TESTUDINID&. 391 
The tibia is a stout bone, whose form may be learned from figure 497, which represents the 
left tibia of No. 1301, just mentioned. It is a much stouter bone chan is the corresponding bone 
in Gopherus polyphemus. Its length is seven-tenths that of the femur, whereas in G. poly- 
phemus the tibia is eight-tenths the length of the femur. 
The lower end of the fibula is quite as broad as that of the tibia. Professor Cope figured 
one of the metatarsals (Ext. Batrach., Rept., Aves N. A., plate vii, fig. 10). 
In a collection of fossils, including some vertebrates purchased by the American Museum 
of Natural History from the late James Hall, there are several eggs which are regarded as 
those of S. nebrascensis. This identification rests on the facts that these eggs were collected in 
the White River deposits of Dakota, in which great numbers of this species occur and a few 
other species of tortoise and that they agree closely in size and form a of Gopherus 
polyphemus, as represented by Agassiz’ s figure (Contrib. Nat. Hist. U. 1, plate vu, figs. 
28, 29). These eggs appear to have been globular, altho now shorter ee one axis, a gontraon 
doubtless due to pressure. The diameter ‘along all the axes, except the shorter, is 47 mm.; along 
the shorter, 43 mm. Fig. 4, plate 59, represents one of these eggs four-fifths the natural size. 
The eggs of G. polyphemus figured by Agassiz have diameters varying from 40 mm. to 
45 mm., the axes of the same egg being, in some cases, unequal. 
495. 
Fics. 493-497.—Stylemys nebrascensts. 
493. Left ulna, radius, and three carpal bones; palmar surface x $. No. 702 
A.M.N.H.. it,intermedian; rad,radius; u/, ulna; ne ulnz ire. 
494. Digit, dorsal surface. 1. No. 702 A.M. N.H. 
495. Pelvis, left side. 4. No.1301 A.M.N.H. ¢/,ilium; pub, pubis. 
496. Left femur, tibial border. * %. No.1301 A.M.N.H. 
2. No. 1301 A. M.N. H. 
497. Left tibia, dorsal surface. 
No. 1435 A. M. N. H. is a specimen of a very young turtle of this species which was col- 
lected by one of the American Museum’s expeditions to South Dakota. The shell is nearly 
complete, but 1s somewhat deprest by the weight of the overlying rocks. The total length 
was near 75 mm., the breadth, 70 mm. Alghor the bones are loosely connected, there are no 
fontanels. “The plastral lip is relatively broad, and in the middle of each lateral half there is a 
notch. The free borders of the carapace have been slightly notcht and mucronated; at least, 
some mucros are seen on the hinder peripherals. 
So far as is known to the writer, no specimens of this species have yet been found in the 
lowermost division of the Oligocene, the Titanotherium beds. They are most abundant in 
the Oreodon beds, but occur in the Protoceras beds also. The species is extremely abundant 
in South Dakota and is found also in Nebraska, Colorado, and Wyoming. In the Cope col- 
lection in the American Museum are specimens that were collected on Old Woman’s Creek, 
Wyoming, by J. C. Isaac, in 1877. Other specimens were obtained in the Oreodon beds of 
Logan County, Colorado, by one of the expeditions from the American Museum of Natural 
History in 1808. 
