ORDER UNGULATA. 



1399 



means the transverse valleys become more or less completely blocked. 

 Closely allied to this species is Mastodon sivalensis^ of the Pliocene of 

 Northern India, of which a last upper true molar is represented from the 

 lateral aspect in fig. 1273 ; in this species there are occasionally five 



Fig. 1273. — Profile view of last upper true molar of Mastodon sivalensis ', from the 

 Pliocene of the Siwalik Hills of India. Reduced. 



ridges in the " intermediate " molars, and the last upper true molar (as in 

 the figure) may have six ridges and a hind talon ; the blocking of the 

 A-alleys by the alternate arrangement of the inner and outer columns of 

 the ridges is well exhibited in the woodcut. Both in this species and M. 

 mvemensis the symphysis of the mandible is short and tuskless, as in 



the modern Elephants ; and the 

 Siwalik species is further charac- 

 terised by the great elevation of 

 the vertex of the skull (fig. 1274), 

 in which respect it also agrees 

 with the last - named group. 

 Both these species must be re- 

 garded as highly specialised 

 forms which have diverged from 

 the line connecting the Trilo- 

 fthodont group with the true 

 Elephants. We may here briefly 

 mention M. perimensis and M. 

 punjabiensis of the Indian Plio- 

 cene, which show certain charac- 

 ters intermediate between the 

 two above - mentioned species 

 and M. longirostris, which we 

 now proceed to notice. The 

 last-named species occurs typi- 

 cally in the Lower Pliocene 

 bone - sand of Eppelsheim in 

 Hessen - Darmstadt, but has 

 been also found in the English Red-Crag. It has an elongated mandi- 

 bular symphysis furnished with a pair of short incisors (fig. 1275), and 

 vol. II. 2 K 



Fig. 1274. — Left lateral view of the skull of 

 Mastodon sivalensis ; from the Siwalik Hills of 

 India. Greatly reduced. (After Falconer and 

 Cautley.) 



