98 



stouter than in Trionyx, but is more likely to be a metacarpal. It is about 

 as long as the vertebrjE, centrum and arch together. The proximal end is 

 transversely truncate, compressed L-shaped ; the shaft compresscd-subquad- 

 rate; the articular extremity hour-glass-shaped, with an inferior projection for 

 the insertion of a flexor-tendon. This bone is not that of a marine turtle, 

 but ot a species of riparian or terrestrial habits. Length, 0™.034; proximal 

 diameter, 0'".013. 



These vertebrae indicate a genus with elongate tail like that of Cheljdra, 

 or probably longer ; but they differ from those in that genus by their procce- 

 lian character. An approach to their incised margins is to be found in Trio- 

 nyx; but in those of that genus, where this character appears, the diapophy- 

 ses are largely developed. The genus is evidently quite distinct from any- 

 thing known, and we await further remains with interest. The species is 

 much smaller than the Protostega gigas, and about equal to the Mississippi 

 Macrochelys. 



TOXOCHELYS, Cope. 



This genus is represented by a single species as yet, which reposes on 

 a number of specimens. These indicate a structure in many respects similar 

 to the genus Chclone, but sufficiently different to belong to another genus 



The mandibular ramus is slender, and has a narrow, flat, alveolar surface. 

 The coronoid process is moderately elevated, and is excavated behind by the 

 anterior extremity of the elongate and deep dental foramen. The cotylus is 

 depressed, and the articular bone ossified; the angle is not produced. The 

 coracoid bone is long and spatuliform, like that of the marine turtles. A 

 fragment of the same skeleton supports a condyle with slender, subcyliiidric, 

 slightly-curved bone attached to one side of it. Were it not a turtle, I should 

 say that these are the extremity of the quadrate, with a slender jugal or 

 malar bone adhering. 



The slenderness of the mandibular rami resembles the form in Chelydra, 

 but it differs in the absence of the alveolar cutting-edge of the latter. The 

 ]>lialanges are broad and flat, and not unlike those of Protostega. 



ToXOCHELYS LATIREMIS, CopC. 



The symphysis mandibuli is very short, and the upper face horizontal. 

 The angle is truncate beliind, flat, and not produced beyond the cotylus. 



