34 ELEPHANTS. 



of M. latidens, which in its turn approaches Elephas (Stegodon) 

 clifti (fig. 21) very closely. In M. latidens there are as a rule 

 five transverse ridges in the second upper molar and six in 

 the last. 



Pier- The next stage is represented by Elephas (Stegodon) clifti 



35 3 (fig. 21). With this species we reach the true elephants, though 

 Table- * ne molars have much lower crowns and fewer transverse ridges 

 case '24. than in the modern species of Elephas ; and, in fact, these 

 Stand J. ear ij er forms are sometimes separated into another genus called 

 Stegodon. Since, however, no real line can be drawn between 

 them and the later types it is perhaps best to call all Elephas, but 

 distinguish these earlier forms by adding the name Stegodon in 

 brackets as above. In all this group the lower incisors have- 

 entirely disappeared, the anterior elongation of the chin at 



Fig. 21. 



Grinding surface of an upper molar tooth of Elephas (Sfagodon) clifti. From 

 Lower Pliocene, Siwalik HillSj India. Showing six transverse ridges. 

 nat. size. 



the same time being reduced to a mere peg-like process 

 (figs. 23 & 30), and a greater or less amount of cement (see 

 above, p. 12) fills the transverse valleys in the crowns of the 

 molars (fig. 22). In Elephas (Stegodon) clifti the number of 

 ridges is greater than in Mastodon cautleyi. In order to express 

 briefly the number of ridges in the molars of this and other 

 species, a formula is used thus : In E. clifti the formula 



