COMPARATIVE ANATOMY. 
committed in naming the parts, as in the 
anterior extremity. 
The proportions of the thigh and leg vary 
in different animals. The latter part ex- 
ceeds the former in the human subject ; 
and the same remark may be made re- 
specting 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 be- 
tween the European and the orang-outang 
in tliese respects. (White on the regular 
Gradation in Man and Animals, &c.) In 
some otlier simiae the leg and fore-arm ex- 
ceed the thigh and arm. In other animals, 
although there are some varieties, the leg is 
generally longer than the thigh. 
The fibula is consolidated to the tibia 
at its lower end in the mole and rat. It 
only exists as a small styloid bone in the 
horse, and becomes anchylosed to the tibia 
in an old animal. 
The structure of the metatarsus in the 
ruminating animals, and the horse, is the 
same with that of the metacarpus. 
The tarsus of the horse is composed of six 
bones ; and is the part known in common 
language by the name ofthe hock. 
Animals of the genus simia and lemur, 
Instead of having a great toe placed paral- 
lel 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 quadruraanous 
or fourhanded. They are not destined to 
go either on two or four extremities, but to 
live in trees, since their four prehensile 
members , enable them to climb with the 
greatest facility. So that Cuvier has de- 
nominated them “ les grimpeurs par ex- 
cellence.” (Lemons d’ Anat. Comp. vol. i. 
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 j and it answers the same pur- 
pose. 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 specjes 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 ; al- 
though the structure both of the bones and 
muscles of the lower extremity of this ani- 
mal approaches considerably to that of 
man. The same fact is stated of the bear 
itself, properly so called, by the Parisian 
dissectors. 
In other animals the body is supported 
upon the phalanges of the toes, as in the dog 
and cat ; in the horse and ruminating ani- 
mals ho part touches the ground but the last 
phalanx. Here the elongation of the meta- 
tarsus removes the os calcis to such a dis- 
tance from the toe, that it is placed midway 
between the trunk and hoof. 
SKELETON OF BIRDS. 
The skull, which in the adult has no su- 
tures, is articulated to the spine by a single 
rounded condyle. This structure gives the 
head a great freedom of motion, particular- 
ly in the horizontal direction. It enables 
the bird to place its bill between the wings 
when asleep ; a situation in which none of 
the mammalia can place the snout. 
The lower jaw is articulated to the cra- 
nium by means of a square bone on each 
side, called os quadratum. The superior 
mandible, which is completely immoveable 
in mammalia, has, with a few exceptions, 
more or less motion in birds. It hither 
constitutes a particular bone, distinct from 
the rest of the cranium, to which it is arti- 
culated, as in the psittaci (birds of the par- 
rot kind); or it is connected into one piece 
with the cranium, by means of yielding and 
elastic bony plates ; as is the case with 
birds in general. It is quite immoveable in 
a very few instances, as the tetrao urogallus 
(cock of the woods) and tlie rhinoceros 
bird. 
The jaws are entirely destitute of teeth. 
The bill may be considered, in some de- 
gree, 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 ani- 
mals as use them for seizing and procuring 
tlieir food. 
It consists of a horny fibrous matter, si- 
milar to that of the nail, or of proper 
horns ; and is moulded to the shape of the 
bones, which constitute tlie two mandibles, 
being formed by a soft vascular substance, 
covering these bones. Its form and struc- 
ture are as intimately connected with the 
habits and general eharacter of the animal, 
