xvi PRIMAR Y FA CTORS OF ORGANIC E VOL UTION. 



PAGE 



Fig. 97. Psittacotherium multifragum Cope, mandibular ra- 



mus 329 



98. Diagrammatic representations of horizontal sections 



of tricuspidate molars of both jaws in mutual rela- 

 tion 333 



99. Deltatherium fundaminis Cope, fragmentary skull . 336 



100. Centetes ecaudatus, skull and molars 337 



101. Inferior molar crowns representing transition from 



the simple to the quadritubercular 338 



102. Stypholophus whitim Cope ; apposition of inferior 



and superior molars 339 



103. Cyno dictis geismariamis Cope ; skull 341 



104. Aelurodon savus Leidy; coadaptation of crowns of 



superior and inferior molars in mastication . . . 342 



105. Smilodon neogceus Lund ; skull 344 



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



107. Cas (oroides ohioensis Foster ; skull 347 



108. Castoro'ides ohioensis Foster ; skull from below . . 350 



109. Ischyromys typus Leidy ; cranium and mandible . . 351 



no. Balcrna mysticetits ; fore limb 353 



in. Feet of Amblypoda 354 



112. Feet of Proterotheriidae 358 



113. Dorsal vertebrae of merospondylous fishes .... 370 



114. Vertebral column of Ery ops megacephalns Cope . . 371 

 114^7 Sleeve of coat 371 



115. JMetatoceras cavatiformis Hyatt 406 



116. Do 407 



117. Temnochilus crassus 407 



118. Metacoceras dubium Hyatt 408 



119. Hyatt on Cephalopoda 410 



120. Diagram explanatory of Diplogenesis . ..... 441 



