60 F. B. Loomis—Rhinocerotidw of the Lower Miocene. 



the well-developed crochet, no crista, and a large " antecro- 

 chet," this being as above the swollen protoconule fold. This 

 and the foregoing species are closely related to each other and 

 represent the European invasion of these American Dicera- 



11 



12 



Fig. 11. Diceratherium minutum 

 nat. size. 



Fig. 12. Diceratherium douvillei ; second molar 



second molar, after Cuvier, one-half 

 after Osborn. 



13 



theres. The two species with their swollen protoconule folds 

 show also relationship to the little known D. hesperium. 



Diceratherium oregonense Marsh. 

 This Journal, vol. v, p. 5, 1873. 



The type is a broken molar tooth from the Loup Fork of 

 Oregon. This very mnch worn tooth shows the continuation 

 of the features of D. schiffi and D. cooki, the crochet having 

 united with the crista and thus isolated the median f ossette. The 

 internal cingulum is w r ell developed. This is the latest known 

 Dicerathere, and in all probability the genus became extinct 

 during early Loup Fork times. 



Beside the rich fauna of Diceratheres, 

 two Aceratheres have been found within 

 the past year in these Lower Harrison 

 beds ; a matter of considerable interest, 

 as it has heretofore seemed that except 

 for the species of Aceratherium which 

 migrated to Asia and Europe, the genus 

 had died out in America. It now ap- 

 pears, however, that a few forms main- 

 tained themselves in this country at least 

 as late as the Lower Miocene. The two 

 species show but slight modification from 

 their Oligocene progenitors, as will be 

 seen from the following descriptions and 

 hVures. 



Fig. 13. Diceratherium 

 oregonense ; type speci- 

 men, being probably 

 molar 2, one-half nat. 

 size. 



Aceratherium stigeri sp. no v. 



Type is No. 1,040 in the Amherst College Museum, a skull 

 lacking only a part of the occipital crest and the premaxillge, 



