112 R. 8. Lull — Primitive Pecora in Yale Museum. 



Hyperiragulus calcaratus Cope. 



The original description of the genns is brief, and two 

 species, H. calcaratus and H. tricostatus, are mentioned 

 without definition, the first adequate description appear- 

 ing in Paleontological Bulletin No. 16, p. 7, under the 

 genus Leptauchenia. In this description Cope mentions 

 several characters which are really of generic value, the 

 real specific distinctions of H. calcaratus being apparently 

 as follows : 



Molars bear a slight external cingulum which has a 

 small cusp between the two outer crescents, representing 

 either an incipient or vestigial mesostyle. M 3 relatively 

 somewhat smaller in TI. calcaratus, and the metastyle, 

 while variable, never as pronounced as in the John Day 

 form. In general, the teeth are somewhat smaller than 

 in the John Day jaws, and in one instance where P 3 is 

 preserved, it is markedly smaller. Interrupted cingula 

 are present in all the Hypertragulus jaws before me, 

 although omitted from every published figure. 



Cope's measurements are: 



mm. 



Length of five molars 26 



Length of three true molars 17.5 



Length of last true molar 8 



Width of last true molar 7 



This species is smaller than the smallest of the genus 

 yet described (Cope). 



Of the Yale material, assuming Cope's figures to be 

 correct, but one specimen agrees exactly with the type 

 in the combined length of the ^ve teeth, and even in this 

 specimen M 3 is only seven-eighths as long. The third 

 molar, however, has been shown to be variable and the 

 degree of wear also affects its dimensions. I find no 

 evidence in the Yale Great Plains material of even sub- 

 specific departure from H. calcaratus. 



Hypertragulus tricostatus Cope. 



Cope thought he recognized a second species about the 

 size of H. calcaratus but distinguished therefrom by the 

 presence of but three ribs on the outer side of the third 



