14 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I31 



by wear of Mi (compare height of cusps shown in lateral view, pi. 2, 

 fig. I, with Osborn's fig. 3A on p. 267, 1913). 



Unlike the type of E. amarorum, the cranial portion of the E. 

 anarsnis skull is poorly preserved, but fortunately the side of the 

 rostrum, missing in the former, is present in the Dry Creek specimen. 

 Perhaps the most striking feature to be revealed by the E. anarsius 

 rostrum is the enlarged canine, evidently not included in the dentition 

 of Moropus. Absence of this tooth has been generally regarded as 

 characterizing the family although in certain forms the complete 

 formula is not known. The upper premolars were not preserved in 



MEASUREMENTS IN MILLIMETERS OF DENTITION IN TYPE OF 



Eomoropiis anarsius, u.s.n.m, no. 21097 



Length of upper molar series, M'-M' inclusive, parallel to tooth row 54.4 



Ml, anteroposterior diameter perpendicular to anterior margin 14.9 



Ml, greatest transverse diameter across parastyle and protocone 16.7 



M2, anteroposterior diameter perpendicular to anterior margin 19.0 



M:, greatest transverse diameter across parastyle and protocone 23.5° 



M3, anteroposterior diameter perpendicular to anterior margin 19.6 



Ma, greatest transverse diameter across parastyle and protocone 25.0 



Length of preserved lower cheek tooth series, P3-M3, inclusive 78.0 



Length of lower premolars, P3-P4 24.0 



Length of lower molars, Mi- Ms 54-0 



P3, anteroposterior diameter : transverse diameter of talonid 12.8 : 7.8 



Pi, anteroposterior diameter: transverse diameter of talonid 11.2: 8.1 



Ml, anteroposterior diameter : transverse diameter of talonid 13.9 : 9.0 



Mj, anteroposterior diameter : transverse diameter of trigonid 16.9: 10.5 



Ms, anteroposterior diameter : transverse diameter of talonid 24.0 : 10.5 



» Approximate. 



No. 21097, but the three molars are complete. Eomoropiis upper 

 molars are characterized by a lophoid protocone and hypocone, more 

 elongate than in Moropus, and with a distinct protoconule. The ex- 

 ternal wall exhibits a strikingly developed parastyle and a prominent, 

 anteroposteriorly compressed mesostyle and paracone rib. The rib 

 on the metacone is weak or wanting. AP exhibits a spurlike metacone 

 directed nearly at right angles to the similarly developed mesostyle. 



Comparison with upper teeth in Cope's type is limited to the lingual 

 portion of AP and no significant differences are observed. Neverthe- 

 less, the anteroexternal root for M- and AP can be observed in Cope's 

 specimen, and its position is not nearly so forward and outward as in 

 E. anarsius, suggesting rather less extension of the parastyle in the 

 molars. Comparison with the excellent upper cheek tooth series pre- 

 served in the type of Eomoropus anncctcns, which Peterson (1919) 



