328 GEOLOGICAL SURVEY OF THE TERRITORIES. 



size bas left abundant but crushed fragments in the yellow cbalk of 

 the Mobrara formation. One species must have measured nearly 25 feet 

 across the wings. The giants of this sea were the Liodon proriger, Cope; 

 L. dyspelor, Co])e', Polycotylus latipinnis^ Cope; and Masmosaurus platyu- 

 rus, Cope. Of these the first was apparently the most abundant. The 

 second was the most elongate, exceeding in length perhaps any other 

 known reptile. The last named had the most massive body, and 

 exhibited an extraordinary appearance in consequence of the great 

 icngth of its neck. 



Okder I.— PYTHONOMOEPHA, Cope. 



Traus. Amer. Philos. Soc, 1868; Proc. Am. Phil. Soc, 1871, December. 



The material obtained during the autumn of 1871 by the writer proves 

 conclusively that this order of reptiles attained a predominant importance 

 during tbe Mobrara epoch of tbe Cretaceous period. This is indicated 

 by the great profusion of individual remains and specific forms. Al- 

 though occurring in America wherever the Cretaceous formation appears, 

 they are so far more numerously represented in Kansas than elsewhere. 

 Though not rare in New Jersey, crocodiles and tortoises outnumber 

 them; but in Kansas all other orders are subordinate to the Pythono- 

 morplia. As is now well known since 1868,* the seas of the American 

 continent were the home of this order, while they were comparatively 

 rare in those of Europe. In the latter country we have four species 

 only determined by paleontologists, viz : 



Mosasaurus , 2 



Liodon 1 



(f) Saurospondylus 1 



In Korth America the species have been exactly determined from 

 three regions, as follows : 



Green-sand of New Jersey, 



Mosasaurus 6 



Baptosaurus 2 



Clidastes 2 



Liodon . 4 



(?) Dii)lotomodon 1 



15 



Rotten limestone, Alabama. 



Mosasaurus 1 



Holcodus 1 



Liodon 3 



Clidastes , 2 



* See Trans. Amer. Philos. Soc, Vol. XIV. 



