260 THE STRUCTURAL EVIDENCE OF EVOLUTION. 



upper molars,* which shall connect it with the W-shaped type 

 proposed above as the probable predecessor of Bathmodon. Or, a 

 pair of oblique parallel crests with rudimental diagonals like the 

 posterior lower molars of Bathmodon may intervene between this 

 form and the Bunodont. This is, however, not probable in view 



Fig. 41. — Bathmodon. 



of the diagonal crest of the upper molars (Fig. 42, Uintatlierium 

 robustum), and especially if the parallel with the type of the 

 lower molars is kept up. These are like those of Bathmodon, ex- 



Figs. 42 and 43. — Uintatherium rohustum. 



cept that the type of the middle molars of the latter is continued 

 to the posterior end of the series in Uintatherium (Fig. 43) ; that 

 is, the last molar of the latter consists of a V and an oblique cross- 

 crest. 



Y. RELATIOKS OF THE TYPES OF DEI^TITIOI^' TO TYPES OF FOOT 



STEUCTURE . 



I hope that I have succeeded in showing that the Bunodont 

 and Lophodont types of dentition form two homologous series, 



* This has since been discovered in Pantolambda (Cope). (Ed. 1886.) 



