Additional Notes on the First Chapter.

[Seite 5]

(A) Ossification does not go on with equal rapi-
dity in all animals, nor in all the bones of the same
animal. Thus the ossification of the internal ear
of man, and the mammalia, is completed before
any other parts; and it surpasses all other bone in
its density, and in the proportional quantity of
phosphate of lime, which it contains. In the cetacea,
particularly the balaena and physeter (the black and
white whales,) this part acquires a density and hard-
ness equal to that of marble. Its section presents an
homogeneous appearance, without the least vestige
of fibres, cellular texture, or vessels.

Bones are slow in acquiring their complete
formation, in proportion to the remoteness of the
period, at which the growth of the animal is
finished. The skeleton remains constantly in a
cartilaginous state in some animals; such are the
shark, skate, sturgeon, and all those fishes, which,
[Seite 6] from this circumstance, have been denominated
cartilaginous, or chondropterygii. Although the
bones of other fishes, of reptiles, and serpents ac-
quire a greater hardness, they constantly remain
more flexible, and retain a larger proportion of
gelatine in their structure, than those of warm-
blooded animals.

The bony texture of the mammalia is not so fine
and delicate as that of man: it is particularly loose
and coarse in the cetacea, where the distinction of
the fibres is very manifest, even on the external
surface. In the jaw and the ribs particularly, they
may be loosened by maceration, and become very
obvious.

The bones of reptiles and fishes have a very
homogeneous appearance, the earthy matter and
the gelatine appearing to be uniformly mingled:
this is more strikingly marked, as we approach to
the cartilaginous fishes, where the gelatine predomi-
nates, and conceals the earth.

Several animals have no medullary cavities even
in their long bones. This is the case with the
cetacea, the seal, and turtle.

The structure of the bones of birds should be
noticed in this place. They are almost universally
hollow: but their cavities, which never contain
marrow, are filled with air. This organization
unites the advantages of lightness and strength.
For a further account of it see the chapter on the
organs of respiration.

[Seite 7]

The horn of the stag is a real bone, as appears
both from its texture, and its component elements.
Its outer part is hard, compact, and fibrous: the in-
ternal substance is reticulated, but very firm; and
possesses no cavities nor marrow. See the chapter
on the skeleton of the mammalia, for the mode of
its formation, &c.

The shells of the testaceous animals are formed
of a calcareous substance, which is sometimes
laminated; sometimes as hard and denfe as mar-
ble. This is mingled, as in other bones, with a
gelatinous matter, from which it may be separated
by means of acids. The earth is not disposed in
fibres or laminae, as in other bones; but is uni-
formly expanded through the animal substance.

The layers of the shell are formed successively,
as the animal increases in size. The exterior or
smallest are formed first: others are successively
deposited on the inner surface of these; each new
layer extending beyond the margin of the former
one, so that the shell, by every addition increases
in thickness and circumference. Are these new
layers formed by vessels existing in the shell itself,
or are they produced by exudation from the sur-
face of the animal? Reaumeur broke the shell
of snails, and found that no reproduction took
place, when he covered the exposed part of the
animal’s body; while the injury was quickly re-
paired, when no artificial obstacle impeded the
effusion of fluids from the surface. This experi-
[Seite 8] ment seems to prove that the shell is formed by
deposition from the body of the animal: but there
is an argument equaily strong in favour of the ex-
istence of vessels in the shell itself. Between the
two last formed layers of the convex shell of the
oyster, a considerable cavity is found, filled with a
fluid, and communicating by a particular opening
with the internal parts of the body. This must be
destroyed and reproduced whenever a new lamina
is added; and we cannot understand how such
processes can be effected without arterial and ab-
sorbing vessels.

Grustaceous animals, (crab, lobster, &c.) have a
skeleton which surrounds and contains their soft
parts, and which serves at the same time the pur-
poses of a skin. When it has attained its perfect
consistence, it grows no more: but as the soft
parts still increase, the shell separates, and is de-
tached, being succeeded by a larger one. This
new covering is partly formed before the other
separates: it is at first soft, sensible, and vascular;
but it speedily acquires a hard consistence by the
increased deposition of calcareous matter.

Some of the mollusca have hard parts in the in-
terior of their body. The common cuttlefish (sepia
officinalis) has a white, firm, and calcareous mass
of an oval form, and slightly convex on its two
surfaces, commonly known by the name of the
cuttlefish-bone, contained in the substance of its
body. It has no connection with any soft part,
[Seite 9] whence it appears completely as a foreign body:
no vessel nor nerve can be perceived to enter it;
nor does it receive the attachment of any tendon.
In the calmar (sepia loligo), this body resembles
horn in its appearance; it is transparent, hard, and
brittle. Its form resembles that of a leaf, except
that it is larger; and sometimes that of a sword-
blade. These parts must grow like shells, by the
simple addition of successive layers.

(B) As chemical analysis has discovered some
interesting differences in the constituent ingredients
of the hard parts of various animals; it seems
right to give a short account of them in the pre-
sent place.

The bones and teeth of red-blooded animals,
consist chiefly of phosphate of lime, deposited in
the interstices of an animal substance; which, when
freed from the earthy matter by the immersion of
the bone in an acid, approaches in its consistence
to cartilage. This is completely dissolved by boil-
ing in a close vessel, and is thereby proved to con-
sist of gelatine. A small quantity of carbonate of
lime is mixed with the phosphate; and hence ef-
fervescence arises when a bone or tooth is sub-
jected to the action of acids.

The relative proportions of these ingredients in
the general structure of bone have not hitherto
been determined with much accuracy; but the
obvious differences of structure and appearance
[Seite 10] not only in the different classes, orders, and genera,
but even in the several bones of the same individual,
and in parts of the same bone, leave no doubt that
much variation must exist in these points.

The horn of the stag is bone, containing a large
proportion of gelatine.

The bones of fishes contain phosphate of lime;
but the animal substance exists in very large pro-
portion, particularly in those which are called car-
tilaginous, where it completely obscures the earthy
matter.

Carbonate and phosphate of lime, deposited on a
cartilaginous basis, which retains the form of the
part, after the earthy matter has been separated,
constitute the external covering of the crustaceous
animals (crab, lobster, &c.). The carbonate is in
greatest quantity.

Carbonate of lime, with a small quantity of phos-
phate, forms the earthy principle of the shell of
the echinus.

The shells of the testacea, are entirely composed
of carbonate of lime, united to a gelatinous sub-
stance. When immersed in acid, a rapid effer-
vescence ensues. Some of them, which are very
hard in their texture, and have an enamelled sur-
face, contain so little animal matter, that it does not
retain the form of the shell, which is completely
dissolved by acids, like the enamel of the teeth.
But others, which consist of what is called mother
of pearl, and are formed by successive strata, (e.g.
[Seite 11] the oyster, muscle, &c.) contain a much larger pro-
portion. When these have been macerated in acid,
a gelatinous substance remains, consisting of se-
veral layers of membrane, arranged stratum super
stratum.

It appears therefore, that phosphate of lime is the
peculiar earth of bone, and carbonate that of shell;
although no bone has been hitherto discovered,
without a small admixture of the latter ingredient.
Hence that singular production from the body of
the cuttle-fish is improperly called bone; as it con-
sists, like shells, of various membranes, hardened
by carbonate of lime, without any phosphate. See
‘“Experiments and Observations on Shell and Bone,”’
by C. Hatchett, Esq. Philos. Trans. 1799.

The same excellent chymist has also found, that
the zoophytes, consist of carbonate of lime joined in
different instances to various proportions of animal
substance. Philos. Trans. 1800, part 2.

Additional Notes to the Second Chapter.

(A) The bones of the head, in birds, are joined
either by the squamous kind of suture; or by the
mere apposition of their margins: which species
of union is termed harmonia. But they are soon
consolidated into a single piece.

(B) The sphenoid bone is often divided into two
parts in the quadrumana; one of these forms the
lesser alae, and anterior clinoid processes; the
[Seite 50] greater alae, the posterior clinoid processes, and
basilar fossa are formed by the other portion.

The two parietal bones form a single piece in
the bat-kind. The same circumstance occurs in
the carnivora, in the pig, tapir, hippopotamus, and
horse.

The frontal and parietal bones of the elephant
become consolidated, at an early period, with all
the other parts of the cranium; so as to form a
bony cavity, in which no trace of sutures can be
discerned. The parietal, occipital, and temporal
bones are likewise soon joined into one piece in
the cetacea.

The pig, hippopotamus, tapir, horse, seal, walrus,
and the rodentia have the os frontis divided by a
middle suture into two portions.

That portion of the os temporis, which contains
the tympanum, is separated from the rest of the
bone by a suture, in the dog, cat, and horse; also
in the ruminantia and rodentia. It is so com-
pletely separated in the cetacea, as to be attached to
the cranium only by soft parts. In the elephant,
where the other bones are consolidated into one
piece, this remains distinct.

The cranium of the mammalia possesses the same
fossae at its basis, as are found in the human sub-
ject: they are however much shallower; and the
eminences, which define them, are much less
strongly marked than in man. This difference is
very perceptible even in the simiae, where the cavi-
[Seite 51] ties which hold the cerebellum, are nearly on a
level with the middle fossae of the basis cranii; and
the sella turcica is more superficial. The same fact
is more strongly marked as we arrive at those
animals, whose general structure deviates more
considerably from that of man. Those mammalia,
which have the occipital foramen situated at the back
of the head, must have the fossae cerebelli moved
upwards; hence that margin of the fossae, which
is posterior in man, passes across the upper part
of the back of the head in these animals. The
bony projections, which bound this fossa in some
mammalia, are described in the chapter on the
brain.

The optic foramina of the elephant commence
from one canal, which receives the two optic
nerves.

The foramen rotundum is sometimes absent, its
place being supplied by the spheno-orbitary fissure,
(foramen lacerum) e.g. in the elephant and horse.
The foramen ovale is also frequently wanting; being
included perhaps in the vacancy left between the pe-
trous portion of the temporal bone, and the body
of the sphenoid. This latter opening does not exist
in the genus simia, nor in the carnivorous mammalia,
nor in the ruminantia. It is on the contrary very
large in the elephant, and in some rodentia.

The carotid canal does not exist in the rodentia;
but the artery enters at the opening between the
sphenoid and temporal bones.

[Seite 52]

The structure of the cranium presents a very re-
markable singularity in the elephant. Its two tables
are separated from each other to a considerable
extent, by numerous bony processes; between
which are formed a vast number of cells, com-
municating with the throat by means of the
eustachian tube, and filled with air, instead of the
bloody or medullary substance, which occupies the
diplöe of animals. The use of this structure in
increasing the surface for attachment of those large
muscles, which belong to the lower jaw, proboscis
and neck; and in augmenting the mechanical
power of these muscles by removing their attach-
ments to a greater distance from the centre of
motion has been very ingeniously explained by
Camper (Oeuvres, tom. 2). These advantages
are attained by the cellular structure, which we
have just described, without augmenting the weight
of the head, and this precaution is particularly
necessary in the present instance, as the head is
on other accounts more heavy and massy in this
than in any other animal. The air cells of birds
in general, and particularly those which pervade
the cranium in the ostrich, eagle, and owl presents
examples of a similar formation, attended with the
same uses; viz. those of increasing the bulk and
strength of the bone, and diminishing its weight.

(C) The crista occipitalis is a sharp and pro-
minent bony ridge, projecting from the upper and
[Seite 53] back part of the cranium in mammalia, chiefly for
the attachment of the temporal muscle.

The size of the temporal fossa, depends upon the
magnitude of the muscle, which it contains. Hence
it is larger in the carnivora than in any other or-
der; not only occupying the whole sides and upper
part of the cranium, but being still further increased
by prominent bony cristae, growing from the frontal,
parietal, and occipital bones. The two temporal
muscles are indeed separated in many of these ani-
mals, merely by the parietal ridge, which would
completely cover the cranium.

These ridges are not so strongly marked in any
animals, as in the carnivora: yet they are discern-
ible in most of the simiae. They occur also in ani-
mals of the pig kind, and in the other pachydermata.

The occipital crista is found where the others do
not exist; as it serves for the attachment of the
muscles of the neck.

(D) The variations in the situation of the occi-
pital foramen are important, when viewed in con-
nexion with the ordinary position of the animal’s
body. In man, who is designed to hold his body
erect, this opening is nearly equi-distant from the
anterior and posterior extremities of the skull. The
head therefore is supported in a state of equilibrium
on the vertebral column. The angle, formed by
the two lines mentioned by Daubenton, is only
of three degrees.

