CONDYLARTHKA. 383 



zation that the primitive types of the Ungulata would be discovered to be 

 characterized by the possession of five-toed plantigrade feet, and tubercular 

 teeth. No Perissodactyle or Artiodactyle mammal was known at that time 

 to possess such feet, nor was any Perissodactyle known to possess tubercu- 

 lar teeth. Shortly after advancing the above hypothesis, I discovered the 

 foot structure of Coryphodon, which is five-toed and plantigrade, but the 

 teeth are not of the tubercular type. For this and allied genera, I defined 

 a new order, the AmUypoda, and I have published the confident anticipa- 

 tion that genera would be discovered which should possess tubercular 

 (bunodont) teeth. This prediction has not yet been realized. The discov- 

 er}' of the Condylarthra went far towards satisfying the generalization first 

 mentioned, and indicates that the realization of the prophecy respecting 

 the AmUypoda is only a question of time. 



In 1873' I described, from teeth alone, a genus under the name of 

 Phenacodus, and although a good many specimens of the dentition have 

 come into my possession since that date, I have never been able to assign 

 the genus its true position in the mammalian class. • The teeth resemble 

 those of suilline Ungulates, but I have never had sufficient evidence to 

 permit its reference to that group. Allied genera recently discovered by 

 me have been stated to have a hog-like dentition, but that their position 

 could not be determined until the structure of the feet shall have been 

 ascei'tained." 



In his recent explorations in the Wasatch Eocene of Wyoming, Mr. J. 

 L. Wortman was fortunate enough to discover nearly entire skeletons of 

 Phenacodus primcevus and P. vortmani, which present all the characters essen- 

 tial to a full determination of the place of Phenacodus in the system. The 

 unexpected result is, that this genus must be placed in a special group of 

 an order which includes also the Prohoscidea? 



The astragalus in this sub-order is absolutely undistinguishable from 

 that of the flesh-eating groups Creodonta and Carnivora. The humerus also 

 presents a character of the unguiculate orders, in possessing an epicondylar 



■ PaliEoatological Bulletin No. 17, Oct. 1873, p. 3; also, Report G. M. Wheeler, U. S. Engineers 

 Expl. W. 100 Mer.. iv, p. 174, 1877. 



2 Proceed. Amer. Philosoph. Society, 1881, p. 495. 

 ^AJierican Naturalist, June, 188-2 (May 17). 



