202 THE WASATrn and p.ridger fauna. 



much larger than in that species. Tlie last true molar is much smaller than 

 the penultimate, and consists ot three anterior cusps and a longer heel. 

 The former are obtuse, the external the larger, the internal equal, the ante- 

 rior on the inner edge of the crown. The heel sustains a low conic tubercle. 

 Measurements will be given in the explanation of the figure above cited. 

 From the Puerco beds of northwestern New Me.xico. 



ESTHOXVX Cope. 



Report Vert. Foss. New Mexico, U. S. Geoj;. Survs. W. of 100th Meridi.nn, 1874, p. G: Id., Ami. Report 

 U. S. Geog. Survs. W. of 100th Mcridi:iii, 1^74, p. 11;^; System. Cat. Vert. Eocene, New Mexico, 

 U. S. Geog. Survs. W. of 100th Meridi.aii, 1875, p. 23; Report U. S. Geog. Survs. W. of 100th 

 Meridian, vol. iv, pt. ii, 1877, p. l.")3. 



The dental formula is, I. ^; C. : P-m. ' ; M. -. 



6 1 6 6 



Incisors of two forms, the inferior subgliriform, but not growing from 

 persistent pulps; the enamel covering a long and narrow external vertical 

 face, and terminating above the alveolus, thus distinguishing crown and 

 root. The superior incisors with the apex incased in enamel, which extends 

 much farther on the outer than the inner side; the crown compressed, not 

 wider than the root. The first superior incisor is large, and the crown is 

 somewhat spoon-shaped. The second incisor is as robust as the first, but 

 the crown is shorter. TJie second premolar has one external and one inter- 

 nal lobe, in the third (fourth) premolar these lobes are much enlarged, and 

 the tooth is transverse. The true molars have two external cusps, which 

 •are flattened, close together, and well within the margin of the base of tlie 

 crown. There is one internal lobe at the junction of two ridges, which in- 

 close a triangular area with the connected bases of the external two cusps; 

 and a strong posterior ledge, as in the opossums. Of the inferior incisors, 

 the median is large and half gliriforni, while the first and third are small. 

 The inferior, like the superior canines, are large. The first and second 

 (third) premolars have no internal lobes, but the second (third) has a heel. 

 The fourth is more or less like the first true molar. 



The inferior molars support two V's, witli rounded apices directed out- 

 ward, the posterior soon wearing into a triangle lower than the anterior. 

 The anterior is elevated and transverse, only distinguished from a triangle by 