[Seite 54]

Quadrupeds, which go on all-fours, have the oc-
cipital foramen and condyles situated farther back,
in proportion as the face is elongated. That open-
ing, instead of being nearly parallel to the horizon,
forms a considerable angle with it; which, mea-
sured, according to Daubenton, is of 90 degrees
in the horse. The weight of the head in these ani-
mals, is not therefore sustained by the spine; but
by a ligament of immense strength, which is either
entirely deficient, or so weak, as to have its exist-
ence disputed in the human subject. This ligamen-
tum nuchae, or cervical ligament, arises from the spines
of the dorsal and cervical vertebrae, (which are re-
markably long for that purpose) and is fixed to the
middle and posterior part of the occipital bone.
It is of great size and strength in all quadrupeds,
but most particularly in the elephant; where the vast
weight of the head, so much increased by the enor-
mous size of the tusks, sufficiently accounts for its in-
creased magnitude. It is bony in the mole, probably
on account of the use, which the animal makes of
its head, in disengaging and throwing up the earth.

Animals of the genus simia and lemur hold a
middle rank between man, who is constantly erect,
and quadrupeds, whose body is supported by four
extremities. Their structure is by no means cal-
culated, like that of man, for the constant mainte-
nance of the erect posture; but they can support it
with greater facility, and for a longer time than
other animals. Hence, in the orang-outang, the
[Seite 55] occipital foramen is only twice as far from the jaws
as from the back of the head, so that Daubenton’s
angle is only of 37°. It is somewhat larger in the
other species of simiae; and measures 47° in the
lemur.

(E) The two organs, which occupy most of the
face, are those of smelling and tasting (including
those of mastication, &c.). In proportion, as these
parts are more developed, the size of the face,
compared to that of the cranium, is augmented.
On the contrary, when the brain is large, the vo-
lume of the cranium is increased in proportion to
that of the face. A large cranium and small face
indicate therefore a large brain, with inconsiderable
organs of smelling, tasting, masticating, &c.; while
a small cranium, with a large face, shew that these
proportions are reversed.

The nature and character of each animal must
depend considerably on the relative energy of its
different functions. The brain is the common
centre of the nervous system. All our perceptions
are conveyed to this part, as a sensorium commune:
and this is the organ, by which the mind combines
and compares these perceptions, and draws infer-
ences from them; by which, in short, it reflects and
thinks. We shall find, that animals partake in a
greater degree of this latter faculty, or at least ap-
proach more nearly to it, in proportion as the mass
of medullary substance, forming their brain, exceeds
[Seite 56] that, which constitutes the rest of the nervous sys-
tem; or, in other words, in proportion as the or-
gan of the mind exceeds those of the senses. Since
then, the relative proportions of the cranium and
face, indicate also those of the brain, and the two
principal external organs, we shall not be surprized
to find, that they point out to us, in great measure,
the general character of animals; the degree of
instinct and docility which they possess. Man com-
bines by far the largest cranium, with the smallest
face; and animals deviate from these relations, in
proportion as they increase in stupidity and fe-
rocity.

One of the most simple methods (though some-
times indeed insufficient), of expressing the relative
proportions of these parts, is by means of the facial
line, which has been already described. This angle
is most open, or approaches most nearly to a right
angle in the human subject; it becomes constantly
more acute, as we descend in the scale, from man;
and in several birds, reptiles, and fishes, it is lost
altogether, as the cranium and face, are completely
on a level. The idea of stupidity is associated, even
by the vulgar, with the elongation of the snout:
hence the crane and snipe have become proverbial.
On the contrary, when the facial line is elevated by
any cause, which does not increase the capacity of
the cranium, as in the elephant and owl, by the
cells, which separate the two tables, the animal ac-
quires a particular air of intelligence, and gains the
[Seite 57] credit of qualities, which he does not in reality pos-
sess. Hence the latter animal has been selected as
the emblem of the goddess of wisdom. The in-
valuable remains of Grecian art shew, that the
ancients were well acquainted with these circum-
stances: they were aware, that an elevated facial
line formed one of the grand characters of beauty;
and indicated a noble and generous nature. Hence
they have extended the facial angle to 90 degrees
in the representation of men, on whom they wished
to bellow an august character. And in the repre-
sentations of their gods and heroes, they have even
carried it beyond a right angle, and made it 100°.

It must, however, be allowed, that the facial an-
gle is of chief importance in its application to the
cranium of the human subject, and of the quadru-
mana; as various circumstances affect the conclu-
sions, which would result from employing it in other
classes of mammalia. Thus in the carnivorous, and
some of the ruminating animals; in the pig, and
particularly in the elephant, the great size of the
frontal sinuses produces an undue elevation of the
facial line. In many of the rodentia, as the hare,
&c., the nose occupies so large a space, that the
cranium is thrown quite back, and presents no point
on a front view, from which this time can be
drawn.

The following are the angles formed, by drawing
a line along the floor of the nostrils, and intersecting
it by another, which touches the anterior margin
[Seite 58] of the upper alveoli, and the convexity of the cra-
nium (whether the latter point be concealed by the
face, or no).

In the 3d and 4th tables of Cuvier’s Tableau
Elementaire de l’Histoire Naturelle, the crania of se-
veral mammalia are represented in profile; so as to
afford a sufficient general notion of the varieties in
the facial angle. A similar comparative view, in
one plate, is given by White, in his account of the
Regular Gradation, &c. from the work of Camper.

A vertical section of the head, in the longitudinal
direction, shews us more completely the relative
proportions of the cranium and face. In the
European, the area of the section of the cranium is
[Seite 59] four times as large as that of the face; the lower
jaw not being included. The proportion of the
face is somewhat larger in the negro: and it in-
creases again in the orang-outang. The area of the
cranium is about double that of the face in the
monkeys: in the baboons, and in most of the carni-
vorous mammalia, the two parts are nearly equal.
The face exceeds the cranium in most of the other
classes. Among the rodentia, the hare and marmot
have it one-third larger; in the porcupine, and the
ruminantia, the area of the face is about double that
of the cranium; nearly triple in the hippopotamus;
and almost four times as large in the horse. In
reptiles and fishes, the cranium forms a very in-
considerable portion of the section of the head;
although it is considerably larger than the brain,
which it contains.

The outline of the face, when viewed in such a
section, as we have just mentioned, forms in the
human subject a triangle; the longest side of which
is the line of junction between the cranium and
face. This extends obliquely backwards and down-
wards, from the root of the nose, towards the fora-
men occipitale. The front of the face, or the
anterior line of the triangle, is the shortest of the
three. The face is so much elongated, even in the
simiae, that the line of junction of the cranium and
face is the shortest side of the triangle; and the
anterior one the longest. These proportions be-
come still more considerable in other mammalia.

[Seite 60]

(F) The want of the os intermaxillare has been
regarded as a chief characteristic of the human sub-
ject; as one of the leading circumstances, which
distinguish man from other mammalia. That this
bone is really wanting in man must be allowed,
notwithstanding the doubts of Vicq d’Azyr. The
well-known transverse slit, behind the alveoli of the
incisors in the human foetus, would form a very
slight and remote analogy between the human
structure, and that of animals: and, when we con-
sider, that the superior or facial surface of the max-
illary bones, so far from being marked by any suture,
does not even bear a slit like that of the inferior
part, it must be put entirely out of the question.

That all other mammalia possess this bone, is not
quite so clear, as that man has it not. The excep-
tions occur in the quadrumana. In addition to
those which the author has stated, it may be ob-
served, that the head of an orang-outang, in the
Hunterian Museum, which possesses all the other
sutures, wants those, which separate the intermaxil-
lary bone: that Tyson did not find this bone in his
specimen of the animal, which was very young,
(see his Anatomy of the Pigmy) and that it did not
exist in a cranium, which was delineated by Dau-
benton. I have also seen the crania of other
monkeys, where the other sutures were all perfect
and distinct, which did not possess this bone.

(G). The zygoma is wanting in the ant-eater;
[Seite 61] where the temporal and molar bones have only a
slight projection instead of the usual zygomatic pro-
cess. This circumstance is sufficiently explained by
the want of teeth, and the consequent want of mas-
tication. The zygomatic suture is so oblique in the
carnivora, that the temporal bone forms the whole
superior margin; and the os malae, the inferior
edge of the zygoma.

The zygoma may be arched both in the vertical
and horizontal directions. A curvature of the lat-
ter kind indicates the existence of a strong temporal
muscle; while one of the former description shews
that the masseter is large. Both these curvatures
are considerable in the carnivora.

(H) The interval between the orbits is always
smaller in the simiae than in the human subject.
In several of these, as in the monkeys, properly so
called, the two orbits are separated at their posterior
part by a simple bony septum. In other mam-
malia, these cavities are thrown towards the side of
the head, and to a great distance from each other,
by the ascending or nasal processes of the upper
jaw-bones, which are very large.

In those mammalia, which have the orbit open
at its outer and back part, so as to communicate
with the temporal fossa, (such as the carnivora, ro-
dentia, edentata, and pachydermata) the os malae
merely contributes to the formation of the zygoma,
without being connected to the frontal or sphenoid
[Seite 62] bones. The superior maxilla merely forms the
anterior border of the cavity, without constituting
the floor of the orbit, which is indeed open below.
The ossa palati, which are large, form a considerable
share of the inner part of the cavity; the ethmoid
bone not contributing to it.

The ruminating animals, as well as the horse and
ass, have the margin of the orbit completed at its
outer part by a bony circle, although the cavity is
open behind to the temporal fossa.

The mole has not, properly speaking, an orbit.
Its diminutive eyes, the very existence of which, was
for a long time questioned, lie under the integu-
ments. Blumenbach’s Description of the Bones,
in German, p. 225. note. The same observation
holds good of the myrmecophuga didactyla. Ibid.

(I) The word horn, which is frequently applied
in English to the antlers of the deer kind, as well
as to the real horns of other genera, would lead to
a very erroneous notion on this subject. The ant-
ler is a real bone; it is formed in the same manner,
and consists of the same elements as other bones;
its structure is also the same.

It adheres to the frontal bone by its basis; and
the substance of the two parts being consolidated
together, no distinction can be traced, when the
antler is completely organized. But the skin of
the forehead terminates at its basis, which is marked
by an irregular projecting bony circle; and there
is neither skin nor periosteum on the rest of it.
[Seite 63] The time of its remaining on the head is one year:
as the period of its fall approaches, a reddish mark
of separation is observed between the process of the
frontal bone, and the antler. This becomes more
and more distinctly marked, until the connection
is entirely destroyed.

The skin of the forehead extends over the process
of the frontal bone, when the antler has fallen: at
the period of its regeneration, a tubercle arises from
this process, and takes the form of the future antler,
being still covered by a prolongation of the skin.
The structure of the part at this time is soft and
cartilaginous; it is immediately inverted by a true
periosteum, containing large and numerous vessels,
which penetrate the cartilage in every direction, and
by the gradual deposition of ossific matter, convert
it into a perfect bone.

The vessels pass through openings in the pro-
jecting bony circle at the base of the antler:
the formation of this part, proceeding in the same
ratio with that of the rest, these openings are
contracted, and the vessels are thereby pressed, until
a complete obstruction ensues. The skin and pe-
riosteum then perish, become dry and fall off; the
surface of the antler remaining uncovered. At the
stated period it falls off, to be again produced, al-
ways increasing in size.

(K) As the motions of the lower jaw must be
materially influenced by the form of its condyle,
[Seite 64] and by the manner in which that process is con-
nected to the articular cavity of the temporal bone;
we shall find, as might have been expected, a close
relation between these circumstances, and the kind
of food, by which an animal is nourished, Thus
the lower jaw of the carnivora can only move up-
wards and downwards, and is completely incapable
of that horizontal motion, which constitutes ge-
nuine mastication. Hence these animals cut and
tear their food in a rude and coarse manner, and
swallow it in large portions, which are afterwards
reduced by the solvent properties of the gastric
juice. Such mammalia, on the contrary, as live on
vegetables, have, in addition to this motion, a power
of moving the lower jaw backwards and forwards,
and to either side; so as to produce a grinding ef-
fect, which is necessary for bruising and triturating
grass, and for pulverising and comminuting grains.
In all these, therefore, the form of the condyle, and
of its articular cavity, allows of free motion in almost
every direction. The teeth may be compared, in
the former case, to scissars; in the latter, to the
stones of a mill.

