Peterson: Platigonus Leptorhinu.s W'ii.liston. 115 



elusion' that all the material representing the fossil jieccaries described 

 up to that date pertain to Platigonus compressus Le Conte. Leidy 

 says, "The various remains originally described^ and now regarded 

 as pertaining to Platigonus compressus were early attributed to nearly 

 half a dozen different species and genera, founded on sligh difTerences, 

 which, before the prevalence of the evolution theory, were looked upon 

 as being of a fixed character and all-sufificient for the distinction of 

 species, and were so adjudged by a master who has since passed from 

 among us" [referring probably to the death of Prof. Louis Agassiz]. 

 On studying the skull (No. 2806) and the articulated skeleton, now 

 in the Carnegie Museum, I find, as Williston did, that in its main 

 anatomical features it compares quite closely with Euchcerus macrops 

 Leidy. The heavy symphysis of the lower jaws due to the extended 

 protuberance on the chin, the shortness of the post-canine diastema, 

 and the general robustness of the jaws and broadness of face, together 

 with the position of the external auditory meatus and the absence of 

 the pits or cul de sac separated by the vertical ridge on the anterior 

 border of the posterior nares I regard as among the most important 

 features of Dr. Williston's enumerated differences in his paper (/. c. 

 25). L^pon recomparing the present specimen with Leidy's descrip- 

 tion and figure of E. macrops (/. c, PI. 36, fig. i) I find that the external 

 auditory meatus agrees approximately with the figure. The anterior 

 marginal wall of the posterior nares also appears to correspond with 

 Leidy's description. There is then left the features of the symphysis 

 of the lower jaws, the difTerences in the diastema between the canine 

 and the cheek-teeth, together with the narrowness of the face and 

 slenderer jaws of the Kentucky specimen. These features are of 

 much interest and importance, especially when we consider the long 

 and slender symphysis, the long post-canine diastema, and the slender 

 muzzle of Mylohyus, a genus which in the later Pleistocene lived con- 

 temporaneously with, and possibly succeeded, Platigonus. If an 

 eastern species of the latter genus should be looked upon as giving rise 

 to Mylohyus, it would naturally follow that Mylohyus would have 

 to be placed in closer relationship to Platigonus than is indicated by 

 Professor F. B. Loomis,*^ and Prostenops would have to be placed in 

 a separate phylum. 



^ Trans. Wagner Free Inst., Vol. II, 1889, p. 49. 



^ Referring to various publications of earlier dates than that paper. 



^ Amer. Jour. Set., Vol. XXX, 1910, p. 384. 



