REVIEW 



THE VERTEBRATA OF THE CRETACEOUS PERIOD FOUND 

 WEST OF THE MISSISSIPPI RIVER. 



BY EDWAKD D. COPE3 A. M. 



Section 1. — On the mutual "relations of the Ceetaceous and 

 Tertiary formations of the West. 



The subject which it is proposed here briefly to discuss is one which 

 has excited considerable interest for several reasons. One of these is, 

 that there exists some discrepancy in the evidences as to the true age of 

 beds at the summit of the Cretaceous period and base of the Tertiary 

 in the Missouri and Eocky Mountain regions, and hence a difference of 

 opinion. Another is, that the question of continuity in topographical, 

 and hence of fauual and floral relations, will be largely elucidated by a 

 proper determination of the beds in question, both geologically and 

 paleontologically. I have endeavored to attain some results in the lat- 

 ter field in the department of vertebrata, which are here presented, 

 with some strati graphical observations made at localities either little or 

 not previously studied. 



Messrs. Meek and Hayden have classified the vast thickness of the 

 Cretaceous system, recognizing five epochs as quite distinctly defined. 

 These are as follows : 



I. The Dakota group, (I^o. 1.) The present list does not include 

 any species as discovered in this formation. Developed on the Missouri, 

 and on the Eio Grande, l^Tew Mexico. 



II. The Benton group. Seen on the Missouri Eiver by Hayden, 

 and stated by him to extend to the Smoky Hill Eiver, in Kansas, and to 

 Texas. The i)resent list includes only three species from it, namely : 

 Hyposaurus vehMi, a crocodile; Apsopelioc sauriformis^ a clupeoid and 

 Pelecorapis vm-ians, a ctenoid fish. Other species of fishes occur in the 

 same formation in Kansas. 



III. The ISTiobbaea group. From the Missouri, Kansas, and Texas, 

 according to Hayden. Confirmatory of the last locality are remains of 

 Pythonomorphor from that State, discovered and sent to me by Dr. A. 

 E. Eoessler. I have also described a species of that order as common 

 to Eastern IS'ew Mexico and Western Kansas j and Hayden and Seconti 

 state that it appears north of the Arkansas in Southern Colorado. Ver- 

 tebrate remains are abundant in this formation, and it has furnished 

 a majority of those enumerated in the following catalogue. They are 

 distributed as follows, among the orders of Vertebrata : 



Aves — 



Natatores 2 



'i Saururce 2 