(L) The teeth of the human subject seem to be
designed for the single purpose of mastication; and
hence an erroneous conclusion might be drawn,
that they serve the same office in other animals.
Many exceptions, however, must be made to this
general rule. Some mammalia, which have teeth
[Seite 65] for the office of mastication, have others, which can
be only considered as weapons of offence and de-
fence, viz. the tusks of the elephant, hippopotamus,
walrus, and manati. The large and long canine
teeth of the carnivora, as the lion, tiger, dog, cat,
&c. not only serve as natural weapons to the ani-
mal, but enable it to seize and hold its prey, and
assist in the rude laceration which the food under-
goes previous to deglutition. The seal, the porpoise,
and other cetacea, as the cachalot (physeter macroce-
phalus) have all the teeth of one and the same
form; and that obviously not calculated for masti-
cation. They can only assist in securing the prey,
which forms the animal’s food.

(M) Animals of the genus baloena (the proper
whales) have, instead of teeth, the peculiar sub-
stance called whalebone, covering the palatine sur-
face of the upper jaw: this resembles in its com-
position hair, horn, and such matters.

The lower surface of the upper jaw forms two
inclined plants, which may be compared to the roof
of a house reversed; but the two surfaces are con-
cave. Both these are covered with plates of the
whalebone, placed across the jaws, and descending
vertically into the mouth. They are parallel to
each other, and exist to the number of two or three
hundred on each of the surfaces. They are con-
nected to the bone by the intervention of a white
ligamentous substance, from which they grow;
[Seite 66] but their opposite edge, which is turned towards
the cavity of the mouth, has its texture loosened
into a kind of fringe, composed of long and slender
fibres of the horny substance; which therefore
covers the whole surface of the jaw. This struc-
ture probably serves the animal in retaining and
confining the mollusca, which constitute its food.

The teeth of the ornithorhynchus paradoxus and
hystrix deviate very considerably from those of
other mammalia. In the former animal there is
one on each side of the two jaws: it is oblong,
flattened on its surface, and consists of a horny
substance adhering to the gum. There are like-
wise two horny processes on the back of the
tongue: these point forwards, and are supposed by
Mr. Home to prevent the food from passing into
the fauces, before it has been sufficiently masticated.
In the o. hystrix, there are six transverse rows of
pointed horny processes at the back of the palate;
and about twenty similar horny teeth on the cor-
responding part of the tongue.

Mr. Home in the Philos. Trans. 1800, part 2.
1802, parts 1 and 2.

(N) The substance composing these tusks, and
commonly called ivory, is certainly different from
the bone of other teeth. It is, generally speaking,
more hard and compact in its texture. The ivory
of the elephant’s tusk is distinguished from all
others by the curved lines, which pass in different
[Seite 67] directions from the centre of the tooth, and form
by their decussation, a very regular arrangement
of curvilinear lozenges. It soon turns yellow from
exposure to the air. The tusk of the hippopota-
mus is harder and whiter; and consequently pre-
ferred for the formation of artificial teeth. In the
walrus, the interior of the tooth is composed of
small round portions, placed irregularly in a sub-
stance of different appearance, like the pebbles in
the pudding stone; and the molar teeth have a
similar structure.

(O) The facts, which the author has here re-
counted, have been some times brought forwards
in order to prove the vascularity of the teeth; a
doctrine, which is refuted by every circumstance
in the formation, structure, and diseases of these
organs. It may be first observed, that the ap-
pearances exhibited by the teeth in question, are
by no means what we should reasonably expect in
such a case. When a bullet has entered the sub-
stance of the body, the surrounding lacerated and
contused parts do not grow to the metal, and be-
come firmly attached to its surface, but they in-
flame and suppurate in order to get rid of the
offending master. If the ivory be vascular and
sensible, why do not the same processes take place
in it?

We can explain very satisfactorily how a bullet
may enter the tusk of an elephant, and become
[Seite 68] imbedded in the ivory without any opening for
its admission being perceptible. It will be shewn
in a subsequent note, that these tusks are constantly
growing during the animal’s life, by a deposition
of successive laminae within the cavity, while the
outer surface and the point are gradually worn
away: and that the cavity is filled for this purpose
with a vascular pulp, similar to that, on which
teeth are originally formed. If a ball penetrate
the side of a tusk, cross it cavity, and lodge in
the slightest way on the opposite side, it will be-
come covered towards the cavity by the newly
deposited layers of ivory, while no opening will
exist between it and the surface, to account for its
entrance. If it have only sufficient force to enter,
it will probably sink, by its own weight, between
the pulp and tooth, until it rests at the bottom of
the cavity. It there becomes surrounded by new
layers of ivory; and as the tusk is gradually worn
away, and supplied by new depositions, it will
soon be found in the centre of the solid part of the
tooth. Lastly, a foreign body may enter the tusk
from above, as the plate of bone, which forms its
socket is thin; if this descends to the lower part
of the cavity, it may become imbedded by the
subsequent formations of ivory. This must have
happened in a case where a spear-head was found
in an elephant’s tooth. The long axis of the
foreign body corresponded to that of the cavity.
No opening for its admission could be discovered,
[Seite 69] and it is very clear, that no human strength could
drive such a body through the side of a tusk.
Philos. Trans. 1801. part 1.

(P) The front teeth are the incisores, or cutting-
teeth; the primores of Linnaeus. The corner teeth
are the canini; laniarii of Linnaeus; cuspidati of
Mr. Hunter. The back teeth are the Molares
or grinders. The term of tusks is applied to such
teeth as extend out of the cavity of the mouth.

(Q) The structure of the incisor teeth, in the
rodentia, deserves attention on several accounts.
They are covered by enamel only on their anterior
or convex surface, and the same circumstance holds
good with respectto the tusks of the hippopotamus.
Hence as the bone wears down much faster than
this harder covering, the end of the tooth always
constitutes a sharp cutting edge, which renders it
very deserving of the name of an incisor tooth.

This partial covering of enamel refutes, as
Blake has observed (Essay on the Structure, &c.
of the Teeth, p. 212), the opinion that the enamel
is formed by the process of crystallization.

The incisor teeth of these animals are used in
cutting and gnawing the harder vegetable sub-
stances; for which their above-mentioned sharp
edge renders them particularly well adapted.
Hence Cuvier has arranged these animals in a
[Seite 70] particular order by the name of rodentia, or the
gnawers. As this employment subjects the teeth
to immense friction, and mechanical attrition, they
wear away very rapidly, and would soon be con-
sumed, if they did not possess a power of growth,
by which this loss is recompenced.

These teeth, which are very deeply imbedded in
the jaw, are hollow internally, just like a human
tooth, which is not yet completely formed. Their
cavity is filled with a vascular pulp, similar to that
on which the bone of a tooth is formed; this
makes a constant addition of new substance on
the interior of the tooth, which advances to sup-
ply the part worn down. The covering of enamel
extends over that part of the tooth, which is con-
tained in the jaw, as we might naturally expect:
for this must be protruded at some future period
to supply the loss of the anterior portion. Although
these teeth are very deeply implanted in the max-
illary bones, they can hardly be said to possess a
fang or root; for the form of the part is the same
throughout; the covering of enamel is like-
wise continued; and that part, which at one period
is contained in the jaw, and would form the fang,
is afterwards protruded to constitute the body of
the tooth.

The constant growth of these teeth therefore
proceeds in the same manner, and is effected on
the same principles as the original formation of any
[Seite 71] tooth; and can by no means furnish an argument
for the existence of vessels in the substance of the
part.

We cannot help being struck with the great
size of these teeth, compared with the others of the
same animal, or even with the bulk of the animal.
Their length in the lower jaw nearly equals that
of the jaw itself, although a small proportion only
of this length appears through the gum. They
represent the segment of a circle; and are con-
tained in a canal of the bone, which descends un-
der the sockets of the grinders, and then mounts
up, in some instances, to the root of the coronoid
process: hence although their anterior cutting
edge is in the front of the mouth, the posterior
extremity is behind all the grinding teeth. No
animal exhibits this structure better than the rat.
The beaver also affords a good specimen of it on a
larger scale. It has been drawn in this animal by
Blake, (Essay on the Structure, &c. of the Teeth,
tab. 9. fig. 3.) The tooth does not extend so far
in the upper jaw; it is there implanted in the inter-
maxillary bone, and terminates over the first
grinder.

The observations which have been made respect-
ing the constant growth of the incisor teeth of the
glires, will apply also to the tusks of the elephant.
These are hollow internally, through the greater
part of their length, and the cavity contains a vas-
cular pulp, which makes constant additions of suc-
[Seite 72] cessive layers, as the tusk is worn down. One of
the elephants at Exeter Change is said to have
nearly bled to death from a fracture of the tusk,
and consequent laceration of the vessels of the
pulp. The tusks of the hippopotamus, and probably
all other teeth of this description grow in the same
manner. Farther and more accurate observation
may hereafter shew, that the same mode of growth
obtains also in other classes of teeth, when they are
exposed to great friction. Something similar may
certainly be observed in the grinders of the horse.
The tooth is not finished when it cuts the gum:
the lower part of its body is completed while the
upper part is being worn away in mastication; and
the proper fang is not added till long after. Hence
we can never get one of these teeth in a perfect
state, for if the part out of the gum is complete,
the rest of the body is imperfect; and there are
no fangs: on the contrary, when the fangs are
formed, much of the body has been worn away in
mastication. Blake also asserts that this structure
is found in the grinders of the beaver, p. 99.
tab. 9. fig. 4.

(R) This animal is found so constantly with
only one tusk, that it has been called in common
language, the sea-unicorn; and Linnaeus has even
given it a similar appellation, that of monodon. Yet
there can be no doubt that it possesses originally
two of these; one in either jaw bone: and that
[Seite 73] which is wanting, must have been lost by some
accidental circumstance, as we can easily suppose,
(Shaw’s Zoology, vol. ii. p. 473.) These tusks
often equal in length that of the animal’s body;
which may be 18 feet or more: yet they are
always slender.

(S) The distribution of the enamel, and bony
substance, varies in the teeth of different animals,
and even in the different orders of teeth in the
same animal.

All the teeth of the carnivora, and the incisors
of the ruminating animals, have the crown only
covered with enamel, as in the human subject.
The immense fossil grinders of the animal incogni-
tum or mammoth have a similar distribution of this
substance.

The grinders of graminivorous quadrupeds, and
the incisors also of the horse have processes of ena-
mel, descending into the substance of the tooth.
These organs have also in the last-mentioned ani-
mals a third component part, differing in ap-
pearance from both the others, but resembling
the bone more than the enamel. Blake has dis-
tinguished this by the name of crusta petrosa;
and Cuvier calls it cement.

The physiological explanation of this difference
in structure is a very easy and clear one. The food
of the carnivora requires very little comminution
before it enters the stomach: hence the form of
[Seite 74] their grinding teeth is by no means calculated for
grinding; and as the articulation of the jaw ad-
mits no lateral motion, the molares, of which the
lower are overlapped by the upper, can only act
like the incisors of other animals. The food of
graminivorous quadrupeds is subject to a long
process of mastication, before it is exposed to the
action of the stomach. The teeth of the animals
suffer great attrition during this time, and would be
worn down very rapidly but for the enamel, which
is intermixed with their substance. As this part is
harder than the other constituents of the teeth, it
resists the attrition longer, and presents the ap-
pearance of prominent ridges on the worn surface,
by which the grinding of the food is much facili-
tated.

The distinction of the three substances is seen
better in the tooth of the elephant than in any
animal. The best method of displaying it is by
making a longitudinal vertical section, and polish-
ing the cut surface. The crusta petrosa will then
be distinguished by a greater yellowness and opacity
in its colour; and by an uniformity in its ap-
pearance, as no laminae or fibres can be distin-
guished.

The pulp of a grinding tooth of a graminivorous
quadruped is divided into certain conical processes,
which are united at their bases. These vary from
two to six in the horse and cow. On these the bone
of the tooth is formed, as on the single pulp of the
[Seite 75] human subject, but it is here divided into as many
separate shells, as there are processes of the pulp:
all of them however inclosed in a common capsule.
The ossification commences, as in all teeth, on the
points of the pulp, and extends towards the basis:
when it has arrived there, the shells unite together;
and they also join at their outer margins. Between
the processes of the pulp other productions descend
from the capsule in a contrary direction; and
deposit, on the surface of the shells, enamel dis-
tinguishable by its crystalline appearance, and hence
denominated by Blake cortex striatus. When
these membranous productions have formed their
portions of enamel, they secrete the crusta petrosa
within the cavities left between these productions of
enamel. The outer surface of the bone of the
tooth is covered by enamel, which may be com-
pared to that which invests the crown of a human
tooth, except that it is deposited in an irregular
waving line, in order to render the surface better
calculated for grinding: and the inequalities of
this surface of enamel are filled up by crusta petrosa.
The exterior enamel, and crusta petrosa, (which
may be so named, by way of distinguishing them
from the processes within the tooth), are formed by
the surface of the capsule.

