1889.] **«^ [Cope. 



position, and is much more prominent than the posterior. Its section is 

 subregular ovah The posterior column is a large process of the posterior 

 inner crescent. The lakes are expanded transversely and their remote 

 borders iiave the usual deep notch. The adjacent borders are very com- 

 plex with rather shallow inflections, with the usual large loop of the an- 

 terior lake represented by two narrow excurrent folds with irregular bor- 

 ders. The crowns wider than long. 



MM. 



Diameters of grinding face (Leidy) 5 ''^•^^'^^^P^^^^'^'' 20 



(. transverse 23 



This species possesses teeth of the H. speriosum type, but with such a 

 distinct style of enamel plication as to preclude the idea of identity with 

 that species. 



From near Archer, Florida, Dr. Neal. 



HipPOTHERiuM GUATUM Leidy. 



Extinct Mammalia of Dakota and Nebraska, p. 287, Plate xviii, Figs. 25, 

 30. Hippotherium ingenuum Leidy, Proceeds. Acad. Phila., 1885, p. 

 33, Fig. 



This species is represented in my collection by two superior molars with 

 lower jaws of three individuals, and two posterior superior molars of an- 

 other individual from the Loup Fork bed of Northern Kansas. Dr. Leidy 

 examined five superior molars from the corresponding liorizon of North- 

 ern Nebraska. 



These specimens indicate a small species of general affinity to the H. 

 speciosum. The internal column is prominent at or before the middle of 

 the crown in position, and of regular oval section. ■ The posterior internal 

 column is small and not prominent, and is well defined externally by a 

 deep sinus. The opposed borders of the lakes are folded into several nar- 

 row sinuses, and the loop of the anterior lake is large and subround. The 

 plication is of intermediate character. The posterior face of the crown of 

 the last superior molar is deeply grooved longitudinally. In a pair of 

 these molars which are well worn, the adjacent borders of the lakes have 

 reduced their plications to serrations, and the loop to a prominent con- 

 vexity. The posterior lobe is still well defined, and the anterior internal 

 column touches the anterior internal crescent. The difference between 

 these and typical teeth is as great as that distinguishing species, but I 

 believe it is due solely to wear. A similar simplification is seen in the H. 

 paniense and H. speciosum. 



MM. 



Diameters of a superior molar \ anteroposterior 19 



c transverse 18 



Diameters of a last sup. molar, little worn \ anteroposterior. . 19 



t transverse 14 



Diameters of a last sup. molar, much worn 5 anteroposterior. . 18 



> transverse 16 



