CRETACEOUS TURTLES. 



INTRODUCTION. 



From the Upper Cretaceous of Kansas four genera and six 

 species of turtles, or Testudinata, all marine, are now known — ■ 

 one from the Benton and the others from the Niobrara. The 

 largest of these, and in many respects the most remarkable of all 

 fossil turtles, is the gigantic Protostega, an animal that may have 

 reached a length of twelve or more feet. The others are much 

 smaller, probably never more than five or six feet in length. 

 Toxochelys is by far the most common of them all, its remains 

 being found, especially in the upper or yellow chalk of the Nio- 

 brara, often in abundance. Protostega has recently been fully 

 described and figured, 65 chiefly from the material in the Univer- 

 sity of Kansas museum, by Professor Case, and the description 

 it is not thought desirable to reproduce here. The Toxochelys 

 remains of the museum have been thoroughly described for the 

 present work by Professor Case, whose studies in this group 

 have well fitted him for the task. 



De8matochely8 occurs in the state, though the type specimen 

 came from Fairbury, Neb., near the Kansas line, in the Benton. 



Remains of turtles are among the most frequent of vertebrate 

 fossils in nearly all the formations from the Triassic to the pres- 

 ent time. Unfortunately, while their distribution has been very 

 general, indicating wide-spread abundance, the remains are 

 usually fragmentary, complete or even approximately complete 

 specimens being comparatively rare. For this reason our 

 knowledge of the fossil forms is yet far from satisfactory in 

 many of the formations. Many genera and species have been 

 proposed, but not a few of them are known so imperfectly that 



65. Journal Morph., June, 1897. 



(351) 



