Cope.] 44o [Mays, 



of the lakes only show indication of plication on their adjacent faces ; 

 here the anterior has traces of three loops and the posterior of one. Ce- 

 mentum full within and without. 



A second superior molar is not so much worn, and displays more pli- 

 cation of the enamel plates. The crown is* curved and not elongate. The 

 posterior inner column is not lost, and the anterior column is not so 

 round in section, but is a short oval. It presents no angle towards the 

 enamel borders of the inner crescents, but there projects a single small 

 loop opposite the middle of the column. The folds of the lakes are con- 

 fined to their adjacent faces, thus agreeing with the tooth No. 1. The 

 folds are also very few, but much deeper than in No. 1. On the pos- 

 terior lake there are three, the inner one deep ; on the anterior lake, one 

 deep one, and another rather deep entering from the inner side approaches 

 it. Slight undulations of the posterior border of the posterior crescent 

 take the place of the folds of other species. 



The Hippotherium paniense evidently difTeis from the other species in 

 the coincident cylindric form of its internal column, with the greater 

 simplicity of its enamel plates. 



Measurements. 



No. 1. M. 



Length of crown on middle of side 012 



„. , • J- r f anteroposterior 020 



Diameters gnndmg face < ' „,, 



^ ^ I transverse 021 



" inner column 005 



No. 3. 

 Length of crown on middle of side 016 



„. , ■ J- r f anteroposterior 019 



Diameters f^rmdmg face < ' „,^ 



I transverse 020 



" of inner column OOo 



I obtained the teeth of this species in 1873 from the Loup Fork beds of 

 the Pawnee Buttes in Northeastern Colorado. 



Hippotherium venustum Leidy. 



Proceedings Academy Phila., 1853, vi, p. 241 ; Holmes, Post Pliocene 

 Fossils of South Carolina, 1859, p. 105, Plate xvl. Figs. 32-3. 



For the character of this species I am compelled to rely on Leidy's fig- 

 ures above cited, as the description at the latter reference cited (there is 

 none at the first) gives no assistance. 



According to the figures in question, the anterior internal column Is 

 median in position, and is nearly round in section. The posterior internal 

 column is small and loop-shaped in section. A single narrow loop of the 

 middle enamel border is directed towards the anterior internal column. 

 The lakes both have the usual inflection of the border on their remote 



