OF THE SPERM WHALE. 
73 
parts of the skeleton are so enclosed, and the spaces 
between the projecting parts are so filled up as to be 
altogether concealed, giving the animal externally a 
uniform and elegant form, resembling an insect enveloped 
in its chrysalis coat. The bones of the head are in 
general so large as to render the cavity which contains 
the brain but a small part of the whole, while in the 
human species and in birds this cavity constitutes the 
principal bulk of the head. This is perhaps most remark- 
able in the spermaceti whale, for on a general view of the 
bones of the head it is impossible to determine where 
the cavity of the skull lies, till led to it by the foramen 
magnum occipitale. 
“ Some of the bones in one genus differ from those of 
another; the lower jaw is an instance of this. In the 
spermaceti and bottle-nose whales, the grampus and the 
porpoise, the lower jaws, especially at the posterior ends, 
resemble each other, but in the large and small whale- 
bone whales the shape differs considerably. The num- 
ber of some particular bones varies likewise very much. 
The structure of the bones is similar to that of quadru- 
peds; they are composed of an animal substance and 
an earth which is not animal. These seem only to be 
mechanically mixed, or rather the earth thrown into the 
interstices of the animal part. In the bones of fishes 
this does not seem to be the case, the earth in many 
fish being so united with the animal part as to ren- 
der them transparent, which is not the case when the 
animal part is removed by steeping the bone in caustic 
E 
