Cope.] ^9^ [April 15, 



I. Internal cones of superior molars separate from external lobes. 

 A. Cusps of inferior molars not completely united ; 



a. External lobes of superior molars more or less conic. 

 Inferior premolars III and IV compressed, three lobed ; a diastema both 



behind and before P-m . II Bhagatherium. 



A A . Cusps of inferior molars united into two Vs. 



a. Incisors present. 



j3, No diastema in front of second inferior premolar. 



Second premolar without inner lobe ; last molar with one inner cone 



Leurocephalus . 

 Second premolar with inner cone ; last superior molar with an inner 



cone PalcBosyops. 



Second premolar with inner cone ; last superior molar with two inner 



cones Limnohyus. 



/SyS. A diastema in front of second inferior premolar. 

 Two inner cones of last superior molar Lambdotherium. 



aa. Incisors absent from both jaws. 

 Last superior molar with one internal cone Nestoritherium . 



II. One or both internal cusps of superior molars united with the exter- 

 nal lobes by cross-crests. 



a. External cusps of superior molars more or less conic ; 



An anteroexternal cingular cusp Propalmotherium . 



aa. External lobes of superior molars, inflected Vs. 



/9. No crescentic inner lobes. 

 No intermediate lobes OhaUcotJierium. 



/5/3. One or more lobes of each molar crescentic. 

 Intermediate lobes, and one internal cone of superior molars 



Meniscotherium. 



The following regions have thus far furnished species of the above-men- 

 tioned genera : 



Europe — Bhagatherium, Propalmotherium, ChaUcotherium. 



N. America — Leurocephalus, Palceosyops, Limnohyus, LamMotherium, 

 Meniscotherium. 



Asia — Nestoritherium. 



Of the American genera, Leurocephalus S. S. & O. has been found by 

 the Princeton exploring expedition of 1877 in the Bridger formation, but I 

 have not met with it myself. Meniscotherium Cops, is known from a 

 single species found by myself in the Wasatch formation of New Mexico, 

 and described in my report to Capt. G. M. Wheeler (1877). 