If then we make a transverse section of a grind-
ing tooth of the horse or cow, the exterior surface
will be found to consist of an irregular layer of
crusta petrosa: this is succeeded by a waving line
[Seite 76] of enamel, within which is the proper bone of the
tooth. But the substance of the latter is penetrated
by two productions of enamel; in the interior of
each of which is crusta petrosa.

The crusta petrosa which fills these internal pro-
ductions of enamel, is sometimes not completely
deposited before the tooth cots the gum: hence
cavities are left in the centre of the tooth, which
become filled with a dark substance composed of
the animal’s food, and other foreign matters. This
seldom happen to any considerable extent in the
grinders of the horse. In the cow and sheep these
cavities are constantly filled with the dark adven-
titious matter; the crusta petrosa being confined to
the exterior surface of the tooth, and not existing
even there so plentifully as in the horse.

The lower grinders of the horse differ very
much in their formation from those of the upper-
jaw. Ossification commences in these by four or
five points, which increase into as many small
shells; yet they unite without any processes of
the capsule passing down between to form internal
productions of the enamel. This substance is
however deposited in a very convoluted manner on
the bone of the tooth, so that the same end is
attained, as if productions of the cortex striatus
had existed in the centre of the part. The crusta
petrosa fills up the irregularities of this waving line
of enamel. An horizontal section of such a tooth
presents the three substances arranged within each
[Seite 77] other: the crusta petrosa is external; then comes
the enamel, which includes nothing but the proper
bone of the tooth.

The incisors of the horse have a production of
enamel in their centre; but the cavity, which this
forms, containing no crusta petrosa, is merely filled
by the particles of food, &c. As these processes of
enamel descend only to a certain extent in the
tooth, they disappear at last from the constant
wear of the part in mastication. This is improperly
called the filling up of the teeth; and hence a
criterion arises of the horse’s age.

The grinding teeth of the elephant contain the
most complete intermixture of the three substances;
and have a greater proportion of crusta petrosa,
than those of any other animal. The pulp forms
a number of broad flat processes, lying parallel to
each other, and placed transversely between the
inner and outer laminae of the alveoli. The bone of
the tooth is formed on these in separate shells, com-
mencing at their loose extremities, and extending to-
wards the basis, where they are connected together.
The capsule sends an equal number of membranous
productions; which first cover the bony shells with
enamel, and then invests them with crusta petrosa;
which latter substance unites and consolidates the dif-
ferent portions. The bony shells vary in number
from four to twenty-three, according to the size of
the tooth, and the age of the animal: they have been
described under the term of denticuli, and have
[Seite 78] been represented as separate teeth in the first in-
stance. It must however be remembered that they
are formed on processes of one single pulp.

When the crusta petrosa is completely deposited,
the different denticuli are consolidated together.
The bony shells are united at their base to the
neighbouring ones; the investments of enamel are
joined in like manner: and the intervals are filled
with the third substance, which really deserves the
name bestowed on it by Cuvier, of cement. The
pulp is then elongated for the purpose of forming
the roots or fangs of the tooth. From the peculiar
mode of dentition of this animal, which will be
explained in a subsequent note, the front portion
of the tooth has cut the gum, and is employed in
mastication, before the back part is completely
formed, even before some of the posterior denticuli
have been consolidated. The back of the tooth
does not appear in the mouth until the anterior part
has been worn down even to the fang.

A horizontal section of the elephant’s tooth pre-
sents a series of narrow bands of bone of the tooth,
surrounded by corresponding portions of enamel.
Between these are portions of crusta petrosa; and
the whole circumference of the section is composed
of a thick layer of the same substance.

A vertical section in the longitudinal direction
exhibits the processes of bone, upon the different
denticuli, running up from the fangs; a vertical
layer of enamel is placed before, and another behind
[Seite 79] each of these. If the tooth is not yet worn by mas-
tication, the two layers of enamel are continuous at
the part, where the bone terminates in a point;
and the front layer of one denticulus is continuous
with the back layer of the succeeding one, at the
root of the tooth; so that the enamel, ascending on
the anterior, and descending on the posterior sur-
face of each denticulus, forms a continued line
through the whole tooth. Crusta petrosa intervenes
between the ascending and descending portions of
the enamel.

As the surface of the tooth is worn down in mas-
tication, the processes of enamel, resisting by their
superior hardness, form prominent ridges on the
grinding surface; which must adapt it excellently
for bruising and comminuting any hard substance.

The grinding bases, when worn sufficiently to
expose the enamel, present a very different appear-
ance in the Asiatic and African elephants. The
processes of enamel, in the former species, represent
flattened ovals, placed across the tooth. In the
latter, they form a series of lozenges, which touch
each other in the middle of the tooth.

It does not appear, that crusta petrosa is an essen-
tial part in the grinders of graminivorous animals.
For those of the rhinoceros do not possess it, although
the enamel descends into their substance, and forms
a cavity, which is filled with the food, &c.

Home and Blake likewise state, that it does not
exist in the hippopotamus, where there are internal
[Seite 80] productions of enamel: but Mr. Macartney,
the learned and ingenious lecturer on comparative
anatomy at St. Bartholomew’s Hospital, has found
it in small quantity on the exterior surface of the
tooth, near its root.

Mr. Corse’s Observations on the different Species
of Asiatic Elephants. Philos. Trans. 1799, part 2.

Some Observations on the Teeth of graminivorous
Quadrupeds, by E. Home, Esq. Ibid. With De-
lineations of the Teeth of the Elephant, Horse, Cow,
Sheep, Hippopotamus, and Rhinoceros.

Blake’s Essay on the Structure and Formation
of the Teeth in Man, and various Animals, with
plates.

Tenon sur une Methode particuliere d’etudier
l’Anatomie, in the Memoires de l’lnstitut National,
tome 1, an. 6.

Cuvier, Léçons d’Anatomie comparée, tome 3.

(T) All the three kinds of teeth are found in
the quadrumana, the carnivora, the pachydermata
(excepting the two horned rhinoceros and elephant),
the horse, and those ruminating animals, which have
no horns.

Cuvier states, that the teeth of an animal, whose
bones are found in a fossile state, resemble those of
man, in being arranged in a continued and un-
broken series.

In the simiae, carnivora, and all such as have ca-
nines longer than the other teeth, there is at least
[Seite 81] one vacancy in each jaw, for lodging the cuspidatus
of the opposite jaw. There is a vacancy behind
each canine in the bear.

The horned ruminating animals not only want
entirely the upper incisors, but they are also destitute
of cuspidati, except the stag, which has rudiments
of these teeth; and the musk (moschus moschifer)
where they are very long, and curved in the upper
jaw.

Between the incisors and grinders of the horse, a
very large vacancy is left, in the middle of which a
small canine tooth, termed the tush, is found in the
male animal; but very rarely in the female.

The elephant has grinders and two tusks in the
upper jaw; but the former only in the lower. The
immense tusks belong properly to the male animal:
as they are so small in the female, generally speaking,
as not to pass the margin of the lip. (Corse in
Phil. Trans. 1799, part 2. p. 208.)

The sloths have grinding and canine teeth, with-
out incisors. The dolphin and porpoise have small
conical teeth, all of one size and shape, arranged
in a continued line throughout the alveolar margin
of both jaws. The cachalot (Physeter macrocepha-
lus) has these in the lower jaw only. The teeth of
the seal are all of one form, viz. that of the canine
kind; conical and pointed.

The narwhal has no other teeth than the two long
tusks implanted in its os intermaxillare; of which
one is so frequently wanting. A head, in which
[Seite 82] there are two of these tusks, is delineated by Dr.
Shaw, in his Zoology, from a specimen in the
Leverian Museum. These tusks are remarkable
for the spirally convoluted appearance of their ex-
ternal surface. They are hollow internally, and
probably have a constant growth like the elephant’s
tusks.

(U) The permanent teeth are generally formed
in cavities near the roots of the temporary ones;
and they succeed to the vacancies left by the dis-
charge of the latter.

A different mode of succession obtains, however,
in some instances. The adult molares of the hu-
man subject are not formed near any of the tem-
porary teeth; but in the back of the two jaws;
from which situation they advance successively to-
wards the front, in proportion as the maxillary
bones are lengthened in that direction. A similar,
but much more remarkable species of succession is
observed in the grinders of the elephant, where it
was ascertained by the labours of Mr. Corse, who
has explained and illustrated the subject, in a series
of beautiful engravings. See Observations on the
different Species of Asiatic Elephants, and their Mode
of Dentition. Phil. Trans. 1799, part 2.

We never see more than one grinder, and part
of another, through the gum in this animal. The
anterior one is gradually worn away by mastication;
its fangs and alveolus are then absorbed: the pos-
[Seite 83] terior tooth coming forwards to supply its place.
As this goes through the same stages as the pre-
ceding grinder; a third tooth, which was contained
in the back of the jaw, appears through the gum,
and advances, in proportion as the destruction and
absorption of the other proceed. The same pro-
cess is repeated at least eight times; and each new
grinder is larger than that which came before it.
The 1st, or milk grinder, is composed of four trans-
verse plates or denticuli, and cuts the gum soon
after birth. The 2d, which has eight or nine
plates, has completely appeared at the age of two
years. The 3d, formed of twelve or thirteen, at
six years. From the 4th to the 8th grinder, the
number of plates varies from fifteen to twenty-
three, which is the largest hitherto ascertained.
The exact age at which each of these is completed,
has not yet been made out. But it appears, that
every new one takes at least a year more for its
formation than its predecessor.

From the gradual manner, in which the tooth
advances, it is manifest, that a small portion of it
only can penetrate the gum at once. A grinder,
consisting of twelve or fourteen plates, has two or
three of these through the gum, whilst the others
are imbedded in the jaw. The formation of the
tooth is complete therefore, first, at its anterior part,
which is employed in mastication, while the back
part is very incomplete; as the succeeding laminae
advance through the gum, their formation is suc-
[Seite 84] cessively perfected. But the posterior layers of the
tooth are not employed in mastication, until the
anterior ones have been worn down to the very
fang, which begins to be absorbed. One of these
grinders can never therefore be procured in a perfect
state: for if its anterior part has not been at all
worn, the back is not completely formed, and the
fangs in particular are wanting; while the structure
of the back of the tooth is not completed, until the
anterior portion has disappeared.

A similar kind of succession, but to a less extent,
bas been ascertained by Mr. Home, in the teeth of
the sus Aethiopicus.

Observations on the Structure of the Teeth of Gra-
minivorous Quadrupeds; particularly those of the
Elephant, and sus Aethiopicus. Phil. Trans. 1799,
part 2.

The researches of the same gentleman have also
proved it to exist in the wild boar to a certain
degree; and have rendered it probable, that it
occurred likewise in the animal incognitum (mam-
moth).

Observations on the Structure and Mode of Growth
of the Wild Boar, and Animal Incognitum. Phil.
Trans. 1801, part 2.

(V) The numbers of cervical vertebrae is the
same in the cetacea, as in other mammalia, according
to Cuvier; but some of them are anchylosed.
Thus the two first are united in the dolphin and
[Seite 85] porpoise; and the six last in the genus physeter.
Léçons d’Anat. Comp. tome 1, p. 154.

It must be accounted a singular circumstance,
that the number of cervical vertebrae should be so
constantly the same in animals, whose neck differs
so much in length; when the number of pieces in
the other regions of the spine, varies greatly in the
different genera. No instance has, I believe, been
recorded, in which more than seven cervical ver-
tebrae have been found in the human subject;
although the number of those in the back and loins
sometimes deviates from the natural standard.

(W) These processes, which are particularly con-
spicuous in such carnivorous animals, as have great
strength in their neck, afford attachment to the large
and powerful muscles, by which the animal exe-
cutes those strong and rapid motions of the head,
which are necessary in attacking its prey, or de-
fending itself. The badger, in this country, affords
an excellent specimen of the structure alluded to.

