F. B. Loomis — Bhinoceroticlce of the Lower Miocene. 57 



Dicer atherium petersoni sp. hoy. 



Type is No. 1,583 in the Amherst College Museum, being 

 the first and second upper molars, found in the Lower Harrison 

 beds, 300 yards north of Agate Spring Quarry, Sioux Co., 

 Nebraska. ' Named for Mr. O. A. Peterson, who has made the 

 Lower Harrison fauna, especially the Diceratheres, famous. 



Fig. T. Diceratherium petersoni ; first and second molars (type specimen), 

 one-half nat. size. 



The species is the largest of those from the Lower Harrison 

 and closely approximates D. armatum in size. The anterior 

 cingulum is reduced and the internal one absent except for a 

 trace between the protocone and the hypocone on the first 

 molar. The crochet is strongly developed but not united to 

 the distinct, though small, crista. In specialization this species 

 is intermediate between D. niobrarense and D. schiffi. 



TThile no skull was found, numerous scattered teeth were 

 collected. 



I) leer either i inn schiffi sp. nov. 



Type is Xo. 1,012 in the Amherst College Museum, being an 

 incomplete skull, including the right upper premolar and molar 

 dentition together with the entire brain case, from the Lower 

 Harrison beds, 300 yards north of Agate Spring Quarry, Sioux 

 Co.. Nebraska. The species is named to honor Mr. M. L. 

 Setoff, one of the supporters of the expedition on which the 

 type was found. 



The species is the smallest and most specialized of the genus 

 so far found. The low flat skull has an unusually wide brain 

 case. The occipital crest is low and the ridges from over the 

 orbits fail to unite in a sagittal crest, but remaining wide apart 

 in both young and old individuals, cause the flat dorsal surface 

 between the orbits to extend back to the rear of the skull. 

 The orbit is large, and the zygomatic arch moderate both in 

 weight and width. On the premolars the internal cingulum is 



