FORT UlSriOISr of crazy mountain field, MONT. 



113 



This delicate species differs so much from Prodiacodon puercensis 

 that the generic reference is not at all certain, but the only alternative 

 would be erecting a new genus, which is highly undesirable at present. 

 The present form is apparently a typical leptictid, peculiar only in 

 minute detaUs, and as close to Prodiacodon as to any other defined 

 genus. It is almost equally close to Leptacodon, but its reference 

 there would make the generic definitions almost unpossible to frame 

 adequately. 



The type is the only known specimen. Its dimensions are as 

 follows: Length P2, 1.3; width P., 0.5; length P^, 2.0; width P„ 1.1; 

 length M3, 1.9; \v4dth M3, 1.2. 



Genus LEPTACODON Matthew and Granger, 1921 



LEPTACODON LADAE Simpson 



Figure 15 

 Leptacodon ladae Simpson, 1935d, p. 228. 



r?/^e.— U.S.N.M. no. 9640, right lower jaw with P4-M3. Collected 

 by A. C. Silberling. 



Horizon and locality. — Gidley Quarry, Fort Union, Middle Paleo- 

 cene horizon, Crazy Mountain Field, Mont. 



Figure 1".. — Leptacodon ladae Simp- 

 son, U.S.N.M. no. 9640, right 

 lower jaw: a. Crown view; 6, in- 

 ternal view. Five times natural 

 size. 



Figure 16. — Leptacodon munuscu- 

 lum Simpson, U.S.N.M. no. 

 9819, left lower jaw: a, Crown 

 view; 6, internal view. Five 

 times natural size. 



Diagnosis. — Slightly larger than L. tener or L. packi and slightly 

 smaller than L. siegfriedti, structurally closer to the former two 

 species (subgenus Leptacodon) than to the latter (subgenus Leipsano- 

 lestes). P4 elongate, paraconid median, metaconid very smaU but in 

 the same poskion as in L. tener, talonid as in that species. Molar 

 paraconids smaller than in L. tener but distinct and internal. Hypo- 

 conulids of M1-3 more projecting than in L. tener. Talonid of M3 

 more elongate and entoconid smaller. 



Remarks. — This species is referable to Leptacodon with very little 

 doubt. Although fairly common in the Gidley Quarry, the speci- 

 mens are all very fragmentary, and they add nothing to knowledge 

 of the genus beyond making it a little more varied. 