The mole and shrew have no spinous processes
in the neck. The vertebrae form simple rings, with
considerable motion on each other. These pro-
cesses are either very short, or altogether deficient
in the long necked animals; as the horse, camel,
giraffe, &c. They would otherwise afford an ob-
stacle to the bending of the neck backwards.

The six last vertebrae of the neck are anchylosed
in the ant-eater and manis.

[Seite 86]

(X) Most of the simiae, and even some, which
very much resemble the human subject, as the
orang-outang, which Camper dissected, (simia pyg-
maeus), have the sacrum formed of three pieces;
which consequently leave only two pair of open-
ings for the passage of the nerves. Now, as
Galen mentions these circumstances of the human
sacrum, in his work on the bones, it must appear
very clearly that the description could not have been
taken from the human subject; but was probably
derived, as Vesalius supposed, from the ape; al-
though Silvius and Eustachius have endeavour-
ed to invalidate this conclusion. See Vesal. Epist.
de rad. Chynae; also his great work, De Corp. hum.
Fabricâ, p. 99.

The true orang-outang (simia satyrus) has a
sacrum composed of five pieces. The elephant has
also five. See Blair Osteogr. Elephantina, p. 29.

(Y) In monkeys, and even in such simiae as have
no tails, where the os coccygis consists at most of
three pieces only; this bone is perforated by a con-
tinuation of the vertebral canal, and by openings
for the transmission of nerves. This structure is
ascribed by Galen to the human coccyx; and
hence Vesalius has derived another argument, to
shew that Galen’s Osteology was not drawn from
the human skeleton.

The orang-outang, like man, has a coccyx com-
posed of five pieces, not perforated. Tyson’s
Anat. of a Pigmy, p. 69.

[Seite 87]

Those vertebrae of the tail of mammalia, which
are nearest to the sacrum, are perforated by a con-
tinuation of the canal for the medulla spinalis.
The lower ones are solid. The want of pelvis ren-
ders it impossible for us to decide the number of
sacral and coccygeal vertebrae in the cetacea: but
the whole number of pieces in the spine of the dol-
phin and porpoise is 66.

(Z) Ossification of the cartilage, which connects
the two ossa pubis, is so rare in the human subject,
that one case only of complete anchylosis of these
bones has been hitherto recorded: (Soemmerring
de Corp. human. Fab. tom. 1. p. 22. note ***) al-
though several instances of partial bony union have
been observed. See Sandifort, Obs. Anat. Pa-
thol, vol. 2.; Wynpresse de Ancylosi; and Mi-
chell de Synchondrotomia pubis. Amstelod. 1783.
Such an occurrence is not, however, very rare in the
horse.

(A a) The onithorhynchus paradoxus and histrix
have ribs of a very singular structure. Their true
ribs, which are six in number, consist of two pieces
of bone; a longer one joined to the spine, and a
shorter connected to the sternum. These are united
by means of a piece of cartilage; so as to constitute
a structure, approaching to that of birds. The false
ribs, ten in number, terminate anteriorly in broad,
flattened, oval bony plates, connected together by
elastic ligaments. Phil. Trans. 1802, part 1, plate 3.

[Seite 88]

(B b) This process may be compared to the keel-
like projection of the sternum of birds. It serves
for the origin of those strong muscles of the anterior
extremity, which assist the animal in digging its way
under ground.

(C c) We may assert, as a general observation,
that the four component parts of the upper extre-
mity, viz. the shoulder, arm, fore-arm, and hand,
can be clearly shewn to exist in the anterior extre-
mities of all mammalia; however dissimilar they
may appear to each other on a superficial inspec-
tion, and however widely they may seem to deviate
from the human structure.

Whenever an animal of one class resembles those
of a different order in the form and use of any part,
we may be assured, that this resemblance is only in
externals; and that it does not affect the number
and arrangement of the bones. Thus the bat has
a kind of wings; but an attentive examination will
prove, that these are really hands, with the pha-
langes of the fingers elongated. The dolphin, por-
poise, and other cetacea, seem to possess fins, consist-
ing of a single piece. But we find under the inte-
guments of the fin-like members, all the bones of
an anterior extremity, flattened in their form, and
hardly susceptible of any motion on each other.
We can recognize very clearly the scapula, hu-
merus, bones of the fore-arm, and a hand consist-
ing of five fingers: the same parts, in short, which
[Seite 89] form the anterior extremity of other mammalia.
See Tyson’s Anatomy of a Porpoise, fig. 10 and
11.: also Blasii Anatomia Animalium, tab. 51,
fig. 3, 4.

The fore-feet of the sea-otter, seal, walrus, and
manati, form the connecting link between the an-
terior extremities of other mammalia, and the pec-
toral fins of the whale kind. The bones are so
covered and connected by integuments, as to con-
stitute a part, adapted for the purposes of swimming:
but they are much more developed than in the lat-
ter animals, and have free motion on each other.

The cold-blooded quadrupeds bear great analogy
in the four component parts, and in the general
structure of their anterior extremities, to the warm-
blooded ones. See Caldesi’s Observations on the
Turtle, tab. 3. fig. 1. 4, 5.

The bones of the wing of birds have a consider-
able and unexpected resemblance to those of the
fore-feet of the mammalia. And the fin-like ante-
rior member of the penguin contains, within the
integuments, the same bones as the wings of other
birds.

(D d) The clavicle supports the anterior extremity,
and maintains the shoulder at its proper distance from
the front of the trunk. It exists, therefore, in all
such animals as make much use of these members,
whether for the purpose of climbing, digging, swim-
ming, or flying. It does not exist, on the contrary,
[Seite 90] in such as use their fore-feet merely for the purpose
of progression; since these limbs must be brought
more forwards on the chest, that they may support
that part, by being placed perpendicularly under it.
In the genera, which hold an intermediate rank be-
tween these; which do not enjoy such an extensive
utility of the fore-feet as the first division of ani-
mals; and are not so limited in their employment
as the second, the clavicular bones, or imperfect
clavicles exist.

(E e) The humerus becomes shorter, in propor-
tion as the metacarpus is elongated; so that in ani-
mals, which have what is called a cannon bone, the
os humeri hardly extends beyond the trunk. Hence
the mistakes, which are made in common language,
by calling the carpus of the horse his fore-knee, &c.

The radius forms the chief bone of the fore-arm
in the mammalia, generally speaking; the ulna is a
small slender bone, terminating short of the wrist
in a point, and often consolidated with the radius,
as in the horse and ruminating animals. A few ge-
nera, which have great and free use of their anterior
extremity, have the power of pronation and supi-
nation. But this power diminishes, as the fore-feet
are used more for the purpose of supporting the
body in standing, and in progression. In this case,
indeed, the extremity may be said to be constantly
in the prone position, as the back of the carpus and
toes is turned forwards.

[Seite 91]

The lower end of the ulna is larger than that of
the radius in the elephant; but this circumstance
occurs in no other instance.

The radius and ulna exist in the seal, manati, and
whales, but in a flattened form.

Several genera of mammalia possess a hand; but
it is much less complete, and consequently less
useful than that of the human subject, which well
deserves the name bestowed on it by Aristotle, of
the organ of all organs. The great superiority of
that most perfect instrument, the human hand,
arises from the size and strength of the thumb,
which can be brought into a state of opposition to
the fingers, and is hence of the greatest use in
grasping spherical bodies, in taking up any object
in the hand, in giving us a firm hold on whatever
we seize; in short, in a thousand offices, which
occur every moment of our lives, and which either
could not be accomplished at all, if the thumb
were absent, or would require the concurrence of
both hands, instead of being done by one only.
Hence it has been justly described by Albinus as
a second hand ‘“manus parva majori adjutrix,”’
de sceleto, p. 465.

All the simiae possess hands: but even in those,
which may be most justly stiled anthropomorphous,
the thumb is small, short, and weak; and the other
fingers elongated and slender. In others, as some
of the cercopitheci, there is no thumb, or at least it
is concealed under the integuments; but these
[Seite 92] animals have a kind of fore paw, which is of some
use in seizing and carrying their food to the mouth,
in climbing, &c. like that of the squirrel. The
genus lemer has also a separate thumb. Other
animals, which have fingers sufficiently long and
moveable for seizing and grasping objects, are
obliged, by the want of a separate thumb, to hold
them by means of the two fore-paws; as the squirrel,
rat, opossum, &c. Those, which are moreover
obliged to rest their body on the fore-feet, as the
dog and cat, can only hold objects by fixing them
between the paw and the ground. Lastly, such
as have the fingers united by the integuments, or
enclosed in hoofs, lose all power of prehension.

The simiae in general have nine bones in the
carpus. Riolani Anthropographia and Osteolog.
p. 908. Paris, 1626; but there are only eight
in the orang-outang, according to Tyson. There
are five carpal bones in the fin of the whale, of a
flattened form, and hexagonal.

The metacarpus is elongated in those animals,
where the toe only touches the ground in standing
or walking; and constitutes the part, which is
commonly called the fore-leg; as the carpus is
termed the knee.

The number of metacarpal bones is the same
with that of the fingers or fore-toes: except in
the ruminating animals. Even in these, as the
author observes, there are two distinct metacarpal
bones, lying close together before birth: the
[Seite 93] opposed surfaces first become thinner, then are
perforated by several openings, and at last disap-
pear; so that the adult animal has a single cannon
bone, possessing a common medullary cavity inter-
nally, and marked on the outside with a slight
groove at the place of the original separation.
There is therefore but one metacarpal bone in the
adult for the two toes. The structure of the meta-
tarsus is the same.

In the horse on the contrary, if we allow the
splint bones to belong to the metacarpus, there will
be three to a single toe. Daubenton considers
the common bone of this animal as supplying the
place of the three metacarpal bones of man: he
compares the outer splint bone to the metacarpal
of the little finger, and the inner to that of the
thumb. Stubbs views the cannon as the meta-
carpal of the middle and ring fingers; and the
inner splint, as that of the fore-finger. Buffon
Hist. Naturelle, 4to. ed. p. 362. vol. 4. Stubbs’s
Anatomy of the Horse.

The single finger or fore-toe of the horse is com-
posed of the usual three phalanges; the first, which
is articulated to the cannon, is called the pastern;
the 2d is the coronet; and the 3d the os basis or
coffin bone; on which the hoof rests. There are
also two sesamoid bones at the back of the pastern,
joint: and an additional part called the shuttle-bone
connected to the coffin.

[Seite 94]

In those animals, which have five toes, as the
carnivora, &c., that which lies on the radial side
of the extremity, and is therefore analogous to the
thumb, is parallel with the others; and the animal
consequently has not the power of grasping any
object. The last phalanx in these supports the nail
of the animal; and sends a process into its cavity.
These parts are so connected that the nail is na-
turally turned upwards, and not towards the
ground; so that its point is not injured in the mo-
tions of the animal. The phalanx must be bent in
order to point the nail forwards or downwards.

The order of rodentia have generally five toes:
that which corresponds to the thumb being the
shortest.

The elephant has five complete toes; but they
are almost concealed by the thick skin.

The pig has four toes; two larger ones, which
touch the ground; and two smaller behind these,
which do not reach so far. There is also a bone,
which seems to be the rudiment of a thumb.

The phalanges of the cetacea are flattened; not
moveable, and joined together in the fin.

(F f) The length of the femur depends on that
of the metatarsus; and it bears an inverse ratio to
the length of that part.

Hence it is very short in the horse, cow, &c.
where the same mistakes are commonly com-
[Seite 95] mitted in naming the parts, as in the anterior
extremity.

The proportions of the thigh and leg vary in
different animals. The latter part exceeds the
former in the human subject; and the same remark
may be made respecting the arm and fore-arm.
These parts are nearly of the same length in the
orang-outang. Some persons have affirmed that the
Negro forms a connecting link between the Eu-
ropean and the orang-outang in these respects.
(White on the regular Gradation in Man and Ani-
mals, &c). In some other simiae the leg and fore-
arm exceed the thigh and arm. In other animals,
although they are some varieties, the leg is gene-
rally longer than the thigh.

The femur of the mammalia is not arched as in
the human subject: it possesses scarcely any neck;
and the great trochanter ascends beyond the head
of the bone.

The fibula is behind the tibia in many animals,
as the dog and the rodentia. It is consolidated to that
bone at its lower end in the mole and rat. It only
exists as a small styloid bone in the horse, and be-
comes anchylosed to the tibia in an old animal.

The structure of the metatarsus in the rumi-
nating animals, and the horse, is the same with that
the metacarpus.

The tarsus of the horse is composed of six bones;
and is the part known in common language by the
name of the hock.

