No. 8.] COPE ON EOCENE VEETEBRATA OF WIND RIVER. 185 



and imbedded in matrix. The former show that the molars have but 

 one root. The latter include the large rodent-like incisors in a frag- 

 mentary condition, and a nearly complete tooth intermediate in charac- 

 ter between the flat-banded teeth and the molar teeth of the known 

 species of Calamodon. It may occui)y an intermediate jiosition in the 

 jaw, but I do not know of any appropriate place for it in the mandible 

 of Calamodon arcamcenus. I think there is little doubt the individual 

 belongs to a species with narrower teeth than any of those of the two 

 species already named. 



The characteristic tooth in question is nearly cylindric, and the part 

 preserved is quite long and slender. Its grinding surface is worn con- 

 cavely, as in the flat teeth of the known species of Calamodon. The 

 enamel is in two bands, one wider than the other, and each of equal 

 width throughout. The space of cementum separating them on one 

 side is nearly twice as wide as that on the other. The cementum layer 

 is not so thick as in the species of the genus hitherto described. The 

 shaft of the tooth is slightly curved, and the wider band of cementum 

 is on the inner side of the curve. 



Measurements. 



M. 



Width of enamel of large incisor 018 



Length of shaft of cylindric tooth 041 



antero-posterior Oil 



transverse 010 



( a: 



Diameters of grinding surface of cylindric tooth < , 



INSECTIVOEA. 

 11. ESTHONYX ACUTIDENS Sp. UOV. 



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 true molar being probably the only tooth miss- 

 ing. Four of the molars of this sx)ecimen are in place, and three are 

 loose. Under the circumstances, I estimate seven molars, of which the 

 fourth premolar is like the first true molar, and the third premolar has 

 its internal lobe very much reduced. The two precediug premolars have 

 one root, and short, compressed, 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. This ridge is without enamel, 

 and the edges are produced and very sharp. The enamel of the exter- 

 nal 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. 



