appendage

200 SKELETON OF THE LION. a
|

to the heel, 68, which helps to sustain the caudo-femoral
membrane. ‘The hind’ digits are five in number, short,
subequal, each provided with a claw; they are the in-
struments by which the bat suspends itself, head down-
wards, during its daily summer sleep, and continued
winter torpor.

SKELETON OF THE CARNIVOROUS
MAMMALIA.

The lion may be regarded as the type of a quadruped.
The well-adjusted proportions of the head, the trunk, the
fore-limbs, and tail concur with their structure to form
an animal swift in course, agile in leaps and bounds, ter-
rible in the overpowering force of the blows inflicted by
the fore-limbs. The strong, sharp, much-curved, retrac-
tile talons, terminating the broad powerful feet, enable
the carnivore to seize the prey it has overtaken, and to
rend the body it has struck down. The jaws have a pro-
portional strength, and are armed with fangs fitted to
pierce, lacerate, and kill.

The carnivorous character of the skull, as exemplified
by the sagittal and occipital crests, by the strength and
expanse of the zygomatic arches, by the breadth, depth,
and shortness of the jaws, by the height of the coronoid
processes, and by the depth and extent of the fossze of the
lower jaw for the attachment of the biting muscles, reaches
its maximum in the hon. The triangular occipital region
is remarkable for the depth and boldness of the sculptur-
ing of its outer surface, indicative of the powerful muscles
working the whole skull upon the neck and trunk. The
conjoined paroccipitals and mastoids form a broad and

SKELETON OF THE LION. 201

od

thick capsular support for the back part of the acoustic
bulle. 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 are comparatively short, and one-half
of the lateral border of the nasals directly articulates with
the maxillaries. The antorbital foramina are largely
indicative of the size of the sensitive nerve supplying
the well-developed whiskers. Within the cranium we
find that ossification has extended into the membrane
dividing the cerebrum from the cerebellum. This bony
tentorium extends above the petrosal to the ridge over-
hanging the Gasserian fossa; the petrosal is short, its,
apex is neither notched nor perforated; the cerebellar
pit is very shallow. The sella-turcica is deep, and well
defined by both the anterior and posterior clinoids. The
rhinencephalic fossa is relatively larger in the lon 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 back-
wards 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.
All the eins of the skeleton are remarkable for their
whiteness and compact structure.

The vertebral formula of the lion (Iig. 48) is—7 cervi-
eal, 18 dorsal, 7 lumbar, 8 sacral, and 23 caudal. The
last cervical vertebra has the transverse processes imper-
forate, being formed only by diapophyses. The eleventh
dorsal is that toward which the spines of the other trunk-
vertebra converge, and indicates the centre of motion of
the trunk in this hounding quadruped. Hight pairs of

202 SKELETON OF THE LION.

ribs directly join the sternum, which consists of eight
bones. The clavicles are reduced to clavicular bones,
58, suspended in the flesh. The supraspinal fossa of
the scapula is less deep than the infraspinal one, and
its border is almost uniformly convex; the acromion is
bifid, the recurved point being little larger than the ex-
tremity or anterior point. The humerus, 53, is perforated

SKELETON OF THE LION (L'elis leo),

above the inner condyle, but not between the condyles.
The radius, 55, and ulna, 54, are so articulated as to
permit a free rotation of the fore-paw. The scaphoid and
lunar bones are connate. Besides these, the bones of the.
carpus are the cuneiforme; the pisiforme; the trapezium,
which gives an articulation to the ulnar side of the base
of the short metacarpus of the pollex; the trapezoides;
the magnum, which is the least of the carpal bones; the
unciforme, which supports, as usual, the metacarpals of

SKELETON OF THE LION. 208

the fourth and fifth digits; and the pisiforme, which pro-
jects far backwards, like a small caleaneum: there is also
a supplementary oscicle wedged in the interspace between
the prominent end of the scapho-lunar bone and _ the
proximal end of the metacarpal of the pollex. The pollex
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.

The pelvis, 62, 68, 64, the femur, 65, the tibia, 66, and
fibula, 67, offer no remarkable modifications of structure;
the patella, 66, is well ossified, and there is a fabella, 67,
behind each condyle of the femur. The tarsal bones are
the astragalus; the scaphoides; the calcaneum; the cu-
boides, which, like the unciforme in the carpus, supports
the two outer digits; the cuneiforme externum, which,
like the magnum, supports the middle digit; the cunei-
forme medium, which, like the trapezoides, supports the
second digit; and the cuneiforme internum, which sup-
ports the rudiment of the metatarsal of the first or inner-
most digit.

The last or ungual phalanx, in both fore and hind feet,
has a bony sheath at its base for the firmer implantation
of the claw; and its joint is at the back part of the proxi-
mal end of the phalanx, whereby it can be drawn upwards
upon the second phalanx, when the claw becomes con-
cealed in the fold of integument forming the interspace
of the digits.

This state of retraction is constantly maintained, except
when overcome by an extending force, by means of elastic
ligaments. The principal one arises from the outer side
and distal extremity of the second phalanx, and is inserted
into the superior angle of the last phalanx; a second arises

204 SKELETON OF THE LION.

from the outer side and proximal end of the second pha-
lanx, and passes obliquely to be inserted at the inner side
of the base of the last phalanx. A third, which arises
from the inner side and proximal extremity of the second
phalanx, is inserted at the same point as the preceding,
The tendon of the flexor profundus perforans is the an-
tagonist of the elastic ligaments. By the action of that
muscle, the last phalanx is drawn forwards and down-
wards, and the claw exposed. In order to produce the
full effect of drawing out the claw, a corresponding action
of the extensor muscle is necessary, to support and fix
the second phalanx; by its ultimate insertion in the ter-
minal phalanx, it serves also to restrain and regulate the
actions of the flexor muscle. As the phalanges of the
hind-foot are retracted in a different direction to those of
the fore-foot, z. e. directly upon, and not by the side of the
second phalanx, the elastic ligaments are differently dis-
posed, but perform the same main office.

It seems scarcely necessary to allude to the final inten-
tion of these beautiful structures, which are, with some
slight modifications, common to the genus Felis. The
claws being thus retracted within folds of the integument,
are preserved constantly sharp, and ready for their des-
tined functions, not being blunted and worn away in the
ordinary progressive motions of the animal; while at the
same time the sole of the foot, being padded, such soft
parts only are brought in contact with the ground as
conduce to the noiseless tread of the stealthy feline tribe.
This highly-developed unguiculate structure, with the
dental system and concomitant modifications of the skull,
complete the predatory character of the typical Carni-
vor.

SKELETON OF THE KANGAROO. 205

SKELETON OF THE KANGAROO.

Australia possesses an indigenous race of herbivorous
mammals, created to enjoy existence on its grassy plains.
But the climate of this fifth continent, as, from its extent,
it has been termed, is subject to droughts of unusual du-
ration; and the parched up grass, ignited by the electric
bolt or other cause, often raises a conflagration of fearful
extent, and leaves a correspondingly wide-spread black-
ened desert. To the antelope, and other ruminants of

Fig. 44.

SKELETON OF THE KANGAROO (J/acropus elegans).

tropical or warmer latitudes, swiftness of limb has been
given, which enables them to migrate to river valleys,
where the vegetation is preserved from the influence of

the dry season. Australia, however, is peculiar for its
18

206 SKELETON OF THE KANGAROO.

scanty supply of perennial streams; the torrents of the
brief periods of rain are reduced to detached pools in the
dry season, and these are parched up in the long droughts,
leaving hundreds of miles of the country devoid of sur-
face water. If, then, the parent herbivore could traverse
the required distance to quench its thirst, or satisfy its
hunger, the tender young would be unable to follow the
dam. A modification of the procreative process has ac-
cordingly been superinduced, which characterizes the
Australian mammals; the young are prematurely brought
forth of embryonic size and helplessness, and are trans-
ferred to a pouch of inverted skin, concealing the udder;
and in this marsupium, as in a well-stored vehicle, they
are easily transferred by the parent to any distance to
which the climatal conditions may compel her to migrate.
The economy of this portable nursery, the requisite ma-
nipulation of the suckling young therein suspended from
the teat, demand a certain prehensile power of the fore-
limbs, a freedom of the digits, with some opposable faculty
‘in them, and the possession of so much sense of touch as
would be impossible were the digit to be incased in a
hoof; the horny matter is accordingly developed only on
the upper surface of the finger-end, and is in the form of
a claw. But the unguiculate pentadactyle extremity—
though a higher grade of structure in the progress of
limbs—is not suited for the exigences of the herbivore,
and would have appeared utterly incompatible with an
existence dependent on grazing in wild pastures, had we
argued from knowledge restricted to the forms and struc-
tures of the hoofed herbivores of the Europzeo-Asiatic,
African, and American continents. How, then, it may
be asked, is this difficulty overcome in the case of a graz-
ing animal, necessarily a marsupial, and consequently an

CONDITIONS OF MARSUPIAL STRUCTURE. 207

unguiculate one? The answer need only be a reference

to Fig. 44; the requisite faculty of migration of the parent
with the tender offspring is gained by transferring the
locomotive power to the hinder pair of limbs extraordi-
narily developed, and aided by a correspondingly power-
_ful tail; the fore-limbs being restricted in their develop-
ment to the size requisite for the marsupial offices and
other accessory uses.

This is the condition or explanation of the seemingly
anomalous form and proportions of the kangaroo—so
strange, indeed, that the experienced naturalists, Banks
and Solander, may well be excused for surmising they
had seen a huge bird when they first caught a glimpse
of the kangaroo in the strange land which they, with
Cook, discovered.

The rapid course of the kangaroo is by a succession of
leaps, in which twenty to thirty yards are cleared at a
bound; the herbivore, instead of a swift courser on four
pretty equally developed hoofed extremities, is, in Aus-
tralia, a leaping animal; and the saltatorial modification
‘of the mammalian skeleton.is here shown in that of one
of the swiftest and most agile of the numerous species of
kangaroo, the Macropus elegans.

In this kangaroo, 13 vertebre are dorsal, 6 are lumbar,
2 are sacral, and 28 are caudal, the first fourteen of which
have hzemapophyses. These elements coalesce at their
distal ends, and form small hemal arches; they overspan
and protect from pressure the great bloodvessels of the
tail, the powerful muscular fasciculi of which derive in-
creased surface of attachment from these hzemal arches.
The pelvis is long; the strong prismatic ilia, 52, and the
ischia, 63; carry out the great flexors and extensors of the

thigh to a distance from their point of insertion—the

208 SKELETON OF THE KANGAROO.

femur, which makes these muscles operate upon that lever
at a most advantageous angle; the trunk, borne along in
the violent leaps, needs to be unusually firmly bound to
the pelvic basis of the chief moving powers. Accord-
ingly, we find a pair of bones, 64’, extending forwards
from the pubic symphysis, 64, along the ventral walls,
giving increased bony origin to the unusually developed
median abdominal muscles attaching the thorax to the
pelvis; and these “marsupial bones,” as they are called,
have accessory functions relating to reproduction in both
sexes of the marsupial quadrupeds. The femur, 65, is
more than twice the length of the humerus; it is propor-
tionally strong, with well-developed great and small
“trochanters,” and a “fabella” behind one or both con-
dyles. The patella is unossified. The fibula, 67, is im-
movably united to the lower half of the tibia. This
bone, 66, is of unusual length and strength, and is firmly
interlocked below with the trochlear astragalus. The
heel-bone sends backwards a long lever-like process for
the favorable insertion of the extensors of the foot. This
member is of very unusual length. The innermost toe,
or hallux, is absent; the second and third toes are ex-
tremely slender, inclosed as far as the ungual phalanx in a
common fold of integument, and reduced to the function
of cleansing the fur. The offices of support and progres-
sion are performed by the two outer toes, 7v and v, and
principally by the fourth, which is enormously developed,
and terminated by a long, strong, three-sided, bayonet-
shaped claw; these two toes are supported, as usual, by
the os cuboides, which is correspondingly large, whilst
the naviculare and the cuneiform bones are proportion-
ally reduced in size. The bones of the fore-limb, though
comparatively diminutive, present all the comp! xities of

SKELETON OF THE QUADRUMANA. 209

structure of the unguiculate limb. The clavicle, 58, con-
nects the acromion with the sternum, and affords a fulerum
to the shoulder-joint. The humerus, articulating below
with a radius and ulna which can rotate on each other,
develops ridges above both inner and outer condyles for
the extended origin:of the muscles of pronation and
supination. The brachial artery pierces the entocondyloid
ridge. The carpal bones, answering to the scaphoid and
lunar in the human wrist, are here confluent. The digits
are five in number, enjoy free, independent movements,
ard are each terminated by a sharp-curved claw.

SKELETON OF THE QUADRUMANA.

The sloth is an exclusively arboreal animal; its diet is
foliage ; it has but to bring its mouth to the leafy food,
and the lips and tongue serve to strip it from the branches.
The extremities, as we have seen, serve mainly to climb
and cling to branches, and occasionally to hook down a
tempting twig within reach of the mouth. There is, how-
ever, another much more extensive and diversified order
of arboreal mammals destined to subsist on the fruits and
other more highly developed products of the vegetable
kingdom than mere leaves. In the monkeys, baboons,
and apes the extremities are endowed with prehensile
faculties of a more perfect and varied character than in
the sloths ; and this additional power is gained by a full
development of the digits in normal number, with free
and independent movements, which in one of them—the
first or innermost—are such as that it can be opposed to
the rest, so that objects of various size can be grasped.
This modification converts afoot into a hand; and, as the

is* |

210 SKELETON OF THE APE TRIBE.

mammals in question have the opposable “thumb” on
both fore and hind limbs, they are called “quadrumana,”

or four-handed. The rest of the limb manifests a corre-
Fig. 46.

SKELETONS OF ORANG (Pithecus satyrus) AND MAN.

STRUCTURE OF THE APE AND MAN. 201

sponding complexity or perfection of structure ; the trunk
is adjusted to accord with the actions of such instruments,
and the brain is developed in proportion with the power
of executing so great a variety of actions and movements
as the four-handed structure gives capacity for.

In the skull of the quadrumana are seen indications of
a concomitant perfection of the outer senses; the orbits
are entire, and directed forwards, with their outlets almost
on the same plane; both eyes can thus be brought to bear
upon the same object. The rest of the face, formed by
the jaws, now begins to bear a smaller proportion to the
progressively expanding cranium. The neck, of mode-
rate length, has its seven vertebree well developed, with
the costal processes large in the fifth and sixth: the dorsal
vertebre, twelve, in the species figured (Pithecus satyrus),
show, by the convergence of their spines towards the ver-
tical one on the ninth, that this is the centre of movement
of the trunk. The lumbar vertebree are four in number;
in the inferior monkeys they are seven, and the anterior
ones are firmly interlocked by well-developed anapophy-
ses and metapophyses. The sacrum is still long and
narrow. ‘The tail, in some of the lower quadrumana, is
of great length, including 30 vertebrz in the red monkey
(Cereopithecus ruber), in which the anterior ones are com-
pleated by having hzmal arches. The clavicles are en-
tire in all quadrumana. The humerus has its tuberosities
and condyloid crests well developed. The radius rotates
freely on the ulna. The wrist has nine bones, owing to
a division of the scaphoid, besides supplementary sesa-
moids adding to the force of some of the muscles of the
hand; the thumb is proportionally shorter in the fore than
in the hind foot. The patella is ossified, and in most
baboons and monkeys there is a fabella behind each con-

212 STRUCTURE OF THE APE AND MAN,

dyle of the femur. The fibula is entire, and articulated
with the tibia at both ends. The tarsus has the same
number and relative position of the bones as in man; but
the heel-bone is shorter, and the whole foot rather more
obliquely articulated upon the leg, the power of grasping
being more cared for than that of supporting the body ;
the innermost toe forms a large and powerful opposable
thumb. i

There is a well-marked gradation in the quadrumanous
series from the ordinary quadrupedal to the more bipedal
type. In the lemurs and South American monkeys, the
anterior thumb is shorter and much less opposable than
the hinder one; in the spider-monkeys it is wanting, and
a compensation seems to be given by the remarkable pre-
hensile faculty of the curved and callous extremity of the
long tail. This member, in the African and Asiatic mon-
keys, is not prehensile, but the thumb of the fore-hand is
opposable. In the true apes, the tail is wanting, 7.¢. it is
reduced to the rudiment called “os coccygis;” but the
fore-arms are unusually developed in certain species, hence
called “long-armed apes.” These can swing themselves
rapidly from bough to bough, traversing wide spaces in
the aerial leap. The orang (Fig. 45) is also remarkable
for the disproportionate length of the arms, but this dif-
ference from man becomes less in the chimpanzees. The
large species called Gorilla, which of all brutes makes the
nearest approach to man, is still strictly “ quadrumanous;”
the great toe, or “hallux,” being a grasping and oppos-
able digit. But the hiatus that divides this highest of the
ape tribe from the lowest of the human species, is more
strikingly and decisively manifested in the skull (Fig. 50).
The common teeth in the male gorilla are developed, as
in the male orang, to proportions emulating the tusks of

STRUCTURE OF THE APE AND MAN. 2138

the tiger; they are, however, weapons of combat and de-
fence in these great apes, which are strictly frugivorous.
Nevertheless, the muscles that have to work jaws so armed
require modifications of the cranium akin to those that
characterize the lion, viz: great interparietal, 7, and occi-
pital, 3, cristae and massive zygomatic arches, ‘The spines
of the cervical vertebre are greatly elongated in relation
to the support of such a skull, the facial part of which
extends so far in advance of the joint between the head
and neck. The chimpanzees, moreover, differ from man
in having thirteen pairs of thoracic movable ribs. The
long and flat iliac bones, 62, the short femora, 65, so arti-
culated with the leg-bones, 66, as to retain habitually a
bent position of the knee, the short calcanea, c, and the
inward inclination of the sole of the foot, all indicate, in
the highest as in the lowest quadrumana, an inaptitude
for the erect position, and a compensating gain of climb-
ing power favorable for a life to be spent in trees.

In the osteological structure of man (Fig. 46), the ver-
tebrate archetype is furthest departed from by reason of
the extreme modifications required to adjust it to the pe-
culiar posture, locomotion, and endless variety of actions
characteristic of the human race.

As there is nothing, short of flight, done by the moving
powers of other animals that serpents cannot do by the
vertebral column alone, so there is no analogous action
or mode of motion that man cannot perform, and mostly
better, by his wonderfully developed limbs. The reports
of the achievements of our athletes, prize wrestlers, prize
pedestrians, funambulists, and the records of the shark-
pursuing and shark-slaying amphibious Polynesians, of
the equestrian people of the Pampas, of the Alpine
chasers of the chamois, and of the scansorial bark-strip-

214 ADAPTATION OF THE HUMAN SKELETON

pers of Aquitaine, concur in testifying to the intensity of
those varied powers, when educed by habit and by skilled
practice. The perfection of almost all modifications of
active and motive structures seems to be attained in the
human frame, but it isa perfection due to especial adapta-
tion of the vertebrate type, with a proportional depart-
ure from its fundamental pattern. Let us see how this
is exemplified in the skeleton of man (Fig. 46), viewing
it from the foundation upwards.

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 we have traced
them through the several gradations (pp. 185, 187, Figs.
80-89), the innermost, 7, is the first to disappear. In man,
it is the seat of excessive development, and receives the
name of “hallux,” or “great toe;” it retains, however, its
characteristic inferior number of phalanges. The tendons
of a powerful muscle, which in the orang and chimpanzee
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
pollicis” is exclusively concentrated.

The arrangement of other muscles, in subordination to
the peculiar development 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 exem-
plifying the lever of the second kind. The strength and
backward production of the heel-bone, c, relate to the
augmentation of the power. The tarsal and metatarsal
bones are coadjusted so as to form arches, both length-
wise and across, and receive the superincumbent weight
from the tibia on the summit of a bony vault, which has
the advantage of a certain elasticity combined with ade-

TO THE ERECT POSTURE. ~ 215

quate strength. In proportion to the trunk, the pelvic
limbs are longer than in any other animal; they even
exceed those of the kangaroo, and are peculiar for the
superior length of the femur, 65, and for the capacity of
this bone to be brought, when the leg is extended, into
the same line with the tibia, 66; the fibula, 67, is a dis-
tinct bone. The inner condyle of the femur is longer
than the outer one, so that the shaft inclines a little out-
wards 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
viscera, and to give increased attachment to the muscles,
especially the “glutei,” which, comparatively small in
other mammals, are in man vastly developed to balance
the trunk upon the legs, and reciprocally to move these
upon the trunk. The great breadth and anterior conca-
vity of the ilium, 62, are characteristic modifications of
this bone in man. The pelvis is more capacious, the
tuberosity of the ischium is less prominent, and the sym-
physis pubis shorter, than in apes. The tail is reduced
to three or four stunted vertebree, anchylosed to form the
bone called “os coccygis.” The five vertebrze which coa-
lesce to form the sacrum, are of unusual breadth, and the
free or “true” vertebra, that rest on the base of the sacral
. wedge, gradually decrease in size to the upper part of the
chest; all the free vertebra, divided into five lumbar,
twelve dorsal, and seven cervical, are so articulated as to
describe three slight and graceful curves, the bend being
forward in the loins, backward in the chest, and forward
again in the neck. A soft elastic cushion, of “interver-

216 MODIFICATIONS OF THE HUMAN SKELETON

tebral” substance, rests between the bodies of the verte-
bree. The distribution and libration of the trunk, with
the superadded weight of the head and arms, are favored
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 forwards when
the balancing action of the muscles ceases, as when the
head nods during sleep in an upright posture.

The framework of the upper extremity shows all the
_ perfections that have been superinduced upon it in the
mammalian series, viz: a complete clavicle, 58, antibra-
chial bones, 54, 55, with rotatory movements as well as
those of flexion and extension, and the five digits, 57,
free and endowed with great extent and variety of move-
ments: of these, the innermost, which is the first to
shrink and disappear in the lower mammalia, is in man
the strongest, and is modified to form an opposable thumb
more powerful and effective than in any of the quadru-
mana. ‘The scapula, 51, presents an expanded surface of
attachment for the muscles which work the arm in its
free socket; the humerus, 53, exceeds in length the bones
of the fore-arm. The carpal bones, 56, are eight in num-
ber, called scaphoides, lunare, cuneiforme, pisiforme, tra-
pezium, trapezoides, magnum, and unciforme: of these
the scaphoid and unciforme are compound bones; 2.e.
they consist each of two of the bones of the type-carpus,
connate.

In the human skull, viewed in relation to the arche-
type, as exemplified in the fish and the crocodile, the fol-

IN RELATION TO THE ARCHETYPE. 217

lowing extreme modifications have been established. In
the occipital segment, the hemal arch is detached and
displaced, as in all vertebrates above fish; its pleurapo-
physis (scapula, 51) has exchanged the long and slender
for the broad and flat form; the hemapophysis (coracoid,
52) is rudimental, and coalesces with 51. The neurapo-
physes (exoccipitals, 2) coalesce with the neural spine
(superoccipital), and next with the centrum (basioccipital).
This afterwards coalesces with the centrum (basisphenoid)
of the parietal segment. With this centrum also the
neurapophyses, called “alisphenoids,” and the centrum of
the frontal vertebra, called “presphenoid,” become anchy-
losed.’ The neural spine (parietal) retains its primitive
distinctness, but is enormously expanded, and is bifid, in
relation to the vast expansion of the brain in man. The
parapophysis (mastoid) becomes confluent with the tym-
panic, petrosal, and squamosal, and with the pleurapo-
physis, called “stylohyal,” of the hzemal (hyoidian) arch.
The hzmapophysis is hgamentous, save at its junction
with the hzemal spine, when it forms the ossicle called
“lesser cornu of the hyoid bone,” the spine itself being
the basihyal or body of the hyoid bone. 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 neurapophyses
(orbitosphenoids) becoming confluent with the centrum
(presphenoid) of the frontal vertebra, and the latter coa-
lescing 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 (ptery-
goid) of the maxillary arch.

The knowledge of the essential nature of such a com-

19

218 MODIFICATIONS OF THE HUMAN SKELETON

pound bone gives a clue to the phenomena of its develop-
ment from so many separate points, which final causes
could never have satisfactorily afforded. As the centrum,
5, becomes confluent with No. 1, a still more complex
whole results, which has accordingly been described as a
single bone, under the name of “os spheno-occipital” in
some anthropotomies. Such a bone has not fewer than
twelve distinct centres of ossification, corresponding with
as many distinct 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, like the parietal bone; but the two halves more fre-
quently coalesce into a single bone, with which the para-
pophysis (postfrontal) is connate. The pleurapophysis of
the heemal arch (tympanic bone) is reduced to its function
in relation to the organ of hearing, and becomes anchy-
losed to the petrosal, the squamosal, and the mastoid.
The hemapophysis is modified to form the dentigerous
lower jaw, but articulates, as in other mammals, with a
diverging appendage (squamosal) of the antecedent hzemal
arch, now interposed between it and its proper pleurapo-
physis; the two hzmapophyses, moreover, become con-
fluent at their distal ends, forming the symphysis mandi-
bulee.

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;” the neurapophyses have been sub-
ject to similar compression, and are reduced to a pair of
vertical plates, which coalesce together, and with parts of
the olfactory capsules (upper and middle turbinals) form-
ing the compound bone called “ zthmoid ;” of which the
neurapophyses (prefrontals) form the “lamina perpendicu-
laris’ in human anatomy. The prefrontals assume this

=

IN RELATION TO THE ARCHETYPE. 219

confluence and concealed position even in some fishes—
xiphias, e. g—and repeat the character in all mammalia
and in most birds; but they become partially exposed in
the ostrich and the batrachia. The spine of the nasal
vertebra (nasal bones) is usually bifid, like those of the
two succeeding segments; but it is much less expanded.
The hzemal, called “maxillary” arch, is formed by the
pleurapophyses (palatines) and by the hsmapophyses
(maxillaries), with which the halves of the bifid haemal
spine (premaxillaries) are partly connate, and become
completely confluent. Hach moiety, or premaxillary, is
reduced to the size required for the lodgement of two ver-
tical incisors: as the canines in man do not exceed the
adjoining teeth in leneth, and the premolars are reduced
to two in number, the alveolar extent of the maxillary is
short, and the whole upper jaw is very slightly promi-
nent. ‘

Of the diverging appendages of the maxillary arch, the
more constant one, called “pterygoid,” 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; it still per-
forms the function assigned to it in lizards and birds,
where it has its typical ray-like figure, of connecting the
maxillary with the tympanic; 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 brdin-case, now attains
its maximum of development, and forms an integral con-
stituent of the cranial parietes, filling up a large cavity
between the neural arches of the occipital and parietal
segments. It coalesces, moreover, with the tympanic,
mastoid, and petrosal, and forms, with the subsequently

220 GENERAL AND SPECIAL TERMS IN OSTEOLOGY.

anchylosed stylohyal, a compound bone called “temporal”
in human anatomy. The key to the complex beginning
of this “cranial” bone is again given by the discovery of
the general pattern on which the skulls of the vertebrate
animals have been constructed. In relation to that pat-
tern, 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, 16. |

The departure from the archetype, which we observe
in the human skull, is most conspicuous in the neural
spines of the three chief segments, which, archetypally,
may be regarded as deformities by excess of growth to
fulfil a particular use, dependent on the maximization of
the brain; the deviation is again marked by arrest of
growth or suppression of parts, as e. g. In certain parapo-
physes, and in the heemal arch of the parietal segment; it
is most frequently exemplified in the coalescence of parts
primarily and archetypally distinct; and it is finally mani-
fested by the dislocation of a part, viz: the heemal arch
of the occipital segment—the diverging rays of which
have become the seat of that marvellous development
which has resulted in the formation of the osseous basis
of the human hand and arm. With the above explana-
tion the structure of the human skull-can be intelligibly
comprehended, and not merely empirically understood,
as through the absolute descriptions penned in reference
to material and utilitarian requirements, and without re-
ference to the great scale of vertebrate structures, of which
man is the summit.

The fruit of a series of comparisons, extended over all
the vertebrate kingdom, being the recognition of the
archetype governing the structure of the vertebrate skele-

GENERAL AND SPECIAL TERMS IN OSTEOLOGY. 221

ton, the expression of such knowledge has necessitated
the use of general terms, such as “vertebra,” for the seg-
ments of the skeleton, “neurapophyses,” for a constant
element of such segment, and the lke “general names”
for other elements. When any of these elements are
modified for special functions, then also a special name
for it becomes a convenience, as when a “pleurapophy-
sis” becomes a jaw or blade-bone, &c., a “diverging ap-
pendage” an arm or a leg. Deep thinking anatomists
have heretofore caught glimpses of these higher, or more
general, relations of the vertebral elements, when much
modified or specialized, as e. g. in the head, and have tried
to give expression to the inchoate notion, as when Spix
called the “maxillary arch” the “arm of the head.” These
glimpses of a great truth were, however, ill received; and
Cuvier alluded to them, with ill-disguised contempt, as
being unintelligible and mystical jargon, in his great work
on Fossil Animals (1825). But the error or obscurity
lay rather in the mode of stating the relationship of cer-
tain bones of the head to those of the trunk, than in the
relationship itself: in the endeavor, e. g. to express the
relation by special instead of general terms. Even in
1845, the learned and liberal-minded editor of Baron Cu-
vier’s last course of lectures, M. de Saint Agy, comment-
ing upon the osteological essays of Spix and Oken,
remarks: “For my part, an ‘upper-jaw’ is an ‘ upper-jaw,’
and an‘arm’is an ‘arm.’ One must not seek to originate
an osteology out of a system of metaphysics.” But a:
jaw is not the less a jaw because it is a “ hamapophysis,”

1 «Pour moi, une m&choire superieure est une mf&choire superieure,
et un bras est un bras, I] ne faut pas chercher 4 faire sortir l’osteologie
dun systéme de metaphysique.”’

