FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 



239 



more or less transitional Ellipsodon aquilonius belongs. It is closer 

 to Ellipsodon acolytus than to Litaletes disjundus or any other species 

 known to me, and, as already stated, that is the reason for referring 

 it to Ellipsodon at present. It is, however, probably closer to Lita- 

 letes disjundus than to Ellipsodon inaequidens. Perhaps it will be 

 necessary to transfer E. aquilonius and E. acolytus to Litaletes at some 

 future time, but that introduces a great difficulty as regards the 

 generic position of E. lemuroides, and for the present the system 

 adopted here seems equally natural and more convenient. 



LITALETES DISJUNCTUS Simpson 



Figures 64, 65 

 Litaletes disjundus Simpson, 1935d, p. 242. 



Type.— U.S. ISSM. no. 9323, right lower jaw with C-M3 (M3 broken). 

 Collected by A. C. Silberling. 



Paratype. — U.S.N. M. no. 9324, right upper jaw with P^-M^ 

 Collected by A. C. Silberhng. 



Horizon and locality. — Gidley Quarry, Fort Union, Middle Paleocene 

 horizon. Crazy Mountain Field, Mont. 



Diagnosis. — Sole laiown species of genus. Measurements given in 

 table 52. 



Discussion. — P^~* and M' of the species are now known only from 

 the paratype, so that their variation is not established. On this 

 specimen both P^ and P^ have distinct parastjde and metastyle and 

 on both the posterior amphicone crest bears a rudimentary metacone, 

 larger on P*. P^ has a rudimentary protocone. On P* the metaconule 

 is not developed on the cingulum but more normally, on the protocone 

 wing, and the cingulum does not cross the inner face of the protocone. 

 On M^~^ the parastyle is unusually prominent and the hypocone is 

 larger than in Ellipsodon aquilonius and not so near the protocone 

 apex. M^ is less reduced, less oval, and the metacone, although 

 smaller than the paracone, is large and distinct. 



Table 52. — Available numerical data on lower teeth of Litaletes disjunctus/rom the 



Gidley Quarry 



