COPE ON NEW EXTINCT VERTEBRATA. 395 



is present and rather wide, and the vertebral scuta are quadrate in out- 

 line. 



A number of specimens of this species was found, which vary some- 

 what in size. 



Measurements, 



No. 1. 



M. 



Length of the posterior lobe of the plastron 0.140 



Width of the posterior lobe of the plastron at the base 0.240 



No. 2. 



Length of the carapace (axial) 0.330 



Width of the carapace at the front 0.320 



Greatest elevation - 0.015 



Length of the nuchal scute 0.004 



Length of the first vertebral 0.090 



Width of the first vertebral 0.115 



Width of the second vertebral , 0.090 



Length of the second vertebral 0.105 



No. 3. 



Length of the carapace behind the bridge 0.085 



Width of the carai^ace at the bridge behind 0.240 



The largest of these is smaller than the two specimens of the X. ortlio- 

 pygius which I have examined. 



PSEUDEMYS HILLII, sp. nOV. 



This water-tortoise, from the same formation as the Xerohates above 

 described, is nearly allied to the existing species P. elegans Wied. It is 

 Represented by a single specimen, which embraces nearly the whole plas- 

 tron, with numerous portions of carapace, cranium, and limbs. 



The vertebral bones preserved are nearly as wide as long, are narrowed 

 posteriorly, and possess a smooth surface. The costals are united with 

 the marginals by gomphosis. Their surface is marked by rather distinct 

 and remote grooves, which are parallel to the circumference of the cara- 

 pace. The marginals are smooth, and their edges are acute, very little 

 recurved, and medially entire, or nearly so. There is a notch at the point 

 of junction of several pairs of the median bones, while there is a rather 

 deep notch at the middle of the anal marginal, which is also not recurved, 

 but straight. The dermal sutures are well marked. The osseous sur- 

 face is delicately crimped below the costo-marginal suture, the grooves 

 of which assume an obliquely posterior direction on the posterior half 

 of each marginal bone. 



The lateral border of the posterior lobe of the plastron is gently con- 

 vex to the end of the anal dermal suture, where it is slightly concave, 

 but not notched. The posterior extremity is slightly emarginate, and 

 the postabdominals are broadly rounded. The mesosternal bone is 

 not deeply received into the hyosternals. The plastron is flat, and the 

 lateral buttresses are low. The superior surfaces of the borders are 



