PRIMARY FACTORS OF ORGANIC EVOLUTION. 



329 



Fig. 97. Psitlacotherium multifragum Cope, mandibular ra- 

 mus 



98. Diagrammatic representations of horizontal sections 



of tricuspidate molars of both jaws in mutual rela- 

 tion . . .... 333 



99. Deltatheriumfundaminis Cope, fragmentary skull 336 

 100. Centetes ecaudatus, skull and molars . . 337 

 loi. Inferior molar crowns representing transition from 



the simple to the quadritubercular . . 338 



102. Stypholofhus ■whitice Cope ; apposition of inferior 



and superior molars . .... 339 



103. Cynodiciis geismarianus Co'^e ', skull . . . 341 



104. Aelurodon smvus Leidy; coadaptation of crowns of 



superior and inferior molars in mastiisation 342 



165. Smilodon neog(Zus Lund ; skull . . 344 



106. Sections of crowns of molars of Ungulata . ' 345 



107. Castoroides ohioensis Foster ; skull . . . 347 



108. Castoroides ohioensis Foster ; skull from below 350 

 rog. Ischyromys typus Leidy ; cranium and mandible . 351 

 no. Balrena mysticetus; lore \imh . . 353 



111. Feet of Amblypoda . . . . 354 



112. Feet of Proterotheriidae ... . . 35S 



113. Dorsal vertebrae of merospondylous fishes 370 



114. Vertebral column of Eryops megacephalus Cope 371 

 ii4« Sleeve of coat . ... . 371 



115. Metatoceras cavatiformis Hyatt . . 406 



116. Do. . . 407 



117. Temnockiius crassus . . 407 



118. Metacoceras dubium Hyatt . . 408 



119. Hyatt on Cephalopoda 410 



120. Diagram explanatory of Diplogenesis .' 441 