19*

ae 2+

222, FACIAL ANGLE.

nor is an arm the less an arm because it is a “ diverging
appendage.” In the same spirit a critic might write:
“Newton calls this earth a ‘planet,’ and the moon a ‘sa-
tellite;’ for me the earth is an earth, and the moon isa
moon. One must not strive to make an ouranology out
of a system of metaphysics.” After the first recognition
of a thing, one may seek to penetrate, and succeed in
knowing, its essential nature, and yet keep within the
bounds of nature. .

In no class of vertebrate animals is the progressive
superiority of the cranium over the face marked by such
distinct stages as in the mammalia. Various methods
of determining these proportions have been proposed;
but the only satisfactory one is by comparing vertical
sections of the skull, as in the series figured in the cuts
47—52.

In the cold-blooded ferocious crocodile (Fig. 47), the

CROCODILE.

cavity 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

ALBATROSS,

PROGRESSIVE EXPANSION OF CRANIUM. 228

propensity to slay and devour: it is the material symbol
of the lowest animal passion.

In the bird (Fig. 48), the brain-case has expanded ver-
tically and laterally, but is confined to the back part of
theskull. In thesmall singing birds, with shorter beaks,
the proportion of the cranial cavity becomes much greater.

DOG.

In the dog (Fig. 49), the brain-case, with more capacity,
begins to advance further forward. In the chimpanzee

CHIMPANZEE.

(Fig. 50), the capacities or area of the cranium and face

are about equal. In man, the cranial area vastly surpasses
that of the face.

294 PROGRESSIVE EXPANSION OF CRANIUM.

A difference in this respect is noticeable between the
savage (Fig. 51) and civilized (Fig. 52) races of mankind;
but it is immaterial as compared with the contrast in this
respect presented by the lowest form of the human head
(Fig. 51) and the highest of the brute species (Fig. 50).

Fig. 51. Fig 562.

AUSTRALIAN. EUROPEAN.

Such as it is, however, 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.

If a line be drawn from the occipital condyle along the
floor of the nostrils, and be intersected by a second touch-
ing 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 intelli-
gence; it is called the facial angle. In the dog, this angle
is 20°; in the great chimpanzee, or gorilla, it is 40°, but
the prominent superorbital ridge occasions some exagge-
ration ; in the Australian it is 85°; in the EKuropean it is
95°. The ancient Greek artists adopted, in their beau
ideal of the beautiful and intellectual, an angle of 100.

CONCLUDING REMARKS. 995

CONCLUDING REMARKS.

A retrospect of the varied forms and proportions of the
skeletons of animals, whether modified for aquatic, aerial,
or terrestrial life, will show that whilst they were per-
fectly and beautifully adapted to the sphere of life and
exigences of the species, they adhered with remarkable
constancy to that general pattern or archetype which was
first manifested on this planet, as Geology teaches, in the
class of fishes, and which has not been departed from even
in the most extremely modified skeleton of the last and
highest form which Creative Wisdom has been pleased to
place upon this earth.

It is no mere transcendental dream, fst true knowledge
and legitimate fruit of inductive Sete that clear in-
sight into the essential nature of each element of the bony
framework, which is acquired by tracing them step by
step, as e. g. from the unbranched pectoral ray of the
lepidésiren to the equally small. and slender. but bifid
pectoral ray of the amphiume, thence to the similar. but
trifid ray of the proteus, and through the progressively
superadded structures and perfections of the limbs in
higher reptiles and in mammals. If the special ho-
mology of each. part of the diverging appendage and its
supporting arch are recognizable from man to the fish,
we cannot close the mind’s eye to the evidences of that
higher law of archetypal conformity on which the very
power of tracing the lower and more special correspond-
ences depend.

Buffon has well remarked, in the Introduction to his
great work on Natural History: “It is only by compar-

226 CONCLUDING REMARKS.

ing that we can judge, and our knowledge turns entirely
on the relations that things bear to those which resemble
them and to those which differ from them; so, if there
were no animals, the nature of man would be far more
incomprehensible than it is.”

And if this be true, as to man’s general nature and
powers, it 1s equally so with regard to his anatomical
structure.

In the same spirit our philosophic poet felt that—

‘Tis the sublime of man,
Our noontide majesty, to know ourselves
Part and proportions of a wondrous whole.’’—CoLERIDGE.

Vertebrated animals of progressively higher grades of
structure have existed at successive periods of time on
this planet, and they were constructed on a common plan
with those that still exist.

Some have concluded, therefore, that the characters of
a species became modified in successive generations, and
that it was transmuted into a higher species; a reptile,
e. g. into a mammal; an ape, into a negro. Let us con-
sider, therefore, the import and value of the osteological
differences between the gorilla—the highest of all apes—
and man, in reference to this “transmutation hypothesis.”
The skeleton of an animal may be modified to a certain
extent by the action of the muscles. By the develop-
ment of the processes, ridges, and crests, the anatomist
judges of the muscular power of the individual to whom
a skeleton under comparison has appertained. A very
striking difference from the form of the human cranium
results from the development of certain crests and ridges
for the attachment of muscles, in the great apes; but
none of the more important differences, on which the

CONCLUDING REMARKS. 227

naturalist relies for the determination of the genus and
species of the orangs and chimpanzees, have such an
origin or dependent relation. The great superorbital
ridge, e. g. against which the facial line rests in Fig. 00,
is not the consequence of muscular action or develop-
ment: it is characteristic of the genus Zroglodytes from
the time of birth; and we have no grounds for believing
it to be a character to be gained or lost through the ope-
rations of external causes, inducing particular habits
through successive generations of a species.

No known cause of change productive of varieties of
mammalian species could operate in altering the size,
shape, or connections of the prominent premaxillary
bones, which so remarkably distinguish the great Troglo-
dytes gorilla from the lowest races of mankind. There is
not, in fact, any other character than that founded upon
the development of bone for the attachment of muscles,
which is known to be subject to change through the
operation and influence of external causes. Nine-tenths
of the differences which have been cited (see the Transac-
tions of the Zoological Society, vol. iii. p. 413), as distin-
guishing the great chimpanzee from the human species,
must stand in contravention of the hypothesis of trans-
mutation and progressive development, until the acceptors
of that hypothesis are enabled to adduce the facts demon-
strative of the conditions of the modifiability of such
characters. Moreover, as the generic forms of the ape
tribe approach the human, type, they are represented by
fewer species. The unity of the human species is demon-
strated by the constancy of those ostenlogical and dental
peculiarities which are seen to be most characteristic of
the bimana in contradistinction from the guadrumana.

Man is the sole species of his genus (iomo)—the sole

228 CONCLUDING REMARKS.

representative of. his order (bimana); he has no nearer
physical relations with the brute kind than those that
belong to the characters which link together the’ unguicu-
late division of the mammalian class.

Of the nature of the creative acts by which the succes-
sive races of animals were called into being, we are igno-
rant. But this we know, that as the evidence of unity
of plan testifies to the oneness of the Creator, so the
modifications of the plan for different modes of existence
illustrate the beneficence of the Designer. Those struc-
tures, moreover, which are at present incomprehensible
as adaptations to a special end, are made comprehensible
ona higher principle, and a final purpose is gained in
relation to human intelligence; for in the instances where
the analogy of humanly invented machines fails to ex-
plain the structure of a divinely created organ, stich
organ does not exist in vain if its truer comprehension,
in relation to the Divine idea, or prime Exemplar, lead
rational beings to a better conception of their own origin
and Creator. :

ON THE PRINCIPAL

FORMS AND STRUCTURES OF THE TEETH.

At the commencement of the 'T'reatise on the Prin-
cipal Forms of the Skeleton, it was stated that “ tooth,”
like “bone,” was the result of the combination of certain
earthy salts with a pre-existing cellular basis of animal
matter. The salts, as shown in a subjoined table, are
nearly the same as those in bone, but enter in a larger
proportion into the composition of tooth, and render it a
harder body. So composed, teeth are peculiar to the
back-boned (vertebrate) animals, and are attached to
parts of the mouth, commonly to the jaws. They pre-
sent many varieties as to number, size, form, structure,
position, and mode of attachment, but are principally
adapted for seizing, tearing, dividing, pounding, or grind-
ing the food. In some species they are modified to serve
as formidable weapons of offence and defence; in others,
as aids in locomotion, means of anchorage, instruments
for uprooting or cutting down trees, or for transport and
working of building materials. They are characteristic
of age and sex; and in man they have secondary rela-
tions subservient to beauty and to speech.

Teeth are always intimately related to the food and

20

230 SUBSTANCE OF TEETH.

habits of the animal, and are, therefore, highly interest-
ing to the physiologist. They form, for the same reason,
important guides to the naturalist in the classification of
; animals; and their value, as zoolo-

ah gical characters, is enhanced by the
facility with which, from their posi-
tion, they can be examined in liy-
ing or recent animals; whilst the
durability of their tissues renders
them not less available to the pale-
onthologist in the determination of
the nature and affinities of extinct
species, of whose organization they
are often the sole remains discove-
rable in the deposits of former

SSE a periods of the earth’s history.
psi ‘GZ A

= ZZ The substance of teeth is not so
LSS: ZA uniform as in bone, but consists

commonly of two or more tissues,
characterized by the proportions
of their earthy and animal consti-
tuents, and by the size, form, and
aS Ze direction of the cavities in the ani-
mal basis which contain the earth,
cine Mi. attain weed) or, the waseulan mana

TOOTH (magnified). }

The tissue which forms the body
of the tooth is called “dentine” (dentinum, Siat.), Fig.
53, 1.

The tissue which forms the outer crust of the tooth is
called the “cement” (cementum, and crusta petrosa, Lat.),
ab. 8.

The third tissue, when present, is situated between the
dentine and cement, and is called “enamel” (encaustum,
or adamas, Lat.), 7b. 4.

ne

KOK SE

Lary

oe

DEFINITION OF DENTAL TISSUES. y45 5

“Dentine” consists of an organized animal basis dis-
posed in the form of extremely minute tubes and cells,
and of earthy particles; these particles have a twofold
arrangement, being either blended with the animal mat-
ter of the interspaces and parietes of the tubes and cells,
or contained in a minutely granular state in their cavities.
The density of the dentine arises principally from the
proportion of earth in the first of these states of combina-
tion. The tubes and cells contain, besides the granular
earth, a colorless fluid, probably transuded “plasma,” or
“liquor sanguinis,” and thus relate not only to the me-
chanical conditions of the tooth, but to the vitality and
nutrition of the dentine.

In hard or true dentine, the tubes called “dentinal
tubes” diverge from the hollow of the tooth, called “ pulp-
cavity,” and proceed with a slightly wavy course at right
angles, or nearly so, to the outer surface. The hard sub-
stance of the tooth is thus arranged in hollow columns,
perpendicular to the plane of pressure, and a certain
elasticity results from their curves: they are upright
where the grinding surface of the crown receives the
appulse of the opposing tooth, and are horizontal where
they have to resist the pressure of contiguous teeth. In
Vig. 54, a highly magnified view is given of a small por-
tion of human dentine, showing the tubuli, in the inter-
tubular substance, with the traces of the primitive cellu-
lar constitution of that substance. For the mode in
which the nucleated cells of the primary basis of the
tooth, called “tooth-pulp,” are converted into dentine,
reference may be made to the author’s “ Odontography”
(Introd., plates 1 and 2). The tubuli, besides fulfilling
the mechanical ends above stated, receive the plasma
transuded from the remains of the vascular pulp, which

232 DEFINITION OF DENTAL TISSUES.

circulates, by anastomosing branches of the tubuli and
by the plasmatic cells of the intertubular substance,
through the dentine, maintaining a sufficient though
languid vitality of the tissue. The delicate nerve-
branches on the pulp’s surface, some minute production

SECTION OF HUMAN TOOTH (highly magnified).

of which may penetrate the tubuli, convey sensations of
impressions affecting the dentine—sensations of which
every one has experienced the acuteness when decay has
affected the dentine, or when mechanical or chemical
stimuli have “set the tooth on edge;” but true “dentine”
has no canals large enough to admit capillary vessels
with the red particles of blood.

The first modification of dentine is that in which capil-
lary tracts of the primitive vascular pulp remain uncal-
cified, and permanently carry red blood into the substance
of the tissue. These so-called “vascular canals” present
various dispositions in the dentine which they modify,
and which modification is called “vaso-dentine.” It is
often combined with true dentine in the same tooth, e. 7.,

'

DEFINITION OF DENTAL TISSUES. 233

in the large incisors of certain rodents, the tusks of the
elephant, the molars of the extinct iguanodon.

A second modification of the fundamental tissue of the
tooth is where the cellular basis is arranged in concen-
tric layers around the vascular canals, and contains
“radiated cells” like those of the osseous tissue; it is
called “osteo-dentine.” The transition from dentine to
vaso-dentine, and from this to osteo-dentine, is gradual,
and the resemblance of osteo-dentine to true bone is very
close.

“Cement” always closely corresponds in texture with
the osseous tissue of the same animal; and wherever it
occurs of sufficient thickness, as,upon the teeth of the
horse, sloth, or ruminant, it is also traversed, like bone,
by vascular canals. In reptiles and mammals, in which
the animal basis of the bones of the skeleton is excavated
by minute radiated cells, these are likewise present, of
similar size and form, in the cement, and are its chief
characteristic as a constituent of the tooth. The relative
density of the dentine and cement varies according to
the proportion of the earthy material, and chiefly of that
part which is combined with the animal matter in the
walls of the cavities, as compared with the size and num-
ber of the cavities themselves. In the complex grinders
of the elephant, the masked boar, and the capybara, the
cement, which forms nearly half the mass of the tooth,
wears down sooner than the dentine.

The “enamel” is the hardest constituent of a tooth,
and consequently the hardest of animal tissues; but it
consists, like the other dental substances, of earthy mat-
ter, arranged by organic forces in an animal matrix,
Here, however, the earth is mainly contained in the
canals of the animal membrane, and in mammals and

20*

234 CHEMICAL COMPOSITION OF TEETH.

reptiles, completely fills those canals, which are compa-
ratively wide, whilst their parietes are of extreme tenuity.

CHEMICAL COMPOSITION OF TEETH.!

MAN. LION. Ox. CROCODILE. | PIKE.

Large teeth
of lowerjaw

Phosphate of lime
with a trace of flu- +| 66.72} 89.82) 60.03) 83.33) 59.57| 81.86) 58.738) 53.69] 53.59) 63.98
até of lime

Carbonate of lime . 8.86] 4.87] 3.00} 2.94) 7.00] 9.33] 7.22) 6.3 6.29) 2.54
Phosphate ofmagnesia| 1.08) 1.34| 4.21) 3.70) 0.99) 1.20} 0.99) 10.22) 9.99) 0.73
Salts ... «4. «| O.83|- 0.88] 0O.77| .0.64) 0.91) 0.93} 0.82) 1.34) 1.49) _0.97
Chondrine ... . .| 27.61] 3.89) 31.57] 9.39] 30.71] 6.66} 31.31] 27.66) 28.15 80.60
Fate. «. « trees... | 70:40). O20) O42 trace}: J0/82), 0:02) -.0:93) O79) O76) Tats

100.00] 100.00/ 100.00] 100.00 100.00|100.00}100.00|100.00}100.00|100.00

The examples are extremely few, and, as far as I know,
are peculiar to the class Pisces, of calcified teeth, which
consist of a single tissue, and this is always a modifica-
tion of dentine. The large pharyngeal teeth of the
wrasse (Labrus) consist of a very hard kind of dentine.

The next stage of complexity is where a portion of the
dentine is modified by vascular canals. Teeth, thus
composed of dentine and vasodentine, are very common
in fishes.

The hard dentine is always external, and holds the
place and performs the office of enamel in the teeth of
higher animals. The grinding teeth of the dugong, and
the conical teeth of the great sperm whale, are examples
of teeth composed of dentine and cement, the latter tissue
forming a thick external layer.

In the teeth of the sloth, and its great extinct conge-

1 Selected from the analytic tables given in the author’s ‘‘Odontogra-
phy,” 4to. vol. i. pp. Ixii., Ixiv. (1840. )

COMPLEX AND COMPOUND TEETH. 235

ner, the megatherium, the hard dentine is reduced to a
thin layer, and the chief bulk of the tooth is made up of
a central body of vaso-dentine, and a thick external crust
of cement. The hard dentine is, of course, the firmest
tissue of a tooth so composed, and forms the crest of the
transverse ridges of the grinding surface, like the enamel
plates in the elephant’s grinder.

The human teeth, and those of the carnivorous mam-
mals, appear at first sight to be composed
of dentine and enamel only; but their
crowns are originally, and their fangs
are always, covered by a thin coat of
cement. ‘There is also commonly a small
central tract of osteo-dentine in old
teeth.

The teeth, called compound or com-
plex, in mammal, differ as regards their
composition from the preceding only by
the different proportion and disposition
of the constituent tissues. Fig. 55 isa
longitudinal section of the incisor of a
horse; d is the dentine, e the enamel, and
c the cement, a layer of which is reflected
into the deep central depression of the
crown; s indicates the colored mass of *2°T!0N OF Horsr’s
tartar and particles of food which fills up nas
the cavity, forming the “mark” of the horse-dealer.

A very complex tooth may be formed out of two tissues
by the way in which these may be interblended, as the
result of an original complex disposition of the constitu-
ents of the dental matrix.

Certain fishes, and a singular family of gigantic extinct

256 COMPLEX AND COMPOUND TEETH.

batrachians, which T have called “ Labyrinthodonts,” ex-
hibit, as the name implies, a remarkable instance of this
kind of complexity. The tooth appears to be of the
simple conical kind, with the exterior surface merely
striated longitudinally; but, on making a transverse sec-
tion, as in Fig. 56, each streak is a fissure into which the
very thin external layer of cement, c, is reflected into the
body of the tooth, following the sinuous wavings of the
lobes of dentine, d, which diverge from the central pulp
cavity, a. The inflected fold of cement, c, runs straight

TRANSVERSE SECTION OF TOOTH OF LABYRINTHODON.

for about half a line, and then becomes wavy, the waves
rapidly increasing in breadth as they recede from the
periphery of the tooth; the first two, three, or four un-
dulations are simple, then their contour itself becomes
broken by smaller or secondary waves; these become
stronger as the fold approaches the centre of the tooth,

1 «Proceedings of the Gevlogical Society,” Jan. 20, 1841, p. 257.

COMPLEX AND COMPOUND TEETH. 23%

when it increases in thickness, and finally terminates by
a slight dilatation or loop close to the pulp-cavity, from
which the free margin of the inflected fold of cement is
separated by an extremely thin layer of dentine. The
number of the inflected converging folds of dentine is
about fifty at the middle of the crown of the tooth, but is
ereater at the base. All the inflected folds of cement, at
the base of the tooth, have the same complicated disposi-
tion with increased extent; but, as they approach their
termination towards the upper part of the tooth, they also
gradually diminish in breadth, and consequently pene-
trate to a less distance into the substance of the tooth.
Hence, in such a section as is delineated (Fig. 56), it will
be observed that some of the convoluted folds, as those
marked cc, extend near to the centre of the tooth; others, as
those marked c’, reach only about half-way to the centre;
and those folds, c’’, which, to use a geological expression,
are “cropping out,” penetrate to a very short distance into
the dentine, and resemble, in their extent and simplicity,
the converging folds of cement in the fangs of the tooth
of the ichthyosaurus.

The disposition of the dentine, d, is still more compli-
cated than that of the cement. It consists of a slender,
central, conical column, excavated, by a conical pulp-
cavity, a, for a certain distance from the base of the tooth;
and this column sends from its circumference, radiating
outwards, a series of vertical plates, which divide into
two, once or twice, before they terminate at the periphery
of the tooth. ach of these diverging and dichotomizing
plates gives off, throughout its course, smaller processes,
which stand at right angles, or nearly so, to the main
plate. They are generally opposite, but sometimes alter-
nate ; many of the secondary plates or processes, which are

2388 COMPLEX AND COMPOUND TEETH.

given off near the centre of the tooth, also divide into two.
before they terminate, as at n; and their contour is seen,
in the transverse section, to partake of all the undulations
of the folds of cement which invest them, and divide the
dentinal plates and processes from each other.

Another kind of complication is produced by an ag-
gregation of many simple teeth into a single mass.

The examples of these truly compound teeth are most
common in the class of fishes; but the illustration here
selected is from the mammalian class. Each tooth of the
Cape ant-eater (Orycteropus), pre-
sents a simple form, is deeply
set in the jaw, but without divid-
ing into fangs; its broad and flat
base is porous, like the section of
a common cane. The canals to
which these pores lead, contain
processes of a vascular pulp, and
are the centres of radiation of as
many independent series of den-
tinal tubules. Each tooth, in fact,
consists of a congeries of long and
slender prismatic denticles of den-
TRANSVERSE sEcTION or Parr tine, Which are cemented together

OF TOOTH OF Orycteropus hy their ossified capsules, the co-

CRED lumnar denticles slightly decreas-
ing in diameter, and occasionally bifurcating as they
approach the grinding surface of the tooth. Fig.57 gives
a magnified view of a portion of the transverse section of
the fourth molar, showing c, the cement; d, the dentine;
and p, the pulp-cavity of the denticles.

In the elephant, the denticles of the compound molars
are in the form of plates, vertical to the grinding surface

COMPLEX AND COMPOUND TEETH. 239

and transverse to the long diameter of the tooth. When
the tooth is bisected vertically and lengthwise, the three
substances, d, dentine, e, enamel, and c¢, cement, are seen
interblended, as in Fig. 58, in which p is the common
pulp-cavity, and 7 one of the roots of this complex tooth.

Such are some of the prominent features of a field of

LONGITUDINAL SECTION OF PART OF GRINDER OF ELEPHANT.

observation which Comparative Anatomy opens out to
our view—such the varied nature, and such the gradation
of complexity of the dental tissues, which, up to December,
1839, continued, notwithstanding successive approxima-
tions to the truth, to be described, in systematic works,
as a “phaneros,” or “a dead part or product, exhaled
from the surface of a formative bulb!”

1 See the Fasciculus of M. de Blainville’s great work, ‘‘ Ostéographie
et Odontographie d’Animaux Vertébrés,” which he submitted to the

240 DENTAL SYSTEM OF FISHES.

DENTAL SYSTEM OF FISHES.

The teeth -of fishés, whether we study them in regard
to their number, form, substance, structure, situation, or
mode of attachment, offer a greater and more striking
series of varieties than do those of any other class of ani-
mals.

As to number, they range from zero to countless quan-

Fig. 59.

SKULL OF THE PIKE, SHOWING THE TEETH.

tities. ‘The lancelet, the ammocete, the sturgeon, the
paddle-fish, and the whole order of lephobranchii, are eden-

Academy of Sciences of the Institute of France on the same day, Decem-
ber 16, 1839, on which I communicated, on the occasion of my election
as corresponding member of that body, my ‘‘ Theory of the development
of dentine by centripetal calcification and conversion of the cells of the
pulp.”

DENTAL SYSTEM OF FISHES. 241

tulous. he myxinoids have a single pointed tooth on
the roof of the mouth, and two serrated dental plates on
the tongue. The tench has a single grinding tooth on
the occiput, opposed to two dentigerous pharyngeal jaws
below. In the lepidosiren, a single maxillary dental plate
is opposed to a single mandibular one, and there are two
small denticles on the nasal bone. In the extinct sharks

with crushing teeth, called ceratodus and tenodus, the jaws
“were armed with four teeth, two above and two below.
In the Aimeere, two mandibular teeth are opposed to four
maxillary teeth. From this low point the number in
different fishes is progressively multiplied, until, in the
pike (Fig. 59), the siluroids, and many other fishes, the
mouth becomes crowded with countless teeth.

With respect to form, it may be premised that, as or-
ganized beings withdraw themselves more and more, in
their ascent in the scale of life, from the influence of the
general polarizing forces,-so their parts progressively de-
viate from geometrical figures; it 1s only, therefore, in the
lowest vertebrated class that we find teeth in the form of
perfect cubes, and of prisms or plates with three sides (as
in myletes), four sides (as in scarus), five or six sides (as in
mylobates, Fig. 60). The cone is the most common form
in fishes; such teeth may be slender, sharp-pointed, and
so minute, numerous, and closely aggregated, as to re-
semble the plush or pile of velvet. These are called
“villiform teeth” (dentes villiformes, Lat.; dents en velours,
Fr.). All the teeth of the perch are of this kind. When
the teeth are equally fine and numerous, but longer, these
are called “ ciliiform” (dentes cilijformes) ; when the teeth
are similar to but rather stronger than these, they are
called “setiform” (dentes setiformes, Lat.; dents en brosse,
V'r.); the teeth in the upper jaw of the pike (Fig. 59) are

21

242 DENTAL SYSTEM OF FISHES.

of this kind. Conical teeth, as close-set and sharp-pointed
as the villiforme teeth, but of larger size, are called “rasp-
teeth” (dentes raduliformes, Lat.; dents en rape, or en cardes,
Fr.); the pike presents such teeth on the back part of the
vomer. The teeth of the sheat-fish (Sclurus glanis) present

JAWS AND TEETH OF THE STING-RAY (J/yliobates).

all the gradations between the villiform and raduliform
types. Setiform teeth are common in the fishes thence
called Cheetodonts; in the genus Citharine they bifurcate
at their free extremities; in the genus Platax they end
there in three diverging points, and the cone here merges
into the long and slender cylinder. Sometimes the cone
is compressed into a slender trenchant blade: and this
may be pointed and recurved, as in the murena; or
barbed, as in trichiurus and some other Scomberoides; or
it may be bent upon itself, like a tenter-hook, as in the
fishes thence called G'ontodonts. In the bonito may be
perceived a progressive thickening of the base of the
conical teeth; and this being combined in other predatory
fishes with increased size and recurved direction, they
then resemble the laniary or canine teeth of carnivorous
quadrupeds, as we see in the large teeth of the pike (Hig.
59), in the lophius, and in certain sharks.

DENTAL SYSTEM OF FISHES. 943

The anterior diverging grappling teeth of the wolf-fish
(Fig. 61), 7, form stronger cones; and by progressive
blunting, flattening, and exparfion of the apex, observ-
able in different fishes, the cone gradually changes to the
thick and short cylinder, such as is seen in the back teeth
of the wolf-fish, m, and in similar grinding and crushing
teeth in other genera, whether the fishes be feeders on
sea-weeds, or on crustaceous and testaceous animals. The
erinding surface of these short cylindrical teeth may be
convex, as in the sheep’s-head fish (Sargus); or flattened,
as in the pharyngeal teeth of the wrasse (Labrus). Some-
times the hemispheric teeth are so numerous, and spread
over so broad a surface, as to resemble a pavement, as in
the pharyngeal bones of the wrasse; or they may be so
small, as well as numerous, as to give a granulated sur-
face to the part of the mouth to which they are attached,
when they are called, in ichthyology, dentes graniforimes.

A progressive increase of the transverse over the ver-
tical diameter may be traced in the molar teeth of differ-
ent fishes, and sometimes in those of the same individual,
as in labrus, until the cylindrical form is exchanged for
that of the depressed plate. Such dental plates (dentes
lamelliformes) may be formed not only circular, but ellip-
tical, oval, semilunar, sigmoid, oblong, or even square,
hexagonal, pentagonal, or triangular; and the grinding
surface may present various and beautiful kinds of sculp-
turing. The broadest and thinnest lamelliform teeth are
those that form the complex grinding tubercle of the
diodon.

In the sharks and rays, the teeth are supported by the
upper and lower jaws, as in most quadrupeds; but many
other fishes have teeth growing from the roof of the
mouth, from the surface of the tongue, from the bony

944 TEETH OF THE WOLF-FISH.

hoops or arches supporting the gills, and some have them
developed from the bone of the nose and the base of the
skull. In the carp and tench the teeth are confined to
this latter unusual position, and to a pair of bones, called
“nharyngeal,” which circumscribe the back outlet of the
mouth. | P

Fishes exhibit, moreover, a greater range of variety in
the mode of attachment of the teeth than any other class
of animals. In the sharks, and the singular fish called
the “angler,” the teeth are movable, their base being tied
by ligaments to the jaw. In the angler the ligaments are
so inserted that they do not permit the teeth to be bent
outwards beyond the vertical position, but yield to pres-
sure in the contrary direction, by which the point of the
tooth may be directed towards the back of the mouth;
the instant, however, that the pressure is remitted, the
tooth returns through the elasticity of the bent ligaments,
as by the action of a spring, to its usual erect position;
the deglutition of the prey of this voracious fish is thus
facilitated, and its escape prevented. The broad and
generally bifurcate bony base of the teeth of sharks is
attached by ligaments to the semi-ossified crust of the
cartilaginous jaws; but they have no power of erecting
or depressing the teeth at will.

The teeth of the sphyreena are examples of the ordinary
implantation in sockets, with the addition of a slight an-
chylosis of the base of the fully-formed tooth with the
alveolar walls; and the compressed rostral teeth of the
saw-fish are deeply implanted in sockets; the hind
margin of their base is grooved, and a corresponding
ridge from the back part of the socket fits into the groove,
and gives additional fixation to the tooth.

The singular and powerfully developed dental system

TEETH OF THE WOLF-FISH. 245

of the wolf-fish (Anarrhicas lupus, Fig. 61) has been a sub-
ject of interest to many anatomists. Most of the teeth
are powerful crushers; some present the laniary type,
with the apices more or less recurved and blunted by use,
and consist of strong cones, spread abroad, like grappling-
hooks, at the anterior part of the mouth, 2, 2.

