1917] 



Dice: American Tertiary Lagomorphs 



183 



Pj has a re-entrant angle originating on the antero-exterior border 

 of the tooth and extending about half way across. This tooth is rela- 

 tively much smaller than is usual in lagomorphs, being little, if any, 

 larger than the anterior column of P 5 . Its enamel pattern, also, is 

 very peculiar, differing radically from that of any other known 

 lagomorph. 



Oreolagus must be considered an aberrant ochotonid, probably not 

 ancestral to any known species, which appeared in North America long 

 before the appearance here of the modern genus Ochotona. 



Transmitted December 20, 1916. 



