PACHYDERMATA. 
some of the hog tribe, the two bones of the 
fore-arm are completely consolidated into one 
mass, the only vestiges of their having been 
originally distinct being the indication of a 
Fig. 475. 
863 
suture near the distal extremity of the fore-arm 
and adeep groove running along the middle third 
of the bone for the lodgement of the inter-osseous 
artery. In the Rhinoceros and Tapir, (figs. 475 
Skeleton of American Tapir. 
and 476,) however, these bones remain perma- 
_nently distinct, the elbow-joint being formed by 
the radius in front, which articulates with both 
condyles of the humerus and the ulna pos- 
teriorly, which completes the articulation, At 
their distal extremity the radius lies in front and 
to the inner side of the ulna, with which it is 
either anchylosed or immoveably connected by 
ligaments, both assisting to form the radio- 
carpal articulation. In the Elephant, the 
arrangement of these bones is very curious and 
erhaps unique: the upper head of the radius 
is firmly fixed between two projections in front 
of the head of the ulna, and assists in forming 
the elbow-joint articulating with the outer con- 
dyle of the humerus only. It then passes 
obliquely downwards across the anterior face of 
the ulna to its distal extremity, where it expands 
into a broad articulating surface, and assists 
almost coequally with the ulna in forming the 
ap joint. 
_ Carpus.—The bones of the carpus are chiefly 
emarkable for their large dimensions; they 
are, however, always distinct and generally 
the same in number as in Man, although from 
their altered shape they little conform to the 
names bestowed upon them in the human sub- 
ject. The first row, consisting of the analogues 
of the scaphoid, the lunar, the cuneiform, and 
he pisiform bones, is firmly connected by liga- 
ments with the distal extremities of the ulna 
and radius to form the wrist-joint, which, how- 
aver, is here only capable of the movements of 
lexion and extension. The second row consists 
of the representatives of the trapezium; the 
apezoid, the os magnum, and the unciform 
ones support the metacarpus and are generally 
ite distinct, although occasionally two or 
nore of them are consolidated into one mass. 
In the Rhinoceros, which has but three toes, 
ne trapezoid, the os magnum, and the unciform 
bones each support a single metacarpal bone. 
The trapezium is totally wanting, but there are 
two supernumerary pieces in connection with 
the scaphoid and unciforme. 
Metacarpus.—The metacarpal bones are ge- 
nerally short and excessively robust, their num- 
ber of course corresponding with that of the 
toes. Thus in the Elephant there are five, and 
in the Hippopotamus, Hog, and Tapir only 
four, which are small and extremely massive 
in proportion to the weight they have to sus- 
tain. In the genus Sus, where the whole bur- 
den_of progression is thrown upon the two 
middle toes, and a considerable degree of ac- 
tivity is permitted, the corresponding metacarpal 
bones are much elongated, and far surpass in 
size and strength those which support the ex- 
ternal and internal fingers, which have rather 
the appearance of appendages to the outer and 
inner sides of the metacarpus, than bones ar- 
ticulated with the carpal series. 
The metacarpus in the Rhinoceros consists 
of only three bones conformable to the number 
of fingers. 
Phalanges——The Elephant alone of all the 
Pachydermata has five complete fingers; but, 
although the bones are thus perfectly developed, 
they are so concealed in the living animal by 
the hoof and overhanging skin of the fore-foot, 
that such a condition of this part of their 
skeleton would hardly be suspected. 
In the ungulate tribes, which have only four 
fully formed fingers, there is still a little bone 
representing the rudiment of a thumb, although 
in the generality of artificial skeletons this 
ossicle is wanting. In the Suide the two 
lateral fingers are much shorter than the two 
middle ones, so that in walking the former do 
not touch the ground at all; they are, however, 
quite complete as relates to the number of their 
phalanges ; and the last phalanges of all the 
