430 FOSSIL TURTLES OF NORTH AMERICA. 
This species differs from 7. undata Cope in that the posterior peripherals do not have a 
strong recurvature outward and the internal thickening is much below the border joining the 
costal bones. From T. flettiana, based on a pygal bone, it differs in not having the right and 
left borders parallel, but div erging upward. The upper border is notcht for the second supra- 
pygal. From 7. orthopygza it differs in having a more elongated skull, a broader plastral lip, 
and the posterior peripherals less abruptly curved upward near their free border. 
The front of the plastron of the younger specimens of this species bears considerable resem- 
blance to the same part of T. nzobrarensis figured by Dr. Leidy (Cont. Ext. Vert. Fauna West. 
Terrs., 1873, p. 225, plate ini, fig. 4). It appears however that the lip of Dr. Leidy’s specimen 
projects farther beyond the points where the sulci on each side of the lip cross the border of the 
plastron, about two-thirds of the lip extending beyond these points. In the specimens of T. 
osborniana at least half of the lip is behind these points, and usually more of it. Only in the 
type specimen is there half of the lip in front of the line joining the points referred to. In 
Leidy’s species, moreover, the front border of the entoplastron falls behind the ledge formed by 
the lip; whereas, in J. oshorniana the front of the entoplastron is slightly in fone of the ledge 
of the lip. Dr. Leidy’s species almost certainly belongs to a different geological level. 
Of this fine species, which has been named in honor of Prof. Henry F. Osborn, of the 
American Museum of Natural History, there are, in the museum mentioned, spécimens which 
give us a knowledge of the whole osteology and of various stages of growth. 
n 
~s 
563. 564. 565. 
Fics. 563-565.—Testudo arentvaga. Pygal and eleventh peripheral of type. 4. 
563. Pygal, eleventh peripheral, and part of suprapygal. 
564. Section of pygal and suprapygal along midline. 
565. Section of eleventh peripheral at union with tenth. 
Testudo arenivaga Hay. 
Figs. 563-565. 
Testudo arenivaga, Hay, Ann. Carnegie Mus., tv, 1906 (1907), p. 16, figs. 6-8. 
The present species is based on a fragmentary individual which belongs to the Carnegie 
Museum, Pittsburg, Pennsylvania. The catalog number is 1509. The remains were found in 
1905, in beds reg papded as belonging to the lower Miocene formation. The locality 1s about 
2 miles north of Agate Springs quarry, in Sioux County, Nebraska. The pygal and the eleventh 
peripheral are selected for description. 
The pygal (figs. 563, 564) has a height, from the free border to sulcus crossing the hinder- 
most suprapygal, ‘of 112mm. The idea at the upper, or anterior, border is 102 mm.; at the 
free border, 58 mm. The upper border is deeply notcht for the last suprapygal, the distance 
