134 



MEMOIRS OF THE CARNEGIE MUSEUM 



Locality: Skull Butte, southwest of Well No. 2, Uinta Basin, Uinta County, 

 Utah. 



Horizon: Horizon B, Uinta formation, Upper Eocene. 



The carapace is elongated oval being more broadly rounded in front than 

 Eclmiatemys callopyge Hay. The median portion is high and vaulted. The 

 length of the carapace is estimated to have been about 360 mm. ; its width about 

 260 mm. The height at the center is 133 mm. The surface of the shell is smooth. 

 The sulci are narrow, but well impressed. 



The nuchal plate has the anterior border missing, so that its greatest length 

 cannot be determined. It has a greatest width of 82 mm., and where the lateral 

 sutures cross the costo-marginal sulcus it is 57 mm. wide. 



The neurals back of the first are all hexagonal with the anterior ends concave. 

 Those preserved are all longer than broad. On either side of the anterior end of 

 the first neural are hollowed out depressions which give this bone the appearance of 

 being bluntly ridged anteriorly, but otherwise there is no indication of carinse. 



The peripherals appear to have been high, but on account of the damaged 

 condition of the borders it is not possible to give their extent. 



Six costals are present in this specimen, the first having a greatest antero- 

 posterior diameter of 63 mm.; a greatest length of 96 mm. On the upper anterior 

 half of the first costal there is a low, rounded, obtuse elevation or horn-like pro- 

 jection, which at once distinguishes this species from all other described forms. The 

 other costals show nothing unusual. The third has a greatest length of 106 mm. 

 The costo-peripheral suture between the third and fourth passes about 17 mm. 

 mesiad of the costo-marginal sulcus. 



The first vertebral scute is unusually narrow, in this respect resembling 

 E. callopyge Hay. The sides of those posterior to the first are strongly urn-shaped. 

 The anterior end of the third is especially narrow and pointed, and extends well 

 forward into the second. The dimensions of the vertebrals are given in the table. 

 On either side of the first vertebral are supernumerary costal scutes, and it is 

 largely within their boundaries that the horn-hke elevations, described above, arise. 



