[Illustration: SPERM WHALE.]
In these Cetaceans the head is of vast size and excessively vaulted, or
arched, especially in front. The upper jaw has no whalebone nor teeth of
any kind, excepting a few rudiments. The lower jaw, which is very narrow
and much elongated, is armed on each side with a lengthy row of teeth of
considerable size and conical shape, the points of which when the mouth
is shut, are received into corresponding depressions in the upper jaw.
The upper region of their prodigious head is made up of vast caverns
filled with an oily fluid, which on cooling becomes solid, constituting
the valuable substance generally known by the name of “spermaceti.” It
is not, however, in the vaults of the head only that this fat is found.
It appears to be distributed through various excavations in the body,
and to be diffused even among the dense mass of blubber which envelopes
the exterior of the animal.
The peculiar odorous substance, so well known under the name of
“ambergris,” is likewise obtained from the Cachalot.
How many species of these monstrous creatures exist in the ocean we
cannot tell, seeing that the observations of the Whale-fishermen are
generally by no means sufficiently precise for the purposes of Natural
History. That which appears to be most frequently met with is the
Great-headed Spermaceti Whale.
This giant of the deep has merely a callous hump upon its back, in place
of a dorsal fin. On each side of its lower jaw are from twenty to
twenty-three large conical teeth. The “blow hole” through which it
respires is a single orifice, situated on the top of the head—not a
double aperture as in most other Cetaceans. The species seems to be
widely distributed, but its range is principally confined to the oceans
south of the Equator.