latero-posterior, the posterior aspect being thickened, and either 

 transverse or convex in section. In the supposed canines the 

 anterior serrulate edge is wanting, or represented by a second 

 posterior edge parallel with the original one, thus forming a com- 

 pressed chair-shaped crown. Numerous specimens of all these 

 forms were obtained by the expedition. 



Examination of the dental series of the Lselaps incrassatus 

 shows that the antero-posterior diameter of one or two teeth 

 in the position of canine, becomes oblique in the curved long 

 axis of the dentary bone. The transverse diameter is also greatly 

 increased so as to equal or even exceed the antero-posterior ; the 

 serrate edges are opposite to each other. A tooth of this tj^pe 

 was the first of this species which I observed, and the name has 

 reference to its peculiar form. A tooth in the position of first or 

 anterior incisor, differs in having the anterior serrate crest re- 

 moved to the middle of the inner aspect of the apical portion of 

 the crown, while tbe posterior edge retains its usual position. 

 Further posterior transfer of the anterior cutting edge and a 

 grooving of the posterior face, would produce a tooth of the form 

 suspected by Leidy to be the canine of Aublysodon horridus, 

 while the canine just described is different from any tooth refer- 

 red by Leidy to the same species. But a large tooth found in 

 immediate association with the jaw, but separated from it, has the 

 posteriorly truncate form described by Leidy as typical, and is very 

 probably the tooth of the maxillary bone, near the position of the 

 superior canine of a mammal. 



It may be observed in conclusion, that if the teeth suspected 

 by Leidy to be canines of Aublysodon horridus, but which I sup- 

 pose to be incisors, are really such, Aublysodon must be regarded 

 as a genus distinct from Lselaps ; while, on the other hand, should 

 such determination prove to be inadmissible, and the two genera 

 be the same, the name Lselaps must be preserved as the older; it 

 was published in 1866, while Aublysodon 'bears date 1868. 



In examining the very numerous teeth discovered by the expe- 

 dition, I find four species in addition to those already named. A 

 list of all the species is now given. 

 Lselaps incrassatus, Cope, Proceed. Acad. Nat. Sci.1876, Oct. 



The dentary bone of this species, above alluded to, is of com- 

 pressed form, and becomes thin and plate-like in its posterior por- 

 tion. The latter is excavated on the inner side, where it is proba- 





