LIFE AND WORKS OF COPE. XXXI 



Kowalevsky, in 1873, had pointed out the significant 

 articulations of the metapodials ; Cope here showed the 

 still greater importance of the mutual articulations of the 

 podials, firmlj' establishing thereupon the orders Condyl- 

 arthra "and Amblypoda, uniting Owen's Perissodactyla and 

 Artiodactyla into the Diplarthra, and by hypothetical 

 phyla connecting the Proboscidia and Hyracoidea with a 

 still-to-be-discovered plantigrade, bunodont stem, the " pro- 

 tungulate " of Huxley and Kowalevsky. These generaliza- 

 tions, despite errors of excess and of detail which Riitimeyer 

 and Osborn have pointed out, constituted the first distinct 

 advance in mammalian classification since Owen demol- 

 ished Cuvier's " pachydermata ; " they rank with Huxley's 

 best work among similar problems, and afford a basis for 

 the phylogenetic arrangement of the hoofed orders which 

 has been adopted by all American and foreign paleontolo- 

 gists. Having thus raised the feet, a region of the body so 

 long neglected by the followers of Cuvier (with the excep- 

 tions noted), to a position of prime importance in classifica- 

 tion, it was his good fortune to discover in the collections 

 from the Puerco or Basal Eocene the following law : 



VI. — Law of Trituberculy. That all Types of Molar Teeth 

 in Mammals originate in Modifications of the Trituhercular 

 Form. — It became apparent that the hoofed mammals had 

 sprung from clawed ancestors, but the Wasatch period was 

 too remote from the parting to furnish conclusive evidence. 

 This evidence came in a flood from the underlying Puerco 

 fauna, the systematic treatment of which constitutes the 

 most unique section of Cope's work among the extinct 

 mammalia. From this material originated the above 

 great generalization — namel}^ that the primitive pattern 

 of the molar tooth consists of three tubercles. Around this 

 trituberculy centers the whole modern morphology of the 

 teeth of the mammalia and the establishment of a series of 

 homologies in the teeth of most diverse types, wholly un- 