[Seite 96]

Animals of the genus simia and lemur, instead of
having a great toe placed parallel with the others,
are furnished with a real thumb: i.e. a part capable
of being opposed to the other toes. Hence these
animals can neither be called biped, nor quadruped,
but are really quadrumanous or fourhanded. They
are not destined to go either on two or four extre-
mities, but to live in trees, since their four prehen-
sile members enable them to climb with the greatest
facility. So that Cuvier has denominated them
‘“les grimpeurs par excellence.”’ (Leçons d’Anat.
Comp. vol. 1. p. 493.) The prehensile tail of
several species is a further assistance in this way of
life. The opossum, and others of the genus didelphis,
have a similar structure with the quadrumana; and
it answers the same purpose. Here however there
is a separate thumb on the posterior extremity only,
whence Cuvier calls them pedimanes.

Man is the only animal, in which the whole
surface of the foot rests on the ground: and this
circumstance arises from the erect stature, which
belongs exclusively to him. In the quadrumana;
in the bear, hedgehog, and shrew, (which are called
by Cuvier plantigrades), the os calcis does not
touch the ground.

The heel of a species of bear belonging to this
country, viz. the badger (ursus meles), is covered
with a long fur, which proves that this part cannot
rest on the ground; although the structure both of
the bones and muscles of the lower extremity of
[Seite 97] this animal, approaches considerably to that of
man. The same fact is stated of the bear itself,
properly so called, by the Parisian dissectors, Descrip-
tion anatomique d’un cameleon, d’un castor, d’un ours,
&c. Paris, 1669, 4to. the plate is contained in
Blasius’s Collection, tab. 32.

In other animals the body is supported upon the
phalanges of the toes, as in the dog and cat; in the
horse and ruminating animals no part touches the
ground but the last phalanx. Here the elongation
of the metatarsus removes the os calcis to such a
distance from the toe, that it is placed midway be-
tween the trunk and hoof.

Additional Notes to the Third Chapter.

(A) This structure gives the head a great free,
dom of motion, particularly in the horizontal direc-
tion. It enables the bird to place its bill between
the wings, when asleep; a situation, in which none
of the mammalia can bring the snout.

[Seite 106]

(B) The os quadratum has a true articulation,
both with the lower mandible and with the cranium.
Another small bone is connected to it, and rests by
its opposite end against the palate. Hence, when
the square bone is brought forwards, which it is by
the depression of the lower mandible, and in a
greater degree by some particular muscles, the se-
cond bone presses against the palate, so as to elevate
the upper jaw.

(C.) The bill of birds may be considered, in
some degree, as supplying the place of teeth;
yet, as none of these animals masticate their food,
but swallow it whole, the bill can only be compared
to the incisors of such animals, as use them for seiz-
ing and procuring their food.

It consists of a horny fibrous matter, similar to
that of the nail, or of proper horns; and is moulded
to the shape of the bones, which constitute the two
mandibles, being formed by a soft vascular sub-
stance, covering these bones. Its form and struc-
ture are as intimately connected with the habits and
general character of the animal, as those of the teeth
are in the mammalia. Hence an enumeration of
its different figures and consistence, belongs pro-
perly to the department of natural history, where
it forms the foundation of classific distinctions.

The accipitres, or rapacious birds, have it very
hard, hooked at the end, and furnished with a pro-
cess on either side; calculated, therefore, in all re-
[Seite 107] spects, for seizing and lacerating their prey. Those
of the parrot kind have it also hard, for bruising the
firmer vegetable fruits; and the wood-pecker, nu-
thatch, &c. for penetrating the bark of trees.

Those birds, which take a softer kind of food,
and which require a sense of feeling in the part, for
distinguishing their food in mud, water, &c. have it
approaching to the softness of skin. Such are the
duck, snipe, woodcock, &c.

In several classes, particularly the accipitres and
gallinae, the base of the bill is covered with a soft
skin, called the cire, of unknown use.

(D) The number of cervical vertebrae in birds,
varies from ten to twenty-three; those of the back
from seven to eleven. From hence to the tail, they
are consolidated into one piece with the os innomi-
natum. The tail has from seven to nine pieces.

The length of the neck increases in general, in
proportion to that of the legs.

The cervical vertebrae are not articulated by plane
surfaces, but by cylindrical eminences, which admit
a more extensive motion, as they constitute real
joints, instead of synchondroses. Four or five of
the upper pieces only bend forwards; while the
lower ones are confined to flexion backwards.
Hence the neck of a bird acquires that double
bend, which makes it resemble the letter S. It is
by rendering the two curvatures more convex, or
[Seite 108] more straight, that the neck is shortened or elon-
gated. The great mobility of the neck, enables
birds to touch every point of their own body with
the bill, and thus to supply the want of the prehen-
sile faculty of the superior extremity.

(E) The point of the fork-like bone is joined to
the most prominent part of the keel of the sternum;
and the extremities of its two branches are tied to
the humeral end of the clavicles, and the front of
the scapulae, just where these bones join each other,
and are articulated with the humerus. Hence it
serves to keep the wings apart in the rapid motions
of flying. ‘“As a general observation, it may be
stated, that the fork is strong and elastic; and its
branches wide, arched, and carried forwards upon
the body, in proportion as the bird possesses strength
and rapidity of flight; and accordingly the stru-
thious birds (ostrich and cassowary), which are in-
capable of this mode of progression, have the fork
very imperfectly formed. The two branches are
very short, and never united in the African ostrich,
but are anchylosed with the scapula and clavicle.
The cassowary has merely two little processes from
the side of the clavicle, which are the rudiments of
the branches of the fork. In the New Holland
ostrich there are two very small thin bones, which
are attached to the anterior edge of the dorsal end
of the clavicles by ligament; they are directed up-
[Seite 109] wards towards the neck, where they are fastened to
each other by means of a ligament, and haver no
connection whatever with the sternum.”’

Macartney, in Rees’s Cyclopaedia. Article
Birds, Anatomy of.

(F) Birds certainly have a fibula, contrary to the
assertion of the author; but it is small, and soon
anchylosed to the tibia.

The lower end of the bone, which answers to
the tarsus and metatarsus, forms as many processes
as there are toes; and each of these has a pulley,
for articulation, with its corresponding toe.

The vast length of the leg in the wading birds
(grallae), the ostrich, and cassowary, is produced by
the tibia, and common bone of the tarsus and meta-
tarsus; for the femur is comparatively short.

‘“The stork, and some others of the grallae,
which sleep standing on one foot, possess a curious
mechanism, for preserving the leg in a state of ex-
tension, without any, or at least with little muscular
effort. There arises from the fore-part of the head
of the metatarsal bone, a round eminence, which
passes up between the projections of the pulley, on
the anterior part of the end of the tibia. This
eminence affords a sufficient degree of resistance to
the flexion of the leg, to counteract the effect of
the oscillations of the body, and would prove an
insurmountable obstruction to the motion of the
[Seite 110] joint, if there were not a socket within the upper
part of the pulley of the tibia, to receive it when the
leg is in the bent position. The lower edge of the
socket is prominent and sharp, and presents a sort
of barrier to the admission of the eminence, that re-
quires a voluntary muscular exertion of the bird to
overcome, which being accomplished, it slips in with
some force, like the end of a dislocated bone.”’

Macartney, loco citato.

Additional Notes to the Fourth Chapter.

(A) This circumstance is still more remarkable
in the crocodile. The cranium of an individual,
measuring thirteen or fourteen feet, will hardly
admit the thumb: and the area of its section does
not constitute the twentieth part of that of the
whole head.

The chameleon affords another instance of the
same structure: its brain, according to the de-
scription of the Parisian dissectors, does not seem
larger than a pea; and the whole of the head,
which is of considerable size, consists of the large
maxillary bones, the orbits, and immense temporal
fossae, which, not being separated by any partition,
give the cranium a very singular appearance.

See the Description anatomique d’un Cameleon, &c.
or Blasius’s Collection, tab. 14.

(B) In may be observed in confirmation of this
remark, that the number of vertebrae is very great
[Seite 119] in fishes of an elongated form; viz. in the eel,
which has above one hundred. The porpoise,
which has no organs of motion, which deserve
mentioning, has between sixty and seventy.

Birds, which have such vast power of locomotion
by means of their wings, have very few vertebrae,
if we consider the anchylosed ones as forming a
single piece. And the frog, with its immense hind
extremities, has a very short spine, consisting of
still fewer pieces.

(C) The occiput is connected to the atlas by a
single condyle in the crocodile and turtle: in the
lizard and tortoise there is a flight appearance of di-
vision into two surfaces: in the frog and toad there
are two condyles; and in the serpents there are
three articular surfaces on a single tubercle.

The condyle of the turtle being deeply imbedded
in the atlas, the motions of the articulation must
be limited: the protraction and retraction of the
head in this animal is effected by the flexion and
extension of the vertebrae of the neck.

The lower jaw is articulated with an eminence of
the cranium in the lizards, turtles, frogs, salaman-
ders, blindworms, (anguis fragilis) and amphisbaena;
besides the crocodile in which the author mentions
it. This bony eminence, is compared by Cuvier
to the os quadratum of birds. The lower jaw only
is moveable in these animals. Its articulation in
[Seite 120] the turtle is by means of a ginglymus. In all the
venomous serpents the upper jaw is moveable on
the head, as in birds: these animals require as ex-
tensive an opening of the mouth as possible, since
they swallow others whole, actually larger than
their own body.

Additional Note to the Fifth Chapter.

(A) Great variety exists in the teeth of fishes;
and their structure, formation, and mode of growth
have been but imperfectly explained hitherto.

Many fishes have simple teeth, formed of a bony
substance, covered by enamel, and probably formed
[Seite 126] as in the mammalia. These are the most common,
and may be seen in the pike. When the crown
has completely appeared, the root becomes anchy-
losed to the jaw.

In other cases they adhere to the gum only, or
at least to a firm cartilaginous substance, which
covers the jaw. This is exemplified in the shark.
These teeth seem not to be formed, as those of the
mammalia are, by the deposition of successive layers
one within the other; but in a manner more nearly
resembling the formation of bone. They are at
first soft and cartilaginous, and pass by successive
gradations, into a state of hardness and density,
not inferior to that of ivory.

A third kind of teeth consists of an assemblage
of tubes, covered externally by enamel, and con-
nected to the jaw by a softer substance, which pro-
bably sends processes or vessels into those bony
tubes. This is the case with the pavement, as we
may call it, of teeth, that covers the jaws of the
skate.

A similar structure is observed in the anarrhichas
lupus; where the teeth, composed of bony tubes,
are connected to spongy eminences of the jaws,
which may be compared to epiphyses; and on their
separation leave a surface like that from which the
antler of the deer falls off.

Besides the two jaws, fishes have teeth implanted
in the bones of the palate; in that which corres-
[Seite 127] ponds to the vomer; in the os hyoides; in the
bones which support the franchiae; and in those
which are placed at the top of the pharynx. The
salmon and pike have them in all these situations.

(B) Birds.

§ 93. As we have spoken above of the cheek-
pouches of some mammalia, we must here take
notice of the throat sack, which is found in the male²
bustard, under the integuments of the front of the
neck; and opens by a wide aperture under the
tongue: its use has not been hitherto discovered³.
See note (N).

§ 94. The oesophagus, which generally de-
scends on the right of the trachea, as well as its
opening into the stomach, is of immense size in
[Seite 141] many carnivorous birds; considerably larger indeed
than the intestinal canal. The capaciousness of this
tube, enables it hold for a time⁴ the entire fish, and
large bones, which these birds swallow, and which
cannot be contained in the stomach; and to facili-
tate the discharge, by vomiting the indigestible re-
mains of the food, which form balls of hair, feathers,
and bony matter. See note (I).

§ 95. The oesophagus expands just before the
sternum into the crop (ingluvies, prolobus, le jabot),
which is furnished with numerous mucous, or sali-
vary glands, disposed in many cases in regular rows.
In such birds, as nourish their young from the crop,
the glands swell⁵ remarkably at that time, and se-
crete a greater quantity of fluid⁶. This part is
found in land birds only, but not in all of these;
it exists in all the gallinae, and in some birds of
of prey⁷. See note (K).