The premaxillary teeth, 22,2, are all conical, and ar-
ranged in two rows; there are two, three, or four in the
exterior row, at the mesial half of the bone, which are the
largest; and from six to eight smaller teeth are irregu-
larly arranged behind. ‘There are three large, strong,
diverging laniaries at the anterior end of each premandi-
bular bone, and immediately behind these an irregular ,
number of shorter and smaller conical teeth, which gra-
dually exchange this form for that of large obtuse tuber-
cles, m,m; these extend backwards, in a double alternate
series, along a great part of the alveolar border of the
bone, and are terminated by two or three smaller teeth
in a single row, the last of which again presents the coni-
cal form. Each palatine bone, 20, supports a double row
of teeth, the outer ones being conical and straight, and
from four to six in number; the inner ones two, three, or
four in number, and tuberculate. The lower surface of
the vomer, 13, is covered by a double irregularly alter-
nate series of the same kind of large tuberculate crushing
teeth as those at the middle of the premandibular bone.
Thus the inside of the mouth appears to be paved with
teeth, by means of which the wolf-fish can break in pieces
the shells of whelks and lobsters, and effectually disen-
gage the nutritious animal parts from them. All the
teeth are anchylosed to more or less developed alveolar
eminences of bones. From the enormous power of the
muscles of the jaws, and the strength of the shells which

rp lag

Fig. 61.

246 TEETH OF THE WOLF-FISH.

are cracked and crushed by the teeth, their fracture and

displacement must obviously be no unfrequent occur- ©

rence; and most specimens of the jaws of the wolf-fish
exhibit some of the teeth either separated at this line of
imperfect anchylosis, or, more rarely, detached by frac-
ture of the supporting osseous alveolar process.

Thus, with reference to the main and fundamental tis-
sue of tooth, we find not fewer than six leading modifica-
tions in fishes.

TEETH OF THE WOLF-FISH (Anarrhicas),

TISSUE OF TOOTH IN FISHES. 247

Hard or true dentine—Sparoids, labroids, lophius,
_balistes, pycnodonts, prionodon, sphyrzena, megalichthys,
rhizodes, diodon, scarus;

Osteodentine—Cestracion, acrodus, lepidosiren, cteno-
dus, hybodus, percoids, sciznoids, cottoids, gobioids,
sharks, and many others;

Vasodentine—Psammodus, chimeeroids, pristis, mylio-
bates ;

Plicidentine—Lophius, holoptychius, bothriolepis; and

Dendrodentine—Dendrodus ;

Besides the compound teeth of the scarus and diodon.

One structural modification may prevail in some teeth,
another in other teeth, of the same fish; and two or more
modifications may be present in the same tooth, arising
from changes in the process of calcification and a persist-
ency of portions or processes of the primitive vascular
pulp or matrix of the dentine.
~ The dense covering of the beak-like jaws of the parrot-
fishes (Scarz) consists of a stratum of prismatic denticles,
standing almost vertically to the external surface of the
jaw bone; this peculiar armature of the jaws is adapted
to the habits and exigences of a tribe of fishes which
browse upon the lithophytes that clothe, as with a richly
tinted carpet, the bottom of the sea, just as the ruminant
quadrupeds crop the herbage of the dry land.

The irritable bodies of the gelatinous polypes, which
constitute the food of these fishes, retreat, when touched,
into their star-shaped stony shells, and the scar? conse-
quently require a dental apparatus strong enough to
break off or scoop out these calcareous recesses. The
jaws are, therefore, prominent, short, and stout, and the
exposed portions of the premaxillaries and premandibu-
lars are incased by a complicated dental covering. The

=

948 TEETH OF THE BARRACUDA FISH.

polypes and their cells are reduced toa pulp by the action
of the pharyngeal jaws and teeth that close the posterior
aperture of the mouth.

There is a close analogy between the dental mass of
the scarus and the complicated grinders of the elephant,
both in form, structure, and in the reproduction of the
component denticles in horizontal succession. But in the
fish, the complexity of the triturating surface is greater
than in the mammal, since, from the mode in which the
wedge-shaped denticles of the scarus are implanted upon,
and anchylosed to, the processes of the supporting bone,
this likewise enters into the formation of the grinding
surface when the tooth is worn down to a certain point.

The proof of the efficacy of the complex masticatory
apparatus above described, is afforded by the contents of
the alimentary canal of the scari. Mr. Charles Darwin,
the accomplished naturalist and geologist, who accompa-
nied Captain Fitzroy, R. N., in the circumnavigatory
voyage of the Beagle, dissected several parrot-fishes
soon after they were caught, and found the intestines
laden with nearly pure chalk, such being the nature of
their excrements; whence he ranks these fishes among
the geological agents to which is assigned the office of
converting the skeletons of the lithophytes into chalk.

The most formidable dentition exhibited in the order of
osseous fishes is that which characterizes the sphyreena,
and some extinct fishes allied to this predatory genus.
In the great barracuda of the southern shores of the
United States (Sphyrena barracuda, Cuy.), the lower-jaw
contains a single row of large, compressed, conical, sharp-
pointed, and sharp-edged teeth, resembling the blades of
lancets, but stronger at the base; the two anterior of
these teeth are twice as long as the rest, but the posterior

TEETH OF THE BARRACUDA FISH. 249

and serial teeth gradually increase in size towards the
back part of the jaw; there are about twenty-four of these
piercing and cutting teeth in each premandibular bone.
They are opposed to a double row of similar teeth in the
upper-jaw, and fit into the interspace of these two rows
when the mouth is closed. The outermost row is situated
on the intermaxillary, the innermost on the palatine
bones; there are no teeth on the vomer or superior max-
illary bones. The two anterior teeth in each premax-
illary bone equal the opposite pair in the lower-jaw in
size; the posterior teeth are serial, numerous, and of small
size; the second of the two anterior large premaxillary
teeth is placed on the inner side of the commencement of
the row of small teeth, and is a little inclined backwards.
The retaining power of all the large anterior teeth is in-
creased by a slight posterior projection, similar to the barb
of a fish-hook, but smaller. The palatine bones contain
each nine or ten lancet-shaped teeth, somewhat larger
than the posterior ones of the lower-jaw. All these teeth
afford good examples of the mode of attachment by im-
plantation in sockets, which has been denied to exist in
fishes.

The loss or injury to which these destructive weapons
are liable, in the conflict which the sphyreena wages with
its living and struggling prey, is repaired by an uninter-
rupted succession of new pulps and teeth. The existence
of these is indicated by the foramina, which are situated
immediately posterior to, or on the inner margin of, the
sockets.of the teeth in place; these foramina lead to alveoli
of reserve, in which the crowns of the new teeth in dif-
ferent stages of development are loosely imbedded. It is
in this position of the germs of the teeth that the sphyree-
noid fishes, both recent and fossil, mainly differ, as to their

250 DENTAL REPRODUCTION IN FISHES.

dental characters, from the rest of the scomberoid family,
and proportionally approach the sauroid type.

In all fishes the teeth are shed and renewed, not once
only, as in mammals, but frequently during the whole
course of their lives. The maxillary dental plates of
lepidosiren, the cylindrical dental masses of the chimeeroid
and edaphodont fishes, and the rostral teeth of the saw-
fish (if these modified dermal spines may be so called) are,
perhaps, the sole examples of “permanent teeth” to be
met with in the whole class. In the great majority of
fishes, the germs of the new teeth are developed like those
of the old, from the free surface of the buccal membrane
throughout the entire period of succession; a circumstance
peculiar to the present class. The angler, the pike, and
most of our common fishes, illustrate this mode of dental
reproduction; it is very conspicuous in the cartilaginous
fishes (Fig. 60, e. g.), in which the whole phalanx of their
numerous teeth is ever marching slowly forwards in rota-
tory progress over the alveolar border of the jaw, the
teeth being successively cast off as they reach the outer
margin, and new teeth rising from the mucous membrane
behind the rear rank of the phalanx.

This endless succession and decadence of the teeth, to-
gether with the vast number in which they often coexist
in the same fish, illustrate the law of “vegetative or irre-
lative repetition,” as it manifests itself on the first intro-
duction of new organs in the animal kingdom, under
which light we must view the above-described organized
and calcified preparatory instruments of digestion in the
lowest class of the vertebrate series.

DENTAL SYSTEM OF REPTILES. 254

DENTAL SYSTEM OF REPTILES.

Tn the class reptilia an entire order (Chelonia), including
the tortoises, terrapenes, and turtles, are devoid of teeth;
but the jaws in these edentulous reptiles are covered by a
sheath of horn, which in some species is of considerable
thickness and density ; its working surface is trenchant in
the carnivorous species, but is variously sculptured and
adapted for both cutting and bruising in the vegetable
feeders. No species of toad possesses teeth; neither have
the jaws the compensatory covering above described in
the chelonians. Frogs have teeth in the upper but not
in the lower jaw. Newts and salamanders have teeth in
both jaws, and also upon the palate; and teeth are found
in the latter situation as well as on the jaws in most ser-
pents and in the iguana lizard. In most other lizards and
in crocodiles, the teeth are confined to the jaws: in the
former they are cemented or anchylosed to the jaw; in
the latter they are implanted in sockets.

The existing lizards exhibit many modifications in the
form of the teeth, according to the nature of the food.
They are pointed with sharp cutting edges in the great
carnivorous monitor (Varanus), and are obtuse and
rounded like paving-stones in the herbivorous or mixed
feeding scinks, called, on account of the shape of the
teeth, cyelodus. The gigantic extinct lizards showed
similar modifications of their teeth. The megalosaurus
had teeth which combined the properties of the knife,
the sabre, and the saw (Fig. 62). When first protruded
above the gum, the apex of the tooth presented a double
cutting edge of serrated enamel; its position and line of

252 DENTAL SYSTEM OF REPTILES.

action were nearly vertical, and its form, like that of the

TOOTH OF THE MEGALO-
-SAURUS.

two-edged sword, cutting equally on
each side. As the tooth advanced in
growth, it became curved backwards
in the form of a pruning-knife, and
the edge of serrated enamel was con-
tinued downwards to the base of the
concave and cutting side of the tooth;
whilst on the other side a similar
edge descended but a short distance
from the point, and the convex part
of the tooth became blunt and thick,
as the back of a knife is made thick
for the purpose of producing strength.
In a tooth thus formed for cutting
along its concave edge, each move-
ment of the jaw combined the power
of the knife and the saw. The back-
ward curvature of the full-grown

teeth enables them to retain, like barbs, the prey which

they had penetrated.

In the iguanodon—the gigantic contemporary of the

megalosaurus—the ‘crown of
the teeth (Fig. 63) wassoshaped

eT AT fon i
(I{(/ Canna

JT |

NEW-FORMED AND WORN TEETH OF

THE IGUANODON.

A =
!
Salle
=
eS

that, after. the -apex became
worn down, it presented a
broad and nearly horizontal
surface, exposing dental sub-
stances of four different de-
erees of density, viz: a ridge
of enamel along the outer bor-
der of the crown; a layer of
hard or unvascular dentine

DENTAL SYSTEM OF REPTILES. 2583

next to this; a layer of softer vascular dentine forming
the inner half of the crown; and a portion of firm osteo-
dentine in the middle of the grinding surface, formed by |
the ossified remnant of the tooth-pulp. The series of
complex teeth, so constructed, seems to have been admi-
rably adapted to the cropping and comminution of such
tough vegetable food as the clathrarie and similar now
extinct plants, the fossil remains of which are found
buried with those of the iguanodon. No existing reptile
now presents so complicated a structure of the tooth in
relation to vegetable food. The. still more complex, and
indeed marvellous structure of the teeth of the extinct
gigantic lizard-like toad, called ZLabyrinthodon, has been
already noticed (Fig. 56, p. 236). But, perhaps, the most
singular dental structure yet found in the ancient mem-
bers of the class Reptilia, is that presented by certain
species of fossil found in South Africa, and probably
from a geological formation nearly as old as our coal
strata. I have called them “Dicynodonts,” from their
dentition being reduced to one long and large canine
tooth on each side of the upper jaw. As these teeth give,
at first sight, a character to the jaws like that which the
long poison-fangs give, when erected, to the jaws of the
rattlesnake, I shall briefly notice their characters before
entering upon the description of the more normal saurian
dentition.

Fig. 64 gives a reduced side view of the skull and
teeth of the Dicynodon lacerticeps.

The maxillary bone, 21, is excavated by a wide and
deep alveolus, with a circular area of half an inch, and
lodges a long and strong, slightly curved, and sharp-
pointed canine tooth or tusk, which projects about two-
thirds of its length from the open extremity of the socket.

22

254 TEETH OF DICYNODON.

The direction of the tusks is forwards, downwards, and
very slightly inwards; the two converging in the descent

SKULL AND TUSKS OF Dicynodon lacerticeps.

along the outer side of the compressed symphysis of the
lower. jaw, cc. The tusk is principally composed of a
body of compact unvascular dentine. The base is exca-
vated by a wide conical pulp-cavity, p, with the apex
extending to about one-half of the implanted part of the
tusk, and a linear continuation extending along the centre
of the solid part of the tusk.

Until the discovery of the rhynchosaurus, this edentu-
lous and horn-sheathed condition of the jaws was supposed
to be peculiar to the chelonian order among reptiles; and
it is not one of the least interesting features of the dicy-
nodonts of the African sandstones, that they should repeat
a chelonian character hitherto peculiar amongst lacertians,
to the above-cited remarkable extinct edentulous genus
of the new red sandstone of Shropshire; but our interest
rises almost to astonishment when, in a saurian skull, we
find, superadded to the horn-clad mandibles of the tor-
toise, a pair of tusks, borrowed, as it were, from the mam-
malian class, or rather foreshadowing a structure which,

TEETH OF GROCODILES. 255

in the existing creation, is peculiar to certain members of
the highest organized warm-blooded animals.

In the other reptilia, recent or extinct, which most
nearly approach the mammalia in the structure of their
teeth, the difference characteristic of the inferior and
cold-blooded class is manifested in the shape, and in the
system of shedding and succession of the teeth; the base
of the implanted teeth seldom becomes consolidated,
never contracted to a point, as in the fangs of the simple
teeth of mammalia, and at all periods of growth one or
more genus of teeth are formed within or near the base
of the tooth in use, prepared to succeed it, and progressing
towards its displacement. The dental armature of the
jaws is kept in serviceable order by uninterrupted change
and succession; but the forming organ of the individual
tooth is soon exhausted, and the life of the tooth itself
may be said to be comparatively short.

If one of the conical, sharp-pointed, and two-edged
teeth of the Gangetic crocodile, called “garrhial,” by the
Hindoos, be extracted, its base will be found hollow, and

Fig. 65.

TOOTH, WITH GERMS OF SUCCESSORS, OF THE GARRAIAL ((avialis gangeticus).

256 TEETH OF POISONOUS SNAKES.

partly absorbed or eaten away, as at a, Fig. 65; and
within the cavity will be seen the half-formed succeeding
tooth, b; at the base of which may probably be found the
beginning or germ, ¢, of the successor of that tooth; all
the teeth in the crocodile tribe being pushed out and re-
placed in the vertical direction by new teeth, as long as
they live. The individual teeth increase in size as the
animal grows; but the number of teeth remains the same
from the period when the crocodile quits the egg to the
attainment of its full size and age. No sooner has the
young tooth penetrated the interior of the old one, than
another germ begins to be developed from the angle be-
tween the base of the young tooth and the inner alveolar
process, or in the same relative position as that in which
its immediate predecessor began to rise; and the processes
of succession and displacement are carried on, uninter-
ruptedly, throughout the long life of these cold-blooded
carnivorous reptiles. The fossil jaws of the extinct
crocodiles demonstrate that the same law regulated the
succession of the teeth at the ancient epochs when they
prevailed in greatest numbers, and under the most varied
specific modifications, as at the present day, when they
are reduced to a single family.

The most complex condition of the dental system in
the reptile class is that which is presented by the poison-
ous serpents, in which certain teeth are associated with
the tube or duct of a poison bag and gland.

These teeth, called “ poison-fangs,” are confined to those
bones of the upper jaw called “maxillary,” and are
usually single; or, when more, one only is connected
with the poison-apparatus, and the others are either
simple teeth, or preparing to take the place of the poi-
son-fang. |

TEETH OF POISONOUS SNAKES. 257

To give an idea of the structure of this
tooth, we may suppose a simple slender
tooth, like that of a boa-constrictor, to be
flattened, and its edges then bent towards
each other and soldered together so as to
form a tube, open at both ends, and inclosing
the end of the poison-duct. Such a tooth is
represented at Fig. 66, where A is the oblique
opening penetrated by the duct, and v the
narrower fissure by which the venom escapes.

The duct which conveys the poison, al-
though it runs through the centre of the porson-rana
tooth, is really on the outside of the tooth. °F R4TTLE-
~The bending of the dentine about it begins mec ee
a little beyond the base of the tooth, where
the poison-duct rests in a slight groove or longitudinal
indentation on the convex side of the fang; as it pro-
ceeds, it sinks deeper into the substance
of the tooth, and the sides of the groove Fig. 67.
meet and seem to coalesce, so that the :
trace of the inflected fold ceases, in some
species, to be perceptible to the naked
eye; and the fang appears, as it 1s com-
monly described, to be perforated by
the duct of the poison-gland.

In the viper, the line of union may
be seen as marked at v, Fig. 66; and
when such a tooth is carefully divided
lengthwise, as in Fig. 67, the true pulp-
cavity in the substance of the tooth is
seen, as at p, p, to terminate in a point;
and the poison-canal, as at #, v, tO TUN — ggorton oF A POISON-
along the forepart of the singularly FaNc—rartrEsNake,

22%

258 DENTAL SYSTEM OF MAMMALIA.

modified tooth. This tooth is soldered to the maxillary |

bone (Fig. 68), which rotates so as to keep the tooth laid
flat in the mouth at ordinary times, and to erect it when
the deadly blow is about to be
struck. The head of the snake

widely open mouth, are struck,
by the force of the powerful
muscles of the head and neck,

SKULL OF A RATTLESNAKE

(Crotalus horridus). into the surface aimed at, the ©

is raised, drawn back, and the —
fangs, erect, and exposed by the ©

poison-bags at the same mo- —
ment are squeezed, and their contents driven through the |
canal in the tooth into the wound. And here may be |
noticed the advantage of having the solid point of the |
tooth prolonged beyond the outlet of the poison-canal, ~

and not weakened by its continuation to the apex.

DENTAL SYSTEM OF MAMMALS.

The class Mammalia, like those of Reptilia and Pisces,
includes a few genera and species that are devoid of
teeth; the true ant-eaters (myrmecophaga), the scaly ant-
eaters or pangolins (mans), and the spiny monotrematous
ant-eater (echidna), are examples of strictly edentulous
mammals. The ornithorhynchus has horny teeth, and
the whales (balena and baleneptera) have transitory em-
bryonic calcified teeth, succeeded by whalebone substi-
tutes in the upper jaw.

‘The female narwhal seems to be edentulous, but Lies
the germs of two.tusks in the substance of the upper
jaw-bones; one of these becomes developed into a large

DENTAL SYSTEM OF MAMMALIA. 259

and conspicuous weapon in the male narwhal, whence the
name of its genus, of monodon, meaning single tooth. In
another cetacean, the great bottle-nose or hyperoodon, the
teeth are reduced in the adult to two in number, whence
the specific name ZH. bidens, but they are confined to the
lower jaw. ;

The elephant has never more than one entire molar, or
parts of two, in use on each side of the upper and lower
jaws; to which are added two tusks, more or less de-
veloped, in the upper jaw.

Some rodents, as the Australian water-rats (Hydromys),
have two grinders on each side of both jaws; which,
added to the four cutting-teeth in front, make twelve in
all; the common number of teeth in this order is twenty,
but the hares and rabbits have twenty-eight each.

The sloth has eighteen teeth. The number of teeth, |
thirty-two, which characterizes man, the apes of the old
world, and the true ruminants, is the average one of the
class mammalia; but the typical number is forty-four.

The examples of excessive number of teeth are pre-
sented in the order Bruta, by the priodont armadillo,
which has ninety-eight teeth; and in the cetaceous order
by the cachalot, which has upwards of sixty teeth, though
most of them are confined to the lower jaw; by the com-
mon porpoise, which has between eighty and ninety teeth;
by the Gangetic dolphin, which has one hundred and
twenty teeth; and by the true dolphins (de/phinus), which
have from one hundred to one hundred and ninety teeth,
yielding the maximum number in the class Mammalia. |

Form.— W here the teeth are in excessive number, as
in the species above cited, they are small, equal, or sub-
equal, and usually of a simple conical form.

In most other mammalia, particular teeth havé special

260 CHARACTERS OF MAMMALIAN TEETH.

forms for special uses: thus, the front teeth, from being
commonly adapted to effect the first coarse division of
the food, have been called cutters or incisors; and the
back teeth, which complete its comminution, grinders or
molars; large conical teeth situated behind the incisors,
and adapted by being nearer the insertion of the biting
muscles to act with greater force, are called holders,
tearers, laniaries, or, more commonly, canine teeth, from
being well developed in the dog and other carnivora.

Molar teeth, which are adapted for mastication, have
either tuberculate, or transversely ridged, or flat summits,
and usually are either surrounded by a ridge of enamel,
or are traversed by similar ridges arranged in various
patterns.

The large molars of the capybara and elephant have
the crown cleft into a numerous series of compressed
transverse plates, cemented together side by side.

The teeth of the mammalia have usually so much more
definite and complex a form than those of fishes and rep-
tiles, that three parts are recognized in them, viz: the
“fang,” the “neck,” and the “crown.” The fang or root
(radix) is the inserted part; the crown (corona) the ex-
posed part; and the constriction which divides these is
is called the neck (cervix).

FIXATION.—It is peculiar to the class mammalia to
have teeth implanted in sockets by two or more fangs;
but this can only happen to teeth of limited growth, and
generally characterizes the molars and premolars; perpe-
tually growing teeth require the base to be kept simple
and widely excavated for the persistent pulp. In no
mammiferous animal does anchylosis of the tooth with the
jaw constitute a normal mode of attachment. Each tooth
has its particular socket, to which it firmly adheres by

CHARACTERS OF MAMMALIAN TEETH. 261

the close coadaptation of their opposed surfaces, and by
the firm adhesion of the alveolar periosteum to the orga-
nized cement which invests the fang or fangs of the tooth.

True teeth implanted in sockets are confined, in the
mammalian class, to the maxillary, premaxillary, and
mandibular, or lower maxillary bones, and form a single
row ineach. They may project only from the premaxil-
lary bones, as in the narwhal, or only from the lower
maxillary bone, as in ziphius; or be apparent only in the
lower maxillary bone, as in the cachalot; or be limited to
the superior and inferior maxillaries, and not present in
the premaxillaries, as in the true peccora (cow, sheep),
and most bruta (sloth, armadillo) of Linnzeus. In general,
teeth are situated in all the bones above mentioned. In
man, where the premaxillaries early coalesce with the
maxillary bones, where the jaws are very short, and the
crowns of the teeth are of equal length, there is no vacant
space in the dental series of either jaw, and the teeth de-
rive some additional fixity by their close apposition and

mutual pressure. No inferior mammal now presents this |

character; but its importance,.as associated with the
peculiar attributes of the human organization, has been
somewhat diminished by the discovery of a like contigu-
ous arrangement of the teeth in the jaws of a few extinct
quadrupeds, e. g. anoplotherium, nesodon, and dichodon.

STRUCTURE.—The teeth of the mammalha usually con-
sist of hard unvascular dentine, defended at the crown by
an investment of enamel, and everywhere surrounded by
a coat of cement. The coronal cement is of extreme
tenuity in man, quadrumana, and the terrestrial carnivora;
it is thicker in the herbivora, especially in the complex
grinders of the elephant. Vertical folds of enamel and
cement penetrate the crown of the tooth in the ruminants,

262 DEVELOPMENT OF MAMMALIAN TEETH.

and in most rodents and pachyderms, characterizing by —
their varions forms the genera of the last two orders.

The teeth of the sloths, armadillos, and sperm-whales
have no true enamel. The tusks of the narwhal, walrus,
and elephant consist of modified dentine, which in the
last great proboscidian animal is properly called “ivory,”
and is covered by cement.

The forming-organ of a mammalian tooth consists, as
in the lower classes, of a pulp and a capsule. The sub-
stance of the pulp is converted into the “dentine;” that
of the capsule into the “cement.” Where enamel is to
be added, a peculiar organ is formed on the inner surface
of the capsule, which arranges the hardening material
into the form, and of the density, characteristic of enamel.
This substance is so hard in the tooth of the hippopota-
mus, as to “strike fire” like flint with steel. The whole
forming-organ is called “matrix.”

The matrix of certain teeth does not give rise during
any period of their formation to the germ of a second
tooth, destined to succeed the first; this tooth, therefore,
when completed and worn down, is not replaced. The
sperm whales, dolphins, and porpoises are limited to this
simple provision of teeth. In the armadillos and sloths,
the want of germinative power, as it may be called, in
the matrix is compensated by the persistence of the ma-
trix, and by the uninterrupted growth of the teeth.

In most other mammalia, the matrix of the first de-
véloped tooth gives origin to the germ of a second tooth,
which sometimes displaces the first, sornetimes takes its
place by the side of the tooth from which it has originated.
All those teeth which are displaced by their progeny are
called temporary, deciduous, or milk teeth; the mode and
direction in which they are displaced and succeeded, viz:

DEVELOPMENT OF MAMMALIAN TEETH. 2683

from above downwards in the upper, from below upwards
in the lower jaw: in both jaws vertically—are the same
as in the crocodile; but the process is never repeated more
than once in any mammiferous animal. A considerable
proportion of the dental series is thus changed; the
second or permanent teeth having a size and form as
suitable to the jaws of the adult as the displaced tempo-
rary teeth were adapted to those of the young animal.

The permanent teeth, which assume places not previ-
ously occupied by deciduous ones, are always the most
posterior in their position, and generally the most com-
plex in their form.

The term “molar,” or “true molar,” is restricted to
these teeth; the teeth between them and the canines are
called “premolars;” they push out the milk-teeth that
precede them, and are usually of smaller size and simpler
form than the true molars. They are called “bicuspids”
in human anatomy.

JAWS AND TEETH OF THE LION.

Thus the class mammalia, in regard to the times of
formation and the succession of their teeth, have been

264 TEETH OF CARNIVORA.

divided into two groups: the monophyodonts,' or those.
that generate a single set of teeth; and the diphyodonts,
or those that generate two sets of teeth.

I proceed next to notice the principal modifications of
the teeth, as they are adapted to carnivorous, herbivorous,
or mixed feeding habits in the diphyodont mammalia.

The lion may be taken as the type of the flesh-feeders
(Fig. 69).

The largest and most conspicuous teeth in this and
other feline quadrupeds are the “canines,” c; they are of
ereat strength, deeply implanted in the jaw, with the fang
thicker and longer than the enamelled crown: this part
is conical, shghtly recurved, sharp-pointed, convex in
front, almost flat on the inner side, and with a sharp
edge behind. The lower canines pass in front of the
upper ones when the mouth is closed.

- The incisors, six in number on both jaws, form a trans-
verse row; the outermost above, 7, is the largest, resem-
bling a small canine: the intermediate ones have broad
and thick crowns indented by a transverse cleft.

The first upper premolar, » 2, is rudimental: there is
no answerable tooth in the lower jaw. The second, p 3,
in both jaws has a strong conical crown supported on two
fangs. The third upper tooth, p4, has a cutting or
trenchant crown, divided into three lobes, the last being
the largest, and with a flat inner side, against which the
cutting tooth, m1, in the lower jaw works, like a scissor-
blade. Behind, and on the inner side of the upper tooth,
pA, there is a small tubercular tooth, m1. A glance at
the long and strong, sub-compressed, trenchant, and
sharp-pointed canines, suffices to appreciate their pecu-

! 26vog, Once: uw, I generate ; odcve, tooth.
2 Se, twice; puw and odous.

TEETH OF CARNIVORA. 265

liar adaptation to seize, to hold, to pierce and lacerate a
struggling prey. The jaws are strong, but shorter than
in other carnivora, and with a concomitant reduction in
the number of the teeth: thus, the canines are brought
~ nearer to the insertion of the very powerful biting mus-
cles (called “temporal” and ‘“ masseter”), which work
them with proportionally greater force. The use of the
small pincer-shaped incisor teeth is to gnaw the soft
eristly ends of the bones, and to tear and scrape off the
tendinous attachments of the muscles and the periosteum.
The compressed trenchant blades of the sectorial teeth
play vertically upon each other’s sides, likes the blades
of scissors, serving to cut and coarsely divide the flesh;
and the form,of the joint of the lower jaw almost re-
stricts its movement to the vertical direction, up and
down. The wide and deep zygomatic arches, and the
high crests of bonesupon the skull, concur in completing
the carnivorous physiognomy of this most formidable of
the feline tribe.

The dentition of the hyena assumes those character-
istics which adapt it for the peculiar food and habits of
the adult. The main modification is the great size and
strength of the molars as compared with the canines,
and more especially the thick and strong conical crowns
of the second and third premolars in both jaws, the base
of the cone bein& belted by a strong ridge which defends
the subjacent gum. This form of tooth is especially
adapted for gnawing and breaking bones, and the whole
cranium has its shape modified which work the jaws and
teeth in this operation.

