424 MEMOIRS OF THE CARNEGIE MUSEUM. 



size as in D. niobrarense. As stated above, the cheek-teeth are much worn. The 

 last molar does not indicate any crochet or crista as in the last named species; the 

 cingulum is, however, equally prominent. M'* on the right side has a small cone in 

 the median valley. 



It is very likely that the above specific characters may be modified, or added 

 to, when more material representing both sexes of this species is obtained. 



Measurements. 



Greatest length of skull from inion to the end of the premaxillaries approximately 'AO mm. 



From occipital condyles to anterior end of maxillary, approximately 490 " 



Occipital condyles to P' 362 " 



Occipital condyles to M' 230 " 



From incisor to orbit 197 " 



From orbit to occipital condyles 310 " 



Incisor to and including M' 266 " 



Greatest transverse diameter of skull at posterior portion of zygomatic arches 258 " 



Greatest transverse diameter of frontals 191 " 



Greatest transverse diameter at constriction back of the enlarged portions of the nasals 97 " 



Length of molar-premolar series 217 " 



Length of premolar series 102 " 



Length of molar series 119 " 



Antero-posterior diameter of P' (greatest diameter) 21 " 



Transverse " " P' " " 20 " 



Antero-posterior " " P^ " " 26 " 



Transverse " " P^ " " 32 " 



Antero-posterior " " P^ " " 31 " 



Transverse " " P^ " " 44 " 



Antero-posterior " " P< " " 34 " 



Transverse " " P-" " " 48 " 



Antero-posterior " " M^ " " 38 " 



Transverse " " M' " " 4.5 " 



Antero-posterior " " M'^ " " 45 " 



Transverse " " M^ " " 47 " 



Antero-posterior " " M' " " 38 " 



Transverse " " M^ " " 44 " 



Antero-posterior " " crown of incisor 19 " 



Transverse " " " " " 9 " 



9. Diceratherium niobrarense Peterson.'-'^ (Plate LX, Fig. 2; PI. LXI, Fig. 2; 

 PI. LXII, Fig. 2, and text-figure 13.) 

 Synonym. — M. (Aceratherium) egrerius}^ 



-1 Science (N.S.), Vol. XXIV, 1906, p. 28; Ann. Car. Mus., Vol. IV, 1906, p. 46, Pis. XIII-XIV; 

 Loomis, F. B., Amer. Jour. Scl., Vol. XXVI, 1908, p. 56. 



^' Loomis, F. B., ibid., p. 61 [Aceratherium, egrerius]; Cook, Harolil ,1., Amer. Naturalist, Vol. XLII, 

 1908, p. 543, 2 figs [Aceratherium egregius]; [Metacocnopus cgregius]; Neb. Geol. Surv., Vol. Ill, 1908, 

 p. 245, PI. I.; Vol. VII, 1912, p. 41. 



