VERTEBRATA. 307 
They have two sets of teeth, the Cetaceans never having 
but one. They have a narrow brain; bristles scantily cov- 
ering the body; and nostrils placed on the snout, which is 
large and fleshy. Such are the Manatee and Dugong. 
9. Proboscidians.—This race of giants, now nearly ex- 
tinct, is characterized by two upper incisors in the form of 
tusks, mainly composed of dentine (ivory). In the extinct 
Dinotherium the tusks projected from the lower jaw; and 
in the Mastodon, from both jaws. Canines are wanting. 
The molars are few and large, with transverse ridges (Ele- 
phant) or tubercles (Mastodon). The cerebrum is large 
and convoluted, but does not cover the cerebellum. The 
skull is enormous, the size arising in great measure from 
the development of air- cavities between the inner and 
outer plates. The nose is prolonged into a flexible trunk, 
which is a strong and delicate organ of prehension. ‘There 
are four massive limbs, each with five toes incased in 
broad, shallow hoofs, and also with a thick, tegumentary 
pad. The knee is below and free from the body, as in 
Monkeys and Men. Clavicles are wanting. The body of 
the Elephant is nearly naked; but the Mammoth, an ex- 
tinct species, had a covering of long woolly hair. Ele- 
phants live in large herds, and subsist on foliage and grass. 
There are but two living species: the Asiatic, with long 
head, concave forehead, small ears, and short tusks; and 
the African, with round head, convex forehead, large ears, 
and long tusks.” 
10. Ungulates, or Hoofed Quadrupeds.—This large or- 
der, comprehending many animals most useful to Man, is 
distinguished by four well-developed limbs, each furnished 
with not more than four complete toes, and each toe in- 
cased in a hoof. The leg, therefore, has no prehensile 
power; it is only for support and locomotion. Clavicles 
are wanting; and the radius and ulna are so united as to 
prevent rotation. There are always two sets of teeth, 2. e., 
29 
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