The strength of the hyena’s jaw is such that, in attack-
ing a dog, he begins by biting off his leg at a single
snap. Adapted, however, to obtain its food from the

23

266 TEETH OF CARNIVORA.

coarser parts of animals which are left by the nobler
beasts of prey, the hyena chiefly seeks the dead carcass,
and bears the same relation to the lion which the vulture
does to the eagle. The hyena cracks, crushes, and de-
vours the bones as well as the softer parts of the animals
it preys upon. In consequence of the quantity of bones
which enter into its food, the excrements consist of solid
balls of a yellowish-white color, and of a compact
earthy fracture. Such specimens of the substance, known
in the old “ Materia Medica” by the name of “album
greecum,” were discovered by Dr. Buckland in the cele-
brated ossiferous cavern at Kirkdale. They were recog-
nized at first sight by the keeper of a menagerie, to
whom they were shown, as resembling both in form and
appearance the feces of the spotted hyena; and, being
analyzed by Dr. Wollaston, were found to be composed
of the ingredients that might be expected in fecal matter
derived from bones—viz., phosphate of lime, carbonate
of lime, and a very small proportion of the triple phos-
phate of ammonia and magnesia. This discovery of the
coprolites of the hyena formed, perhaps, the strongest of
the links in that chain of evidence by which Dr. Buck-
land proved that the cave at
Kirkdale, in Yorkshire, had
been, during a long succes-
sion of yéars, inhabited as
a den by hyenas, and that
they dragged into its recess-
es the other animal bodies,
whose remains, splintered,
and bearing marks of teeth
of the hyena, were found
mixed indiscriminately with
their own.

SKULL AND TEETH OF THE MORSE.

TEETH OF THE PORCUPINE. 267

Before quitting the carnivorous order, the peculiar
development of the upper canines of the morse or walrus
deserve to be noticed. The staple food of this large mo-
dified seal is shell-fish, crustaceans, and sea-weed, which
are pounded to a pulp by its small obtuse molar teeth.
The canines (Fig. 70), c, exist only in the upper jaw,
where they are imbedded in deep and large prominent
sockets, whence they sweep down, slightly incurved,
forming large and long tusks, which serve as weapons of
attack and defence, and as instruments in aid of climbing
the floes and hummocks of ice, amongst which the walrus
passes its existence.

In the order of mammalia, called gnawers or rodents,
some of which, e. g. the rat, are mixed feeders, but most
of them herbivorous, the canine teeth are wanting in
both jaws, and the incisors, reduced to two in number,
are the seat of that excessive and uninterrupted growth,
which makes them allied to tusks.

These incisors (Fig. 71), 7, are curved, the upper pair

SKULL AND TEETH OF A PORCUPINE.

describing a larger part of a smaller circle, the lower
ones a smaller part of a larger circle, the latter being the

268 TEETH OF THE PORCUPINE.

longest, and usually having their sockets extending from
the fore to the back part of the under jaw. The tooth
consists of a body of compact dentine, with a plate of
enamel laid upon its anterior or convex surface, and the
enamel commonly consists of two layers, of which the
anterior and external one is the densest. Thus the sub-
stances of the incisor diminish in hardness from the front
to the back part of the tooth. The wear and tear from
the reciprocal action of the upper and lower incisors pro-
duce, accordingly, an oblique surface, sloping from a
sharp anterior margin formed by the denser enamel, like
that which, in a chisel, slopes from the sharp edge formed
by the plate of hard steel laid on the back of that tool,
whence these teeth have been called “ chisel-teeth” (dentes
scalprarti). Their growth never ceases while the animal
lives, and the implanted part retains the form and size of
the exposed part, and ends behind in a widely open or
hollow base, which contains a long, conical, persistent —
forming pulp. This law of unlimited growth is uncon-
ditional, and constant exercise and abrasion are required
to maintain the normal form and serviceable proportions
of the scalpriform teeth of the rodents. When, by acci-
dent, an opposing incisor is lost, or when, by the distorted
union of a broken jaw, the lower incisors no longer meet
the upper ones, as sometimes happens to a wounded hare
or rabbit, the incisors continue to grow until they pro-
| ject, like the tusks of the elephant, and the extremities,
/in the poor animal’s attempts to acquire food, also become
_ pointed like tusks. Following the curve prescribed to
| their growth by the form of their socket, their points
often return against some part of the head, are passed
_ through the skin, cause absorption of the bone, and per-
' haps again enter the mouth, rendering mastication im-

TEETH OF THE RODENT MAMMALIA. 269

practicable, and causing death by starvation. In the |
Museum of the College of Surgeons there is a lower jaw
of a beaver, in which the scalpriform incisor has, by un-
checked growth, described a complete circle; the point |
has pierced the masseter muscle, entered the back of the/
mouth, and terminated close to the bottom of the socket;
containing its own hollow root. |

The difference in the diet of the rodent quadrupeds has
been alluded to; there is a corresponding difference in the
mode of implantation of their molar teeth. Those which
subsist on mixed food, and which, like the rats, betray a
tendency to carnivorous habits, or which subsist, like
squirrels, on the softer and more nutritious vegetable sub-
stances, as the kernels of nuts, suffer less rapid abrasion
of the grinding teeth; a less depth of crown is, therefore,
needed to perform the office of mastication during the
brief period of life allotted to these active little mammals;
and, as the economy of nature is manifested in the smallest
particulars as well as in her grandest operations, no more
dental substance is developed after the crown is formed
than is requisite for the firm fixation of the tooth in the
jaw.

The rodents that exclusively subsist on vegetable sub-
stances, especially of the coarser and less nutritious kinds,
as herbage, foliage, and the bark and wood of trees, wear
away more wepialy the grinding surface of the molar
teeth; the crowns are, therefore, larger, and their growth
er atiahes by a reproduction of the formative matrix at
their base in proportion as its calcified constituents, form-
ing+the working part of the tooth, are worn away. So
long as this reproductive force is active, the molar tooth
is implanted, like the incisor, by a long, undivided con-
tinuation of the crown. ‘These rootless and perpetually

93%

AO

*

270 TEETH OF THE RODENT MAMMALIA.

srowing molars are always more ‘or less curved, for they
derive from this form the same advantage as the incisors,
in the relief of the delicate tissues of the active vascular
matrix from the effects of the pressure which would other-
wise have been transmitted more directly from the grind-
ing surface; the capybara, and the Patagonian hare
(Dolichotis), afford good examples of this more complex
condition of the grinding teeth.

The variety in the pattern of the folds of enamel that
penetrate the substance of the tooth, and add to its tritu-
rating power, is almost endless; but the folds have always
a tendency to a transverse direction across the crown of
the tooth in the rodents. This direction relates to the
shape of the joint of the lower jaw, which almost restricts
it to horizontal movements to and fro, during the act of
-mastication. In the true hoofed herbivorous animals, in
which the joint of the lower jaw allows a free rotatory
“movement, the folds of enamel take other forms and
directions, with modifications, constant in each genus, and
characteristic of such.

The horse is here selected as an example of such her-
bivorous dentition (Fig. 72). The grinding teeth are six
in number, on each side of both upper and lower jaws,
with thick square crowns of great length, and deeply im-
planted in the sockets, those of the upper jaw being
slizhtly curved. When the summits or exposed ends of
these teeth begin to be worn down by mastication, the
interblended enamel, dentine, and cement show the pat-
tern figured in Cut 72; it is penetrated from within by a
valley, entering obliquely from behind forwards, and
dividing into or crossed by the two crescentic valleys,
which soon become insulated. There is a large lobe at

the end of the valley. The outer surface of the crown is

TEETH OF THE HORSE. OTA

impressed by two deep longitudinal channels. In the lower
jaw the teeth are narrower transversely than in the upper
jaw, and are divided externally into two convex lobes, by
a median longitudinal fissure; internally they present
three principal unequal convex ridges, and an anterior
and posterior narrower ridge. All the valleys, fissures,

GRINDING SURFACES OF THE UPPER AND LOWER MOLARS OF A HORSE.

and folds in both upper and lower grinders are lined by
enamel, which also coats the whole exterior surface of the
crown. Of the series of six teeth in each jaw, the first
three, p 2, 3, 4, are premolars, the rest, m 1, 2, 8, are true
molars. —

The canines are small in the horse, and are rudimental
in the mare; the unworn crown is remarkable for the
folding in of the anterior and posterior margins of enamel.
The upper canine is situated in the middle of the long
interspace between the incisors and molars; the lower
canine is close to the outer incisor, but is distinguished by
its more pointed form. The incisors are six in number
in both jaws; they are arranged close together in a curve,

272 DEVELOPMENT OF TEETH IN THE HORSE.

#t the end of the jaw; the crown is broad, and the contour
of the biting surface, before it is much worn, approaches
an ellipse. The incisors of the horse are distinguished
from those of ruminants by their greater length and cur-
vature, and from those of all other animals by the fold of
enamel (Fig. 55), a, which penetrates the crown from its
flat summit, like the inverted finger of a glove. When
the tooth begins to be worn, the fold becomes an island
of enamel, inclosing a cavity partly filled by cement, and
partly by the substances of the food, and is called the
“mark.” In aged horses, the incisors are worn down
below the extent of the fold, and the “mark” disappears.
This cavity is usually obliterated in the first or mid in-
cisors at the sixth year, in the second incisors at the
seventh year, and in the third or outer incisors at the
eighth year, in the lower jaw. The mark remains some-
what longer in the incisors of the upper jaw.

The following is the average course of development
and succession of the teeth in the horse (Hquus caballus):
The summits of the first functional deciduous molar, d, 2,
“first grinder” of veterinary authors, are usually appa-
rent at birth; the succeeding grinder, d 3, sometimes
arises a day or two later, sometimes together with the
first. Their appearance is speedily followed by that of
the first deciduous incisor—“ centre nipper” of veterina-
rians—which usually cuts the gum between the third and
sixth days. The second deciduous incisor appears be-
tween the twentieth and fortieth days, and about this
time the rudimental grinder, p 1, comes into place, and
the last deciduous molar, d 4, begins to cut the gum;
about the sixth month the inferior lateral, or third inci-
sors, with the deciduous canine, make their appearance.
' The minute canine is shed about the time that the con-

TEETH OF THE ELEPHANT. 273

tiguous incisor is in place, and is not retained beyond »
the first year. The upper deciduous canine is shed in
the course of the second year. The first true molar, m 1,
appears between the eleventh and thirteenth months.
The second molar follows before the twentieth month,
The first functional premolar, p 2, displaces the deci-
duous molar, d 2, at from two years to two years
and a half old. The first permanent incisor protrudes
from the gum at between two years and a half and three
years. At the same period, the penultimate premolar, p
8, pushes out the penultimate milk molar, d 3, and
the penultimate true molar comes into place. The last
premolar displaces the last deciduous molar at between
three years and a half and four years; the appearance
above the gum of the last true molar, m 3, is usually
somewhat earlier. ‘The second incisor pushes out its
deciduous predecessor about the same period. The per-
manent canine, or “tusk,” next follows; its appearance
indicates the age of four years, but it sometimes comes
earlier. The third, or outer incisor, pushes out the deci-
duous incisor about the fifth year, but is seldom in full
place before the horse is five and a half years old. Upon
the rising of the third permanent incisor, or “corner
nipper” of the veterinarians, the “colt” becomes a “horse,”
and the “filly,” a “mare,” in the language of the horse-
dealers. After the disappearance of the “mark” in the
incisors, at the eighth or ninth year the horse becomes
“aged.” .

The most complex condition of teeth adapted to a
vegetable diet is that presented by the elephant. The
dentition of the genus Hlephas includes two long tusks
(Hig. 78), one in each of the intermaxillary bones, and large
and complex molars (7d.), m 8, 4, and 5, in both jaws; of

274 TEETH OF THE ELEPHANT.

the latter there is never more than one wholly, or two
partially, in place and use on each side at any given time,

MY ANY ai) ft VAS \
i] \\ Lo | wey i Va ( VSS
= lip (i; 3 Mh
p /) /
ait
fi }

SECTION OF SKULL AND TEETH OF ELEPHANT.

for the series is continually in progress of formation and
destruction, of shedding and replacement; and all the
grinders succeed one another, like true molars, horizon-
tally, from behind forward. |

The total number of teeth developed in the elephant
2—2,_ ¢—T

m

0—0 T—7
incisors being preceded by two small deciduous ones, and
the number of molar teeth which follow one another on
each side of both jaws being seven, or at least six, of

appears to be 7

=32, the two large permanent

TEETH OF THE ELEPHANT. $35

which the last three may, by analogy, be regarded as
answering to the true molars of other pachyderms.

The incisors not only surpass other teeth in size, as
belonging to a quadruped so enormous, but they are the
largest of all teeth in proportion to the size of the body;
representing, in a natural state, those monstrous tusks of)
the rodents, which are the result of accidental suppres-.
sion of the wearing force of the opposite teeth.

The tusks of the elephant consist chiefly of that modi-
fication of dentine that is called “ivory,” and which shows,
on transverse fractures or sections, strize proceeding in
the are of a circle from the centre to the circumference,
in opposite directions, and forming by their decussations
curvilinear lozenges. This character is peculiar to the
tusks of the proboscydian pachyderms.

In the Indian elephant, the tusks are always short and
straight in the female, and less deeply implanted than in
the male; she thus retaining, as usual, more of the cha-
racters of the immature state. In the male, they have
been known to acquire a length of nine feet, with a basal .
diameter of eight inches, and to weigh one hundred and
fifty pounds; but these dimensions are rare in the Asiatic
species.

A mammoth’s tusk has been dredged up off Dungeness
which measured? e28ven’ feet in length.’ In several of
the instances of mammoth’s tusks from British strata, the
ivory has been so little altered as to be fit for the pur-
poses of manufacture; and the tusks of the mammoth,
which are still better preserved in the frozen drifts of
Siberia, have long been collected in great numbers as
articles of commerce. In the account of the mammoth’s

1 Owen’s ‘‘ History of British Fossil Mammalia,” 8vo. 1844, p. 244.

276 TEETH OF THE ELEPHANT.

bones and teeth of Siberia, published in the Philosophical
Transactions for 1787, No. 446, tusks are cited which
weighed two hundred pounds each, and “are used as
ivory to make combs, boxes, and such other things, being
but little more brittle, and easily turning yellow by wea-
ther and heat.” From that time to the present there has
been no intermission in the supply of ivory, furnished by
the tusks of the extinct elephants of a former world.

The musket-balls and other foreign bodies which are
occasionally found in ivory, are immediately surrounded
by osteo-dentine in greater or less quantity. It has often
been a matter of wonder how such bodies should become
completely imbedded in the substance of the tusk, some-
times without any visible aperture, or how leaden bullets
may have become lodged in the solid centre of a very
large tusk without having been flattened. The explana-
tion is as follows: a musket-ball, aimed at the head of
an elephant, may penetrate the thin bony socket and the
thinner ivory parietes of the wide conical pulp-cavity
_ occupying the inserted base of the tusk; if the projectile
force be there spent, the ball will gravitate to the opposite
and lower side of the pulp-cavity, as indicated in Fig. 78.
The presence of the foreign body exciting inflammation
of the pulp, an irregular course of calcification ensues,
which results in the deposition around the ball of a cer-
tain thickness of osteo-dentine. The pulp then resuming
its healthy state and functions, coats the surface of the
osteo-dentine inclosing the ball, together with the rest of
the conical cavity into which that mass projects, with
layers of normal ivory.

The portions of the cement-forming capsule surround-
ing the base of the tusk, and the part of the pulp, which
were perforated by the ball in its passage, are soon re-

TEETH OF THE ELEPUANT. 277

placed by the active reparative power of these highly
vascular bodies. The hole formed by the ball in the base
of the tusk is then more or less completely filled up by
a thick coat of cement from without, and of osteo-dentine
from within.

By the continued progress of growth, the ball so in-
closed is carried forwards, in the course indicated by the
arrow in Fig. 78, to the middle of the solidified exserted
part of the tusk. Should the ball have penetrated the
base of the tusk of a young elephant, it may be carried
forwards by the uninterrupted growth and wear of the
tusk, until that base has become the apex, and be finally
exposed and discharged by the continual abrasion to
which the apex of the tusk is subjected.

I had the tusk and pulp of the great elephant at the
Zoological Gardens longitudinally divided, soon after the
death of that animal in the summer of 1847. Although
the pulp could be easily detached from the inner surface
of the pulp-cavity, it was not without a certain resistance;
and when the edges of the coadapted pulp and tooth were |
examined by a strong lens, the filamentary processes from
the outer surface of the pulp could be seen stretching as
they were withdrawn from the dentinal tubes before they
broke. They are so minute that, to the naked eye, the
detached surface of the pulp seems to be entire, and Cu-
vier was thus deceived in concluding that there was no
organic connection between the pulp and the ivory.

The molar teeth of the elephant are remarkable for
their great size, even in relation to the bulk of the ani-
mal, and for the extreme complexity of their structure.
The crown, of which a great proportion is buried in the
socket, and very little more than the grinding surface
appears above the gum, is deeply divided into a number

24

278 TEETH OF THE ELEPHANT.

of transverse perpendicular plates, consisting each of a
body of dentine, coated by a layer of enamel, e, and this
again by the less dense bone-like substance, c, which fills
the interspaces of the enamelled plates, and here more
especially merits the name of “cement,” since it binds
together the several divisions of the crown before they
are fully formed and united by the confluence of their
bases into a common body of dentine. As the growth
of each plate begins at the summit, they remain detached,
and like so many separate teeth or denticules, until their
base is completed, when it becomes blended with the bases
of contiguous plates to form the common body of the
crown of the complex tooth, from which the roots are
next developed.

| I I! il
leg

iis

African. Asiatic. Elephas primigentus.

MOLAR TEETH OF ELEPHANTS AND THE SIBERIAN MAMMOTH.

TEETH OF THE ELEPHANT. 279

The plates of the molar teeth of the Siberian mammoth
(Elephas primigenius), (Fig. 74), are thinner in proportion
to their breadth, and are generally a little expanded at
the middle; and they are more numerous in proportion
to the size of the crown than in the existing species of
Asiatic elephant (7b.). In the African elephant (vd.), on
the other hand, the lamellar divisions of the crown are
fewer and thicker, and they expand more uniformly from
the margins to the centre, yielding a lozenge-form when
cut or worn transversely, as in mastication.

The formation of each grinder begins with the summits
of the anterior plate, and the rest are completed in suc-
cession; the tooth is gradually advanced in position as its
growth proceeds ; and in the existing Indian elephant the
anterior plates are brought into use before the posterior
ones are formed. When the complex molar cuts the gum,
the cement is first rubbed off the digital summits; then
their enamel cap is worn away, and the central dentine
comes into play with a prominent enamel ring; the digi-
tal processes are next ground down to their common
uniting base, and a transverse tract of dentine, with its
wavy border of enamel, is exposed; finally, the trans-
verse plates themselves are abraded to their common
base of dentine, and a smooth and polished tract of that
substance is produced. From this basis the roots of the
molar are developed, and increase in length to keep the
worn crown on the grinding level, until the reproductive
force is exhausted. When the whole extent of a grinder
has successively come into play, its last part is reduced to
a long fang, supporting a smooth and polished field of
dentine, with, perhaps, a few remnants of the bottom of
the enamel folds at its hinder part. When the complex

es \

280 TEETH OF THE ELEPHANT.

molar has been thus worn down to a uniform surface, it
becomes useless as an instrument for grinding the coarse
vegetable substances on which the elephant subsists; it is
attacked by the absorbent action, and the wasted portion _
of the molar is finally shed.

The grinding-teeth of the elephant progressively increase
in size, and in the number of lamellar divisions, from the
first to the last; they succeed each other from behind
forwards, moving not in a right line, but in the are of a
circle, shown by the curved line in Fig. 78. The position
of the growing tooth in the closed alveolus, m, 5, is almost
at right angles with that in use, the grinding surface being
at first directed backwards in the upper jaw, and forwards
in the lower jaw, and brought by the revolving course
into a horizontal line in both jaws, so that they oppose
each other when developed for use. The imaginary pivot
on which the grinders revolve is next their root in the
upper jaw, and is next the grinding surface in the lower
jaw; in both,. towards the frontal surface of the skull.
Viewing both upper and lower molars as one complex
whole, subject to the same revolving movement, the sec-
tion dividing such whole into upper and lower portions
runs parallel to the curve described by the movement,
the upper being the central portion, or that nearest the
pivot; the lower, the peripheral portion. The grinding
surface of the upper molars is consequently convex from
behind forwards, and that of the lower molars concave;
the upper molars are always broader than the lower ones.

The bony plate forming the sockets of the growing
teeth is more than usually distinct from the body of the
maxillary, and participates in this revolving course, ad-
vancing forwards with the teeth.

SUCCESSION OF THE ELEPHANT’S GRINDERS. 281

Succrssion.— As the rate of increase, both of size and
in the number of the component plates of the grinding
tooth, is nearly identical in both jaws, it will suffice to
briefly describe the teeth and the periods at which they
successively appear in the lower jaw of the Asiatic ele-
phant.

The first molar, which cuts the gum in the course of
the second week after birth, has a sub-compressed crown,
nine lines in antero-posterior diameter, divided by three
transverse clefts into four plates, the third being the
broadest, and the tooth here measuring six lines across;
the base slightly contracts, and forms a neck as long as
the enamelled crown, but of less breadth, and this divides
into an anterior and posterior, long, sub-cylindrical, di-
verging, but mutually incurved fangs; the total length
of this tooth is one inch and a half. The corresponding
upper molar cuts the gum a little earlier than the lower
one: the neck of this tooth is shorter, and the two fangs
are shorter, larger, and more compressed than those of
the lower first molar. The first molar of the elephant is
the homologue of the probably deciduous molar (Fig.
75), d2, in other ungulates; it is not a mere miniature
of the great molars of the mature animal, but retains,
agreeably with the period of life at which it is developed,
a character much more nearly approaching that of the
ordinary pachydermal molar, manifesting the adherence
to the more general type by the minor complexity of the
crown, and by the form and relative size of the fangs.
In the transverse divisions of the crown we perceive the
affinity to the tapiroid type, the different links connecting
which with the typical elephants are supplied by the ex-
tinct lophiodons, dinotheriums, and mastodons. The

24%

282 SUCCESSION OF THE ELEPHANT’S GRINDERS.

subdivision of the summits of the primary plates recalls
the character of the molars, especially the smaller ones,
of the phacochere in the hog tribe. As the elephant ad-
vances in age, the molars pais acquire their more spe-
cial and alone character.

The first molars are completely in place and in full
use at three months, and are shed when the elephant is
about two years old. 4

The sudden increase and rapid development of the
second molar may account for the non-existence of any
vertical successor, or “ premolar,” to the former tooth, in
the elephant. The eight or nine plates of the crown are
formed in the closed alveolus, behind the first molar by
the time this cuts the gum, and they are united with the
body of the tooth, and most of them in use, when the
first molar is shed. The average length of the second
molar is two inches and a half, ranging from two inches
to two inches and nine lines. The greatest breadth,
which is behind the middle of the tooth, is from one
inch to one inch three lines. There are two roots; the
cavity of the small anterior one expands in the crown,
and is continued into that of the three anterior plates.
The thicker root supports the rest of the tooth. The
second molar is worn out and shed before the beginning
of the sixth year.

The third molar has the crown divided into from eleven
to thirteen plates; it averages four inches in length, and
two inches in breadth, and has a small anterior, and a
very large posterior root; it begins to appear above the
gum about the end of the second year, is in its most
complete state and extensive use during the fifth year,
and is worn out and shed in the ninth year. The last

SUCCESSION OF THE ELEPHANT’S GRINDERS. 283

remnant of the third molar is shown at m3 (Fig. 73). It
is probable that the three preceding teeth are analogous
to the deciduous molars, d2, d3, and d4, in the hog
(Fig. 7).

The fourth molar presents a marked superiority of size
over the third, and a somewhat different form; the ante-
rior angle is more obliquely abraded, giving a pentagonal
figure to the tooth in the upper jaw (Fig. 73), m4. The
number of plates in the crown of this tooth is fifteem or
sixteen, its length between seven and eight inches, its
breadth three inches. It has an anterior simple and
slender root supporting the first three plates, a second of
larger size and bifid, supporting the four next plates, and
a large contracting base for the remainder. The fore-
part of the grinding surface of this tooth begins to pro-
trude through the gum at the sixth year; the tooth is
worn away, and its last remnant shed, about the twentieth
or twenty-fifth year. It may be regarded as the homo-
logue of the first true molar of ordinary pachyderms
(Fig. 75), m 1.

The fi/th molar, with a crown of from seventeen to
twenty plates, measures between nine and ten inches in
length, and about three inches and a half in breadth.
The second root is more distinctly separated from the
first simple root than from the large mass behind. It
begins to appear above the gum about the twentieth
year; its duration has not been ascertained by observa-
tion, but it probably is not shed before the sixtieth year.

The sixth molar is the last, and has from twenty-two
to twenty-seven plates; its length, or antero-posterior
extent, following the curvature, is from twelve to fifteen
. inches; the breadth of the grinding surface rarely ex- ©

9284 DEVELOPMENT OF ELEPHANT’S GRINDERS.

ceeds three inches and a half. One may reasonably con-
jecture that the sixth molar of the Indian elephant, if it
make its appearance about the fiftieth year, would, from
its superior depth and length, continue to do the work of
mastication until the pondrous pachyderm had —
the century of its existence.

DEVELOPMENT.—The long-mistaken phenomena of the
formation of the dental substances will be here described
as they have been observed in the large teeth of the ele-
phant; if the description be comprehended in regard to
these, the most complex members of the dental system,
the true theory of dental development will be readily
understood in regard to all the various forms and grada-
tions of teeth. The matrix, or formative organ of the
tusk, consists of a large conical pulp, which is renewed
quicker than it is converted, and thus is not only pre-
served, but grows, up to a certain period of the animal’s
life; it is lodged in the cavity at the base of the tusk;
this base is surrounded by the remains of the capsule, a
soft, vascular membrane of moderate thickness, which is
confluent with the border of the base of the pulp, where
it receives its principal vessels.

Each molar of the elephant is formed in the interior
of a membranous sac—the capsule, the form of which
partakes of that of the future tooth, being cubical in the
first molar, oblong in the last, and rhomboidal in most of
the intermediate teeth; but always decreasing in vertical
extent towards its posterior end, and closed at all points,
save where it is penetrated by vessels and nerves. It is
lodged in an osseous cavity of the same form as itself,
and usually in part suspended freely in the maxillary
' bone, the bony case being destined to form part of the

DEVELOPMENT OF ELEPHANT’S GRINDERS. 285

socket of the tooth. The exterior of the membranous
capsule is simple and vascular, as shown at m5, Fig. 73;
its internal surface gives attachment to numerous folds
or processes, as in most other ungulate animals.

The dentinal pulp rises from the bottom of the capsule,
or that part which lines the deepest part of the alveolus,
in the form of transverse parallel plates extending to-
wards that part of the capsule ready to escape from the
socket. ‘These plates adhere only to the bottom of the
capsule; their opposite extremity is free from all adhe-
sion. ‘This summit is thinner than the base; it might be
termed the edge of the plate; but it is notched, or divided
into many digital processes. The tissue of these digitated
plates is identical with that of the dentinal pulp of simple
Mammalian teeth; it becomes also highly vascular at the
parts where the formation of the dentine is in active
progress.

Processes of the capsule descend from its summit into
the interspaces of the dentinal pulp-plates, and conse-
quently resemble them in form; but they adhere not only
by their base to the surface of the capsule next the mouth,
but also by their lateral margins to the sides of the cap-
sule, and thus resemble partition-walls, confining each
plate of the dentinal pulp to its proper chamber; the
margin of the partition opposite its attached base is free
in the interspace of the origins of the dentinal pulp-
plates.

- The enamel organ, which Cuvier appears to have re-
cognized under the name of the internal layer of the cap-
sule, is distinguishable by its light blue sub-transparent
color and usual microscopic texture, adhering to the free
surface of the partitions formed by the true inner layer

286 DEVELOPMENT OF ELEPHANT’S GRINDERS.

of the capsule. Although the enamel-pulp be in close
contact with the dentinal pulp prior to the commence-
ment of the formation of the tooth, one may readily con-
ceive a vacuity between them, which is continued uninter-
ruptedly, in many foldings, between all the gelatinous
plates of the dentinal pulp, and the partitions formed by
the combined enamel-pulp and the folds of the capsule.
According to the excretion view, this delicate apparatus
must have been immediately subjected to the violence of
being compressed in the unyielding bony box, by the de-
position of the dense matters of the tooth in the hypo-
thetical vacuity between the enamel and dentinal pulps;
a process of absorption must have been conceived to be
set on foot immediately that the altered condition of the
gelatinous secreting organs took place; and, according to
Cuvier’s hypothesis, the secreting function must be sup-
posed to have proceeded, without any irregularity or in-
terruption, while the process of absorption was superin-
duced in the same part to relieve it from the effects of
pressure produced by its own secretion.

The formation of the dentine commences immediately
beneath the membrana propria of the pulp; a part which
Cuvier distinctly recognized, and which he accurately
traced as preserving its relative situation between the
dentine and enamel throughout the whole formation of
the dentine, and discernible in the completed tooth “as a
very fine grayish line, which separates the enamel from
the internal substance,” or dentine.

