96 THE INHABITANTS OF THE SEA. 
thick layer of fat, and by their simple or double blow-hole, which 
is situated at the top of the head, and corresponds to the nostrils 
of the quadrupeds, though not for 
the purpose of smelling, but 
merely as an organ of respiration. 
Our knowledge of the ceta- 
ceans is still very incomplete ; and 
this is not to be wondered at, when 
we consider that they chiefly dwell 
in the most inaccessible parts of 
the ocean, and that when met with, 
the swiftness of their movements 
rarely allows more than a flighty 
view of their external form. Thus 
their habits and mode of living 
are mostly enveloped in obscurity ; 
and while doubtless many ceta- 
ceans are to the present day un- 
known, one and the same species 
has not seldom been described 
under different-names, to the no 
small confusion of the naturalist. 
The cetaceans are either with- 
out a dental apparatus, or pro- 
vided with teeth. The former, or 
the whalebone whales, have two 
blow-holes on the top of the head, 
in the form of two longitudinal 
fissures; while in the latter, 
(sperm-whales, unicorn-fish, dol- 
phins,) which comprise by far the 
greater number of species, there 
is but one transversal spout-hole. 
In all whales the larynx is con- 
tinued to the spouting canal, and deeply inserted or closely 
imbricated within its tube. Thus no tones approaching to a 
voice can be emitted except through the spiracles, which are 
encumbered with valves, and evidently badly adapted for the 
transmission of sound. Scoresby assures us that the Green- 
land whale has no voice, and Bennett frequently noticed sperm 
i 
NON 
hi i 
Ni 
ii! 
we \\ \ 
WY \ 
XY 
<A) 
AWN 
NY Ny \\ \\ 
\\\\\ 
Bones of the Anterior Fin of a Whale. 
