228 TROCEEDINGS OF THE NATIONAL MUSEUM vol.83 



Family LEPTICTIDAE 



Genus PRODIACODON Matthew and GrSnger 



PKODIACODON CONCORDIARCENSIS," new species 



TVpe.— U.S.N.M. no. 9637, left lower jaw with Po, P4, M3, and 

 alveoli. Collected b}^ Dr. J. W. Gidley. 



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

 cene horizon. Crazy Mountain Field, Mont. 



Diagnosis. — Much smaller than Prodiacodon puercensis. P4 with 

 paraconid projecting more anteriorly and median, talonid with 3 

 cusps (4 in P. puercensis). M3 with trigonid slenderer, paraconid 

 more median, talonid less elongate, and 3 (not 4) talonid cusps. 

 P4 length 2 mm, width 1.1 mm. M3 length 1.9 mm, width 1.2 mm. 

 (The species may not belong in Prodiacodon, but it is evidently closely 

 allied to it, and the specimen is insufficient basis for a generic 

 definition.) 



Genus LEPTACODON Matthew and Granger 



LEPTACODON LADAE.i' new species 



Type.— U.S. IS^.M. no. 9640, right lower jaw wdth P4-M3. Collected 

 by A. C. Silberling. 



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

 ocene horizon. Crazy Mountain Field, Mont. 



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

 smaller than L. sicgfriedti, structurally closer to the former (subgenus 

 Leptacodon) than to the latter (subgenus Leipsanolestes). P4 elongate, 

 paraconid median, metaconid very small but in the same position as 

 in L. tener, talonid as in that species. Molar paraconids smaller than 

 in L. tener but distinct and internal. Hypoconulids of Mi_3 more 

 projecting than in L. tener. Talonid of M3 more elongate and ento- 

 conid smaller. Length Mi_3 in type 4.5 mm. 



LEPTACODON MUNUSCULUM," new species 



Type.— V.S.N. M. no. 9819, left lower jaw with M, and M3. Col- 

 lected by A. C. Silberling. 



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

 ocene horizon. Crazy Mountain Field, Mont. 



Diagnosis. — Slightly smaller than Leptacodon tener, paraconids 

 more reduced and more strictly internal, talonid of M3 relatively 

 narrower. Mi length 1.2 mm. M3 length 1.1 mm. 



1' Concordia, union + arx, fort + -ensis. From the Fort Union Oroup. 



i*Ladae, Latin genitive of AAiai, a Greek (Laconian) athlete famous for his agiJity and speed, this 

 species presumably having the same qualities. 

 » Munuscutum, a small gift. 