The calcification and conversion of the cells of the
dentinal pulp commence as usual at the peripheral parts
of the lamelliform processes furthest from the attached
base. It may readily be conceived, therefore, that, at the

PEVELOPMENT OF ELEPHANT’S GRINDERS. 287

commencement, there is formed a little cap upon each of
the processes into which the edges of the pulp-plates are
divided. As the centripetal calcification proceeds, the
caps are converted into horn-shaped cones. When it has
reached the bottom of the notches of the edge of the pulp-
plate, all the cones become united together into a single
transverse plate; and, the process of conversion, having
reached the base of the pulp-plate, these plates coalesce
to form a common base to the crown of the tooth, which
would then present the same eminences and notches that
characterized the gelatinous pulp, if, during the period of
conversion, other substances had not been formed upon
the surface and in the interspaces of the pulp-plates.
Coincident, however, with the formation of the dentine,
is the deposition of the hardening salts of the enamel in
the extremely slender prismatic cells, which are for the
most part vertical to the plane of the inner surface of the
folds of the capsule to which they are attached. The
true inner part of the capsule forms those thick transverse
folds or partitions which support the enamel organ, and
with it fill the interspaces of the dentinal pulps. With
regard to the formation of the cement, Cuvier, after citing
the opinion of Tenon—that it was the result of ossifica-
tion of the internal layer of the capsule, and that of
Blake—that it was a deposition from the opposite surface
of the capsule to that which had deposited the enamel,
states his own conviction to be that the cement is pro-
duced by the same layer and by the same surface as that
which has produced the enamel. The proof alleged is,
that so long as any space remains between the cement
and the external capsule, that space is found to contain a
soft internal layer of the capsule with a free surface next
the cement. The phenomena could not, in fact, be other-

2988 DEVELOPMENT OF ELEPHANT’S GRINDERS.

wise explained according to the “excretion theory” of
dental development. To the obvious objection that the
same part is made, in this explanation, to secrete two
different products, Cuvier replies, that it undergoes a
change of tissue: “ Whilst it yielded enamel only, it was
thin and transparent; to give cement, it becomes thick,
spongy, and of a reddish color.” The external characters
of the enamel-organ and cement-forming capsule are cor-
rectly defined; only, the one, instead of being converted
into the other, is in fact changed into its supposed transu-
dation; the enamel fibres being formed, and properly dis-
posed in the direction in which their chief strength is to
lie, by the assimilative properties of the prearranged
elongated, prismatic, non-nucleated cells, which take from
the surrounding plasma the required salts, and compact
them in their interior.

Whilst this process is on foot, and before the enamel
fibres are firm in their position, the capsule begins to
undergo that change which results in the formation of the
thick cement; the calcifying process commences from
several points, and proceeds centrifugally, radiating there-
from, and differing from the ossification of bone chiefly
in the number of these centres, which, though close to the
new-formed enamel, are in the substance of the inner
vascular surface of the capsular folds. The cells arrange
themselves in concentric layers around the vessels, and
act like those of the enamel pulp in receiving into their
interior the bone-salts in a clear and compact state. Dur-
ing this process they become confluent with each other,
their primitive distinctness being indicated only by their
persistent granular nuclei, which now form the radiated
Purkingian capsules. The interspaces of the concentric
series of confluent cells become filled with the ealcareous

DEVELOPMENT OF ELEPHANT’S GRINDERS. 289

salts inarather more opaque state; and the conversion of
the capsule into cement goes on, according to the pro-
cesses more particularly described in the Introduction to
my Odontography, until a continuous stratum is formed
in close connection with the layer of enamel.
Calcification extending from the numerous centres, the
different portions coalesce, and progressively add to the
thickness of the cement, until all the interspaces of the
coronal plates and the whole exterior of the crown are
covered with the bone-like substance. The enamel-pulp
ceases to be developed at the base of the crown, but the
capsule continues to be formed part passu with the partial
formation of the pulp, as this continues, progressively
contracting, from the base of the crown, to form, by its
calcification, the roots. The calcification of the capsule
going on at the same time, a layer of cement is formed
in immediate connection with the dentine. The circum-
scribed spaces at the bottom of the socket to which the
capsule and dentinal pulp adhere, where they receive
their vessels and nerves, and which are the seat of the
progressive formation of these respective moulds of the
two dental tissues, become gradually contracted, and sub-
divided by the further localization of the reproductive
forces to particular spots, whence the* subdivision of the
base into roots. The surrounding bone undergoes corre-
sponding modifications, growing and filling up the inter-
spaces left by the dividing and contracting points of
attachment of the residuary matrix. All is subordinated
to one harmonious Jaw of growth by vascular action and
cell-formation, and of molecular decrement by absorption.
Mechanical squeezing, or drawing out, has no share in
these changes of the pulp or capsule; pressure at most
20

290 DEVELOPMENT OF ELEPHANT’S GRINDERS.

exercises only a gentle stimulus to the vital processes.
Cuvier believed that there were places where the dentinal
pulp and the capsule were separate from each other. I
have never found such, except where the enamel-pulp
was interposed between them in the crown of the tooth,
or where both pulp and capsule adhered to the periosteum
of the socket, below the crown. Cuvier affirms that the
number of fangs of an elephant’s molar depends upon
the number of points at which the base of the gelatinous
(dentinal) pulp is attached to the bottom of the capsule;
and that the interspaces of these attachments constitute
the under part of the crown or body of the tooth, the
attachments themselves forming the first beginnings of
the fangs. True to his hypothesis of the formation of the
dental tissues by excretion, he says that the elongation
of the fangs is produced by two circumstances; first, the
progressive elongation of the layers of osseous substance
(dentine) which force the tooth to rise and emerge from
its socket; secondly, the thickening of the body of the
tooth by the addition of successive layers to its inner sur-
face, which, filling up the interior cavity, leaves scarcely
room for the gelatinous pulp, and forces it down into the
interior of the roots. :

This pulling up ef the fang on the one hand, and squeez-
ing down the pulp on the other, are forces too gross and
mechanical to be admitted in actual physiology to explain
the growth of the root of a tooth or of any other organized
product; such modes of explanation were, however, in-
evitable in adopting the “excretion theory” of dental
development.

There are few examples of organs that manifest a more
striking adaptation of a highly complex and beautiful
structure to the exigences of the animal endowed with it,

DEVELOPMENT OF ELEPHANT’S GRINDERS. 291

than the grinding teeth of the elephant. We perceive, for
example, that the jaw is not incumbered with the whole
weight of the massive tooth at once, but that it is formed
by degrees as it is required; the division of the crown
into a number of successive plates, and the subdivision of
these into cylindrical processes, presenting the conditions
most favorable to progressive formation. But a more
important advantage is gained by this subdivision of the
tooth; each part is formed like a perfect simple tooth,
having a body of dentine, a coat of enamel, and an outer
investment of cement. A single digital process may be
eompared to the simple canine of a carnivore; a transverse
row of these, therefore, when the work of mastication has
commenced, presents by virtue of the different densities
of their constituent substances, a series of cylindrical
ridges of enamel, with as many depressions of dentine, and
deeper external valleys of cement; the more advanced
and more abraded part of the crown is traversed by the
transverse ridges of the enamel inclosing the depressed
surface of the dentine, and separated by the deeper chan-
nels of cement; the forepart of the tooth exhibits its least
efficient condition for mastication, the inequalities of the
grinding surface being reduced, in proportion as the
enamel and cement have been worn away. This part of
the tooth is, however, still fitted for the first coarse crush-
ing of the branches of a tree; the transverse enamel
ridges of the succeeding part of the tooth divide it into
smaller fragments, and the posterior islands and tubercles
of enamel pound it to the pulp fit for deglutition.

The structure and progressive development of the
tooth not only give to the elephant’s grinder the advantage
of the uneven surface which adapts the millstone for its
office, but, at the same time, secure the constant presence

292 TEETH OF THE MEGATHERIUM.

of the most efficient arrangement for the finer comminu-
tion of the food, at the part of the mouth which is nearest
the fauces.

In the tusks of the Mastodon giganteus, the outer layer
of cement is relatively thicker than in the tusks of the
mammoth, or in those of the Indian elephant. The ge-
neral character of the microscopic structure of the ivory
of the mastodon’s tusk is the same as that of the ele-
phant.

By the minuteness and close arrangement of the den-
tinal tubes, and especially by their strongly undulating
secondary curves, a tougher and more elastic tissue is
produced than results from their disposition in ordinary
dentine; and the modification which distinguishes “ivory”
is doubtless essential to the due degree of coherence of so
large a mass as the elephant’s tusk, projecting so far from
the supporting socket; and to be reamcatly apphed in
dealing hard blows a thrusts.

TEETH OF THE MEGATHERIUM.

The megatherium (Gr. megas, great; therion, beast), so
called from its colossal size—being as large as the
elephant, and even surpassing that hugest of existing
quadrupeds in some of its proportions—was once an in-
habitant, and apparently in some numbers, of the Ameri-
can continent, especially its southern division, and sub-
sisted on a similar kind of food to the elephants, viz: the
smaller branches and leaves of trees; but all the genera
and species of megatheroid beasts are now extinct.
Nevertheless, from the fossil remains of the megatherium
the anatomist is able unerringly to deduce the nature of

TEETH OF THE MEGATHERIUM. 293

its food and many of its peculiar habits; and also to bring
to light a system of dentition, designed, like that of the
elephants, for the service of crushing and masticating a
coarse vegetable diet throughout a long-protracted indi-
vidual existence; and yet, by a modification of the forma-
tive processes and economy of the teeth, quite different
from those that have been adopted for the same ends in
the elephant tribe. |

In these, as has been shown, the supply of a masticat-
ing apparatus, to serve the requirements of a gigantic
animal during one or perhaps two centuries of existence,
was provided by a succession of different molar teeth pre-
senting the due complexity of structure. In the mega-
therium, the same end was obtained by a perpetual growth
of the same complex molar teeth—the different dental
substances being formed at and added to the base of the -
tooth, in proportion as they were ground down at the
exposed summit.

The true number of teeth was determined by a removal
of the mineral substances adhering to the surface of a
portion of a fossil skull of a megatherium, brought by
Mr. Charles Darwin, from South America (Fossil Mam-
malia of the “Voyage of the Beagle,” 4to. 1840, p. 102),
The animal has not, as in the elephant, any tusks; its
teeth are molars or grinders exclusively ; they are five in
number on each side of the upper jaw, and four on each
side of the lower jaw—eighteen in all. All these teeth
are remarkable for their great length in proportion to
their breadth or thickness, being from eight to ten inches
in length, and between two and three inches only in
breadth. They are very deeply implanted in the jaw,
and the lower jaw has a quite peculiar form, in order to

25%

994 DENTAL SYSTEM OF THE MEGATHERIUM.

acquire the requisite room for the lodgement of the lower
teeth and their ‘‘ matrices,” or formative organs.

The next peculiarity to be noticed in these remarkable
teeth is the great length of the conical cavity at their
base, for lodging the part of the matrix called the “ pulp ;”
the apex of the pulp-cavity rising as far as the part of the
tooth where it emerges from the socket. A transverse
fissure is continued from this apex to the middle concavity
of the grinding surface of the tooth, which is thus divided
into two halves. Each of these halves consists of three
distinct substances—a central column of “ vaso-dentine,”
a. peripheral and nearly equally thick layer of “ cement,”
and an intermediate thinner stratum of true or “hard-
dentine.” This latter has been described as being enamel;
but it is only analogous to that differently constituted
and harder substance in the compound teeth of the ele-
phant, in regard to its relative situation, and its degree of
density to the other constituents of the tooth of the me-
gatherium.

No species of the order called “Bruta,” or “Kdentata,”
to which the extinct megatherium belongs, has true ena-
mel entering into the composition of its teeth; but the
modifications of structure which the teeth present in the
different genera of this order are considerable, and their
complexity is not less that that of the enamelled teeth of
the herbivorous, ruminant, and other hoofed animals, in
consequence of the introduction of a dental substance—the
“ vaso-dentine”—into their composition, analogous in struc-
ture to that of the teeth of the Myliobates and other carti-
laginous fishes. The cement of the megatherium’s tooth
differs from the vaso-dentine in the larger size and wider
interspaces of its medullary canals, and by the presence
of radiated bone-cells in their interspaces; but they dare

DENTAL SYSTEM OF THE MEGATHERIUM. 295

brought into organic communication with each other, not
only by means of the tubes of coarse dentine, but by
occasional continuity of the vascular canals across that
substance. The tooth of the megatherium thus offers an
unequivocal example of a course of nutriment from the
dentine to the cement, and reciprocally; so that the main
substance, or body of the tooth, can obtain the requisite
supply for its languid vitality from the vessels of the cap-
sule as well as from those of the pulp.

The conical cavity at the base of the tooth attests the
large size, and demonstrates the form of the persistent
pulp in the living megatherium; the diameter of its base
‘is equal to the part of the tooth which is formed by the
combined dentine and vaso-dentine. From the gradual
thinning off and final disappearance of those substances
as they reach the base of the tooth, it may be inferred
that both were formed at the expense of the pulp. The
fine dentinal tubes must have been established and cal-
cified in the peripheral layer of the pulp, which layer
must have been wholly so converted into the dentine;
but as the deposition of the hardening salts proceeded
in the rest of the pulp, certain tracts of that soft and
vascular substance were left uncalcified, to form the me-
dullary or vascular canals which characterize the vaso-
dentine. The space between the inserted base of the
tooth and the walls of the socket indicates the thick-
ness of the dental capsule, by the ossification of which the
exterior layer of cement was formed; and this modifica-
tion of the tooth-forming organ in the megatherium per-
mitted the progressive addition of cement, as the persist-
ence of the compound pulp occasioned the uninterrupted
and continuous formation of the harder dentine, which is
analogous to the enamel in the elephant’s grinder.

296 DENTAL SYSTEM OF THE MEGATHERIUM.

In all essential characters the teeth of the megatherium
repeat, on a magnified scale, the dental peculiarities of the
sloth; and since, from a similarity of the form, number,
kinds, and structure of teeth, a similarity of food is to be
inferred, it may be concluded that the leaves and soft
succulent sprouts of trees formed the staple diet of the
megatherium, and of the cognate and contemporary me-
galonyx and mylodon, as of the existing sloths. The
enormous claws of those great extinct sloth-like quadru-
peds, to judge by the fossorial (digging and scratching)
character of the powerful mechanism of the limbs that
worked them, were employed, not, as in the sloths, to
carry the animal to its food, but to bring the food within
the reach of the animal, by uprooting the trees on which
it grew.

In the remains of the megatherium, we have evidence
of the framework of a quadruped equal to the task of un-
dermining and tearing down the largest trees in a tro-
pical forest. In the latter operation, it is obvious that
the immediate application of the anterior extremities to
the trunk of the tree would demand a corresponding
fulerum to be effectual; and it is the necessity for an ad-
equate basis of support and resistance to such an applica-
tion of the fore-extremities which gives the explanation
of the seemingly anomalous development of the pelvis,
tail, and hinder extremities of the megatherium and its
extinct allies. No wonder, therefore, that their type of
structure should be so peculiar; for, where shall we now
find quadrupeds equal, like them, to the habitual task of
uprooting trees for food.

TEETH OF THE EXTINCT ANOPLOTHERIUM. 297

TEETH OF THE ANOPLOTHERIUM.

Of the extinct quadrupeds with hoofs, and which were
consequently herbivorous, the species restored by Cuvier
from fossil remains discovered in the quarries at Mont-
martre, near Paris, was one of the most ancient. The
ereat comparative anatomist called it anoplotherium, from
the Greek words signifying ‘‘ weaponless,” because it had
neither horns nor tusks. It was, however, characterized
by the most complete system of dentition; for it not only
possessed incisors and canines in both jaws, but these
were so equably developed that they formed one un-
broken series with the premolars and molars, which cha-
racter is now found only in the human species.

The dental formula of the genus Anoplotherium is ex-
pressed by: pan pine pant ys

8—3’ 1-1" 4-4 383
ing that it had, on each side of both upper and lower
jaws, three incisors, one canine, four premolars, and three
true molars; in all, forty-four teeth.

Those teeth which are transitorily manifested in the
embryo state of some ruminants, as the upper incisors
and canines and the anterior premolars, p 1, were in the
ancient anoplothere retained and raised to a proportional
equality of size and function with the rest of the teeth.
The true molars had a broad grinding surface, with ena-
mel-covered crescentic lobes, remotely resembling those
of the existing ruminants. In some of the smaller species
of anoplotherium, the ruminant type of grinding surface
was more closely adhered to, and the fossil lower jaws of
such species, as e.g. of the Dichobune cervinum, have been

= 44, signify-

298 TEETH OF RUMINANTS.

mistaken for those of a ruminant, and have been referred
to the genus Moschus. One of these interesting transitional
extinct quadrupeds, described in the Geological Journal,
for 1847, under the name of Dichodon, had forty-four teeth
in one uninterrupted series, and of the same kinds, as in
the anoplothere; but the teeth there marked p4, and
m1, upper jaw, I have ascertained to be “ milk-teeth.”

TEETH OF RUMINANTS.

The even-toed or artiodactyle Ungulata, superadd the
characters of simplified form and diminished size to the
more important and constant one of vertical succession in
their premolar teeth. These teeth, in the ruminants, re-
present only the moiety of the true molars, or one of the
two semi-cylindrical lobes of which these teeth consist,
with at most a rudiment of the second lobe. An ana-
logous morphological character of the premolars will be
found to distinguish them in the dentition of the genus
Sus (Fig. 75, p2, p38, p 4), in the hippopotamus, and in the
phacocherus, or wart-hog, where the premolar series is
greatly reduced in number; yet this instance of a natural
affinity, manifested in so many other parts of the organi-
zation of the artiodactyle genera, has been overlooked in
F. Cuvier’s work, above cited, although it is expressly
designed to show how much zoological relations are
illustrated by the teeth.

Most of the deciduous teeth of the ruminants resemble
in form the true molars; the last, e.g. has three lobes in
the lower jaw like the last true molar. When, therefore,
the third grinder of the lower jaw of any new or rare
ruminant shows three lobes, the crowns of the premolars

TEETH OF SEALS. 299

should be sought for in the substance of the jaw below
these, and above their opponents in the upper jaw; and
thus the true characters of the pageeca ee dentition may
be ascertained.

The deciduous molars are three in number on each
side, and, being succeeded by as many premolars, the
—3 38—8
| 911. ee
3— 3—3
but there is a rudiment of an anterior milk-molar, d@1, in
the embryo fallow-deer, and in one of the most ancient
of the extinct ruminants (dorcatherium, Kaup) the normal

number of premolars was fully developed.

The molar series of all the Diphyodonts is naturally
divisible into only two groups, premolars and molars;
4—4 3—8
Hi A Bia 18
individual tooth may be determined and symbolized
throughout the series, as is shown in the instances under

Cut 75.

the typical number of these is ; and each

SEAL TRIBE.

(Phocide).—There is a tendency to deviate from the
ferine number of the incisors in the most aquatic and
piscivorous of the Musteline quadrupeds, viz., the sea-
otter (enhydra), in which species the two middle incisors of
the lower jaw are not developed in the permanent denti-
tion. In the family of true seals, the incisive formula is
further reduced, in some species even to zero in the lower

jaw, and it never exceeds as All the phocide possess

ted

powerful canines; only in the aberrant walrus are they
absent in the lower jaw; but this is compensated by the

800 TEETH OF SEALS.

singular excess of development which they manifest in
the upper jaw (Fig. 70). In the pinnigrade, as in the
plantigrade family of carnivores, we find the teeth which
correspond to true molars more numerous than in the
digitigrade species, and even occasionally rising to the
typical number, three on each side; but this, in the seals,
is manifested in the upper, and not, as in the bears, in
the lower jaw. The entire molar series usually includes
five, rarely six teeth on each side of the upper jaw, and
five on each side of the lower jaw, with crowns, which
vary little in size or form in the same individual; they
are supported in some genera, as the eared seals (otarze),
and elephant seals (cystophora), by a single fang; in other
genera by two fangs, which are usually connate in first
or second teeth; the fang or fangs of both incisors, ca-
nines and molars, are always remarkable for their thick-
ness, which commonly surpasses the longest diameter of
the crown. The crowns are most commonly compressed,
conical, more or less pointed; in a few of the largest
species they are simple and obtuse, and particularly so
in the walrus, in which the molar teeth are reduced to a
smaller number than in the true seals. In these, the line
of demarcation between the true and false molars is very
indefinitely indicated by characters of form or position;
but, according to the instances in which a deciduous
dentition has been observed, the first three permanent
molars in both jaws succeed and. displace the same
number of milk molars, and are consequently premo-
lars; occasionally, in the seals with two-rooted molars,
the more simple character of the premolar teeth is
manifested by their fangs being connate, and in the
Slonorhynchus serridens the more complex character of

TEETH OF QUADRUMANA. 301

of the true molars is manifested in the crown. In the
Stenorhynchus leptonyx, each molar tooth in both jaws is
trilobed, the anterior and posterior accessory curving to-
wards the principal one, which is bent slightly back-
wards; all the divisions are sharp-pointed, and the crown
of each molar thus resembles the trident or fishing-spear;
the two fangs of the first molar in both jaws are connate.
In the Stenorhyncus serridens, the three anterior molars on
each side of both jaws are four-lobed, there being one
anterior and two posterior accessory lobes; the remaining
posterior molars (true molars) are five-lobed, the princi-
pal cusp having one small lobe in front, and three deve-
loped from its posterior margin; the summits of the lobes
are obtuse, and the posterior ones are recurved like the
principal lobe. Sometimes the third molar below has
three instead of two posterior accessory lobes. Occasion-
ally, also, the second, as well as the first molar above,
has its fangs connate: but the essentially duplex nature
of the seemingly single fang, which is unfailingly mani-
fested within by the double pulp-cavity, is always out-
wardly indicated by the median longitudinal opposite
indentations of the implanted base.

TEETH OF QUADRUMANA.

The chief aim of comparative anatomy being the bet-
ter comprehension of the structure of man, we shall
finally describe those modifications of the dental system
which throw more immediate light on the nature of the
teeth in the human subject, and which are met with, as
might be expected, in the order (Quadrumana) of mam-

26

302 TEETH OF ORANG AND CHIMPANZEE.

maha that makes the nearest approach to that repre-
sented by the genus homo.

Through a considerable part of the quadrumanous
series, ¢.g., in all the apes and monkeys of the Old World,
in all the genera, indeed, which are above the lemurs
(cat-monkeys and slow monkeys) of Madagascar, the same
number and kinds of teeth are present as in man; the
first deviation being the disproportionate size of the ca-
nines and the concomitant break, or “diastema,”’ in the
dental series for the reception of their crowns when the
mouth is shut. This is manifested in both the chimpan-
zees and orangs, together with a sexual difference in the
proportions of the canine teeth.

In that large ape of tropical Africa, called the “gorilla”
(Troglodytes gorilla), which, in some important particulars,
more resembles man than does the smaller kind of chim-
‘panzee (Troglodytes niger), the dentition seems to approach
nearer to the carnivorous type, at least in the full-grown
male (see Fig. 50, p. 223). It is nevertheless strictly
quadrumanous in its essential characters, as in the broad,
flat, tuberculate grinding surfaces of the molar teeth; but
in the minor particulars in which it differs from the denti-
tion of the orang, it approaches nearer the human type.
In the upper jaw the middle incisors are smaller, the
lateral ones larger than those of the orang; they are thus
more nearly equal to each other; nevertheless, the pro-
portional superiority of the middle pair is much greater
than in man, and the proportional size of the four inci-
sors both to the entire skull and to the other teeth is
greater. Each incisor has a prominent posterior basal
ridge, and the outer angle of the lateral incisors, 7 2, is
rounded off as in the orang. The incisors incline for-
wards from the vertical line as much as in the great

TEETH OF ORANG AND CHIMPANZEE. 308

orang. The characteristics of the human incisors are, in
addition to their true incisive wedge-like form, their near
equality of size, their vertical or nearly verticalgposition,
and small relative size to the other teeth and to the en-
tire skull. The diastema, between the incisors and the
canine on each side, is as well marked in the male chim-
panzee as in the male orang. The crown of the canine
(7b.), c, passing outside the interspace between the lower
canine and premolar, extends, in the male Troglodytes
gorilla, a little below the alveolar border of the under
jaw when the mouth is shut: the canines in both jaws
are twice the size of those teeth in the female gorilla.

Both premolars are bicuspid; the outer cusp of the
first and the inner cusp of the second being the largest,
and the first premolar consequently appearing the largest
on an external view. The anterior external angle of the
first premolar is not produced as in the orang, which, in
this respect, makes a marked approach to the lower quad-
yumana. In man, where the outer curve of the premolar
part of the dental series is greater than the inner one, the
outer cusps of both premolars are the largest; the alter-
nating superiority of size in the chimpanzee accords with
the straight line which the canine and premolars form
with the true molars.

The three true molars are quadricuspid, relatively
larger in comparison with the bicuspids than in the
orang. In the first and second molars of both species of
chimpanzee, a low ridge connects the antero-internal with
the postero-external cusp, crossing the crown obliquely,
asinman. ‘There isa feeble indication of the same ridge
in the unworn molars of the orang; but the four princi-
pal cusps are much less distinct, and the whole grinding
surface is flatter and more wrinkled than in the chim-

304 TEETH OF ORANG AND CHIMPANZEE.

panzee. The repetition of the strong sigmoid curves,
which the unworn prominences of the first and second
true molgrs present in man, is a very significant indica-
tion of the near affinity of the gorilla and the chimpanzee,
as compared with the approach made by the orangs or
any of the inferior guadrumana, in which the four cusps
of the true molars rise distinct and independently of each
other. The premolars as well as molars are severally im-
planted by one internal and two external fangs, diverging,
but curving towards each other at their ends as if grasp-
ing the substance of the jaw. In no variety of the human
species are the premolars normally implanted by three
fangs; at most the root is bifid, and the outer and inner
divisions of the root are commonly connate. It is only
in the black varieties, and more particularly that race in-
habiting Australia, that I have found the wisdom tooth,
or last true molar, with three fangs as a general rule; and
the two outer ones are more or less confluent.

The molar series in both species of chimpanzee forms
a straight line, with a slight tendency in the upper jaw to
bend in the opposite direction to the well-marked curve
which the same series describes in the human subject.
This difference of arrangement, with the more complex
implantation of the premolars, the proportionally larger
size of the incisors as compared with the molars; the still
greater relative magnitude of the canines; and, above all,
the sexual distinction in that respect illustrated by the
skull of the full-grown male gorilla (Fig. 50, p. 228),
stamp the chimpanzees most decisively with not merely
specific but generic distinctive characters as compared
with man. For the teeth are fashioned in their shape
and proportions in the dark recesses of their closed
formative alveoli, and do not come into the sphere of ope-

TEETH OF ORANG AND CHIMPANZEE. 305

ration of external modifying causes, until the full size of
the crowns has been acquired. The formidable natural
weapons, with which the Creator has armed the powerful
males of both species of chimpanzee, form the compensa-
tion for the want of that psychical capacity to forge de-
structive instruments which has been reserved as the
exclusive prerogative of man. Both chimpanzees and
orangs differ from the human subject in the order of the
development of the permanent series of teeth ; the second
molar, m 2, comes into place before either of the pre-
molars has cut the gum, and the last molar, m 8, is ac-
quired before the canine. We may well suppose that the
larger grinders are earlier required by the frugivorous
chimpanzees and orangs than by the higher organized
omnivorous species with more numerous and varied re-
sources; and probably one main condition of the earlier
development of the canines and premolars in man may
be their smaller relative size. |

In the South American quadrumana, the number of
teeth is increased to thirty six, by an addition of one
tooth to the molar series on each side of both jaws. It
might be concluded, @ priort, that as three is the typical
number of true molars in the placental mammalia with
two sets of teeth, the additional tooth in the cebine would
be a premolar, and form one step to the resumption of the
normal number (four) of that kind of teeth. The proof
of the accuracy of this inference is given by the state of
the dentition in any young spider-monkey (Afeles), or
Capucin-monkey (Cebus), which may correspond with that
of the human child in Fig. 76, ze. where the whole of the
deciduous dentition is retained, together with the first
true molar (m 1) on each side of both jaws. If the germs
of the other teeth of the permanent series be exposed in

26*

306 TEETH OF MONKEYS AND LEMURS.

the upper jaw (as in Fig. 76), the crown of a premolar
will be found above the third molar in place, as well as
above the second and first. As regards number, there-
fore, the molar series, in the South American monkeys
(Mycetes, Ateles, Cebus), is intermediate between that of the
genus Mustela and of Felis (Fig. 69); the little premolar,
p2, in Mustela, shows plainly enough which of the four is
wanting to complete the typical number in the South
American monkey, and which is the additional premolar
distinguishing its dental formula from that of the Old
World monkeys and man.

Zoologists have rightly stated, as a matter of fact, that
the little marmoset monkeys (Hapale, Ouzstit?) “ have only
the same number of teeth as the monkeys of the Old

4 1—1 5—d,,
World—viz: 82, dt ala coe
is much greater than this numerical conformity would
intimate. In a young Jacchus penicillatus, I find that
there are three deciduous molars displaced by three pre-
molars, as in the other South American quadrumana, and
that it is the last true molar, m 38, the development of
which is suppressed, not the premolar, » 2, and thus these
diminutive squirrel-like monkeys actually differ from the
Old World forms more than the Cebide do; 7. e. they differ

But the difference

not only in having four teeth ( p 2 i

= which the mon-
keys of the Old World do not possess, but also by want-
ing four teeth (m 6 eg which those monkeys, as well

as the Cebide, actually have. It is thus that the investi-
gation of the exact homologies of parts leads to a recog-
nition of the true characters indicative of zoological
affinity.

TEETH OF MONKEYS AND LEMURS. 307

ey ap meee together with
d—d 38—d

remarkable modifications of their incisive and canine
teeth, of which an extreme example is shown in the pecti-
nated tooth of the galcopithecus. The inferior incisors
slope forwards in all, and the canines also, which are
contiguous to them, and very similar in shape.

