141 



Regarding all the specimens under consideration as pertaining to a single 

 species, this would retain the original name of Emys wyomingensis. 



The composition of the shell so far as relates to the attachment of the 

 carapace and plastron, the number of bones or plates and the number and 

 relation of the corneous scutes, is the same as in living species of the genus 

 Emys. 



In the mature condition, the shell of Emys wyomingensis is upward of a 

 foot in length, with about three-fourths the same measurement in breadth. 



To what degree the shell varies in form, that is to say in relation of length 

 and breadth with the height, and in outline, cannot be determined from the 

 material at command, on account of the imperfection of the specimens, or 

 their distortion from the original condition, due to pressure or to a crushing 

 force applied to them while imbedded in the strata from which they were ob- 

 tained. 



The elements of composition, especially the vertebral plates and scutes, 

 differ more or less in different specimens, both in form and in the relation of 

 length to the breadth. While the length of the vertebral scutes in general 

 exceeds the breadth, especially in the case of those intermediate, in some 

 specimens even to the extent of being a third greater, it nevertheless varies 

 so much that in some instances it barely exceeds the breadth. The verte- 

 bral plates vary in the same manner in different specimens, nor does this 

 variation always accord with that of the same character in the vertebral scutes, 

 that is to say the elongation of the scutes is not always accompanied in a 

 proportionate degree with elongation of the plates. 



1. Emys wyomingensis was originally described from an isolated episternal 

 bone, sent to the writer by Dr. Carter. It was the first of the remains of 

 turtles from the Bridger Tertiary deposits, which could be referred to the 

 genus. It is represented in Fig. 5, Plate IX, and exhibits the usual form of 

 that in living species, but further presents the appeai-ance of being impressed 

 by a narrow intergular scute. The presence of the latter I suspect to be ac- 

 cidental or anomalous, though it may be normal, and may really indicate that 

 the fossil belongs to a species distinct from those which I am now disposed 

 to view as the same. The front of the specimen is truncated and slightly 

 notched at the outer part. 



2, 3. Emys Stevensonianus is the name originally given to a supposed 

 species founded on the specimens represented in Figs. 2, 4, Plate IX. These 



