156 MEMOIRS OF THE CARNEGIE MUSEUM 



Genus Amyda Oken. 

 17. Amyda egregia Hay. 



Amyda egregia Hay, Fossil Turtles of North America, 1908, p. 531, plate 107, 



figs. 1-3, text-fig. 691. 



A specimen (C. M. No. 3254), collected by Earl Douglass from Horizon B, of 

 the Uinta formation, three or four miles northeast of Well 2, Uinta Basin, Utah, in 

 1908, is identified as belonging to Amyda egregia Hay. This specimen consists of 

 the articulated nuchal, the greater portion of the first neural, the first, second, 

 third, fourth, fifth, and sixth costals, all, excepting the first, lacking portions of 

 their upper extremities. In the matrix on the left side are the free ends of the 

 second, third and fourth costal ribs. These appear to be in their proper positions 

 in relation to the other parts of the shell which are preserved, and serve to give 

 some idea of the width and general contour of the carapace. The shell is broadly 

 rounded in front and considerably arched transversely. The width is estimated to 

 have been about 465 mm. The nuchal has a transverse extent of 255 mm. and 

 measures 52 mm. antero-posteriorly. Hay States that the latter measurement in 

 the type of the species is but 22 mm., although the figure published by him shows 

 it to be at least 42 mm. As in the type specimen the outer end of the nuchal over- 

 laps the free end of the rib of the first costal. The first neural at the anterior end 

 is 40 mm. wide. The sculpture of the carapace is coarse. On the inner ends of the 

 costals the pits and ridges form a honeycomb arrangement, but on their outer 

 fourths the ridges and pits are arranged in rows across the costals, toward their 

 ends on some of the costals the honeycomb pattern again prevails, on others the 

 rows persist to the smooth bevelled border. 



In the form of the anterior end of the carapace, with slight emargination of 

 the border at the sutural junction of the nuchal, and the close resemblance of the 

 sculpture of the carapace, this specimen is in close agreement with the type of the 

 species. The chief differences observed are the considerably larger size of the 

 present specimen and the sloping bevel of the smooth ends of the costals, as con- 

 trasted with the abrupt bevel of the type. 



A second specimen, C. M. No. 3255, in this collection consisting of many frag- 

 ments of the neurals and costals is provisionally referred to this species. This 

 specimen is from Horizon B, Uinta formation, and from the same locality as the 

 individual previously discussed. It was collected by Dr. W. J. Holland, and Earl 

 Douglass in 1908. 



The type of Amyda egregia Hay is from the lower Washakie beds south of Hay- 



