synopsis; of the vkktebkatk fauna of the ruEnco seizes. 353 



the (.•xtriiial anterior. The opposite cusps of the heel are well developed, but ihe 

 posterior mediiui is quite rudimental. The first and second premolars are larger than 

 the molars, but not disjjroportionately so, and they have a characteristic form. Tiie 

 ci'own is wide at the principal cusp, but the heel is small and is at the inner side of 

 its posterior face. There is an anterior cusp which is a little to the inner side of the 

 middle Hue of the principal cusp, and which is distinct at a point much above the 

 base of the crown, being marked oif from the main cusp below by a shallow groove. 

 A line passing through the long axis of the crown is an open sigmoid. The last true 

 molar rises on the base of the coronoid process. Both the exteiiial side ol" the laiuus 

 and its inferior margin are gently convex. The anterior border of tlie masseteric 

 fossa is distinct, but there is no inferior border. 



Measurements. M. 



Leiiglli of superior molars except p. lu. iv 03.') 



Length of true molars 0113 



f anteroposterior 001 



Diameters of p. m. iv ^ 



j transverse 0005 



Dposterior 0035 



007 



Length inferior molars less p. m. iv and iii 02:5 



Length true molars 0125 



anteroposterior 0048 



{anleroposterui 

 transverse . . . 



1 anteroposterior, 

 transverse 



Diameters of p. ni. i , „„,„ 



' transverse OO.Ju 



.0015 



.0038 



Depth of ramus at m. i 010 



" m. ii (posteriorly) 013 



Jaws of eight iiulividiials of this species have come into my ])Osscssion. 



IlE.Miriii.Krs KowAi.KvsKiANUS Cope ; Auier. Naturalist, 1883, p.. 833; Tertiary Vertebrata, 1885, p. lO."). 



A ciiished cranium of this species shows some points prcviousl}' unknown. The 

 sagittal crest is low and divides into the temporal crests, which divergi- widely and 

 rapidly to the postorbital angles. These arc distinct, but not produced. The orbits 

 are small, and have a partially upward direction. The infraorbital foramen opens 

 above the antei-ior border of the second premolar. The latter tooth has a well-tlevel- 

 oped internal cusp. The palate is wide, but as the skull has been crushed this width 

 is probably exaggerated. 



Ill the inferior dentition this species may be readily distinguished by the very 

 robust first and second premolars which arc shorter and wider than in any other. 



