358 PALEONTOLOGY 



less deeply grooved lengthwise, or cleft at top, so that masti- 

 cation 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. 



The last lower molar of the Mast, angustidcns from La 

 Rochetta di Tanaro,* exhibits the same five principal trans- 

 verse ridges and the hinder one, as in the corresponding tooth 

 in the Eppelsheim Mastodon (fig. 115, m 3), and being the 

 first of the series of narrow mastodontoid teeth to which 

 Cuvier applied the name angustidens, it may be regarded as 

 the type of that species. The characteristic premolar of the 

 Mast, angustidcns, with a quadrate crown of two ridges, each 

 cleft into two tubercles (fig. 114, p 3), is figured by Cuvier, in 

 Op. cit. pi. i., fig. 3, and again, in situ, with the last deciduous 

 molar (d 4) in a portion of the upper jaw of the Mastodon 

 angustidens from Dax (ib. pi. iii., fig. 2). The nature of this 

 quadrituberculate tooth as a premolar, i.e., as a tooth which 

 displaced and succeeded an earlier or deciduous tooth in the 

 vertical direction, was recognized by Cuvier. " Je crois encore 

 qu'on pent en conclure que la dent anterieure etait susceptible 

 de remplacement de haut ou bas, comme dans l'hippopotame : 

 ma raison est, que cette petite dent de Dax n'est pas encore 

 us^e et qu'il faut qu'elle soit venue apres la grande qui lVst."'t 

 Dr. Kaup has described and figured the same premolar in the 

 upper jaw of a younger individual of the Mastodon angustidcns 

 (his longirostris), in whicli it is still concealed in its formative 

 cavity above the three-lobed deciduous tooth which it has 

 replaced in Cinder's specimen. The tooth next behind, which 

 is the homologuc of the last milk-molar (d 4> fig. 114) of the 

 typical series, consists, in both the Dax and Eppelsheim speci- 

 mens, of three principal ridges and a posterior bituberculate 

 talon ; this accessory portion being more developed in the 



* Cuvier, Op. cit. Divers Mastodontes, pi. iv., fig. 1, top view, fig. 2, side view, 

 f Ossemcne Fossiles, 4to, 1821, torn, i., p. 256. 