In the hoofed quadrupeds with toes in uneven number
( peressodactyla), whose premolars, for the most part, repeat
both the form and the complex structure of the true
molars, such premolars are distinguished by the same
character of development as those of the artiodactyla, or
ungulates, with toes in even number; although here the
premolars are distinguished also by modifications of size
and shape. The complex ridged and tuberculate crowns
of the second, third, and fourth grinders of the rhinoceros,
hyrax, and horse, no more prove them to be true molars
than the trenchant shape of the lower carnassials of the
lion proves them to be false molars. It is by develop-
ment alone that the primary division of the series of
grinding teeth can be established, and by that character
only can the homologies of each individual tooth be de-
termined, and its proper symbol applied to it.

In Fig. 72, the three posterior teeth of the almost uni-
form grinding series of the horse’s dentition are thus
proved to be the only ones entitled to the name of “true
molars;” and, if any one should doubt the certainty of
the rule of counting, by which the symbols, p 4, p 3, and
p 2, are applied to the three large anterior grinding teeth
(vb.), which are commonly the only premolars present in
each lateral series of the horse’s jaws, yet the occasional
retention of the diminutive tooth (p 1), would establish
its accuracy, whether such tooth be regarded as the first

Most of the Lemurine have p

-

308 HOMOLOGIES OF THE TEETH.

of the deciduous series unusually long retained, or the
unusually small and speedily lost successor (p 1) of an
abortive (d 1).

The law of development, so beautiful for its instructive-
ness and constancy in the placental diphyodonts, is well
illustrated in the little hyrax, in which the d 1 is normally
developed and succeeded by a permanent, p 1, differing
from the rest only by a graduated inferiority of size,
which, in regard to the last premolar, ceases to be a dis-
tinction between it and the first true molar.

The elephant, which by its digital characters belongs to
the odd-toed, or perissodactyle, group of pachyderms, also
resembles them in the close agreement in form and struc-
ture of the grinding teeth representing the premolars, with
those that answer to the true molars of the hyrax, tapir,
and rhinoceros. The gigantic proboscidian pachyderms
of Asia. and Africa present, however, so many peculiari-
ties of structure as to have led to their being located in a
particular family in the Systematic Mammalogies. And
this seems to be justified by no character more than by
the singular seeming exception which they present to the
diphyodont rule which governs the dentition of other
hoofed quadrupeds. In fact, the elephant, like the du-
gong, sheds and replaces vertically only its incisors,
which are also two in number, very long, and of constant
growth, forming tusks, with an analogous sexual differ-
ence in this respect in the female of the Asiatic species.
The molars, also, are successively lost, are not vertically
replaced, and are reduced finally to one on each side of
both jaws, which is larger than any of its predecessors.
These analogies are interesting and suggestive in connec-
tion with the other approximations in the “Sirenia” to
the pachydermal type.

HOMOLOGIES OF THE TEETH. 309

In the mammalian orders with two sets of teeth, these
organs acquire fixed individual characters, receive special
denominations, and can be determined from species to
species. This individualization of the teeth is eminently
significative of the high grade of organization of the ani-
mals manifesting it. Originally, indeed, the name “in-
cisors,” “laniaries,” or “canines,” and “molars” were given
to the teeth, in man and certain mammals, as in reptiles,
in reference merely to the shape and offices so indicated ;
but they are now used as arbitrary signs, in a more fixed
and determinate sense. In some carnivora, e. g. the frént
teeth have broad tuberculate summits, adapted for nip-
ping and bruising, while the principal back teeth are
shaped for cutting, and work upon each other like the
blades of scissors. The front teeth in the elephant pro-
ject from the upper jaw, in the form, size, and direction
of long-pointed horns. In short, shape and size are the
least constant of dental characters in the mammalia; and
the homologous teeth are determined, like other parts, by
their relative position, by their connections, and by their
development.

Those teeth which are implanted in the premaxillary
bones, and in the corresponding part of the lower jaw, are
called “incisors,” whatever be their shape or size. The
tooth in the maxillary bone, which is situated at, or near
to, the suture with the premaxillary, is the “ canine,” as is
also that tooth in the lower jaw which, in opposing it,
passes in front of its crown when the mouth is closed.
The other teeth of the first set are the “deciduous molars ;”
the teeth which displace and succeed them vertically are
the “ premolars;” the more posterior teeth, which are not
displaced by vertical successors, are the “ molars” properly
so called.

310 DECIDUOUS AND PERMANENT TEETH OF HOG.

The hog is one of the few existing quadrupeds which
retain the typical number and kinds of teeth.

Figure 75, part of the lower jaw of a young hog, illus-
trates the phenomena of development which distinguishes
the premolars from the molars. The first premolar, p 1,

DECIDUOUS AND PERMANENT TEETH OF THE HOG.

and the first molar, m 1, are in place and use, together
with the three deciduous molars, d 2, d 3, and d 4; the
second molar, m 2, has just begun to cut the gum; p 2,
p 8, and p 4, together with m 8, are more or less incom-
plete, and concealed in their closed alveolh.

The premolars must displace deciduous molars in order
to rise into place; the molars have no such relations. It
will be observed that the last deciduous molar, d 4, has
the same relative superiority of size to d 3, and d 2, which
m 8 bears to m 2 and m1; and the crowns of p 8 and p
4 are of a more simple form than those of the milk-teeth
which they are destined to succeed.

The germ of the permanent canine has not yet appeared
below the deciduous one, c; those of the permanent in-
cisors, 2 1, ¢ 2, 7 8, are seen ready to push out the decidu-
ous incisors d 1,d2,d38. When the whole of the second

HOMOLOGIES OF THE HUMAN TEETH. SEE

set of teeth is in place, its nature is indicated by the
chad ata Deh ane icc eciled 2 STA sig-
Seal aie Aee a = e8

nifies that there are, on each side of both upper and lower
jaws, three incisors, one canine, four premolars, and three
molars, making in all forty-four teeth; each distinguished
by the symbol marked in the cut.

When the premolars and the molars are below their
typical number, the absent teeth are missing from the fore
part of the premolar series, and from the back part of the
molar series. The most constant teeth are the fourth
premolar and the first true molar; and, these being known
by their order and mode of development, the homologies
of the remaining molars and premolars are determined by _
counting the molars from before backwards, e. g., “ one,”
“two,” “three,” and the premolars from behind forwards,
“four,” “three,” “two,” “one”

Examples of the typical dentition are exceptions in
the actual creation; but it was the rule in the forms of
mammalia first introduced into this planet; and that, too,
whether the teeth were modified for animal or vegetable
food.

With regard to the human dentition, the discovery by
the great poet Goethe of the limits of the premaxillary
bone in man, leads to the determination of the incisors,
which are reduced to two on each side of both jaws; the
contiguous tooth shows by its shape, as well as position,
that it is the canine, and the characters of size and shape
have also served to divide the remaining five teeth in
each lateral series into two bicuspids and three molars.
In this instance, the secondary characters conform with
the essential ones. But, since we have seen of how little
value shape or size are, in the order carnivora, in the de-

iss 7

312 HOMOLOGIES OF THE HUMAN TEETH.

termination of the exact homologies of the teeth, it is
satisfactory to know that the more constant and important
character of development gives the requisite certitude as
to the nature of the so-called bicuspids in the human sub-
ject. In Fig. 76, the condition of the teeth is shown in

DECIDUOUS AND PERMANENT TEETH, HUMAN, £7. 7.

the jaws of a child of about six years of age. The two
incisors on each side, d, 7, are followed by a canine, ¢, and
this by three molar teeth like those of the adult; in fact,
the last of the three, m, is the first of the permanent
molars; it has pushed through the gum, like the two
molars which are in advance of it, without displacing any
previous tooth, and the substance of the jaw contains no
germ of any tooth destined to displace it; it is, therefore,

NOTATION AND SYMBOLS OF TEETH. als

by this character of its development, a true molar, and
the germs of the permanent teeth, which are exposed in
the substance of the jaw, between the diverging fangs of
the molars d3 and d4, prove those molars to be tempo-
rary, destined to be replaced, and prove also that the teeth
about to displace them are premolars. According, there-
fore, to the rule previously laid down, we count the per-
manent molar in place as the first of its series, m1, and
the adjoining premolar as the last of its series, and con-
sequently the fourth of the typical dentition, or p 4.

We are thus enabled, with the same scientific certainty
as that whereby we recognize in the middle toe of the
foot the homologue of that great digit which forms the
whole foot and is incased by the hoof of the horse, to
point to p 4, or the second bicuspid in the upper jaw, and
to m1, or the first molar in the lower jaw, of man, as the
homologues of the great carnassial, or flesh-cutting teeth
of the lion (ig. 69). We also conclude that the teeth
which are wanting in man to complete the typical molar
series are the first and second premolars, the homologues
of those marked p1 and p 2 in the hog. The character-
istic shortening of the maxillary bones required this dimi-
nution of the number of their teeth, as well as their size,
and of the canines more especially; and the still greater
curtailment of the premaxillary bone is attended with a
diminished number and an altered position of the incisors.

The homologous teeth being thus determinable, they
may be severally signified by a symbol as well as by a
name. ‘The incisors, e.g., are here represented by their
initial letter, 7, and individually by an added number, 71,
22,and 73; the canines by the letter c; the premolars by
the letter p; and the molars by the letter m; these also
being differentiated by added numerals. Thus the num-

27

/

-

314 NOTATION AND SYMBOLS OF TEETH.

ber of these teeth, on each side of both jaws, in any given

Species—man, e.g.—may be expressed by the following
aa GP si

brief formula: axe Ce pay ae 582 and the

homologies of the typical formula may be signified by 71,

72;¢; p3, p4; m1, m2, m3; the suppressed teeth being

28, pl, and p 2.

These symbols, it is hoped, are so plain and simple as
to have formed no obstacle to the full and easy compre-
hension of the facts explained by means of them. If
these facts, in the manifold diversities of mammalian
dentition, were to be described in the ordinary way, by
means of verbal phrases or definitions of the teeth—e. g.
“the second deciduous molar, representing the fourth in
the typical dentition,” instead of d4, and so on—the de-
scription would occupy much space, and would levy such
a tax upon the attention and memory as must tend to
enfeeble the judgment, and impair the power of seizing
and appreciating the results of the comparisons.

Each year’s experience strengthens my conviction that
| the rapid and successful progress of the knowledge of
animal structures, and of the generalization deducible
therefrom, will be mainly influenced by the determina-

tion of the nature or homology of the parts, and by the
| :

' concomitant power of condensing the propositions relating

to them, and of attaching to them signs or symbols equiva-
lent to their single substantive names. In my work on
the Archetype of the Skeleton, I have denoted most of the

bones by simple numerals, which, if generally adopted,

might take the place of names; and all the propositions
respecting the centrum of the occipital vertebra might be
predicated of the figure “1” as intelligibly as of “basi-

* occipital.”

NOTATION AND SYMBOLS OF TEETH. 315

The symbols of the teeth are fewer, are easily under-.
stood and remembered, render unnecessary the endless
repetition of the verbal definitions of the parts, harmonize
conflicting synonymes, serve as a universal language, and
express the author’s meaning in the fewest and clearest
terms. The entomologist has long found the advantage
of such signs as ° and 9, signifying male and female, and
the like; and it is time that the anatomist should avail
himself of this powerful instrument of thought, instruc-
tion, and discovery, from which the chemist, the astrono-
mer, and the mathematician have obtained such important
results.

i % i Te
Fas em are Cy OY gee A
WRC pe al
7 s = A “

+ awed ad ae
Paved titadhy: ae a erent e
9 opted y yea alder st igtidg ia 2 Bee a F

Risa

=y p

Lge: bgt Bara shea sd fel ps ‘ot ey
¥ ‘apyiyi Sagodt SS radanetded hype aie te
| ee Ritaont if ry Fogle ano ya roi eae go

¥ id et shat esis bi iiriatsinddinerhiieie
ih twit lo i’ et “Rok Aer” Mat Be

a :
. GC 7 ay ¥ , He, ee a . 4 j
—- # he » <

re oe Mae +4 > 7
ane a ee ae

F . Ps
va
an A tice : ae ae ae

P 4 as ;
; a ole i ‘gt “ hs 4
; SITS terial
~
a AM f

‘. ) j ,
<< e
> aj S Jee Le ake
~ 7.
‘ °
——" ¢
es 4t—- )
sf 2
: ‘
pats * f i
r
7 *
a , &y
: 7 ’
‘ f ?
¥ a” | 2 i
uz.)
‘
Lf “ J . «dy r \ 'd
1
.

INDEX,

GLOSSARIAL, EXPLANATORY, AND REFERENTIAL.

A

Acrodus (Gr. akros extreme, and
odous a tooth), osteodentine of
the, 247

Albatross,
the, 222

Alisphenoid bone of the python’s
skull, 78

Amphiceelian type of vertebra (Gr.
amphi both, and keiles concave),
98

Amphiuma, batrachian (Gr. amphi
about, and hymen a membrane),
skeleton and limbs of the, 184

Anapophysis (Gr. ana backwards,
and apophysis springing from), 27

Anarrhicas lupus (Gr. the wolf-
fish), teeth of the, 245

‘‘Angler,” teeth of the fish so called,
244

cranial development of

Animals, original substance of, 13 ;
extinct races of, 227

Anoplotherium (Gr. anoplos un-
acmed, and therion a_ beast),
teeth of the, 297

Ant-eaters, teeth of the, 238; eden-
tulous mammals, 258

Anthropotomist (Gr. anthropos a
man, and tome dissection), 117

Antibrachial bones (Gr. anti against,
and brachia arms), 216

Ape, skeleton of the, 210; dentition
of the, 302

Apodal (Gr. @ and podes wanting
feet), 90

Aponeurotic (Gr. apo from, and

neuron & nerve), membranes so
called, 16 :
Archetype of the human skeleton,
modifications of the, 215 et seg.
Armadillo, dermal bones of the, 19;
teeth of the, 259

Articular, the bone, of fishes, 46

Artiodactyla (Gr. artios in even
number, and dactylos finger),
family of the, 182; dentition of
the, 307

Astragalus (Lat. the ankle-bone),
188; of the hind foot in quadru-
peds, 185, 187

Ateles (Gr. ateles imperfect), denti-
tion of the, 805

Atlas and axis vertebre of the
crocodile, 96

Australian skull, facial angle . of
the, 224

B

Balena (Lat. a whale), teeth of the,
258

Balistes (Gr. balivs speckled), den-
tine of the, 247

Barracuda fish, formidable denti-
tion of the, 248

Basioccipital of the python (Gr.
basis the base, and Lat. occiput
back of the head), 72

Basisphenoid bone of the python’s
skull (Gr. basis the base, and
sphenand eidos, wedge-shaped), 79

Bat, skeleton of the, 198

Batrachia. (Gr. batrachos a frog),

i

d18

skeleton of the, 64 et seg.
FROG. )

Bicuspis (Lat. bis twice, and cuspis
a point), shape of the molars, 303

Birds, composition of their bones,
15; skeleton of, 154 et seq.; wing
bones of, 141; pelvis and leg
bones of, 144; structure of the
foot in, 148; mechanism of flight
in, 149

Boa-constrictor, skull of the, 81;
jaws of the, 83; section of its
skull, 90

Bones, on the formation and com-
position of the, 15 et seg.; of the
vertebrate animals, 15; their che-
mical composition, 15; matter of,
variously disposed, 2b.; the blas-
tema and cartilage of, 21; the
primitive bases of, 21; the growth
of, 22; structure of, in different
classes of animals, 24; names of
different cells, 7b. (see SKELETON);
of the fish, 35 et seg.; of the head,
general and special names of, 48;
classification of the, 50

Bonito, teeth of the, 242

Bothriolepis (Gr. dothrion a hollow
pit, and lepis a scale), pliciden-
tine of the, 247

Bottle-nose cetacean, teeth of the,
259

Bradypus tridactylus (Gr. bradus
slow, and pous a foot; trza three,
and daktylot fingers), bones of
the, 191

Brain, the upper or anterior divi-
sion of the great trunk of the
nervous system, 30

Branchial arches (Gr. branchia the
gills), 49

Branchiostegal rays (Gr. branchia
the gills, and Lat. tego to cover),
44, 50

Bruta, order of their numerous
teeth, 259; dentition of the, 294

(See

C

Cachalot, teeth of the, 259
Calcaneum bone, or calcaneal pro-

INDEX.

cesses (Lat. calz, or caleaneum,

the heel), 188, 146, 147; of the

hind foot in animals, 185, 187.
Calcification of the dental process,

286

Canines (Lat. canis a dog), of the
Carnivora, 264; of the horse, 271

Capucin monkey, dentition of the,
305

Carapace (Gr. karabos a crab) of
the turtle, 124

Carnivora (Lat. caro flesh, and voro
to devour), teeth of the, 264

Carnivorous mammalia, skeleton of
the, 200

Carpal bones of the cod-fish (Gr.
karpos the wrist), 41, 42; of the
crocodile, 118; in man, 216

Caudal vertebrae (Lat. cauda the
tail), modifications of the, 55, 102

Cebus (Gr. kebus a species of mon-
key), dentition of the, 505

Cellular substance of animals, 13

Cement of the teeth, 233

Centrum (Gr. kentron a centre), the
centre bone of the vertebra, 26,
32, 33; of the parietal vertebra,
called basisphenoid, 48; called
presphenoid, 45

Ceratohyal (Gr. keras a horn, and
hualos glass), 44, 58

Cercopithecus (Gr. kerkos a tail, and
pithex an ape), skeleton of the, 211

Cestracion (Gr. kestron a dart), os-
teodentine of the, 247

Cetacea, or Cetacians (Gr. kete a
whale), limbs of the, 151; skele-
ton of the, 153

Cetiosaurus (Gr. kee a whale, and
saura a lizard), vertebra of the,
98

Cheetodonts (Gr. chaite a bristle, and
odou a tooth), teeth of the, 242

Chelonian reptiles (Gr. chelone a
tortoise), osteology of the, 100 e¢
seq. (see Tortoise); masticating
organs of the, 249

Chimeroids (Gr. chimera a mon-
ster, and eédos resemblance), va-
sodentine of the, 247

Chimpanzee, cranial development of
the, 223; dentition of the, 302

INDEX.

Citherine (Gr. cithara a harp),
teeth of the, 242

Clavicles (Lat. clavis a key), 98

Cobra, skeleton of the, 74

Cod-fish, bones of the, 86 e¢ seq. ;
its skull, 37; its occipital verte-
bra, 40

Condyloid cavity (Gr. kondylos a
protuberance, and eidos resem-
blance), 145; in birds, 147

Confluent (Lat. conjflwens flowing to-
gether), 42

Connate (Lat. con and naius born
together), 42

Coracoid bone (Gr. kerax and eidos
crow-like), 40

Cottoids (Gr. kotte a head, and eidos
resemblance), osteodentine . of
the, 247

Cotyloid cavity (Gr. kotyle a drink-
ing-cup, and eidos resemblance),
144

Cranial arches (Lat. cranium the
skull), 102

Cranium (Gr. kranion the skull),
application of the term, 52; its
progressive expansion in various
animals, 222

Crocodile, osteology of the, 95 et
seg.; Skeleton of the, 95, 113;
vertebre of the, 96; vertebrz of
extinct species, 97, 98; its skull,
103 et seg.; its limbs, 115, 117;
pelvis and hind-limb of the, 119;
its cranial development, 222; its
teeth, 256

Ctenodus (Gr. odouws a tooth), osteo-
dentine of the, 247

Cuboides bone (Gr. kubos a cube,
and eidos resemblance), 134; cu-
boid of the hind foot in animals,
185, 186

Cuneiforme, one of the carpal bones,
216

Cuvier, Baron, his contempt for
metaphysical theorizing, 221

D

Dendrodentine (Gr. dendron a tree,
and Lat. dens a tooth), in fishes,
247

d19

Dendrodus (Gr. dendron a tree, and
odous a tooth), dendrodentine of
the, 247

Dental systems (see TEETH).

Dentary, the, 46

Dentinal tissues of the teeth, 231

Dentine (Lat. dens a tooth), the tis-
sue forming the body of the tooth,
230; first modification of, 232;
disposition of the, 287; modifi-
cations of, in various genera of
fishes, 247; of the elephant, 286

Dentition (see TEETH).

Dermoskeleton (Gr. derma the skin,
and skeleton), 16; of the stur-
geon, 17; of thé armadillo, &c.,
19; chief developments of the,
51; the cranial bones, the supra-
temporals, the superorbitals, the
suborbitals, the lachrymal, and
the labials, 52

Diapophyses (Gr. dia across, apo
from, and phusis growth), bones
of the vertebra, 26 et seg. sepe;
of parietal vertebra called mas-
toid bone, 43

Diastema of the horse (Gr. dia be-
tween, and ‘semi to stand), 169

Dicynodon lacerticeps (Gr. di two,
kuon dog, and odous a tooth, and
Lat. dacerta a lizard), skull and
teeth of the, 253

Dicynodonts (Gr. see ante), denti-
tion of the, 253

Diodon (Gr. dis double, and odous a
tooth), 243, 247

Diver, tarso-metatarse of the, 148

Dog, cranial development of the,
293

aavo

Dolphin, teeth of the, 259

Duck, skeleton of the, 141; quill
feathers of the, 144

Dugong, skeleton of the, 157

1D)

Ectocalcaneal (Gr. ektos out of, and
calcaneum the heel), 147

Ectocarotid canal (Gr. ekto out of,
and karos stupor), 169

Ectocondyloid surface (Gr. ektes out

320
of, and kondylos a protuberance),
146

Ectocuneiform (Gr. ektos out of,
and Lat. cuneus a wedge), 170;
of the hind foot in animals, 185,
186

Ectometatarse (Gr. ekios out of,
meta over, and tarsos the palm of
the hand or foot), 147

Ectocnemial ridge (Gr. ektos out of,
and kneme the knee), 145

Ectopterygoid (Gr. ektos sixth, pte-
ryxz a Wing, and eédos, likeness),
angle of the, 80, 82 et seq. spe.

Edaphodonts (Gr. dapio to tear, and
odous a tooth), dental masses of
the, 250

Edentata (Lat. edens eating), skele-
tons of the, 152, dentition of the,
294

Elephant; its tarsal bones, 187;
dentition of the, 238, 2389, 259,
309; its skull and teeth, 273; its
tusks and molars, 274 et seq.

Enamel of the teeth, 238; of the
elephant’s tooth, 285

Endoskeleton (Gr. exdos and skeletos
the inner skeleton), 119

Entocalcaneal process (Gr. entos
within, and Lat. calcanewm the
heel), 147

Entocondyloid cavity (Gr. entos
within, condylos a protuberance,
and eidos resemblance), 147

Entometatarse (Gr. entos within,
meta over, and tarsos, the palm of
the hand or foot), 147

Entopterygoids (Gr. entos within,
and pterygoidos wing-like), 48, 169

Entosternum (Gr. entos within, and
sternon the breast-bone), 128

Epapophysis (Gr. epi above, and
apophysis springing from), 28

Epicnemial ridge (Gr. epiupon, and
kneme the knee), 145

Epidermoid system (Gr. epi upon,
and dermos the skin), 141

Epiphyses (Gr. epi and phuo grow-
ing upon), the ossified ends of
bones, 22

Episternal (Gr. epi and sternon on
the breast-bone), 128

INDEX.

Episternum (Gr. wi ante), 128; of
the crocodile, 115

Epitympanic bone (Gr. epi and tym-
panon on the drum), 43 _

European skull, facial angle of the,
224

Eustachian process (leading from
the pharynx to the tympanum, so
called from Eustachius the dis-
coverer), 169

Ex-occipitals of the python (Lat. ex
from, and occiput the back of the
head), 76

Exoskeleton (Gr. ex and skeletos the
outer skeleton), 119

F

Fabella (Lat. a little bean) of the
sloth, 192

Facial angle, representations of the,
in various animals, 222; of the
Australian and the European, 224

Femur (Lat. the thigh-bone) of the
crocodile, 120

Fibula (Lat. fidula the lesser bone
of the leg) of the crocodile, 120;
of the sloth, 198

Fins of fishes; structure of the, 55;
the ventral, 62; general action of
the, ib.

Fishes, composition of their bones,
14; vertebree of, 33; skeleton of,
ib. et seq.; the first forms of ver-
tebrate life, 50; arrangement of
bones in their heads, 7b. ; modifi-
cations of the jaws of, 51; their
caudal vertebrae, 55; modifica-
tions of the fin-rays of, 56; oste-
ological structure of their heads,
2b.; adaptation of their skull and
skeleton to aquatic life, 59, 61;
action of their fins, 68; their
system, 240; shedding and dental
renewal of the teeth in, 249

Flying lizard, vertebrze of the, 92

Foot, distinct bones of the, in dif-
ferent mammalia, 185, 186; law
of simplification of the, 187

Foramina (Lat. foramen an open-
ing), 80

INDEX.

Frog, skeleton of the, 68, 69, 71;
metamorphosis of its skeleton,
68; of its skull, 70

Frontal segment, or vertebrae, 45.

Frontals (Lat. frons the front) of
the python’s skull, 79

Fureulum bone (Lat. furca a fork),
189

G

Galeopithecus (Gr. gale a weasel,
and pithikos a monkey), teeth of
the, 307.

Ganoid (Gr. ganos brightness), a
term applied to the scales of cer-
tain fishes, 19

Ginglymoid condyle (Gr. ginglymos
and eidos hinge-like), 46

Graffe, skeleton of the, 170; bony
structure of its head, 174

Glossohyal (Gr. glossa the tongue,
and hyoid the bone like the Greek
letter upsilon), 53

Glyptodons (Gr. glupho to engrave,
and odous a tooth) of S. America,
20

Gobioids (Lat. gobio a gudgeon, and
Gr. eidos resemblance), osteoden-
tine of the, 247

Goniodonts (Gr. gonia an angle, and
odous a tooth), teeth of the, 242

Goose, skeleton of the, 140; quill
feathers of the, 144

Gorilla, dentition of the, 802

Grinders of the elephant, 281 et seq.

Gryllotalpa (Gr. grillizo to grunt,
and Lat. talpa a mole), bones of
the, 197

Il

Heemal arch (Gr. haima blood), of
the vertebra, 26, 43; of the occi-
pital vertebra of the cod-fish, 40;
called the hyoidean arch, 43

Hemal arches of the skull—the
scapular, the hyoidean, the man-
dibular, and the maxillary, 51;
diverging appendages of the—

o21

the pectoral, the branchi-ostegal,
the opercular, and the pterygoid,
51

Heemal spine of parietal vertebra,
its divisions— basihyal, glosso-
hyal, and urohyal, 44

Heemapophyses (Gr. haima blood,
and apophysis springing from),
bones of the vertebra, 27 et seg.
sepe.

Heemapophysis of the parietal ver-
tebra, its divisions—epihyal and
ceratohyal, 44

Hallux (Lat. the great toe), 146

Head, bones of the, 48; and their
classification, 48, 49; structure
of the, in fishes, 56

Hearing, organ of, 31; in the cod-
fish, 43; the petrosal and the
otosteal of the cod-fish, 43

Hippopotamus (Gr. hippos a horse,
and potamos a river), skeleton of
the, 178; tarsal bones of the, 187

Hog, osteology of the, 180; denti-
tion of the, 310

Holoptychius (Gr. holos entire, and
plychos a fold), plicidentine of
the, 247

Hoofed beasts, even-toed, osteologi-
cal characters of, 180

Hoofed quadrupeds, skeletons of,
162

Hornbill, enormous beak of the, 24

Horse, skeleton of the, 162; its
vertebral formula, 164; its tarsal
bones, 185, 186; incisor tooth of
the, 285; herbivorous dentition
of the, 270; its upper and lower
molars, 271; development and
succession of teeth in the, 272

Human teeth, homologies of the,
3138

Hyena, dentition of the, 265;
strength of his jaw, 7.

Hybodus, (Gr. hybos hump-backed,
and odous a tooth), osteodentine
of the, 247

Hydromys (Gr. hydor water, and
mus 2 mouse), 259

Hyoidean arch (Gr. w-eidos like the
letter U), the name of a hemal
arch, 44, 53

22

Hyosternal (Gr. hyo, and sternon
the breast bone), 128

Hypapophysis (Gr. hypo below, and
apophysis springing from), 28

Hyperoodon (Gr. hyper above, and
odous a tooth), dentition of the,
259

Hyposternal (Gr. hypo under, and
sternon the breast-bone), 128

Hypotympanic bone (Gr. hypo and
tympanon under the drum), 45

Hyrax (Gr. hyrax the rock rabbit),
dentition of the, 308

I

Ichthyosaurus (Gr. ichihus a fish,
and sauwra a lizard), vertebre of
the, 98

Tguana, osteology of the, 91, 93

Iguanodon (Gr. iguana a saurian
reptile, and odows a tooth), den-
tition of the, 252

Iliac bones (Lat. da the flanks), 130

Incisor tooth, magnified section of
the, 230

Incisors (Lat. incedo to cut in), 0
the carnivora, 264 ,

Intercondyloid tract (Lat. inter be-
tween, and Gr. kondylos a protu-
berance), 146

Ischium (Gr. ischis the lumbar re-

gion), 131

Ivory, supplied from the discovered
tusks of the mammoth, 275; mus-
ket-balls often found in, 276

J

Jacchus (Gr. iacho to ery aloud),
dentition of the, 806

Jaws of fishes, modifications of the,
53; of the boa-constrictor, 83

K

Kangaroo, skeleton of the, 205

INDEX,

L

Labroids (Gr. Jabros voracious, and
eidos appearance), dentine of the,
247

Labyrinthodonts (Gr. labyrinthos a
labyrinth, and odous a tooth), a
singular variety of extinct Batra-
chians, 236; teeth of the, 7.