[Seite 142]

§ 96. There is another glandular and secretory
organ, much more common than the crop, belong-
ing indeed most probably^* to the whole class.
This is the bulbus glandulosus (echinus, infundibulum,
proventriculus, corpus tubulosum), which is situated
before the entrance of the oesophagus into the pro-
per stomach, and whose form and structure vary
considerably in the different genera and species. In
the ostrich, for example, its magnitude and form
give it the appearance of a second stomach⁸. In
some other birds, as the psittaci, ardeae (crane,
stork, &c.), its appearance is different from that of
the proper stomach, but its size is larger; while,
on the contrary, in gallinaceous fowls, it is much
smaller⁹. See note (L).

§ 97. In most birds, the stomach lies at the
upper¹⁰ part of the abdomen, that is, close to the
spine, and rests, in a manner, on a stratum of in-
testines; in the cuckoo, on the contrary, it lies be-
low. This peculiarity does not, however, belong
[Seite 143] exclusively to that curious bird¹¹; for I have found
it in the ramphastos, and the corvus caryocatactes (the
nut-cracker).

A deviation from the natural structure, which is
completely unparalleled, occurs in the stomach of
the cuckoo. The gizzard of this bird is covered
internally with an abundance of short, bristly, and
spiral hairs, lying close together.

§ 98. The structure of the stomach differs most
widely in the different orders and genera of this
class. It appears merely as a thin membranous
bag, in several of those which feed on flesh and
insects, when compared with the thick muscular
globes of the granivorous genera. But there are
both many intermediate links¹² between these ex-
tremes, and at the same time considerable analogies
on the structures, which are apparently the most op-
posite. This is particularly observable, in the course
of the muscular fibres¹³,, and in the callous structure
and appearance of the internal coat¹⁴; in which
[Seite 144] points, many of what are called membranous sto-
machs, have a great resemblance to those of the
gallinae.

§ 99. Both parts, but particularly the muscular,
are very strong in the gizzard (ventriculus bulbosus)
of granivorous birds¹⁵. We find here, instead of
a muscular coat, four immensely thick and powerful
muscles: viz. A large hemispherical pair at the
sides (laterales), and two smaller ones (intermedii)
at the two ends of the cavity. All the four are
distinguished, both by the unparalleled firmness of
their texture¹⁶, and by their peculiar colour, from
all the other muscles of the body.

The internal callous coat must be considered as
a true epidermis; since, like that part, it becomes
gradually thicker from pressure and rubbing¹⁷. It
forms folds and depressions towards the cavity of
the stomach: and these irregularities are adapted to
each other on the opposed surfaces. The cavity of
this curious stomach, is comparatively small; its
lower orifice is placed very near the upper. Every
part of the organ is, indeed, calculated for producing.
[Seite 145] very powerful trituration¹⁸; and this is still further
promoted, by the well-known instinctive practice of
granivorous birds, of swallowing small hard stones
with their food¹⁹.

C. Amphibia.

§ 100. The capacious oesophagus of the turtle,
has a very striking peculiarity in its structure: its
[Seite 146] internal coat is beset with¹ innumerable large, firm,
and pointed processes of a white colour. Their
points are all directed towards the stomach; and
they probably serve to prevent the return of the
food, which can only enter the stomach gradually.

§ 101. The oesophagus of the crocodile is of the
funnel shape; the stomach of the animal resembles,
although not very closely, that of the granivorous
birds, in the nearness of its two apertures, and the
thickness of its coats.

§ 102. The stomach of serpents can hardly be
distinguished from the oesophagus, except that it is
somewhat larger. It is very short, when compared
with the great length of that tube. (See note (M).

(D) Fishes.

§ 103. The oesophagus is short in most of this
class. But this character is not universal, as Aris-
[Seite 147] totle supposed²; nor is a long oesophagus pecu-
liar to fishes of an elongated form. (See note (N).

§ 104. The size and form of the stomach vary³
very considerably in this class. Its coats are thin
in most fishes; but in some they are very thick and
muscular⁴, and have a callous internal covering:
still, however, the resemblance between these and
the stomachs of granivorous birds is very remote.

(E) Insects.

§ 105. I have already observed, on another
occasion⁵, that the business of nutrition in insects,
does not seem to have for its object, the mere pre-
servation of the individual, as in most red-blooded
animals; but chiefly the consumption of organised
matter; which will appear clearly, from considering
the structure of their alimentary canal. In most of
those, which are subject to a metamorphosis, the
stomach, in the larva state, is of a great size, in
[Seite 148] comparison with the short intestinal canal: while
those on the contrary, which take little or no nou-
rishment in their perfect state, have this organ re-
markably diminished, and as it were contracted².

§ 106. Our limits will allow us to take but
little notice here of the endless varieties, and pecu-
liarities of internal structure, which occur in the
different genera and species of this multiform class
of animals. We shall therefore only bestow two
words³ on those of the oesophagus and stomach.
In several cases, the commencement and termina-
tion of the alimentary canal, the oesophagus and
rectum, are surrounded by an anular portion of
the spinal marrow.

[Seite 149]

In the earwig (forsicula auricularia), the upper
orifice of the stomach is furnished with two rows
of teeth⁴.

In some of the grylli (grasshoppers), the stomach
itself is small, but the oesophagus much larger.

In some species of that genus, particularly in the
gryllus gryllotalpa, the stomach consists of three or
four vesicular portions⁵, which have been com-
pared with the stomachs of the ruminating mam-
malia⁶.

We have already (§ I, note l.) mentioned the
stomach of the lobster, and some other species of
the genus cancer⁷; which is provided with several
portions of bone. It contains also three teeth,
which, together with the stomach itself, are annually
reproduced, at least in the craw-fish (cancer astacus),
(See note (O).

(F) Vermes.

§ 107. We can only select a few instances¹,
[Seite 150] as examples of this class, which includes a great
number of creatures, differing widely from each
other.

The aphrodite aculeata (sea-mouse), which is
well-known, on account of its beautiful colours,
possesses a very remarkable stomach. The form
and size of the viscus, resemble those of a date,
while in strength and compactness of texture, it
approaches to that of granivorous birds².

The oesophagus is expanded into a crop in many
testacea, particularly among the bivalves; and it is
covered internally with numerous small teeth³.

[Seite 151]

The powerful stomach of the bulla lignaria, con-
tains three hard calcareous shells, by which the ani-
mal is enabled to bruise and masticate the other
testacea, on which it feeds⁴.

In most of the proper mollusca, the stomach is of
a simple membranous structure, and of very dif-
ferent comparative magnitudes. I have found it
very large in the scyllaea pelagicum. It occupies the
greatest part of the body in the leech, and is di-
vided internally by means of ten imperfect parti-
tions, into somewhat separate portions.

Lastly, the armed polypes (hydra), and other
similar zoophytes, can hardly be considered as any
thing more than a mere stomach, having its open-
ing furnished with tentacula. (See note (P) at the
end of the chapter.)

---

Additional Notes to the Sixth Chapter.

(A) A cheek-pouch exists also in the ornitho-
rhynchus paradoxus. Phil. Trans. 1800, part 1,
tab. 2. fig. 2.

The salivary glands of the mammalia exhibit
[Seite 152] very few variations in structure. They are small in
the carnivora, as mastication, properly so called,
can hardly be said to take place in them. On the
contrary, the ruminantia and solipeda have them
very large. The size of the sub-maxillary gland,
in particular, is remarkable in the cow and sheep:
it extends along the side of the larynx, quite to the
back of the pharynx.

The parotid and sublingual glands do not exist
in the amphibious mammalia, as the seal: the teeth
of that animal are only adapted for seizing their
prey, and must be utterly incapable of mastication.
The same remark may be made on the cetacea, where
the salivary system seems to be altogether deficient.

The mucous glands, which constitute the labiales
and buccales of man, are larger and more distinct
in some animals. There is a row of these opposite
to the molar teeth of the dog and cat, penetrating
the membrane of the mouth by several small open-
ings. Thore is also a considerable gland in the
dog, under the zygoma, and covered by the masse-
ter. Its duct, equal in size to that of the parotid,
or sub-maxillary glands, opens at the posterior ex-
tremity of the alveolar margin of the upper jaw.
The molar glands and their openings, are very con-
spicuous in the pig. The cow and sheep have an
assemblage of similar glands in the zygomatic fossa:
their excretory ducts open behind the last superior
molar tooth.

[Seite 153]

(B) No mammalia possess an uvula, except
man, and the simiae. As the cetacea possess no
nostrils, they have not of course any velum pa-
lati.

The parts about the pharynx exhibit a very
singular structure in these animals. The la-
rynx is elongated, so as to form a pyramidal
production, on the apex of which, its opening is
found. The projection of this part will divide the
pharynx; and the food must pass on either side of
the pyramid. A muscular canal extends from the
pharynx to the blowing holes, and is attached to
the margin of those apertures. The circular fibres
of this tube, form a sphincter muscle; which, by
contracting round the pyramid, cuts off the com-
munication between the blowing holes and the
mouth and pharynx.

(C) In the animals alluded to in this para-
graph, the left half of the stomach is covered
with cuticle, while the other portion has the
usual villous and secreting surface. The cuti-
cular covering, forms a more or less prominent
ridge at its termination. The left portion of
the cavity may be regarded as a reservoir, from
which the food is transmitted to the true di-
gestive organ; and the different states, in
which the food is found in the two parts of the
cavity, justify this supposition. Hence these sto-
machs form a connecting link between those of
[Seite 154] ruminating animals on one side; and such as have
the whole surface villous, on the other.

(D) The larvae of the astrus equi (the large
horse-bot), attach themselves to every part of the
stomach, but are in general most numerous about
the pylorus; and are sometimes, but much less
frequently, found in the intestines. They hang
most commonly in clusters, being fixed by the
small end to the inner membrane of the stomach,
where they adhere, by means of two small hooks,
or tentacula. When removed from the stomach,
they will attach themselves to any loose membrane,
and even to the skin of the hand; for this purpose,
they draw back their hooks almost entirely within
the skin, till the two points of these hooks come
close to each other; they then present them to the
membrane, and keeping them parallel till it is
pierced through, they expand them in a lateral di-
rection; and afterwards, by bringing the points
downwards, or towards themselves, they include a
sufficient piece of the membrane with each hook,
and thus remain firmly fixed, for any length of
time, without any further exertion of the animal.
They attain their full growth about the latter end
of May, and are coming from the horse from this
time to the latter end of June. On dropping to
the ground, they soon change to the chrysalis, and
in six or seven weeks the fly appears. This bot is
larger and whiter than that of the aestrus hae-
[Seite 155] morhoidalis, which has a reddish cast; but in its
structure, and situation in the animal, resembles the
former. It is found, however, to hang about the
rectum, previously to quitting it, which the large
horse-bot never does.

Veterinary practitioners do not seem to have de-
cided hitherto, whether these animals are prejudicial
to the horse; nor even whether they may not be
actually beneficial. Their almost universal exist-
ence at a certain season, even in animals perfectly
healthy, shews that they produce no marked ill
effect: yet the holes which they leave, where they
were attached to the stomach, could hardly be made,
without causing some injurious irritation.

For the mode, in which these bots gain admission
into the stomach, as also for a most interesting ge-
neral account of their history and structure, see
Rees’s Cyclopaedia, art. Botts ; which was fur-
nished by Mr. Clarke, and from which the pre-
ceding account is borrowed.

(E) The food of carnivorous animals approach-
ing in its constituent elements more nearly to
those of the animal, than that of the herbivorous
tribes; is more easily reduced into the state, which
is required for the nourishment of the body, in the
former than in the latter case. Hence arises a lead-
ing distinction between the stomachs of these classes.
In the latter animals, the oesophagus opens consi-
derably to the right of the great extremity, so as
[Seite 156] to leave a large cul de sac on the left side of the
stomach; and the small intestine commences near
the cardia, leaving a similar blind bag on the right.
The food must be detained for a long time in such
a stomach, as the passage from the oesophagus, to
the pylorus is indirect and highly unfavourable
to speedy transmission. Animals of the mouse kind,
and the rodentia shew this structure very well; it
is very remarkable in the mus quercinus, (Cuvier
Leçons, &c. tom. 5. pl. 36. fig. 11.) In the car-
nivora, the stomach, which is of a cylindrical form,
has no cul de sacs; the oesophagus opens at its
anterior extremity, and the intestine commences
from the posterior; so that every thing favours a
quick passage of the food. Animals of the weasel
kind, which are very truly carnivorous, exhibit
this structure the most completely. The seal also
exemplifies it: and the lion. (Cuvier, pl. 36.
fig. 7).

