FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 



243 



The sharp posterior protoconid crest bears a very sHght thickening or 

 cuspule. The anterointernal region is somewhat excavated and has a 

 cingulum below it. P3 has no metaconid, but P4 has a small papilla 

 about halfway up the crown, and above and external to it, between it 

 and the protoconid apex, is a small pit or pocket. 



The lower molars, wdth their acute, well-separated major cusps, 

 resemble those of Oxyacodon. The paraconids are vestigial, forming 

 a small shelf or crest connected with the anterior protoconid wing 

 but not wdth the metaconid. On Mi this nearly reaches the inner 

 border, on M2 it is submedian, and on M3 fully median. Protoconid 

 and metaconid are of nearly equal size. The heels are well basined 

 and the entoconids are sharp and distinct, nearly as high as the 

 hypoconids and on Mi_2 larger and higher than the small hypoconu- 

 lids. On M3 the hypoconulid is as high as the hypoconid and projects 

 sharpl}^ posteriorly. 



Only five specimens, all from the Gidley Quarry, are recognized as 

 of this species. Measurements are given in table 54. 



Table 54. — Individual measurements {in mm) of upper and lower denlition of 



Litomylus dissentaneus 



U.S.N.M. no. 



9557. 

 9580. 



Ml 



3.2 

 2.9 



W 



4.2 

 3.9 



M» 



3.3 

 3.2 



W 



4.7 

 4.5 



M3 



Genus HAPLALETES Simpson 



Haplaletes Simpson, 1935d, p. 243. 



Type. — Haplaletes disceptatrix Simpson. 



Distribution.— Middle Paleocene, Fort Union, Montana. 



Diagnosis. — P4 not trenchant, with distinct paraconid and meta- 

 conid and relatively large basined heel. Molars bunodont, cusps 

 rather rounded and low. Paraconids reduced and median. M3 

 somewhat reduced, hypoconulid of M3 slightly projecting, markedly 

 less than in Litomylus. Amphicones of P^~* more rounded than in 

 Litolestes. P* with rudimentary metacone. Upper molars rounded. 

 Hypocones of M^~^ distinct, but smaller than in Litomylus. M^ less 

 transverse and more rounded. 