Lachrymals (Lat. lacryme tears), 81

Lamelliform teeth of fishes (Lat.
lamina a thin plate, and forma
shape), 248

Lancelet-fish, skeletal framework of
the, 25

Lemuride (Lat. lemur a hobgoblin),
teeth of the, 307

Lemurs, teeth of, 307

Lepidosiren (Gr. lepis a scale, and
siren & water-nymph), osteoden-
tine of the, 247

Lepidosteus (Gr. lepis and osteon
bony-scaled), a fish of the Ohio,
19

Leptobranchii (Gr. leptos slender,
and branchos the throat), order
of the, 240

Limbs of animals, nature of, 183;
of the protopterus, 7b.; of the
sloth, 189, 192; of the batra-
chians, 65

Lion, skeleton of the, 198-204 ; its
jaws and teeth, 263, 264

Lithophytes (Gr. lithos a stone, and
phuton a plant), the food of the
Seari, 247

Lizards, osteology of, 91-95; dental
system of, 253

Loggerhead, a species of turtle so
called, 123

Lophioid fishes (Gr. lophos a crest
or mane, and eidos resemblance),
61

Lophius (Gr. lophos a crest), den-
tine of the, 247; plicidentine of
the, 247

Lumbar vertebra (Lat. Jumbus the
back), 100

Lunare (Lat. one of the carpal
bones), 216

INDEX.

M

Macropus elegans, or kangaroo (Gr.
makros long, and pous a foot),
skeleton of the, 205

*Magnum (Lat. magnus great), one
of the carpal bones, 216

Mammalia, bones of the, 14, 24;
principal forms of the skeleton in
the, 151; dental system of the,
258, 261

Mammoths, tusks of, discovered in
various parts of the world, 275;
molars of the, 278, 279

Man, limbs of, 151; skeleton of,
209 et seg.; his varied powers of
action, 213; skull of, 216; his
adaptation to an erect posture,
214; modifications of the skele-
ton of, 215; the sole species of
his genus, and the only repre-
sentative of his order, 227; his
teeth, deciduous and permanent,
312

Mandibular arch (Lat. mandibula
the jaw) of the boa-constrictor,
82

Manubrium (Lat. a hilt) of the
mole, 198

Marmoset monkeys, teeth of the,
306

Marsupial bones (Gr. marsupion a
pouch), 16

Mastodon giganteus (Gr. mastos an
udder, and odous a tooth), tusks
of the, 292

Mastoid (Gr. mastos and etdos nip-
ple-shaped), 78

Maxillary bone (Lat. maxilla the
jaw), 48, 52; of the boa-con-
strictor, 81; diverging append-
ages of the, 219

Megalichthys (Gr. megas great, and
ichthus a fish), dentine of the, 247

Megalosaurus (Gr. megas great, and
sauros a lizard), tooth of the, 251

Megalonyx (Gr. megale great, and
onyx % claw), an extinct race of
quadrupeds, 188

Megatherium (Gr. mega great, and |
therion a beast), an extinct race
of quadrupeds, 188; teeth of the,

5293

292; deductions from the dental
system of the, 296

Menopome, vertebral skeleton of
the, 65

Mesocalcaneal process (Gr. mesos
middle, and Lat. calcanewm the
heel), 147

Mesencephalic (Gr. mesos middle,
en in, and kephale the head), 79

Mesocuneiform (Gr. mesos middle,
and Lat. cwneus a wedge), of the
hind foot in animals, 185, 186

Mesosternals (Gr. mesos middle, and
sternon the breast-bone), 128

Mesotympanic bone (Gr. mesos and
tympanon the middle drum), 45

Metacarpal (Gr. meta with, and car-
pos the wrist), 118

Metapophysis (Gr. meta between,
and apophysis springing from), 28

Molars of the elephant, 274 et seq. ;
their succession, 281; their de-
velopment, 284; of the hog, 310

Mole, skeleton and bones of the, 195

Monkeys, teeth of, 305

Morse, skull and teeth of the, 266

Mustela (Lat. the weasel), dentition
of the, 306

Mycetes (Gr. mukao to howl), den-
tition of the, 306

Mylodon (Gr. mule a grinder, and
odous a tooth), an extinct race of
quadrupeds, 188

Myliobates (Gr. myliao to grind,
and batos a thorn), a genus of
fishes belonging to the family
Raides, 241; vasodentine of the,
247

Myonine matter (Gr. myon a mus-
cle) of animals, 13

Myrmecophaga (Gr. myrmos an ant,
and phago to eat), edentulous
animals, 258

Myxinoids (Gr. myzxa mucus, and
eidos resemblance), teeth of the,
241

N
Narwhal, jaw-bones of the, 258

Nasal vertebra, 48; spine of the,
219

324

Natatorial birds natatores
swimmers), 150

Neural arch (Gr. neuron a nerve) of
the vertebrae, 26

Neural arches of the skull—the en-
cephalic, the mesencephalic, the
prosencephalic, and the rhinen-
cephalic, 51

Neural spine of parietal vertebra,
called parietal bone, 43; of fishes,
ib.

Neurapophysis (Gr. newron a nerve,
and apophysis springing from), a
neural process, 27 et seq. swpe;
of parietal vertebra, called ali-
sphenoid, 48

Neurine matter of animals, 13

Neuro-skeleton, 16, 18; segmental
composition of the, 26

Neuro-skeletal segments of verte-
bre of the skull—the occipital,
the parietal, the frontal, and the
nasal, 51

Notation of teeth, 313

Notochord (Gr. notos the back, and
chorda cord), the oS alas dor-
sal gelatinous chord}

(Lat.

O

Occipital vertebra (Lat. occiput the
back part of the head), of the
cod-fish, 40; of the python, 77

Odontoid process of the axis (Gr.
odous a tooth, and eidon resem-
blance), 96

Olfactory capsule (Lat. o/facio to
smell, and capsula a little cover-
ing), 81

Olfactory lobes, the, 47

Operculum (Lat. a covering flap),
bones of the, 46; consists of four
bones, the preopercular, the oper-
cular, the subopercular, and the
interopercular, 7b.

Ophidia (see SERPENT TRIBE).

Opisthoceelian type of vertebre
(Gr. opisthos behind, and koilos
concave), 97

Optic foramina (Gr. optomai to see,
and Lat. foramen an opening), 80

INDEX.

Orbitosphenoid bones (Lat. orbis a
circle, Gr. sphen a wedge, and
eidos resemblance), 45, 80

Ornithorhynchus (Gr. ‘ornithos 8
bird, and rhynchos a beak), teeth
of the, 258

Orycteropus (Gr. orykter a digger,
and pous a foot), tooth of the, 288

Os coccygis (Lat. os a bone, and Gr.
kokkux a cuckoo), 215

Os spheno-occipital of the skull, 218

Osseous system, primary classifica-
tion of the, 16

Ossicles (Lat. ossieulum
bone), 120

Osteine (Gr. osteon a bone), the
matter or tissue so called, 13;
arrangement of, 21

Osteodentine (Gr. osteon a bone, and
Lat. dens a tooth), 283; in vari-
ous genera of fishes, 247

Osteology (Gr. osteon and logos a
discourse on bones), principles
of, 18; general and special terms
in, 221 (see SKELETON AND
Bones).

Otocrane (Gr. ota the ears, and
cranion the skull), 31

Ourang-outang, skeleton of the,
210; dentition of the, 502

Ox, tarsal bones of the, 185

a little

P

Pachydermata (Gr. pachus thick,
and dermata skins), dentition of
the, 308

Palatine bones or Palatines (Lat.
palatum the palate), 47

Palato-pterygoid process (Lat. pa-
latum the palate, and Gr. ptery-
goidos wing-like), 168

Parapophyses (Gr. para transverse,
and apophysis a process), 27 et
seg. spe.

Parietal vertebra (Lat. paries a
wall), 44

Paroccipitals (Gr. para from, and
Lat. occiput back of the head), 182

Parrot-fishes, jaws and food of the,
247

INDEX.

520

Patella (Lat. a little dish), 183; of | Post-frontals of the skull (Lat. post

the sloth, 192

Pectoral fin of the cod-fish (Lat.
pectus the breast), 41

Pelvic arch of the crocodile, 119

Pelvis of birds (Lat. pelvis a basin),
144

Pentadactyle foot of birds (Gr.
pente five, and daktylos a finger
or toe), 148

Perch, teeth of the, 241

Percoids (Gr. perkos spotted, and
eidos appearance), osteodentine of
the, 247

Periosteum (Gr. pert and ositeon
around the bone), 22

Perissodactyla or Perissodactyles
(Gr. perissos an odd number, and
daktylos a finger or toe), 169,
171; the extinct and existing
genera of, 171; dentition of the,
307

Petrosal bone (Gr. petros a stone),
48

Phalanx (Gr. a row of soldiers), 118

Pike, skull and teeth of the, 240

Pisiforme bone (Lat. piswm a pea,
and forma form), 118; one of the
carpal bones, 216

Pithecus Satyrus (Gr. pithex an
ape), skeleton of the, 210, 211

Plasma (Gr. plasma assimilation),
the colorless fluid of the blood, 13

Plastron of the turtle, 126

Platax (Gr. platus wide), teeth of
the, 242

Platycoelian type of vertebree (Gr.
platus flat, and koilos concave), 98

Pleurapophyses (Gr. pleuron a rib,
and apophysis springing from),
bones of the vertebra, 27 et seq.
sape.

Plicidentine (Lat. plico to knit to-
gether, and dens a tooth), in vari-
ous genera of fishes, 247

Poison-fangs of snakes, 256, 257

Polypterus (Gr. polu and pteron
many-finned), a fish of the Nile,
£9

Porcupine, skull and teeth of the,
267

Porpoise, teeth of the, 259

28

behind, and frons the forehead),
45, 80

Postglenoid process of the horse
(Lat. post behind, and Gr. glene
the pupil of the eye), 169

Prefrontals of the skull (Lat. pre
before, and frons the forehead),
47, 80

Premandibular bone (Lat. pre be-
fore, and mandibula the mandi-
ble), 245

Premaxillary (Lat. pre before, and
maxilla the jaw), process of the, 82

Premaxillary teeth, 245

Premolars (Lat. pre before, and
molo to grind) of the carnivora,
264; of the hog, 310

Presphenoid bone (Lat. pre before,
and Gr. sphen and eidos wedge-
like), 45; of the python’s skull,
19

Pretympanic bone (Lat. pre before,
and Gr. tympanon a drum), 45

Primariz, the primary quill-fea-
thers of birds, 141

Prionedon (Gr. prion a saw, and
odous a tooth), dentine of the,
247

Pristis (Gr. a sawyer), vasodentine
of the, 247

Processes of the skull, 50

Procnemial ridge (Gr. pro before,
and kneme the knee), 145

Prooeelian (Gr. pros before, and
koilos concave) type of vertebra,

Prosencephalon (Gr. pros before, en
in, and kephale the head), 79

Proteus (Gr. proteus a marine deity),
skeleton and limbs of the, 184

Protopterus (Gr. protos the first,
and pteryx a wing or fin), 64;
skeleton and limbs of the, 183

Psammodus (Gr. psammos sand, and
odous a tooth), vasodentine of the,
247

Pseudopus (Gr. gseudos false, and
pous a foot) of the lizard kind, 91

Pterygoid process (Gr. pieryx and
eidos wing-like), 48, 168; of the
boa-constrictor, 80

326

Pubis (Lat. pubes the secret parts),
131

Pulp-cavity of the teeth, 231

Pyecnodonts (Gr. pyknos thick, and
odous a tooth), dentine of the,
247

Python (Greek name of a large
serpent, from pytho to poison),

osteology of the, 76; skull of the,

78

Q

Quadricuspid (Lat. guatuor four,
and cuspis a point) shape of the
molars, 803

Quadrumana (Lat. guatuor four, and
manus hands), limbs of the, 151;
skeleton of the, 209, 210; teeth
of the, 301; of South America,
304, 305

Quadrupeds (Lat. guatuor four, and
pedes feet), herbivorous, skeleton
of the, 171, 173; extinct genera
of, 171, 182; odd-toed, 169;
even-toed, 172, 180; extinct
races of, 188

Quill-feathers of birds, their differ-
ent names, 143

R

Radius of the cod-fish (Lat. radius
the lesser arm-bone), 41

Raptorial birds (Lat. raptores seiz-
ers), 149

Rasp teeth, 242

Rattlesnake, vertebra of the, 85;
poison-fang of the, 257; skull of
the, 258

Reptilia, or Reptiles (Lat. reptilis
creeping along), composition of
their bones, 14; principal forms
of the skeleton in, 64 et seg. ;
dental system of, 251

Rhinoceros, skeleton of the, 202,
203; tarsal bones of the, 167, 187

Rhizodes (Gr. rhiza a root, and
eidos resemblance), dentine of
the, 247

INDEX.

Rhynchosaurus (Gr. rhyncus a
snout, and saurus a lizard), jaws
of the, 254

Rodent mammalia (Lat. rodo to
gnaw), teeth of the, 267

Ruminants (Lat. rumino to chew
the cud), skeleton of, 169; teeth
of, 298

8
Sacral vertebrae (Lat. sacer sacred),

Saurians (Gr. saura a lizard), skele-
ton of the, 938, 94; armed with
tusks, 254

Scaphoides (Gr. skaphe a skiff, and
etdos resemblance), 183; of the
hind foot in animals, 185; one of
the carpal bones, 216

Scapula (Lat. scapula the shoulder-
blade), 91

Scapular arch (Lat. see ante), 40;
of the crocodile, 117

Scapulariz (Lat. scapula), the sca-
pulary feathers of birds, 144

Scapulo-coracoid arch (Lat. scapula
the blade-bone, and Gr. korax and
eidos crow-like), 116, 117

Scari (Gr. skaroi parrot-fishes), den-
tine of the, 247; jaws and food
of the, 247

Scizenoids (Gr. skia a shadow, and
eidos resemblance), osteodentine
of the, 247

Sclerotal bones (Gr. skleros hard),
48

Sclero-skeleton (Gr. skleros hard,
and skeleton), 16

Sclerotic capsule of the eye (Gr.
skleros hard, and Lat. capsula a
little cover), 81

Scomberoids (Gr. skombros a marine
fish, and eidos resemblance), teeth
of the, 242

Sea-perch, skeleton of the, 38, 52;
fin-formula of the, 56

Seal, skeleton of the, 158; denti-
tion of the, 299

Secundariz, the secondary quill-
feathers of birds, 144

INDEX.

Senses of animals, nerves of the,
30, 31.

Serpents (Lat. serpens creeping),
osteology of, 75 et seg.; skeleton
of the cobra, 74; structure of the
skull of, 76; the python, 2.;
poisonous, skull of, 84

Sharks, their adaptation to aquatic
life, 62; teeth of, 243; osteo-
dentine of, 247

Sheat-fish, teeth of the, 242

Sheep’s-head fish, teeth of the, 243

Sight, organ of, 31

SKELETON (Gr. skeletos a dried
body), on the principal forms of
the, 13 et seg.; composition and
classification of the bones consti-
tuting the, 14, 15; the dermo
and neuro skeletons, 16, 17;
growth of bones, 21, 22, 238;
structure of bones in different
classes, 24; its segmental compo-
sition, 26; vertebra of the, 28,
88; archetype of the, 29, 80; of
the fish, 37 et seg.; general and
special names of the bones of the,
49, 50; principal forms of the, in
the class Reptilia, 64; of the
frog, 65 et seq. ; the serpent tribe,
75; the lizard, 91; the crocodile,
95 et seg.; of Chelonian Reptiles,
122; of birds, 184; of the class
Mammalia, 151; of the Cetacea,
158; of the seal and walrus, 158,
159; of hoofed quadrupeds, 162;
the horse, 1638; the rhinoceros,
167; the giraffe, 170; of herbi-
vorous quadrupeds, 172; the ca-
mel, 174; the hippopotamus, 178;
the hog tribe, 180; even-toed
hoofed beasts, 7b. ; nature of limbs,
183; of the protopterus, 2b.; limbs
of the amphiuma, the proteus, the
horse, the ox, the rhinoceros, the
hippopotamus, the elephant, 184,
185; of the feet, 1&5; of the sloth,
188; of the ant-eater, 193; of the
mole, 194; of the bat, 199: of the
carnivorous mammalia, 200; of
the lion, 201; of the kangaroo,
Z05; of the quadrumana, 209;

327

of the ape tribe, and of man, 211;
terms in osteology, 221; facial
angle, 222; progressive expansion
of the cranium, 222, 228; Aus-
tralian and European skulls, 224;
retrospect of the various forms of
the, 225

Skull, the four upper or anterior
segments of the osseous system,
30; various segments of, in fishes,
40 et seq.; structure of, in ser-
pents, 76; of the python, 78; of
the boa-constrictor, 81; of poi-
sonous serpents, 84; of the lizard,
92; of the crocodile, 103 et seq. ;
of the sloth, 193; modifications
in the skull of man, 216

Skulls of different animals,
223; of an Australian and a Eu-
ropean, 224

Sloth, skeleton of the, 188; extinct
races of the, 188; its habits and
aptitudes, 188, 189; limbs and
skull of the, 192; dentition of
the, 193

Smell, sense of organ of, 31

Snakes, poisonous, teeth of the, 257

Sparoids (Gr. sparos a sea-fish, and
eidos resemblance), dentine of the,
247

Sphyrena (Gr. the hammer-fish),
teeth of the, 244; dentine of
the, 247; formidable dentition of
the, 247

Spider-monkey, dentition of the, 305,

Splanchno-ske'eton (Gr. splanchna
the bowels), 16; its various parts
—the petrosal, the sclerotal, the
turbinal, the branchial, and the
dental, 51

Splint-bone, one of the carpal bones,
186

Spuriz (Lat. spurius illegitimate),
the bastard feathers of birds, 144

Sting-ray, jaws and teeth of the, 247

Sturgeon, skeleton of the, 15, 16,
17; its habits, 18

Suborbital bones (Lat. swb and or-
bita under the orbit), 49

Superorbital bones (Lat. super and
orbita above the orbit) of fishes,
119

999

<5

528

Supertemporal bones (Lat. super and
tempora above the temples), 49
Suprascapular of the crocodile

(Lat. supra above, and scapula
the shoulder-blade), 115
Swan, skeleton of the, 187, 138;
calcaneal prominence of the, 146
Sword-fishes, premaxillaries of the,

Symbols of teeth, 318
Symphysis (Gr. sun and physis
growing together), 131

r
Tadpole, metamorphoses of the, 68,
69

Tarsal bones (Gr. tarsos the palm of
the hand or foot), of different
mammalia, 185, 187

Tarso-metatarse (Gr. tarsos the
palm of the hand, and meta over),
146; modifications of the, 146

Taste, organ of, 31

Tectrices (Lat. tectum a covering),
the wing coverts of birds, 144

TEETH, on the principal forms and

structures of the, 229 et seqg.; in-
timately related to the food and
habits of the animal, 2b.; vascu-
lar canals of the, 231; dental
tissues and pulp-cavities, 231 ;
chemical and structural composi-
tion of, 254; cement and enamel
of the, 7b.; complex and com-
pound teeth, 285; dental system
of fishes, 240 e¢ seg.; shedding
and renewal of, in fishes, 250; of
reptiles, 250, 251 et seg.; of croco-
diles and poisonous snakes, 257 ;
of mammalia, 258; form, fixation,
and structure of, in the mamma-
lia, 259-261 et seg.; of the carni-
vora, 264; of the morse and the
porcupine, 266, 267; of the
horse, 271; of the elephant, 272-
290; their succession, develop-
ment, &c., 281, 284; of the me-
gatherium, 292; of the anoplo-
therium, 297; of the ruminants,

INDEX.

298; of the seal tribe, 299; of
the quadrumana, 3801; of the
orang and chimpanzee, 805; of
monkeys and lemurs, 306, 307;
homologies of, 308, 312; of the
hog, 810; notation and symbols
of, 313

Tentorium (Lat. a tent), 16

Tibia (Lat. the shin-bone) of the
crocodile, 120; of the sloth, 192

Toes, of birds, 146

Tooth, human, magnified section of
the, 232

Tooth-pulp, the primary basis of
the tooth, 231

Tortoise, osteology of the, 122 et
seq.; skeleton of the, 123; cara-
pace and plastron of the, 124,
126; vertebree of the, 129; skull
of the, 131; limbs of the, 183

Trapezium (Gr. trapezion a four-
sided geometrical figure), one of
the carpal bones, 216

Trapezoides (Gr. trapezion [ut ante]
and eidos resemblance), one of
the carpal bones, 216

Trochanter (Gr. trochao to turn), of
the crocodile, 120

Trochlea, tibial (Gr.
wheel), 145

Troglodytes (Gr. trogle a cavern,
and duno to dwell in), facial an-
gle of the genus, 227

Turbinal bones, or Turbinals (Lat.
turbo a top), 48; of the skull, 80

Turtle, osteology of the, 122; cara-
pace of the, 124; plastron of the,
126

Tusks of the elephant and the mam-
moth, 274, 278

Tympanic bone (Gr. tympanon a
drum), 46, 53; of the boa-con-
strictor, 82

trochos a

U

Ulna of the cod-fish (Lat. wlna the
elbow), 41, 42

Unciforme (Lat. wneus a hook, and
forma shape), one of the carpal
bones, 216

INDEX.

Unguiculator (Lat. wnguis a claw), |

limbs of the, 151

Unguinal phalanges (Lat. unguis a
claw, and Gr. phalan
soldiers), 119

Ungulata (Lat. wngula a hoof), limbs |

of the, 151
Urohyal (Gr. owron urine), 53

V

Varanus, osteology of the, 91, 93;
dentition of the, 251

Vascular canals of teeth, 231

Vasodentine (Lat. vasum a vessel,
and dens a tooth), 285; in various

. genera of fishes, 247

Vertebra (Lat. verio to turn, or
vertebra a turning joint), a gene-
ral term for the vertebral seg-
ments of the skeleton, 221; the
parietal and thoracic, 28; auto-
genous and exogenous parts of
the, 27, 28; frontal segment, 45;
parietal, 44

Vertebre of the neuroskeleton, 26;
various modifications of the, 28;
development of the, 83; the cau-
dal, modifications of the, 55; of
the ophidian reptiles, 84, 86;
of the lizard, 91; of the croco-
dile, 95 et seg.; various types of,
97 et seg.; lumbar and sacral, of
the crocodilia, 100; caudal, 102;
of the tortoise, 129; of the swan,
139; formula of the, in herbivo-
rous quadrupeds, 175; of the!

THE

x a row of |

329

{

bat, 198; of the lion, 201,

of the kangaroo, 207

Vertebrata (Lat. vertebra a turning
joint), the highest division of the
animal kingdom, 14; the four
classes of, 14, 15; composition
of their bones, 7d.

Vertebrated animals, their success-
ive transmutations, 226

Vespertilio murinus (Lat. the com-
mon bat), skeleton of the, 199

Villiform teeth, 241

Vomer (Lat. a ploughshare), 47, 80

202 «

W

Walrus, skeleton of the, 159

Water-rats of Australia, dentition
of the, 259

Whale, its skeleton, 153; its teeth,
258

Wing of the duck tribe, 148

Wolf-fish, teeth of the, 245, 246

Wrasse, teeth of the, 243

Xx
Xiphisternum (Gr. ziphos a sword,
and sternon the breast bone), 128
Z
Zygantium, 86

Zygapophysis (Gr. zugos junction,
and apophysis springing from), 27

END.

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It is certainly the most brilliant contribution to English history made within our recollee-
tion; it has the charm and freedom of Biography combined with the elaborate and care-
ful comprehensiveness of History.—N. Y. Tribune.

BY THE SAME AUTHOR—TO MATCH—(Now Ready.)
LAVES: OF. E

CHIEF-JUSTICES OF ENGLAND,
From the Norman Conquest to the Death of Lord Mansfield.

SECOND EDITION.

In two very neat vols., crown 8vo., extra cloth, or half morocco.
To match the ‘‘Lives of the Chancellors’’ of the same author.

In this work the author has displayed the same patient investigation of histo-
rical facts, depth of research, and quick appreciation of character which have
rendered his previous volumes so deservedly popular. Though the “ Lives of
the Chancellors’? embrace a long line of illustrious personages intimately con-
nected with the history of England, they leave something still to be filled up to
complete the picture, and it is this that the author has attempted in the present
work. The vast amount of curious personal details concerning the eminent
men whose biographies it contains, the lively sketches of interesting periods
of history, and the graphic and vivid style of the author, render it a work of
great attraction for the student of history and the general reader.

Although the period of history embraced by these volumes had been previously tra-
versed by the recent work of the noble and“learned author, and a great portion of ils
most exciting incidents, especially those of a constitutional nature, there narrated, yet
in “The Lives of the Chief-Justices” there is a fund both of interesting information and
valuable matter, which renders the book well worthy of perusal by every one who
desires to obtain an acquaintance with the constitutional history of his country, oe as-
pires to the rank of either a statesman or a lawyer. Few lawyers of Lord Campbell’s
eminence could have produced such a work as he has put forth. None but lawyers ot
his experience and acquirements could have compiled a work combining the same in-
terest as a narration, to the public generally, with the same amount of practical infor-
mation for professional aspirants more particularly.—Britannia.

2 BLANCHARD & LEA’S PUBLICATIONS.—(Miscellaneous.)

THE ENCYCLOPEDIA AMERICANA;

A POPULAR DICTIONARY OF ARTS, SCIENCES, LITERATURE, HIS-
TORY, POLITICS, AND BIOGRAPHY.

In fourteen large octavo volumes of over 600 double-columned pages each.
For sale very low, in various styles of binding.

Some years having elapsed since the original thirteen volumes of the ENCY-
CLOPAEDIA AMERICANA were published, to bring it up to the present day,
with the history of that period, at the request of numerous subscribers, the pub-
lishers have issued a

SUPPLEMENTARY VOLUME (THE FOURTEENTH),
BRINGING THE WORK THOROUGHLY UP.

Edited by HENRY VETHAKE, LL. D.

In one large octavo volume, of over 650 double-columned pages, which may be
had separately, to complete sets.

MURRAY’S ENCYCLOPADIA OF GEOGRAPHY.

THE ENCYCLOPADIA OF GEOGRAPHY, comprising a Complete Description
of the Earth, Physical, Statistical, Civil, and Political ; exhibiting its Rela-
tion to the Heavenly Bodies, its Physical Structure, The Natural History of
each Country, and the Industry, Commerce, Political Institutions, and Civil
and Social State of all Nations. By Hueu Murray, F.R.S.E., &c. Assisted
in Botany, by Professor Hooker—Zoology, &c., by W. W. Swainson—Astrono-
my, &c., by Professor Wallace—Geology, &c., by Professor Jameson. Re-
vised, with Additions, by THomas G. Braprorp. The whole brought up, by
a Supplement, to 1843. In three large octavo volumes various styles of
binding.

This great work, furnished at a remarkably cheap rate, contains about NINETEEN

HUNDRED LARGE IMPERIAL PaGEs, and is illustrated by EIGHTY-TWOSMALL Maps, and a

colored Map oF THE UNITED SrareEs, after Tanner’s, together with about ELEVEN HuN-
DRED W OoD-cuTs executed in the best style.

YOUATT AND SKINNER ON THE HORSE.

THE HORSE.
BY *W4IDLGLIAM VOUAFT:

A new edition, with numerous Illustrations.

TOGETHER WITH A GENERAL HISTORY OF THE HORSE} A DISSERTATION ON THE
AMERICAN TROTTING HORSE } HOW TRAINED AND JOCKEYED 3 AN ACCOUNT
OF HIS REMARKABLE PERFORMANCES; AND AN ESSAY ON THE
ASS AND THE MULE.

BY d: S.fS KINDER,

Assistant Postmaster-General, and Editor of the Turf Register

This edition of Youatt’s well-known and standard work on the Management, Dis-
eases, and Treatmentof the Horse, embodying the valuable additions of Mr. Skinner, has
already obtained such a wide circulation throughout the country, that the Publishers,
need say nothing to attract toitthe attention and confidence of all who keep Horses or
are interested in their improvement.

YOUATT AND LEWIS ON THE DOG.

THE DOG. By William Youatt. Edited by E. J. Lewis, M.D. With numerous and
beautifulillustrations. In one very handsome volume, crown 8vo., crimson cloth, gilt.

BLANCHARD & LEA’S PUBLICATIONS.—(History § Biography.) 3

NEW AND IMPROVED EDITION.

LIVES OF THE QUEENS OF ENGLAND

FROM THE NORMAN CONQUEST.
WITH ANECDOTES OF THEIR COURTS.

Now first published from Official Records, and other Authentic Documents, Private
as well as Public.
NEW EDITION, WITH ADDITIONS AND CORRECTIONS.

BY AGNES STRICKLAND.

In six volumes, crown octavo, extra crimson cloth, or half morocco, printed on
fine paper and large type.

Copies of the Duodecimo Edition, in twelve volumes, may still be had.

A valuable contribution to historical knowledge, to young persons especially. It con-
tains a mass of every kind of historical matter of interest, which industry and resource
could collect. We have derived much entertainment and instruction from the work.—
Atheneum. ~

The execution of this work is equal to the conception. Great pains have been taken
to make it both interesting and valuable.—Literary Gazette.

A charming work— full of interest, at once serious and pleasing.—Monsieur Guizot.

To be had separate.

LIVES OF THE QUEENS OF HENRY VIII, and of his mother, Elizabeth
of York. By Miss Strickland. Complete in one handsome crown octavo
volume, extra cloth. (Just Issued.)

»

MEMOIRS OF ELIZABETH, Second Queen Regnant of England and Ireland.
By Miss Strickland. Complete in one handsome crown octavo volume, extra
cloth. (Just Issued.)

