Williston.] Turtles. 353 



Cretaceous belong to this suborder. The Pleurodira include a 

 much smaller number of living turtles, all of which are con- 

 fined to the southern hemisphere. The carapace is always fully 

 ossified ; the head is brought into the shell by turning side wise, 

 and not by a vertical flexion. The earliest known turtles are 

 Pleurodira. 



The large green turtle of the West Indies sometimes attains 

 a weight of five hundred pounds. 



DESMATOCHELYS LOWII. 



BY S. W. WILLISTON. 



In November of 1893 I received from Mr. M. A. Low, general 

 attorney for the Chicago, Rock Island & Pacific railroad, a 

 skull of a turtle, of unusual interest, which had been obtained by 

 Mr. Schrantz, roadmaster of the Rock Island road, near Fair- 

 bury, Neb. From the matrix yet adhering to the specimen I 

 recognized its age as that of the Benton Cretaceous. 



Mr. Low, with his usual generosity towards the University, 

 enabled me shortly afterward to visit the locality whence it had 

 been obtained. I found, as I had suspected, the formation to 

 be the Benton, and probably from the horizon named the Ostrea 

 Shales by Mr. Logan. An associated fossil was Xiphactinus lowii 

 Stewart, recently described. The late Doctor Eaton, of Fairbury, 

 kindly assisted me in the examination of the region, and, by 

 his intervention, I obtained various other parts of the skeleton. 

 The animal had been fossilized nearly entire, but had unfor- 

 tunately suffered loss and mutilation in its collection and pres- 

 ervation. It nevertheless permits nearly all of the essential 

 characters to be made out with considerable certainty. It 

 represented a new species, which I have named in honor of 

 Mr. Low, as a slight appreciation of the many favors that he 

 has done to the University and indirectly for science, and a 

 new genus, which I have called Desmatochelys, and a new family, 

 Desm atochelyidse . 



While this type specimen, from which the following descrip- 



