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PROCEEDINGS OF THE NATIONAL MUSEUM 



VOL. 83 



larly M3 short and broad, with very slightly elevated trigonids and 

 low blunt cusps, paraconids vestigial, median, not fusing with meta- 

 conids, external cusps lower than internal. W~^ similar to Litaletes,, 

 but protocones relatively smaller and hypocones relatively larger. 



HAPLALETES DISCEPTATRIX.m new species 



Type.— U.S.N. M. no. 9500, right lower jaw with P3-M3. Collected 

 by A. C. Silberling. 



Paraf?/pg.— U.S.N. jM. no. 9555, right upper jaw with P--M-. Col- 

 lected by Dr. J. W. Gidley. 



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

 cene horizon, Crazy Mountain Field, Mont. 



Diagnosis. — Sole known species of genus. Dimensions of type in, 

 millimeters: 



Order AMBLYPODA 



The only periptychid so far found is an anisonchine apparently 

 indistinguishable from the Torre j on Anisonchus sedorius. The ab- 

 sence of Periptychus, so abundant in contemporaneous beds elsewhere,, 

 is striking and emphasizes the poor representation of the macrofauna 

 in contrast with the remarkable variety of the microfauna. 



Family PANTOLAMBDIDAE 



Genus PANTOLAMBDA Cope 



PANTOLAMBDA INTERMEDIUS, new species 



Type. — U.S.N. M. no. 8384, left lower jaw with M1.2 and alveoH of 

 C-P4, associated w^ith symphysis fragment wdth right Ii.o and alveoli 

 of left I1.3. Collected by Dr. J. W. Gidley. 



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

 cene horizon. Crazy Mountain Field, Mont. 



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

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

 diastema. P2-4 2-rooted. Lower molars closely resembling those of 

 P. cavirictus but entoconid more distinct. Mi length 13.2 mm, width 

 11.2 mm. Mo length 14.8 mm, width 12.1 mm. (The widths may 

 have been reduced somewhat by corrosion.) 



M Disceptalrix, one who decides. From its apparently decisive evidence of union between the hyop«' 

 sodonts and mioclaenines. 



U. S. GOVERNMENT PRINTING OFFICE: l»3B 



