258 0. C. Marsh — Discovery of Cretaceous Mammalia. 



The smaller forms, including the genus Cimolestes and its 

 near allies, are less rare, and thus admit of more accurate 

 determination. Of these forms, there are at least three genera, 

 which may be readily separated from the specimens now 

 known. Cimolestes, which has in the lower jaw seven teeth 

 behind the canine, forming a close series without diastema; 

 Batodon, with four premolars separated from each other ; and 

 Telacodon, an allied form, with five lower premolars. The 

 upper molar teeth referred provisionally to these genera have 

 also marked characters, as shown in the various figures repre- 

 senting them, but more perfect specimens must settle the 

 question of their exact relations to each other. 



Telacodon Icevis, gen. et sp. nov. 



The type specimen of this genus is the right lower jaw 

 figured on Plate IX, figure 3. It contains three premolars in 

 good preservation, and has alveoles for two more between these 

 and the canine. An upper premolar referred to this species is 

 shown in figure 2, and an upper molar, also referred provision- 

 ally to this form, is given on Plate XI, figure 1. Their exact 

 relation to each other is, of course, uncertain. They are all 

 from the same locality, although not found closely associated. 



A second species, somewhat larger in size, is represented by 

 several specimens, one of which, the lower jaw shown on 

 Plate IX, figure 4, may be taken as the type. The lower 

 molar represented on Plate XI, figure 8, is referred to the same 

 species with doubt. This species may be called Telacodon 

 'prcestans. 



All the remains of this genus so far as known are from the 

 Laramie of Wyoming. 



Batodon tenuis, gen. et sp. nov. 



The present genus is represented by several specimens, of 

 which the lower jaw on Plate XI, figure 5, may be regarded as 

 the type. In this specimen, the canine is in position. It is 

 comparatively large, and directed well forward. Just behind 

 the canine, there was a very small premolar, not preserved. 

 Following this are two others with low compressed crowns 

 pointing forward. The fourth premolar is quite large, with 

 the crown standing high above the jaw, as shown in the figure. 

 In Plate X, figure 6, a right lower jaw is shown, which may 

 be referred to the same species. It has the last two molars in 

 place, well preserved. An upper molar shown on Plate XI, 

 figure 2, is likewise referred to the present species. 



All the known remains are from the Laramie of Wyoming. 



