842 
. In all the mammiferous Quadrupeds pos- 
sessed of unguiculate feet, the digital phalanges 
of the anterior extremity present nothing worthy 
of special notice in this place, minor differences 
being noticed under the proper heads; but in 
the ungulate Pachydermata, such as the Rumi- 
nants and Solipeds, remarkable exceptions to 
the usual arrangement are met with. In the 
Ruminants only the two central fingers are well 
developed, each consisting of three large pha- 
-langes, the distal one of which is enclosed in a 
strong hoof, so as to give the cloven appearance 
to the whole foot which is so characteristic of 
the order; but besides these, two rudimentary 
toes exist, one on the outer, the other on the 
inner side of the foot, but so small as not to 
reach the ground or to be serviceable in the or- 
dinary progression of these creatures. 
In the Solipeds even the division between 
the central large toes that exists in the Rumi- 
nant becomes obliterated, and the whole foot 
appears to be made up of a single toe consisting 
of three strong phalanges, the distal one being 
encased in a large semicircular hoof. Even in 
these animals, however, rudiments of two other 
toes are distinguishable, but very imperfectly 
developed. 
Ilium.—This is the principal bone entering 
into the composition of the pelvic arch, and fre- 
ews is the only one met with in this part of 
e skeleton. In the osseous Fishes it is not yet 
connected with the spine, so that the posterior 
part of the body is left perfectly free and un- 
trammelled, in order to allow of the extensive 
movements of the tail required for the propul- 
sion of these aquatic animals through the water. 
There is consequently here no sacrum, and we 
are not surprised to see the posterior limbs ex- 
tremely variable in their arrangement, being 
placed far back or advanced towards the ante- 
rior part of the body as circumstances require. 
Even in the cartilaginous Fishes the pelvis has 
no connection with the spine, the whole con- 
sisting of a broad transverse osseous band 
placed beneath the terminal portion of the 
abdomen. 
In the Batrachia, too, the iliac bones retain 
to some extent the form of ribs, and in the 
Frog are two bones of considerable length 
attached to the prolonged transverse processes 
of the last vertebra, which of course, in this 
case, represents the sacrum, 
In the Toad another step is made towards 
strengthening the posterior part of the spine, 
preparing it to support locomotive organs of 
greater energy by fixing the iliac bones to two 
of the vertebral transverse processes, forming a 
sacrum composed of two bones, which is in 
fact the usual condition of this part of the ske- 
leton in the higher Reptiles. ; 
In the Chelonians, however, the iliac bones 
are again attached to asingle vertebra and pelvis, 
like the bones of the shoulder placed internal 
to the ribs which form the carapax or dorsal 
shield, 
The ilium, in all the class of Birds, is enor- 
mously developed in proportion to the unfa- 
vourable circumstances under which they sup- 
OSSEOUS SYSTEM. (Comp. Anat.) 
rt themselves wu their posterior extre- 
ary It extends aan the sides of the ver- 
tebral column, to which it is solidly anchy- 
losed, converting into one immense sacrum — 
from eight to nineteen of the posterior vertebra, — 
which are so completely fused to each other 
and to the iliac bones that their number is only 
distinguishable from the positions of the inter- _ 
vertebral foramina through which the nerves 
escape from the spinal canal in this region, 
In Mammals the iliac bones are likewis 
greatly developed, except in the Cetacea, w 
in consequence of the necessity for fish-lil 
flexibility in the hinder part of the body, m 
hinder extremities exist. The sacrum is cor 
pave of a considerable number of ve 
ere anchylosed together and consid Y 
dified in their form, to which the 
ilii are firmly secured by ligaments and ar 
interposed cartilage, giving a firmness to this 
part of the skeleton second only to what is 
observable in the feathered races. a 
The ossa ischit, the second elements entering 
into the composition of the pelvic frame ’ 
are not so invariably present as the iliac bor 
In Fishes they are not to be found: but in 
the Reptilia, where the elements of the skeleton 
remain permanently disunited to a much greate) 
extent se in warm-blooded animals, they are 
constantly present, except, of course, where t 
hinder extremities are deficient, and are sepa. 
rated by a very distinct line of demarcat 
from the other bones of the pelvis. 
As in the shoulder, the articular cavity for 
the attachment of the anterior limbs when al 
the elements of that part are fully developed, 
formed by the union of three bones, so li 
in the pelvis, which is only a repetition of 
same apparatus modified in form, do all th 
three bones of which it consists enter into th 
formation of the cotyloid cavity, a cireumst: 
which, in Reptiles, is particularly conspi 
In the class Aves, notwitl 
a 
hstanding the 
rant condition of the pelvis, the ischia are € 
distinguishable from their position, boundi 
as they do the obturator foramen on the o1 
side, and the sacro-ischiatic notch on the othe 
In the Cetacean Mammals this element 
the skeleton is again obliterated, but in allt 
other orders it is present, and in the ear 
stages of life is readily demonstrable as a ¢ 
tinct bone of the pelvis. a 
The ossa pubis are the third pair of eleme 
entering into the composition of the pelvic 
vity, and to these the same remarks are 
cable as we have already made concerning 
ischia. In Fishes they are not present, 
throughout the Reptile orders that posse: 
pelvis they are very distinct and important 
of the skeleton, meeting each other anter 
in the mesial line, where they are unit 
strong symphysis. , 
The pubic bones in Birds occupy 2 
responding position; they are here, how 
remarkable from the circumstance that t 
distal extremities never (except in the 
trich) meet to form a pubic symphysis, but 1 
always widely separated from each othe 
