192 THE WASATCn AND BRIDGER FAUNAE. 



A young specimen apparently of this species is represented by the 

 crowns of four mohxr teefli and by a canine. All are unworn and display 

 the character of the unmodified grinding surfaces. The external and in- 

 ternal enamelled faces of the canine approach each other at the apex, as in 

 Edoganns, and are separated by a well-marked notch. The crowns of the 

 molars are a good deal like those of Psittacotherium. They support two 

 transverse crests which are separated by a deep open valley. The posterior 

 crest is the shorter, and in most of the molars is divided into three tuber- 

 cles, of which the median is the smallest. The anterior crest is divided by 

 a deep fissure into two tubercles, each of which has a subacute transverse 

 edge. Enamel smooth. From the Big Horn. J. L. Wortman. 



Calamodon cylindeifek Cope. 



Bulletin U. S. Geol. Surv. Terr.s. F. V. Hayden, 1881, p. 184. 

 Pl.ite XXIV a ; ligs. IjVK!. 



The only individual of this species discovered by Mr. Wortman is 

 represented by fragments of the jaws, with several teeth, both loose and 

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

 The latter include the large rodent-like incisors in a fragmentary condition, 

 and a nearly complete tooth . intermediate in character between the flat 

 banded teeth and the molar teeth of the known species of Calamodon. It may 

 occupy an intermediate position in the jaw, but I do not know of any appro- 

 priate 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 chiiracteristic 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 otlier, nnd each of equal width through- 

 out. 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 sliglitly 

 curvied, and tlie wider band of cementum is on tlic inner side of the curve. 