(NOW READY.)
HISTORY OF OLIVER CROMWELL
AND THE ENGLISH COMMONWEALTH,
From the Execution of Charles I, to the Death of Cromwell.

BY M. GUIZOT,.
TRANSLATED BY ANDREW R. SCOBLE.

In two large and handsome royal 12mo. volumes, extra cloth.
(JUST ISSUED.)
MEMORIALS AND CORRESPONDENCE

OF
CHARLES JAMES FOX. -
- Epitep sy LORD JOHN RUSSELL.

In two very handsome volumes, royal 12mo., extra cloth.

(JUST READY.)

WISE SAWS AND MODERN INSTANCES.
BY THE AUTHOR OF SAM SLICK.

In one royal 12mo. volume.

4 BLANCHARD & LEA’S PUBLICATIONS.—(Educational Works.)
A NEW TEXT-BOOK ON NATURAL PHILOSOPHY.
HANDBOOKS —

OF NATURAL PHILOSOPHY AND ASTRONOMY.

BY DIONYSIUS LARDNER, LL.D., ETC.
FIRST COURSE, containing

Mechanics, Hydrostatics, Hydraulics, Pneumatics, Sound, and Opties.

In one large royal 12mo. volume of 750 pages, strongly bound in leather, with
over 400 wood-cuts, (Just Issued.)

THE SECOND COURSE, embracing

HEAT, MAGNETISM, ELECTRICITY, AND GALVANISM,

Of about 400 pages, and illustrated with 250 cuts, is now ready.
THE THIRD COURSE, containing
METEOROLOGY AND ASTRONOMY;
Of nearly 800 pages, with 37 plates, and over 200 wood-cuts, is now ready.

The intention of the author has been to prepare a work which should embrace the
principles of Natural Philosophy, in their latest state of scientific development, divested
of the abstruseness which renders them unfitted for the younger student, and at the same
time illustrated by numerous practical applications in every branchof art and science.
Dr. Lardner’s extensive acquirements in all departments of human knowledge, and his
well-known skill in popularizing his subject, have thus enabled him to present a text-
book which, though strictly scientific in its groundwork, is yet easily mastered by the
student, while calculated to interest the mind, and awaken the attention by showing the
importance of the principles discussed, and the manner in which they may be made
subservient to the practical purposes of life. ‘To accomplish this still further, the editor
has added to each section a series of examples, to be worked out by the learner, thus
impressing upon him the practical importance and variety of the results to be obtained
from the general laws of nature. The subject is sti]l further simplified by the very large
number of illustrative wood-cuts which are scattered through the volume, making plain
to the eye what might not readily be grasped by the unassisted mind ; and every care
has been taken to render the typographical accuracy of the work what it should be.

Although the first portion only has been issued, and that but for a few months, yet it
has already been adopted by many academies and colleges of the highest standing and
character. A few of the numerous recommendations with which the work has been
favored are subjoined.

From Prof. Millington, Univ. of Mississippi, April 10, 1852.

T am highly pleased with its contents and arrangement. It contains a greater number
of every-day useful practical facts and examples than I have ever seen noticed ina
similar work, and I do not hesitate to say that as a book for teaching I prefer it to any
other of the same size and extent that lam acquainted with. During the thirteen years
that I was at William and Mary College J had to teach Natural Philosophy, and I should
have been very glad to have such a text-book.

From Edmund Smith, Baltimore, May 19, 1952.
I have a class using it, and think it the best book of the kind with which I am ae-
quainted.
From Prof. Cleveland, Philadelphia, October 17, 1851.

I feel prepared to say that it is the fullest and most valuable manual upon the subject
that has fallen under my iotice, and I intend to make it the text-book for the first class
in my school.

From 8S. Schooler, Hanover Academy, Va..

The “ Handbooks” seem to me the best popular treatises on their respective subjects
with which I am acquainted. Dr. Lardner certainly popularizes science very well, and
a good text-book for schools and colleges was not before in existence.

From Prof. J. 8. Henderson, Farmer's College, O., Feb. 16, 1852.

It is an admirable work, and well worthy of public patronage. For clearness and
fniness it is unequalled by any that Ihave seen.

BLANCHARD & LEA’S PUBLICATIONS.—(Educational Works.) 5

NEW AND IMPROVED EDITION.—(Now Ready.)

OUTLINES OF ASTRONOMY.
BY SIR JOHN F. W. HERSCHEL, F. R. S., &e.

A NEW AMERICAN FROM THE FOURTH LONDON EDITION.

In one very neat crown octavo volume, extra cloth, with six plates and nu-
merous wood-cuts.

This edition will be found thoroughly brought up to the present state of as-
tronomical science, with the most recent investigations and discoveries fully
discussed and explained.

We now take leave of this remarkable work, which we hold to be, beyond a doubt,
the greatest and most remarkable of the works in which the laws of astronomy and the
appearance of the heavens are described to those who are not mathematicians nor ob-
servers, and recalled to those who are. It is the reward of men who can descend from
the advancement of knowledge to care for its diffusion, that their works are essential
to all, that they become the manuals of the proficient as well as the text-books of the
learner.— Atheneum. ,

There is perhaps no book in the English language on the subject, which, whilst it con-
tains so many of the facts of Astronomy (which it attempts to explain with as little tech-
nical language as possible), is so attractive in its style, and so clear and forcible in its
illustrations.— Evangelical Review.

Probably no book ever written upon any science, embraces within so smalla compass
an entire epitome of everything known within all its various departments, practical,
theoretical, and physical.— Examiner.

A TREATISE ON OPTICS.

BY SIR DAVID BREWSTER, LL. D., F.R.S8., &c.
ANEW EDITION.

WITH AN APPENDIX, CONTAINING AN ELEMENTARY VIEW OF THE APPLICATION
OF ANALYSIS TO REFLECTION AND REFRACTION.

BY A. D. BACHE, Superintendent U. 8. Coast Survey, &c.
In one neat duodecimo volume, half bound, with about 200 illustrations.

BOLMAR’S FRENCH SERIES.

New editions of the following works, by A. Bormar, forming a complete
series for the acquisition of the French language :—

LEVIZAC’S THEORETICAL AND PRACTICAL GRAMMAR OF THE
FRENCH LANGUAGE. With numerous Corrections and Improvements;
a complete Treatise on the Nouns and all the Verbs, by A. Bolmar, In one
volume, 12mo.

A SELECTION OF ONE HUNDRED PERRIN’S FABLES, accompanied by

a Key, containing the text, a literal and free translation, arranged in such a manner as
to point outthe difference between the French and English idiom, &e. In one vol.12mo.

A COLLECTION OF COLLOQUIAL PHRASES, on every topic necessary to
maintain conversation. Arranged under different heads, with numerous remarks on
the peculiar pronunciation and uses of various words; the whole so disposed as con-
siderably to facilitate the acquisition of a correct pronunciation of the French. In
one vol. 18mo.

LES AVENTURES DE TELEMAQUE, PAR FENELON, in one vol. 12mo.,

accompanied by a Key to the first eight books. In one vol. 12mo., containing, like the
Fables, the ‘Text, a literal and free translation, intended as a sequel to the Fables.
Either volume sold separately. 5

ALL THE FRENCH VERBS, both regular and irregular, in a small volume.
1*

6 BLANCHARD & LEA’S PUBLICATIONS.—(Educational Works.)

ELEMENTS OF NATURAL PHILOSOPHY;

BEING
AN EXPERIMENTAL INTRODUCTION TO THE PHYSICAL SCIENCES,
Illustrated with over Three Hundred Wood-cuts.

BY GULDING BIRD, M.D.,

Assistant Physician to Guy’s Hospital.

From the Third London edition. In one neat volume, royal 12mo.

We are astonished to find that there is room in so small a book for even the bare
recital of so many subjects. Where everything is treated succinetly, great judgment
and much time are needed in making a selection and winnowing the wheat from the
chaff. Dr. Bird has no need to plead the peculiarity of his position as a shield against
criticism, so long as his book continues to be the best epitome in the English lan-
guage of this wide range of physical subjects——North American Review, April 1, 185.

From Prof. John Johnston, Wesleyan Univ., Middletown, Ct.

For those desiring as extensive a work, I think it decidedly superior to anything of
the kind with which I am acquainted.

From Prof. R. O. Currey, East Tennessee University.

I am much gratified in perusing a work which so well, so fully, and so clearly sets
forth this branch of the Natural Sciences. For some time I have been desirous of ob-
taining a substitute! for the one now used—one whieh should embrace the recent dis-
coveries in the sciences, and I can truly say that such a one is afforded in this work of
Dr. Bird’s.

From Prof. W. F. Hopkins, Masonic University, Tenn.

It is just the sort of book I think needed in most colleges, being far above the rank of

a mere popular work, and yet not beyond the comprehension of all but the most accom-

plished mathematicians.

ELEMENTARY CHEMISTRY;

THEORETICAL AND PRACTICAL.
BY GEORGE FOWNES, Pu. D.,

Chemical Lecturer in the Middlesex Hospital Medical School, &e. &e.
WITH NUMEROUS ILLUSTRATIONS.
Third American, from a late London edition. Edited, with Additions,

BY ROBERT BRIDGES, M.D.,

Professor of General and Pharmaceutical Chemistry in the Philadelphia
College of Pharmacy, &e. &c.

In one large royal 12mo. volume, of over five hundred pages, with about 180
wood-cuts, sheep or extra cloth.

The work of Dr. Fownes has long been before the public, and its merits have been
fully appreciated as the best text-book on Chemistry now in existence. We do not, of
course, place it in a rank superior to the works of Brande, Graham, Turner, Gregory,
or Gmelin, but we say that, as a work for students, itis preferable to any of them.—Lon-
don Journal of Medicine.

We know of no treatise so well calculated to aid the student in becoming familiar
with the numerous facts in the science on which it treats, or one better calculated as
a text-book for those attending Chemical Lectures. * * * * The best text-book on Che-
mistry thathas issued from our press.—American Med. Journal.

We know of none within the same limits, which has higher claims to our confidence
as a college class-book, both for accuracy of detail and scientific arrangement.—Au-
gusta Med. Journal.

ELEMENTS OF PHYSICS.

OR, NATURAL PHILOSOPHY, GENERAL AND MEDICAL. Written for uni-
versal use, in plain, or non-technical language. By Neitt Arnotr, M.D. In one
octavo volume, with about two hundred illustrations.

BLANCHARD & LEA’S PUBLICATIONS.—(Educational Works.) 7

NEW AND IMPROVED EDITION.—(Now Ready.)

PHYSICAL GHOGRAPHY.
; BY MARY SOMERVILLE.

A NEW AMERICAN FROM THE LAST AND REVISED LONDON EDITION.
WITH AMERICAN NOTES, GLOSSARY, ETC.

BY W. S. W. RUSCHENBERGER, M.D., U.S. N.

In one neat royal 12mo. volume, extra cloth, of over five hundred and fifty pages.

The great success of this work, and its introduction into many of our higher schools
and academies, have induced the publishers to prepare a new and much improved
edition. In addition to the corrections and improvements of the author bestowed on
the work in its passage through the press a second time in London, notes have been
introduced to adapt it more fully to the physical geography of this country; and a
comprehensive glossary has been added, rendering the volume more particularly suited
to educational purposes.

Our praise comes lagging in the rear, and is wellnigh superfluous. But we are
anxious to recommend to our youth the enlarged method of studying geography which
hér present work demonstrates to be as captivating as it is instructive. We hold
such presents as Mrs. Somerville has bestowed upon the public, to be of incalculable
value, disseminating more sound information than all the literary and scientific insti-
tutions will accomplish in a whole cycle of their existence.—Blackwood’s Magazine.

From Lieutenant Maury, U.S. N.
National Observatory, Washington, June 26, 1853.

I thank you for the “ Physical Geography” itis capital. I have been reading it, and
like it so much that! have made it a school-book for my children, whom i am teaching.
There is, in my opinion, no work upon that interesting subject on which it treats— Physical
Geography—that would make a better text-book in our schools and colleges. I hope it
will be adopted as such generally, for youhave Americanized it andimproved it in other
respects. Yours, truly,

M. F. MAURY.
Dr. W.S. W. RuscHENBERGER, U.S.N.,
Philadelphia.

i _ ._ From Thomas Sherwin, High School, Boston. ;
T hold it in the highest estimation, and am confident that it will prove a very efficient

aid in the education of the young, and a source of much interest and instruction to the
adult reader. e

From Erastus Everett, High School, New Orleans.

I have examined it with a good deal of care,and am glad to find thatit supplies an im-
portant desideratum. The whole work is a masterpiece. Whether we examine the
importance of the subjects treated, or the elegant and attractive style in which they are
presented, this work leaves nothing to desire. I have introduced it into my school for
the use of an advanced class in geography, and they are greatly interested init. I have
no doubt that it will be used in most of our higher seminaries.

JOHNSTON'S PHYSICAL ATLAS.

THE PHYSICAL ATLAS

OF NATURAL PHENOMENA.
FOR THE USE OF COLLEGES, ACADEMIES, AND FAMILIES.
BY ALEXANDER KEITH JOHNSTON, F.R.G.S., F.G.8.

In one large volume, imperial.quarto, handsomely and strongly bound. With
twenty-six plates, engraved and colored in the best style. Together
with one hundred and twelve pages of Descriptive Letter-press,
and a very copious Index.

A work which should be in every family and every school-room, for consultation and
reference. By the ingenious arrangement adopted by the author, it makes clear to the
eye every fact and observation relative to the present condition of the earth, arranged
under the departments of Geology, Hydrography, Meteorology, and Natural History.
The letter-press illustrates this with a body of important information, nowhere else to
be found condensed into the same space, while’a very full Index renders the whole
easy of reference.

8 BLANCHARD & LEA’S PUBLICATIONS.—(Educational Works.)
SCHMITZ AND ZUMPT’S CLASSICAL SERIES.

Under this title BLancHArp & Leta are publishing a series of Latin School-
Books, edited by those distinguished scholars and critics, Leonhard Schmitz
and C.G. Zumpt. The object of the series is to present a course of accurate
texts, revised in accordance with the latest investigations and MSS., and the
most approved principles of modern criticism, as well as the necessary element-
ary books, arranged on the best system of modern instruction. The former are
accompanied with notes and illustrations introduced sparingly, avoiding on the
one hand the error of overburdening the work with commentary, and on the other
that of leaving the student entirely to his own resources. The main object has
been to awaken the scholar’s mind to a sense of the beauties and peculiarities
of his author, to assist him where assistance is necessary, and to Jead him to
think and to investigate for himself. For this purpose maps and other en-
gravings are given wherever useful, and each author is accompanied with a
biographical and critical sketch. The form in which the volumes are printed
is neat and convenient, while it admits of their being sold at prices unpre-
cedentedly low, thus placing them within the reach of many to whom the cost
of classical works has hitherto proved a bar to this department of education;
while the whole series being arranged on one definite and uniform plan, enables
the teacher to carry forward his student from the rudiments of the language
without the annoyance and interruption caused by the necessity of using text-
books founded on varying and conflicting systems of study.

CLASSICAL TEXTS PUBLISHED IN THIS SERIES.

I. CHESARIS DE BELLO GALLICO LIBRI IV., 1 vol. royal 18mo., extra
cloth, 232 pages, with a Map, price 50 cents.

II. C.C. SALLUSTII CATILINA ET JUGURTHA, 1 vol. royal 18mo., extra
cloth, 168 pages, with a Map, price 50 cents.

III. P. OVIDII NASONIS CARMINA SELECTA, 1 vol. royal 18mo., extra’
cloth, 246 pages, price 60 cents.

IV. P. VIRGILII MARONIS CARMINA, 1 vol. royal 18mo., extra cloth, 438
pages, price 75 cents.

V. Q. HORATII FLACCI CARMINA EXCERPTA, 1 vol. royal 18mo., extra
cloth, 312 pages, price 60 cents.

VI. Q. CURTII RUFI DE ALEXANDRI MAGNI QU SUPERSUNT, 1
vol. royal 18mo., extra cloth, 326 pages, with a Map, price 70 cents.

VII. T. LIVII PATAVINI HISTORIARUM LIBRI I., II., XXI., XXII., 1
vol. royal 18mo., ex. cloth, 350 pages, with two colored Maps, price 70 cents.

VIII. M. T. CICERONIS ORATIONES SELECT/E XII., 1 vol. royal 18mo.,
extra cloth, 300 pages, price 60 cents.

IX. CORNELIUS NEPOS, 1 vol. royal 18mo., price 50 cents.

ELEMENTARY WORKS PUBLISHED IN THIS SERIES.

lz
A SCHOOL DICTIONARY OF THE LATIN LANGUAGE. By Dr. J. H.
KaxttscHmipt. In two parts, Latin-English and English-Latin.

Part I., Latin-English, of nearly 500 pages, strongly bound, price 90 cents.
Part II., English-Latin, of about 400 pages, price 75 cents.
Or the whole complétg in one very thick royal 18mo. volume, of nearly 900
closely printed double-columned pages, strongly bound in leather,
price only $1 25.

hi be
GRAMMAR OF THE LATIN LANGUAGE. By Lronuarp Scumirz, Ph.
D., F.R.S.E., Rector of the High School, Edinburgh, &c. In one hand-
some volume, royal 18mo., of 318 pages, neatly half bound, price 60 cents.

BLANCHARD & LEA’S PUBLICATIONS.—(Educational Works.) 9

SCHMITZ AND ZUMPT’S CLASSICAL SERIES—Continued.

ed

ELEMENTARY GRAMMAR AND EXERCISES. By Dr. Leonwarp Scumitz,
F.R.S.E., Rector of the High Schoo], Edinburgh, &c. In one handsome
royal 18mo. volume of 246 pages, extra cloth, price 50 cents. (Just Issued.)

PREPARING FOR SPEEDY PUBLICATION.
LATIN READING AND EXERCISE BOOK, 1 vol., royal 18mo.
A SCHOOL CLASSICAL DICTIONARY, 1 vol., royal 18mo.

It will thus be seen that this series is now very nearly complete, embracing
eight prominent Latin authors, and requiring but two more elementary works
to render it sufficient in itself for a thorough course of study, and these latter
are now preparing for early publication. During the successive appearance of
the volumes, the plan and execution of the whole have been received with
marked approbation, and the fact that it supplies a want not hitherto provided
for, is evinced by the adoption of these works in a very large number of the
best academies and seminaries throughout the country.

But we cannot forbear commending especially both to instructors and pupils the
whole of the series, edited by those accomplished scholars, Drs. Schmitz and Zumpt.
Here will be found a set of text-books that combine the excellencies so long desired
in this class of works. They will not cost the student, by one half at least, that which
he must expend for some other editions. And who will not say that this is a consider-
ation worthy of attention? For the cheaper our school-books can be made, the more
widely will they be circulated and used. Here you will find, too, no useless display of
notes and of learning, but in foot-notes on each page you have everything necessary to
the understanding of the text. The difficult points are sometimes elucidated, and often
is the student referred to the places where he can find light, but not without some effort
of his own. We think that the punctuation in these books might be improved; but
taken as a whole, they come nearer to the wants of the times than any within our know-
ledge.—Southern College Review.

Uniform with SCHMITZ AND ZUMPT’S CLASSICAL SERIES—(Now Ready.)
THE CLASSICAL MANUAL;

AN EPITOME OF ANCIENT GEOGRAPHY, GREEK AND ROMAN
MYTHOLOGY, ANTIQUITIES, AND CHRONOLOGY.

CHIEFLY“ (INTENDED FORTHE USE OF SCHOOLS.
BY JAMES SS. BAIRD OT Ceps

Assistant Classical Master, King’s School, Gloucester.

In one neat volume, royal 18mo., extra cloth, price Fifty cents.

This little volume has been prepared to meet the recognized want of an Epi-
tome which, within the compass of a single small volume, should contain the
information requisite to elucidate the Greek and Roman authors most com-
monly read in our schools. The aim of the author has been to embody in it
such details as are important or necessary for the junior student, in a form and
space capable of rendering them easily mastered and retained, and he has con-
sequently not incumbered it with a mass of learning which, though highly
valuable to the advanced student, is merely perplexing to the beginner. In the
amount of information presented, and the manner in which it is conveyed, as
well as its convenient size and exceedingly low price, it is therefore admirably
adapted for the younger classes of our numerous classical schools.

10 BLANCHARD & LEA’S PUBLICATIONS.—(Educational Works.)

SCRIPTURE GHOGRAPHY AND HISTORY.—(Now Ready.)

——__—_

OUTLINES OF

SCRIPTURE GEOGRAPHY AND HISTORY,

Illustrating the Historical Portions of the Old and New Testaments.

DESIGNED FOR THE

USE OF SCHOOLS AND PRIVATE READING,
BY EDWARD HUGHES, F.R.A.S., F.G.8., &e. &e.

In one neat volume, royal 12mo., extra cloth, of about four hundred pages, with
‘twelve colored Maps.

The intimate connection of Sacred History with the geography and physical
features of the various lands occupied by the Israelites renders a work like the
present an almost necessary companion to all who desire to read the Scriptures
understandingly. To the young especially, a clear and connected narrative of
the events recorded in the Bible, is exceedingly desirable, particularly when il-
lustrated, as in the present volume, with succinct but copious accounts of the
neighboring nations and of the topography and political divisions of the countries
mentioned, coupled with the results of the latest investigations, by which
Messrs. Layard, Lynch, Olin, Durbin, Wilson, Stephens, and others have suc-
ceeded in throwing light on so many obscure portions of the Scriptures, verify-
ing their accuracy in minute particulars. Few more interesting class-books could
therefore be found for schools where the Bible forms a part of education, and
none, perhaps, more likely to prove of permanent benefit to the scholar. The
influence which the physical geography, climate, and productions of Palestine
had upon the Jewish people will be found fully set forth, while the numerous
maps present the various regions connected with the subject at their most pro-
minent periods.

HISTORY OF CLASSICAL LITERATURE.—(Now Ready.)

HISTORY OF ROMAN CLASSICAL LITERATURE.

BY R. W. BROWNE, M.A.,

Professor of Classical Literature in King’s College, London.
In one handsome crown octavo volume, extra cloth.

ALSO,
Lately Issued, by the same author, to match.

A HISTORY GF GREEK CLASSICAL LITERATURE,

In one very neat volume, crown 8vo., extra cloth.

From Prof. J. A. Spencer, New York, March 19, 1852. Ae

It is an admirable volume, sufficiently full and copious in detail, clear and precise in
style, very scholar-like in its execution, genial in its criticism, and altogether display-
ing a mind well stored with the learning, genius, wisdom, and exquisite taste of the
ancient Greeks. Itis in advance of everything we have, and it may be considered
indispensable to the classical scholar and student.

From Prof. N. H. Griffin, Williams College, Mass., March 22, 1852.

A valuable compend, embracing in a small compass maiter which the student would

have to go over much ground to gather for himself.

GEOGRAPHIA CLASSICA:

OR, THE APPLICATION OF ANCIENT GEOGRAPHY TO THE CLASSICS.
By SaMvEL But er, D. D., late Lord Bishop of Litchfield. Revised by his Son. Sixth
American, from the last London Edition, with Questions on the Maps, by JOHN FRost,
LL.D. In one neat volume, royal 12mo., half bound.

AN ATLAS OF ANCIENT GEOGRAPHY.

By Samvuet Butter, D. D., late Lord Bishop of Litchfield. In one octavo volume, half
bound, containing twenty-one quarto colored Maps, and an accentuated Index.

BLANCHARD & LEA’S PUBLICATIONS.—( Educational Works.) 11

ELEMENTS OF THE NATURAL SCIENCES—(Now Ready.)

THE BOOK OF NATURE:
AN ELEMENTARY INTRODUCTION

TO THE SCIENCES OF
PHYSICS, ASTRONOMY, CHEMISTRY, MINERALOGY, GEOLOGY, BOTANY,
PHYSIOLOGY, AND ZOOLOGY,

BY FREDERICK SCHOEDLER, Pu. D.

Professor of the Natural Sciences at Worms.

First American Edition, with a Glossary and other Additions
and Improvements.

FROM THE SECOND ENGLISH EDITION,
TRANSLATED FROM THE SIXTH GERMAN EDITION,

BY HENRY MEDLOCK, F.C.S., &c.
Illustrated by six hundred and seventy-nine Engravings on Wood.
In one handsome volume, crown octavo, of about seven hundred large pages.

To accommodate those who desire to use the separate portions of this work,
the publishers have prepared an edition, in parts, as follows, which may be had
singly, neatly done up in flexible cloth, at very reasonable prices.

NATURAL PHILOSOPHY, . - 114 pages, with 149 Illustrations.
ASTRONOMY, . 4 . =, G4 *¢ 51

CHEMISTRY, : : : :
MINERALOGY AND GEOLOGY, 104 cls 167
BOTANY 5l0- sis , : : ares 22 176
ZOOLOGY AND PHYSIOLOGY, . 106 OG 84
INTRODUCTION, GLOSSARY, INDEX, &c., 96 pages.

Copies may also be had beautifully done up in fancy cloth, with gilt stamps,
. suitable for holiday presents and school prizes.

The necessity of some acquaintance with the Natural Sciences is new so uni-
versally admitted in all thorough education, while the circle of facts and princi-
ples embraced in the study has enlarged so rapidly, that a compendious Manual
like the Book or Nature cannot fail to supply a want frequently felt and ex-
pressed by a large and growing class.

The reputation of the present volume in England and Germany, where re-
peated editions have been rapidly called for, is sufficient proof of the author’s
success in condensing and popularizing the principles of his numerous subjects.
The publishers therefore would merely state that, in reproducing the work,
they have spared no pains to render it even better adapted to the American
student. It has been passed through the press under the care of a competent
editor, who has corrected such errors as had escaped the attention of the English
translator, and has made whatever additions appeared necessary to bring it com-
pletely ona level with the existing state of science. These will be found prin-
cipally in the sections on Botany and Geology; especially the latter, in which
references have been made to the numerous and systematic Government surveys
of the several States, and the whole adapted to the nomenclature and systems
generally used in this country. A copious Glossary has been appended, and
numerous additional illustrations have been introduced wherever the elucidation
of the text appeared to render them. desirable.

Itis therefore confidently presented as an excellent Manual for the private stu-
dent, or as a complete and thorough Class-book forcollegiate and academical use.

Written with remarkable clearness, and scrupulously correct in its details.—Mining
Journal.

His expositions are most lucid. There are few who will not follow him with pleasure
as well as with profit through his masterly exposition of the principles and primary laws
ofscience. It should ceriainly be made a class-book in schools.— Critic.

\

12 BLANCHARD & LEA’S PUBLICATIONS.—(Educational Works.)
NEW AND IMPROVED EDITION—(Now Ready.)

OUTLINES OF ENGLISH LITERATURE.
BY THOMAS B. SHAW,

Professor of English Literature in the Imperial Alexander Lyceum, St. Petersburg

SECOND AMERICAN EDITION.
WITH A SKETCH OF AMERICAN LITERATURE.
BY HENRY T. TUCKERMAN,

Author of “ Characteristics of Literature,” ** The Optimist,” &ce.

In one large and handsome volume, royal 12mo., extra cloth, of about 500 pages.

The object of this work is to present to the student a history of the progress
of English Literature. To accomplish this, the author has followed its course
from the earliest times to the present age, seizing upon the more prominent
** Schools of Writing,’ tracing their causes and effects, and selecting the more
celebrated authors as subjects for brief biographical and critical sketches,gana-
lyzing their best works, and thus presenting to the student a definite view of the
development of the language and literature, with succinct descriptions of those
books and men of which no educated person should be ignorant. He has thus
not only supplied the acknowledged want of a manual on this subject, but by
the liveliness and power of his style, the thorough knowledge he displays of his
topic, and the variety of his subjects, he has succeeded in producing a most
agreeable reading-book, which will captivate the mind of the scholar, and re-
lieve the monotony of drier studies.

This work having attracted much attention, and been introduced into a large
number of our best academies and colleges, the publishers, in answering the call
for a new edition, have endeavored to render it still more appropriate for the
student of this country, by adding to it a sketch of American literature. This
has been prepared by Mr. Tuckerman, on the plan adopted by Mr. Shaw, and
the volume is again presented with full confidence that it will be found of great
utility as a text- “book, wherever this subject forms part of the educational course ;
or as an introduction to a systematic plan of reading.

From Prof. R. P. Dunn, Brown University, April 22, 1852.

Thad already determined to adopt it as the principal book of reference in my depart-
ment. This is the first term in which it has been used here; but from the trial which I
have now made of it, Ihave every reason to congratulate myself on my selection of it
as a text-book.

From the Rev. W. G. T. Shedd, Professor of English Literature in the University of Vt.

I take great pleasure in saying that it supplies a want that has long existed of a brief
history of English literature, written in the right method and spirit, to serve as an intro-
duction to the crilical study of it. I shall recommend the book to my classes.

From James Shannon, President of Bacon College, Ky.

I have read about one-half of “‘ Shaw’s Outlines,” and so far [am more than pleased
with the work, I concur with you fully in the opinion that it supplies a want long felt
in our higher educational institutes of a critical history of English Jiterature, occupying
a reasonable space, and written in a manner to interest and attract the attention of the
student. I sincerely desire that it may obtain, as it deserves, an extensive circulation.

HANDBOOK OF MODERN EUROPEAN LITERATURE.

British, Danish, Dutch, French, German, Hungarian, Italian, Polish and Rus-
sian, Portuguese, Spanish, and Swedish. With a full Biographical and
Chronological Index. By Mrs. Foster. In one large royal 12mo. volume,
extra cloth. Uniform with ** Shaw’s Outlines o {English Literature.”

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