MASTODON ANGUSTIDENS. 285 
in fact, which strictly correspond with the deciduous teeth 
of ordinary Pachyderms. Cuvier’s specimen shows the 
first of the series of permanent teeth just coming into 
place, with its mastoid eminences fresh and unwom; 
this permanent tooth, the only one corresponding to the 
teeth called premolars, false molars, and bicuspides in 
other Mammalia, is developed above the deciduous molars 
in the upper jaw, beneath them in the lower jaw, and 
it succeeds and displaces them vertically in both jaws. Its 
crown is divided into four tubercles, and it is consequently 
more simple than the second deciduous tooth which it 
displaces, agreeing in this respect with the premolar teeth, 
or dents de remplacement, i other Mammalia. 
When the milk-teeth are shed, and their quadri-tuber- 
culate successor is in place, the molar tooth (fig. 100) is 
the second of the molar series, but presents a character 
which must seem strange to one unacquainted with the law 
of the succession of teeth in the Mastodons, viz., a much 
more abraded crown than the smaller tooth which pre- 
cedes it. The smaller tooth is therefore the first of the 
permanent series of molars, and the one figured in cut 100 
is the second of that series; but, although they are termed 
permanent molars, agreeably with the general analogies 
of the Mammalian dentition, their duration is brief in 
comparison with the life-time of the animal; and they 
are successively shed, as in the Elephant, the Hog, and 
the Kangaroo, from before backwards ; the dentition in the 
Mastodon being ultimately reduced to the last great molar 
tooth, which is the seventh in the order of development. 
To facilitate the determination of the teeth of the 
Mastodon angustidens, | shall briefly denote their general 
characters, as they succeed each other in the order of their 
development. 
