REPTILIA. 
267 
and an acromion process that almost equals it 
in size, is quite peculiar to the Chelonian rep- 
Fig. 178. 
Scapular Apparatus of Chelys. 
a, scapula ; b, acromion process ; c, coracoid bone. 
tiles, nothing like it existing in any other ver¬ 
tebrate animals : nevertheless, the relations of 
these bones, and the muscles derived from 
them, prove clearly enough their identity, and 
allow of strict comparison with those of other 
races of vertebrata. 
The pelvis is always composed of three 
distinct bones on each side, which contribute, 
as in quadrupeds, to the formation of the coty¬ 
loid cavity, viz. the ilium (fig. 179, a.), which is 
Fig. 179. 
Pelvis of the Turtle, 
a, os ilii ; b, os pubis ; c, os iscbii. 
of an elongated form, and attached by liga¬ 
ments to the transverse processes of the 
sacral vertebrae, as well as to the neighbour¬ 
ing part of the eighth pair of dilated ribs : 
secondly, the pubis b, and the ischium c, both 
of which, expanding as they descend towards 
the plastrum, terminate by joining their fellows 
of the opposite side. 
The cylindrical bones of the extremities 
resemble those of other four-footed reptiles, 
and present no peculiarity worthy of special 
notice, except in a geological point of view. 
In the turtles, all the bones of the carpus are 
flattened, and of a squarish form. In the first 
row there are two bones (fig. 180, c, d.) con- 
Fig. 180. 
Anterior extremity of a Turtle. (After Cuvier.') 
nected with the ulna ; and in the second row 
there are five smaller ones (1, 2, 3, 4, 5.), to 
which are appended the five metacarpal bones. 
In addition to the above, there is an interme¬ 
diate bone (e), situated beneath the ulnar car¬ 
pal bone (c), and above the second and third 
bones of the last row, (2, 3.) This piece, 
Cuvier thinks, corresponds with the dismem¬ 
bered portion of the trapezoid bone, met with 
in monkeys. Lastly, there is a great crescent¬ 
shaped bone (/), which is adherent to the 
ulnar margin of the piece which supports the 
metacarpal bone of the little finger : this is the 
os pisiforme, although its situation is so low 
down. 
Between the bone (1), which supports the 
metacarpal bone of the thumb, and the ra¬ 
dius (a), the connexion during a long period 
is effected entirely by ligaments, without any 
appearance of the great scaphoido-semilunar 
bone which exists in the other sub-genera, 
but with age a small ossicle makes its appear¬ 
ance in this situation. In very large indivi¬ 
duals, the two antepenultimate bones of the 
second row are consolidated into one. 
The metacarpal bone of the thumb is