PHYLOGENY. 141 



ries us back to the order Condylarthra, the hoofed 

 cotemporary of the Bunotheria. The even and odd 

 toed hoofed mammals are traceable back to the Am- 

 blypoda, whose oldest representatives are the Panto- 

 donta of the Puerco. The Proboscidia and Hyracoidea 

 come directly from the Condylarthra. Moreover, the 

 phalanges of the lemurs are not distinguishable by any 

 important characters from the hoofs of the Hyracoidea 

 and Condylarthra. Not only this, but the structure of 

 the foot in these three groups is identical in regard to 

 the mode of articulation of the first and second rows 

 of the tarsal and carpal bones. 



Fifth. The characters of the feet of the Condylar- 

 thra agree with those of unguiculate placental Mam- 

 malia, and bind the two series together. The synthesis 

 of the ungulate and unguiculate lines is accomplished 

 by exceptions to the characters which define them. 

 Thus the hoofs of Pantolambda (Amblypoda), Peripty- 

 chus (Condylarthra), and Mesonyx (Creodonta) do not 

 differ by any marked character. Claws occur in the 

 Hapalidae of the quadrumanous line, and the ungues 

 of some Glires are absolutely intermediate between 

 the hoofs and claws. Many Edentata have claws on 

 the fore feet and hoofs on the hind feet. The Condy- 

 larthra with tritubercular molar teeth are then trace- 

 able to Bunotheria with tritubercular teeth, of which 

 many are known from the Puerco beds ; and the quadri- 

 tubercular forms from corresponding quadritubercular 

 or tritubercular Bunotheria, of which latter, some are 

 known. 



Sixth. The anthropoid line may be traced directly 

 through the lemurs to the Condylarthra. The changes 

 which have taken place in the skeleton are slight, and 



