270 BULLETIN 169, UNITED STATES NATIONAL MUSEUM 



PANTOLAMBDA INTERMEDIUS Simpson 



Figure 80 

 Pantolamhda intermedius Simpson, 1935d, p. 244. 



Type. — U.S.N.M. No. 8384. Left lower jaw with Mi_2 and alveoli 

 of C-P4, associated with symphysis fragment with right Ii_2 and 

 alveoli of left I,_3. Collected by Dr. J. W. Gidley. 



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

 horizon, Crazy Mountain Field, Mont. 



FiGDRE &Q.—Pantolambda inlermedius Simpson, U.S.N.M. no. 8384, right lower jaw: a, Crown view; b, 



external view. Natural size. 



Diagnosis. — Intermediate in size between P. bathmodon and P. 

 caviridus. Pi with one large root, close to canine, followed by short 

 diastema. P2_4 2-rooted. Lower molars closely resembling those of 

 P. caviridus but entoconid more distinct. 



Discussion. — The type has Mi_2 somewhat corroded on the inner 

 side. An isolated lower premolar, probably P2, no. 9598, from the 

 same quarry as the type, is probably of this species. It is 2-rooted 

 (as was P2 of the type) and is as long as Pg of P. caviridus but is con- 

 siderably narrower and simpler. In P. caviridus the posterointernal 

 crest from the main apex bifurcates and a sharp branch runs from it 

 anterointernaUy, whereas in this tooth the posterointernal descending 

 crest is less prominent throughout and has no bifurcation or antero- 

 internal branch. The talonid is a narrow, simple heel. 



On the whole this species seems to resemble P. caviridus but is 

 both smaller and more primitive structurally. Length Mi, 13.2; 