(**) The peculiar structure of the stomach in
the camel and lama, which enables these animals
to lake at one time a sufficient quantity of water
to last them for two, three, or more days, and
thereby renders them adapted to inhabit the dry
and sandy deserts, which constitute their natural
abode, has been entirely omitted by the author.
The fluid, which they drink, is deposited in nume-
rous cells formed in the substance of their first and
second stomachs, by strong bands of muscular
[Seite 157] fibres crossing each other at right angles. It should
seem that the animal has the power of closing these
cells, by the contraction of those fibres which form
the mouths of the cavities; or of expelling the
contained fluid by putting the other portions of
fibres in action.

This cellular structure is found in two parts
of the first stomach; and it occupies the whole of
the second. It was found in a dead camel, that
these cavities would hold two gallons of fluid:
but they were probably more capacious during
life, as the animal in question always drank six or
seven gallons of water every other day, and took
more in the intermediate time. Mr. Bruce states
in his travels, that he procured four gallons
from one which he slaughtered in Upper Egypt.
(Shaw’s Abridgment of Bruce’s Travels, ed. 3.
p. 371).

As all the food which the animal takes passes into
the first stomach, the water of the cells in that part
becomes turbid; but it remains perfectly pure in the
second, where it resides in the greatest quantity:
which circumstance accounts for travellers being
able to drink it on an emergency. The muscular
bands, which form the groove described at § 90,
are particularly strong; and by drawing the third
stomach to the oesophagus, convey the ruminated
food through the second, without polluting the
water in its cells. Hence the food that has been
macerated in the paunch must be sent back to the
[Seite 158] mouth directly from that cavity, without passing
into the second stomach, as it does in the cow. See
‘“Observations on the camel’s stomach, respecting
the water which it contains,”’ &c. by E. Home,
Esq. Philos. Trans. 1806.

The cells are described and delineated, but very
imperfectly, by the Parisian dissectors. Description
Anatomique, &c.p. 80.

The structure of these parts, in the lama, accord-
ing to the account which Cuvier has given of
them, from the examination of a fetus, does not
seem to differ essentially from that of the camel.

Léçons d’Anat. Comp. tom. 3. p. 397.

Mr. Home also describes a projecting glandular
body in the fourth stomach, near the pylorus, both
in the cow and camel. He states that it may
shut that aperture. The same body is represented
as very large in the lama, by Cuvier loc. cit.

(F) According to Cuvier, there is a gland, as
large as the head of a man, situated between the
the coats of the stomach in the manati (tricheus
manatus borealis). It is placed near the oesophagus,
and discharges, on pressure, a fluid like that of the
pancreas by numerous small openings.

Léçons d’Anat. Comp. tom. 3. p. 401.

Mr. Home is of opinion, that a glandular struc-
ture exists in the stomach of the sea-otter near the
pylorus. Philos. Trans. 1796. pl. 2. And Mr.
Macartney has discovered an arrangement of
[Seite 159] glandular bodies in the dormouse, round the oeso-
phagus just before its termination, similar in situa-
tion and appearance to the gastric glands of birds.

(G) The stomach of the ornithorhynchus hystrix
is covered with cuticle, and possesses sharp horny
papillae near the pylorus. The animal swallows
sand, which may probably assist in the reduction of
the food, as the gravel does, which is swallowed by
the gallinaceous birds. Home in the Philos. Trans.
1802. p. 2.

(H) A very remarkable dilatation of the fauces
occurs in the pelican. An immense pouch, capable
of holding several quarts of water, lies between the
branches of the lower mandible, and constitutes
a reservoir for the food, which consists of fishes.
By means also of this bag, the animal seeds its
young, until they are of sufficient strength to pro-
vide for themselves.

(I) Proper salivary glands, such I mean, as se-
crete that clear and limpid fluid constituting the
saliva, do not exist in birds. For mastication, or
the comminution of the food, and its reduction
into a soft paste, to which function these glands are
entirely subservient, is not performed in the mouth
these animals, but in their gizzard. Birds
however have a very copious apparatus of those
mucous follicles, which form the glandulae labiales,
[Seite 160] buccales, linguales, &c. of the human subject. The
sides of the tongue, the under surface of that organ,
and the entrance of the oesophagus, are beset with
numerous openings of these glands, which furnish an
abundant supply of viscid mucus to defend the
tender lining of these parts from the hard bodies,
which constitute the food of several birds. These
apertures are very conspicuous in the gallinae.
The ostrich in particular, has two flattened bodies
at the upper and back part of the palate, which
may be compared in some respects to tonsils. The
surface of these is covered with innumerable fora-
mina, from which a tenacious mucus may be ex-
pressed. The soft palate, &c. are entirely deficient
in birds: the nostrils open on the bony palate by
longitudinal slits, the sides of which are guarded
by soft pointed papillae.

(K) The crop of the common fowl, and of the
other gallinae, is of a globular form, and placed
just in front of the chest. The oesophagus, which
opens at its upper part, commences again about
the middle of the bag, so that the crop itself forms
a cul de sac, or bag out of the regular course of
communication between the two openings of the
oesophagus. In the pigeon there is a spherical bag
formed on both sides of the oesophagus; which tube
itself is very large in the pouting pigeon, and admits of
being distended with air, so as to cause the appear-
ance from which the name of the bird is derived.
[Seite 161] In the birds, which we have now mentioned, the
crop must be considered as an organ for macerating
the dry and hard vegetable substances, which con-
stitute the food of these animals. The accipitres
also have this dilatation; but it must be regarded
in them merely as a reservoir for the food, which
does not require any previous softening. It is want-
ing in the piscivorous birds; but its place is sup-
plied by the great size of the oesophagus, in which
entire fishes are held until they can pass into the
stomach. The heron, cormorant, &c. exemplify
this.

(L) The term bulbus glandulosus (ventricule suc-
centurié, Cuvier) is applied to a small portion of
the oesophagus, just before its termination in the
stomach. This part is obviously rather larger and
thicker in its coats than the rest of the tube. Its
structure may be most clearly discerned in the gal-
linaceous genera. The oesophagus consists, as in
other parts, of its two coats, the muscular and
villous: but a vast number of glandular bodies,
cylindrical in form, and arranged in close apposi-
tion to each other, are interposed between these
tunics, and entirely surround the tube; constituting
the ‘“zone of gastric glands”’ of Mr. Macartney,
(Rees’s Cyclopaedia, Art. Birds). These bodies
have a hollow internally, and they open into the
cavity of the bulbus. The fluid secreted by them,
which from their number and size, must be furnished
[Seite 162] in great abundance, passes into the gizzard, and
mixes with the food in proportion as it is triturated
by that organ. These glands are much less distinct
in those birds which live on animal food, as the
accipitres, and the piscivorous genera, but they exist
universally, and their openings can always be dis-
cerned. The ostrich affords an opportunity of ex-
amining them to great advantage. In the African
species, of which I dissected an individual, the
oesophagus was dilated into an immense bag, capa-
ble of holding several pints of water, and five or
six times larger than the gizzard itself, which was
placed on the right and anterior part of this dilata-
tion. The glands did not surround the tube, so
that the term of zone would be here inapplicable.
They formed a long but narrow band, commencing
at the termination of the oesophagus, and running
along the front of the bag towards the gizzard.
This band measured about twelve inches in length,
and not more than three at its greatest breadth.
The size of the individual glands varied: they were
largest in the middle, and decreased towards either
margin of the band. Some of them equalled a
large pea; and their openings were in proportion.
They were arranged in close apposition to each
other, and the inner surface of the pouch was
covered by a continuation of the insensible lining
of the gizzard, which separated very easily from
the surface.

[Seite 163]

(M) Reptiles resemble birds in having their
nostrils terminate by two longitudinal slits on the
palate; and in the want of velum palati, and
epiglottis.

The oesophagus of the serpent kind is of im-
mense magnitude; for these reptiles swallow ani-
mals larger than themselves, which are retained for
a considerable time in the tube, and descend into
the stomach by degrees, where they are slowly sub-
jected to the action of the gastric juice. The whole
process sometimes occupies many days or even
weeks.

(N) From the peculiar formation of the nose
of fishes; and from their respiring by means of
gills, their fauces have no connexion with any
nasal cavity, or glottis.

The oesophagus is of great width in fishes; and
is distinguished with difficulty in many cases from
the stomach. These animals swallow their food
whole, without subjecting it to any mastication;
and if the stomach will not hold the whole, a part
remains in the oesophagus, until that, which has
descended lower, is digested. The alimentary
canal is generally very short; sometimes extending
straight from the mouth to the anus with very
little dilatation; as in the lamprey (Petromyzon
marinus).

[Seite 164]

(O) The crustacea, and some insects, are fur-
nished with organs of mastication of similar structure.
Their mouth is formed of two or more pairs of
jaws placed laterally. These move from without
inwards, and vice versâ; whereas those of red-
blooded animals move from above downwards,
and back again. The parts, which are termed
the lips of insects, are two bodies; of which one
is placed above or in front of the jaws, and the
other below or behind them. The palpi or feelers
are articulated to the jaws. All insects, which
have jaws, possess the power of masticating hard
animal and vegetable substances; for these parts
are of a firm horny texture, and in many cases are
very large, when compared with the size of the
animal.

The locusts (grylli), the dragon-fly (libellula),
the beetles, and particularly the lucanus cervus, or
stag-beetle, and the staphylinus maxillosus, are ex-
amples in which the jaws are very large and mani-
fest, and often possess denticulated edges. All the
genera of the following orders have jaws; viz. the
coleoptera, orthoptera, neuroptera and hymenoptera.
The insects of the remaining orders derive their
nourishment chiefly from liquids; which they get
either from animal or vegetable substances by
means of a spiral and tubular tongue, or a soft
proboscis, (as in the lepidoptera), with a broad
opening, admitting of extention and retraction,
[Seite 165] (the hemiptera), or a horny pointed tube, contain-
ing sharp bristly bodies internally (the diptera and
aptera).

The stomach of the bee is a transparent mem-
branous bag, in which the nectar of the flowers is
elaborated and converted into honey. The animal
vomits it up from this reservoir, and deposits it in
the hive.

The stomach of the crab and lobster is a very
singular organ. It is formed on a bony apparatus,
in short a species of skeleton; and does not there-
fore collapse when empty. To certain parts of
this bony structure, round the pylonus, the teeth
are affixed. Their substance is extremely hard,
and their margin is serrated or denticulated: as
they surround the tube, near the pylorus, nothing
can pass that opening, without being perfectly com-
minuted. These bones and teeth are moved by
peculiar muscles.

(P) In those mollusca, which possess jaws, these
parts are fixed in the flesh of the animal, as there is
no head to which they can be articulated. They are
two in number in the cuttle-fish, are composed of
a horny substance, and resemble exactly the bill of
a parrot. They are placed in the centre of the
lower part of the body, and are surrounded by
the tentacula, which enable the animal to attach
itself to any objects. By means of these parts, the
shell-fish, which are taken for food, are completely
[Seite 166] triturated. The common snail and slug have a single
jaw, semilunar in its form, and denticulated. The
tritonia has two jaws, which act like the blades of a
pair of scissars. The other mollusca possess no or-
gans of this kind; but have, in some instances, a
sort of proboscis; as the buccinum, murex, voluta,
doris, scyllaea, &c.

In the worms, properly so called, there are some-
times hard parts forming a kind of jaws or teeth.
Thus in the nereis, the mouth possesses several cal-
careous pieces. The aphrodite (sea-mouse), has a
proboscis, furnished with four teeth, which it can
extend and retract at pleasure. Within the mouth
of the leech are three semicircular projecting bodies,
with a sharp denticulated edge: by this apparatus
the animal inflicts its wound of the well-known
peculiar form in the skin.

The teeth of the echinus, (sea-hedgehog) are of a
very singular arrangement; a round opening is
left in the shell for the entrance of the food; a
bony structure, on which five teeth are placed, fills
up this aperture; and as these parts are moved by
numerous muscles, they form a very complete or-
gan of mastication.

The stomach of the vermes is, in general, a mem-
branous bag; but in some cases its structure is
more complicated. In addition to the instances
mentioned by the author, we may observe that
the helix stagnalis, and the onchidia, have gizzards.
The aplysia has three strong muscular stomachs,
[Seite 167] provided with pyramidal bony processes. This
structure, together with that of the bulla lignaria,
and of the lobster and crab, presents a new analogy,
as Cuvier, has observed, between the membranes
of the intestines, and the integuments of the body.
This is particularly strengthened by the annual
shedding of the lobster’s teeth, when its crustaceous
covering falls off.