O. C. Marsh — Cretaceous Mammalia. 177 



Art. XXII. — Discovery of Cretaceous Mammalia. Part II ; 

 by Professor 0. C. Marsh. (With Plates YII and VIII.) 



In the last number of this Journal, the writer announced the 

 discovery, in the Cretaceous, of many remains of Mammalia, 

 and gave brief descriptions, and figures, of some of the more 

 important forms secured.* The present article is a continu- 

 ation of the same subject, and contains notices of other new 

 species from the same localities, together with some additional 

 information in regard to those first described. In a future 

 article, the relations of these various forms to each other, and 

 to other Mesozoic Mammals will be discussed. 



Cimolomys digona, sp. nov. 



A species of this genus, somewhat larger than those de- 

 scribed, is represented by various remains, the most character- 

 istic of which is the tooth figured on Plate VII, figures 1-4, 

 which may be considered the type specimen. The crown is 

 elongate, rounded in front, and angular at the posterior corners. 

 It is apparently from the left side, and has nine cones in the 

 outer row, and ten in the middle row. In the inner row, there 

 are eleven cones, the posterior ones being minute. The square 

 end of the crown indicates that it adjoined another tooth 

 behind it. This specimen is from the Laramie of Wyoming. 



The remains now known of this genus represent a distinct 

 family, which may be called the Cimolomidce. 



Selenacodon brevis, sp. nov. 



A second smaller species of this genus is indicated by a num- 

 ber of teeth, one of which is figured on Plate VII, figures 9-12, 

 and may be regarded as the type. This tooth is an upper 

 molar, apparently from the left side, and the form of its crown 

 is well shown in the figures named. The front of the crown is 

 rounded and narrow, while the posterior end is broad, and 

 slightly concave, indicating another molar behind it. The val- 

 leys between the rows of cones are less deep than in the larger 

 species, a typical molar of which is shown on the same Plate, 

 figures 5-8. 



The specimens representing the present species were found 

 in Wyoming, in the Laramie. 



* This Journal, vol. xxxviii, pp. 81-92, plates ii-v, July, 1889. 



