F. B. Loomis — Rhinocerotidce of the Lower Miocene. 61 



from the Lower Harrison beds, 300 yards north of Agate Spring 

 Quarry, Sionx Co., Nebraska. The specific name is given to 

 honor Mr. W. D. Stiger, an earnest promoter of the expedition 

 on which the type was found. 



Fig. 14. Aceratherium stigeri ; the premolar and molar series of the type 

 specimen, one-half nat. size. 



The small skull is elongated, light in build, and rather 

 narrow. The orbit is large and the zygomatic arch light. 

 The premolar teeth are crowded, there being neither an ante- 

 rior or posterior cingulum, though one is developed along the 

 inner face around the protocone, running out on the hypocone. 

 Crista and crochet are wanting on these teeth of a rather old 

 individual, except that on the fourth premolar there is a faint 

 trace of a crista, and on the third premolar a small antecrochet 

 is developed. On the molars the cingulum is reduced as in 

 the premolars ; and both crochet and crista are wanting. The 

 protoconule, however, is swollen, making a considerable fold 

 as in European Diceratheres. A. stigeri is closely related to 

 A. egrerius, but is smaller and has the cingulum on the pre- 

 molars and the crochet on the molars less developed. 



Measurements. 



Total length of the skull _ . about 345 mm 



Width between the orbits H7 mm 



Length of the premolar-molar series . 1 68 mm 



Length of second molar tooth 2 9 mm 



Width of second molar tooth 37 mm 



Aceratherium egrerius Cook. 

 Science, N. S.. vol. xxvii, p. 256. 



Type a skull and lower jaws in the private collection of Mr. 

 Harold Cook, from the Lower Harrison beds, at Agate, Sioux 

 Co., Nebraska. 



This larger species has an elongate skull, of moderately light 

 build, the facial portion being unusually elongated ; so that the 



