LSI 



ORDINAL TYPES OK MOLARS: l'i;< >!',< )S( 'I I >KA 



The gradations leading- back from the plated tt-cth of 

 through Sta/odon, with its numerous crests and short crowns, to Ma*ft>dnn, 

 were long ago followed in Falconer and Cuutlry's Fauna A/i//<//"> 

 Sivalensis and in Gaudrv's Enchaincmcnts du Monde Animal/' : but. the* 



nmz runs fcm+ mj. m.- =gj 



* -. -. -t-~ ^r*-~ -r - ;'" 

 ^/ 



Fio. 188. Upper cheek teeth and basal view of skull of Puheomastoilon beadnelli, (cf. Fig. IN;>. 



After Andrews. Scale, about J_. 



recent researches of Andrews have carried the evolution back through 

 Palceomastodon (Figs. 187, 188) to the quadritubercular molars of 

 Mceritkerium, a middle Eocene stage representing the African atavus 

 of the Proboscidea. By analogy with all the other groups we have 



ex.oc. 



Fio. ISO. Side view of the skull of M<> , itln /-//'//i Im 



[Scale, about 1. 



o 



xi. (Cf. Fig. 100.) After Andrews. 



been considering, there is no question that the quadritubercular 

 molars of Mceritherium (Figs. 180, 190) sprang from an ultimately 

 tritubercular type. 



The quadritubercular molar of the Mceritkerium type by (1) 

 transverse connection of its pairs of cones, produced a bilophodont 

 crown similar to the lower molars of the Tapirs; (2) by continuous 



