210 TOE WASATCn AND BRIDGER FAUN^. 



ESTHONYX ACUTIDENS Cope. 



Bulletin U. S. Gcol. Surv. Terrs. F. V. Ilayden, 1681, p. 185. 

 Plate xxiva.figs. 17-21. 



The largest species of the genus, and represented by two individuals. 

 The first of these includes the last molars of both series and an anterior true- 

 molar ; the second includes most of the dentition of one maxillary bone, the 

 last two true molars being probably the only teeth missing. Four of the 

 molars of this specimen are in ))lace, and three are loose. Under the cir- 

 cumstances, I estimate six molars, of which the foui-th premolar is like the 

 first true molar, and the third premolar has its internal lobe very much 

 reduced. The two preceding premolars have one root, and short, com- 

 pressed, and acute crowns. The second is abruptly very much smaller 

 than the third, and is close to it ; the first is close to the second, and 

 is a little larger. The canine is larger still, and is somewhat compressed. 

 Externally viewed, it looks like the canine of a carnivorous mammal ; but 

 viewed from within, it displays marked peculiarities. It has here a median 

 rib, separated from the fore and aft edges of the crown by a groove on each 

 side. This ridge is without enamel, and the edges are produced and very 

 sharp. The enamel of the external face extends twice as far towards the 

 base as on the interior side. The enamel of this tooth, with that of the 

 premolars, is wrinkled ; that of the molars is smoother. The two external 

 cusps of the last premolar are closer together than those of the true molare. 

 The posterior part of the external basal cingulum of the second and third 

 true molars is more prominent tlian the anterior part. 



The details of the inferior teeth preserved do not difiFer much from 

 those of the E. bisulcatus, excepting that the heel of the last true molar is 

 much more produced. 



The E. acididens is considerably larger than either of the species of the 

 genus heretofore described. 



Measurements. 



No. 1. M. 



lertical 00r>5 



Diameters of last inferior molar^ antero-postcrior 0130 



transverse 0064 



^. . - . , C antoro-po.sferior 0095 



Diameters of u I mo molar { . „~., 



I triinsverse wrii 



r< ar 

 < tr 



0- 

 Vf 



_..,,, , < anlero-poHtcrinr 0097 



Diameters of Jaat buperior iiioliir ? _ _ q.o- 



