Ob PROCEEDINGS OF THE ACADEMY OF 



3. Trionyx guttatds. 



Remains apparently of the same species of Trionyx as that indicated by 

 the small fragments above mentioned, were discovered by Dr. F. V. Hayden 

 in a Tertiary deposit at Church Buttes, ner.r Fort Bridger, Wyoming. The 

 most characteristic specimen obtained by Dr. Hayden, during a geological sur- 

 vey on account of the Commissioners of the General Land Office at Wash- 

 ington, belongs to the Geological Cabinet of that Office, and has been sub- 

 mitted to my inspection by its Secretary, Dr. A. R. Roessler. 



The specimen consists of the portion of a carapace adherent to a homo- 

 geneous, greenish gray, argillaceous rock. It retains the third to the seventh 

 vertebral plates inclusively entire, Avith part of the second one; and the 6th 

 and 7th right costal plates, together with parts of those of the second to the 

 fifth inclusively of the same side, and smaller portions of several of the 

 same plates of the left side. 



The plates are for the most part marked by distinct or separate circular pit- 

 tings, which only run into one another more or less at the outer third of the 

 costal plates. 



The carapace appears to have been longer than broad, and has approxi- 

 mated about 14 inches in length by about a foot in breadth. The fourth and 

 fifth costal plates appear to have been unusually expanded or widened out- 

 wardly. The sixth costal plates conjoin in the median line, though their inner 

 angles are separated by the sixth and seventh vertebral plates. The breadth 

 of the last costal plate is within half an inch of its length. 



The third vertebral plate is six-sided or coffin-shaped in outline. It mea- 

 sure 23 lines long, 5 lines wide at the fore part, gradually widening to a little 

 over an inch, and then rapidly narrowing to 8 lines at its back part. 



The second vertebral plate appears to have had the same form and a some- 

 what greater size. 



The fourth vertebral plate in the specimen is rather irregular at the sides, 

 and the right posterior angle is twice as long as on the left side. Its length 

 is 20^ lines ; its width where greatest posteriorly is 10^ lines. 



The fifth vertebral plate is smaller than the former and has its lateral 

 borders approaching in a curve at the hinder extremity. Its length is 19^ 

 lines ; its anterior border is 7 lines wide , and its greatest breadth is 8i lines. 



The sixth vertebral plate is cordiform or five-sided in outline, and is almost 

 10 lines in length and breadth. 



The seventh vertebral plate is lozenge-shaped and occupies the interval 

 between the approximate angles of the 6th and 7th pairs of costal plates. It 

 is 5i^ lines long and 5 lines wide. 



The last costal plates include a deep wide emargination behind, and each 

 exhibits a deeper and more abrupt notch at the outer extremity. The length 

 of the plate from the back angle of the last vertebral plate to its outer end, in 

 a straight line is 25 lines ; its breadth is 19 lines. 



The length of the sixth costal plate along the middle is 41 lines. It is 

 narrowest at the middle, where it measures 16 lines. At the inner extremity 

 it is 19 J lines wide ; at the outer end 18 lines. 



The length of the fifth costal plate along the middle is 57 lines ; its breadth 

 internally 22 lines ; externally 40 lines. The species may be distinguished by 

 the name of Trionyx guttatus. 



4. Emys Wyomingensis. 



An episternal bone, among the specimens, obtained by Mr. Carter near Fort 

 Bridger, Wyoming, indicates a species of Emys about as large as the living 

 Emys^Trachemys) scabra or E. [Ptychemys] rugosa, but it possessed a pro- 

 portionately thicker shell than in either of these species. The bone is re- 

 markably like the corresponding one of Eir.ys petroki (Pr. A. N. S. 1868, 176) 

 from Harden Co., Texas, but is shorter along the median suture, propor- 

 tionately broader and rather less produced at its fore part. 



The portion of the bone impressed by the gular scutes projects abruptly for- 



[April, 



