GILMORE: the fossil turtles of the UINTA FORMATION 139 



septaria. The plastron is flat, but in an uncrushed specimen the bridges would 

 doubtless curve upward to the margin of the shell. In this specimen they are but 

 little above the level of the plastron. 



The hyoplastrals meet on the midline for a distance of 80 mm.; the hypoplas- 

 trals for 97 mm.; the xiphiplastrals for 66 mm. 



The gular scutes along the midline are about 52 mm. long; the humerals 37 

 mm.; the pectorals 63 mm.; the abdominals 101 mm.; the femorals 48 mm.; and 

 the anals 53 mm. 



Echmatemys ohscura is distinguished from all species of the genus, in which 

 the nuchal region is known, by the extreme narrowness of the nuchal plate, it 

 being the only species known, in which the nuchal plate is longer than wide. 

 From Echmatemys cibollensis, E. megaulax, and E. euthneta (the nuchal region of all 

 three being unknown) the present species is distinguished: from the former by 

 having the gulars overlapping the entoplastron ; and from the latter two by having 

 the gular-humeral sulcus crossing the rear portion of the entoplastron. This 

 species is further distinguished by the greater relative widths of the neurals and 

 especially the vertebrals. The obscure, but characteristic, ornamentation of the 

 costal region of the carapace will also aid in recognizing this species. 



11. Echmatemys depressa sp. nov. 

 Plate XXIII, fig. 2; text-fig. 16. 



Type: C. M. No 2936, consisting of the carapace, lacking much of the anterior 

 margin, the peripherals, and outer halves of the costals of the left side, and most 

 of the peripherals posterior to the inguinal notch of the right side. The plastron 

 is represented by a few fragments only, though the impression in the matrix gives 

 some idea of its proportions. Collected by 0. A. Peterson, August 5, 1912. 



Locality: Six miles east of Myton, Uinta County, Utah. 



Horizon: Horizon C, Uinta formation. Upper Eocene. 



Although the open sutures of the type specimen give evidence of the im- 

 maturity of the individual, it appears to represent one of the smaller species of the 

 genus Echmatemys. I was first inclined to regard it as referable to the genus 

 Palceotheca on account of its small size and the presence of a dorsal keel, but a 

 comparison with the types of the two species pertaining to that genus {Palceotheca 

 terrestris Cope, and P. polycypha Cope) both of which are in the U. S. National 

 Museum, shows differences which lead me to believe that it can with greater 

 propriety be referred to the genus Echmatemys. The apparent absence of a second 

 suprapygal and the extremely wide vertebrals may with other characters to be 

 observed in a more perfect specimen show its distinctness from that genus. 



