FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 



241 



does not necessarily imply a coefficient of variation higher than 5 

 on the hypothesis that a single species is present, and this is a very 

 moderate degree of variation for one species. 



Table 53. — Measurements (in mm) of available upper teeth of Litaletes disjvuictus 



Subfamily Hyopsodontinae Trouessart, 1879 ' 



Revised definition. — Paleocene and Eocene hyopsodontid condy- 

 larths with P'*4 not inflated, generally moderate in size, cuspidate, 

 somewhat molariform but never exactly so, P4 generally with a meta- 

 conid and wide but imperfect talonid basin. Molar paraconids 

 median to subinternal, not fusing with metaconids, entoconids dis- 

 tinct and high, talonid basins closed. M^3 little or not reduced. 

 M'~^ with definite hypocone, small in earlier and large in later forms, 

 sharply distinct from tip of protocone. 



Remarks. — Aside from the type genus, I place here Oxyacodon, 

 Litomylus, Litolestes, and Haplaletes v/ith some assurance, Protoselene 

 and Haplomylus very doubtfully. Litomylus and Haplaletes represent 

 the subfamily in the present collection. 



Genus LITOMYLUS Simpson 



Litomylus Simpson, 1935d, p. 243. 



Type. — Litomylus dissentaneus Simpson. 



Distribution. — Middle Paleocene, Fort Union, Montana. 



Diagnosis. — P4 trenchant, paraconid rudimentary, metaconid dis- 

 tinct, separated from the protoconid by a small pit. Molar cusps 

 rather bunodont but acute, paraconids reduced and median, M% 

 Uttle reduced, hypoconulid of M3 sharply projecting. Hypocones of 

 M^~2 relatively large and internal. M^ transverse, triangular. 



LITOMYLUS DISSENTANEUS Simpson 



Figure 66, 67 



Litomylus dissentaneus Simpson, 1935d, p. 243. 



r^/pe.— U.S.N.M. no. 9425, left lower jaw with P3-M3. Collected 

 by A. C. Silberling. 



» "Hyopsodinae" in the original publication, but the emendation can hardly be claimed to change 

 authorship. 



