SYSTEM OF NATURE. 
23 
molars have no true roots, but are united to the jaw-bones 
by means of cartilage. It is truly remarkable, that although 
the Northern Seas appear to be teeming with this strange 
animal, it does not exist in any of our museums, and a 
most profound ignorance seems to prevail respecting it. 
Even Swainson, a zoologist of distinction, states it is from 
the South Seas, an assertion which the narrations of voy¬ 
agers do not bear out. This animal appears intermediate 
between the normal whales and the Halicoridae, of which 
group the Indian dugong is the only known living repre¬ 
sentative. There is, however, an extinct animal, — the 
Dinotherium,—which, from the structure of its molar teeth, 
has been supposed a tapir : this I think will eventually be 
found, when we attain a more precise knowledge of its 
skeleton, to be intermediate between the dugong and the 
Belluae. This huge animal was eighteen or twenty feet in 
length: its scapula was like that of the mole; whence 
Mantell and other authors argue that its fore-feet were 
formed for digging : but its chief distinction from all ex¬ 
istent animals was in the enormous curved ivory tusks, 
equalling the elephant’s in size, and resembling those of 
the walrus in curvature, but by a strange anomaly placed 
in the lower instead of the upper jaw. Until further 
knowledge is obtained of the Dinotherium, we must con¬ 
sider that it approaches both the tapirs and the dugongs, 
the latter group certainly occupying a natural position at 
C, intermediate between the true whales and the Belluae, 
the former being supposed the normal and central group 
of Cete, while the dolphins, situated at D, lead to the 
true fishes. It cannot be said that my object in uniting 
the seals and walruses to the marine Mammalia is the 
support of my own views of natural arrangement, for in 
