MASTODON. 380 



incisors, followed by two permanent incisors developed as 

 tusks ; six deciduous molars (three on each side, cl z, 3, 4, fio-. 

 142); two premolars (one on each side, p 3, fig. 142), and six 

 true molars (three on each side, m 1, 2, 3, figs. 142 and 143) ; 

 — in the lower jaw, two incisors 

 as tusks (uncertain whether pre- 

 ceded by deciduous tusks), de- 

 ciduous molars, premolars, and 

 molars, as in the upper jaw. 

 The elephantoid animal 



Mastodon longirOStris, Kaup ; Deciduous dentition, young Mas- 

 /ir . 7 ,., . todonlonqirostris. 



[MaMoaon angustmens, in part, 



Cuvier) which exhibited the above instructive dentition of the 

 proboscidian family, once roamed over the part of the earth 

 now forming England, France, Italy, and Germany. The first 

 steps in our knowledge of its dentition were made by Cuvier, 

 who called it the narrow-toothed Mastodon " Mastodon a dents 

 etroites/' or Mastodon angustidens. This name was suggested 

 by the less breadth of the grinding surface of the teeth as com- 

 pared with those of a previously described species of Mastodon 

 from North America, called the Mast, giganteus, or M. Oliioti- 

 cus. Cuvier describes and figures a last molar, upper jaw, from 

 Trevoux, consisting, as in the specimen from Norfolk Crag, 

 (fig. 141), and as in that from Eppelsheim (fig. 143, m 3), of 

 five transverse ridges, with a front and back talon or subsidiary 

 ridge. The latter is the largest, and subdivided into teat- 

 shaped tubercles, so as almost to merit the name of a sixth 

 division of the tooth. The principal ridges are divided into 

 two chief or primary tubercles, with secondary tubercles in 

 the interspace ; the chief tubercles are more or less deeply 

 grooved lengthwise, or cleft at top, so that mastication wore 

 them down to small circles of dentine surrounded by a thick 

 border of enamel, and further attrition reduced these to a 

 trilobed or trefoil form. 



