E. L. Troxell — Homed Eocene Ungulates. 37 



The posterior extension of the ectoloph on M 3 , the form 

 of the slender premaxillaries and of the nasals, the 

 presence of erect canines, the deep posterior nares, all 

 remind one of Amynodon erect us nobis, and it seems that 

 there must have been a rather near relationship. The 

 notches on the anterior ends of the nasals are found also 

 in Gcenopus alius nobis. 



The following are important measurements of Metahy- 

 racliyus bicornutus: 



mm. 



Molar-premolar length Ill 



Molar series, length 64.5 



P 4 , width 21.7 



P 4 . lensth 16.5 



M 2 , width 26.3 



Summary. 



Two Eocene specimens are figured and described here 

 which are unusual in having on the nasals slight thicken- 

 ings, or centers of ossification, which resemble the horn 

 supports in later rhinoceroses. One is the type of the 

 well known Colonoceras agrestis Marsh and the other 

 the type of Metahyrachyus bicornutus, gen. et sp. nov. 

 The latter may be distinguished by the caniniform I 3 , 

 the large P 1 , the median cross ridge on P 2 , and the odd 

 forms of P 3 - 4 with their strong development of the tetar- 

 tocone and much reduced metaloph. 



