;88 



QRDERS OF MAMMALIA. 



Post-Pliocene period, and another species existed during the 

 same time in South America. M. giganteus ranged from 

 Canada to Texas, and very perfect specimens have been 

 exhumed from morasses and swamps, large individuals at- 

 taining a length of seventeen feet (exclusive of the tusks), 

 the height being eleven feet, and the tusks twelve feet in 

 length. 



The last of the Proboscidca is the singular Dcinotlicrium of 

 the Miocene, which presents certain points of resemblance 

 to the Sirenians, and is sometimes referred to that order. 





Fig. 671. — Skull of Dcinotherhna 

 giganteum. Miocene Tertiary. 



Fiy. 6~2. — A, Side view of tlie tljiril 

 molar of Deinotherlum gigantewn ; b, 

 Grinding surface of the same. Mio- 

 cene Tertiary. (After Kaup.) 



The genus is principally known by the huge skull of the only 

 certainly determined species — namely, D. gig ant emu (fig. 671). 

 The most noticeable feature in the skull is the presence in 

 the lower jaw of two enormous tusk-like incisors, which are 

 directed vertically downwards, in consequence of the abrupt 

 downward flexure of the front portion of the mandible. No 

 canines are present in either jaw, and there are apparently 

 no upper incisors ; but both jaws possess a series of pre- 

 molars and molars, the whole of which are in use at one 

 time, the milk-molars being displaced by vertical successors 

 in the usual manner. The crowns of the molars are crossed 

 by strong transverse ridges (fig. 672), and exhibit marked 

 Tapiroid characters, while in some respects they resemble 



