208 Wortman — Studies of Eocene Mammalia in the 



beds, and I now further venture to believe that all the South 

 American Ungulates, including the Toxodonts, Typotheres r 

 Astrapotheres, etc., are but modified descendants of our North 

 American Condylarths, and were derived from the same region 

 as the Edentates and Primates. 



Subfamily Anaptomorph ince. 



As already indicated, the genera of this subfamily agree in 

 having only eight teeth in the lower jaw. It is in all proba- 

 bility not a natural assemblage, since it is tolerably clear that 

 the missing teeth are not the same in the various genera. Until 

 this is more fully determined by better specimens, the present 

 classification must be regarded as by no means final. The 

 genera composing this group can be distinguished by the fol- 

 lowing characters : 



Lower molars having four cusps on trigon, all distinct ; heel of 

 last molar with four cusps ; first and second molars not especially 

 wider behind than in front; last molar largest of the series ; 

 fourth lower premolar w 7 ith moderately strong internal cusp and 

 rudimental heel ; third premolar with very small rudiment of 

 internal cusp ; canine larger than second premolar or incisor ; 

 only one pair of incisors in lower jaw (?) ; superior molars tri- 

 tubercular, with more or less rectangular outline ; intermediate 

 cusps small, but distinct; postero-internal cusp well developed on 

 crown of first and second molars, but not distinct on third. 



Washakius. 



Lower molars having only two cusps on trigon ; last molar 

 unknown in type ; first and second molars widening rapidly 

 behind ; third and fourth lower premolars without internal cusps; 

 canine larger than incisors ; second premolar absent in type ; two 

 pairs of incisors in lower jaw ; upper teeth unknown in type. 



Anaptomorphus. 



Lower molars having only two cusps on trigon, a vestigial 

 anterior cusp on first ; heel of last molar with three cusps ; first 

 and second molars wider behind than in front ; last molar not 

 reduced ; fourth lower premolar with well-developed internal 

 cusp ; second tooth of the series vestigial and implanted external 

 to the tooth line ; superior molars quadritubercular. 



Necrolemur. 



Washakius insignis Leidy. 

 Washakius insignis Leidy, Contr. Ext. Fauna West. Terr., 1873, p. 123. 



Leidy's type of this genus and species consists of a fragment 

 of a lower jaw carrying the second and third molars so much 

 worn as not to display the arrangement of the cusps. Up to 

 the present, this specimen has remained the sole example of 

 the species, which on account of its imperfect representation 



