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PROCEEDINGS OF THE NATIONAL MUSEUM 



VOL. 83 



Thryptacodon. Molar trigonids higher than in Thryptacodon, para- 

 conids reduced and in nearly same position as in Thryptacodon, but 

 more distinct, higher on crown, trigonids less basined and wdth fewer 

 accessory cuspules. Only one distinct inner talonid cusp, the ento- 

 conid (two in Thryptacodon). 



PROTHRYPTACODON FURENS." new species 



Type. — U.S.N.M. no. 9260, right lower jaw with P4-M3 and alveoli. 

 Collected by A. C. Silberling. 



Horizon and locality. — Gidley Quarry (referred specimen from 

 SilberUng Quarry), Fort Union, Middle Paleocene horizon. Crazy 

 Mountain Field, Mont. 



Diagnosis. — Sole known species of genus. Measurements of type 

 in milUmeters: 



Genus CHRIACUS Cope 



CHRIACUS PUSILLUS,30 new species 



TV^je.— U.S.N.M. no. 9270, right lower jaw with P2-M2. Collected 

 by Dr. J. W. Gidley. 



Horizon and locality. — Gidley and Silberling Quarries, Fort Union, 

 Middle Paleocene horizon, Crazy Mountain Field, Mont. 



Diagnosis. — Much smaller than C. pelvidens, lower premolars high 

 and slender. Anterior basal cusp and talonid of P4 relatively small. 

 Trignoid of Mx short. M3 slightly reduced. Measurements of type 

 in millimeters: 



w Furens, raging. 

 M Pusillm, puny. 



