A NEW SPECIES OF EXTINCT TURTLE FROM THE UPPER 

 PLIOCENE OF IDAHO 



By Charles W. Gilmore 



Curator, Division of Vertebrate Paleontology 

 United States National Museum 



Among the fossils obtained bj^ the Smithsonian expedition of 

 1930 under the direction of the late Dr. J. W. Gidley, exploring 

 in the vicinity of Hagerman, Twin Falls County, Idaho, were two 

 unusually well-preserved emydid turtles. One of these is of more 

 than common interest in having the complete skull, lower jaws, 

 hyoid arch, and much of the appendicular skeleton present. So 

 complete a specimen is a rare occurrence among the extinct Chelonia, 

 and an opportunity is presented for comparison with living forms 

 that is seldom offered by fossil remains of these animals. 



Except for a slight difference in size the two specimens are struc- 

 turally in close accord, both pertaining to a new species for which 

 the name idahoensis is proposed. They are provisionally referred 

 to the genus Pseudemys. 



PSEUDEMYS IDAHOENSIS, new species 



Tijpe. — U.S.N.M. No. 12059 consists of the nearly complete cara- 

 pace and plastron; skull, lower jaws, hyoid arch, pectoral and pelvic 

 girdles, 11 caudal vertebrae, incomplete humerus, femora and tibia, 

 and much of an articulated hind foot. Collected by S. R. Wells, 1930. 



Paratype. — U.S.N.M. No. 12060 consists of a nearly complete 

 carapace and plastron. Collected by S. R. Wells, May 28, 1930. 



Locality. — Plesippus Quarry, NW. % sec. 16, T. 75, R. 13 E., 

 near Hagerman, Idaho. 



Horizon. — Hagerman lake beds, Upper Pliocene. 



Description. — Both the type and paratype have suffered somewhat 

 from post-mortem crushing, but otherwise they are in a nearly 

 perfect state of preservation. There is a slight difi'erence in size, 

 and the carapace of the paratype is more distinctly sculptured than 

 that of the type; otherwise the two are in perfect accord. 



In outline the carapace (fig. 1) is elongate, broadly truncate 

 in front, with a pointed posterior extremity. As a whole the shell 

 appears to have been moderately elevated.^ 



1 In the descriptive matter to follow, two measurements arc given, the first in each instance being of 

 the type, the second, in parentheses, of the paratype. 



No. 2950. — Proceedings U. S. National Museum, Vol. 82, Art. 9 



150260—33 1 



