J(jO FOSSIL TURTLES OF NORTH AMERICA. 



No. 1571 of the Carnegie Museum, Pittsburg, furnishes a nearly complete skull of a small 

 individual (text-figs. 488, 489, 490). This skull is accompanied by enough of the shell to 

 establish clearly the species. The remains were collected in 1905, by Mr. Earl Douglass, of 

 the Carnegie Museum, in the Oreodon beds of the Little Badlands, southwest of Dickinson, 

 Stark County, North Dakota. So far as the parts presented by this skull and that belonging 

 to Princeton University are common, they agree closely. The length of the skull, from the 

 snout to the occipital condyle, is 38 mm.; the width at the quadrates, 30 mm. The hinder 

 border of the postorbital bar is equally distant from the occipital condyle and the snout. The 

 bar just mentioned is 5 mm. wide; the zygomatic bar is slightly wider. The interorbital 

 space is 10.5 mm. wide. The antero-posterior diameter of the orbit is II mm.; the vertical, 

 9 mm. The longest diameter of the auditory chamber is 9 mm. The pterygoid region is 10 

 mm. wide. The pedicel of the quadrate is unusually narrow, only 4 mm. from side to side. 



The palate is deeply excavated, and a low sharp ridge runs along the middle of it. Most 

 of the lower jaw is firmly held in its natural position; but the removal of the tip exposes a low 

 median ridge along the palatal part of the symphysis of the premaxillae. It is evident therefore 

 that the larger skull described above is correctly identified. 



Few satisfactory specimens of the bones constituting the shoulder-girdle of adult individ- 

 uals have been secured. In the American Museum these bones belonging to a young animal 

 (No. 699, from South Dakota) are present. The scapula is slender and makes an angle of about 

 1 20 degrees with the procoracoid process. The coracoid broadens greatly toward the free end. 



No figure of the humerus has hitherto been publisht. Professor Cope (Ext. Bat., Kept, 

 Aves N. A., 1869, plate vii, figs. 12, I2a) presents a figure which is explained as being that of 

 the humerus of this species; but the figure is that of the femur. The humerus of the specimen 

 mentioned above, No. 699 of the American Museum, shows that the bone had nearly the form 

 that it has in G. polyphemus, but it is bent slightly more than in the species just named. Other 

 larger but imperfect specimens confirm this conclusion. Fig. 491 is taken from one of these, 

 No. 700, American Museum, but a portion of the shaft is missing. This specimen was found 

 with the shell. Figure 492 is a view taken from the proximal end, to show the head and the 

 radial and ulnar processes. The ulnar process does not rise so much above the head as in 

 Testudo radiata. The angle between the processes is reduced as in Testudo and is thus different 

 from the condition found in the Emydidae. The ectepicondylar foramen is close to the distal 

 end of the bone. 



The Amerian Museum of Natural History possesses the left forearm and some foot bones 

 of a large specimen believed to be of this species, No. 702, collected by the museum's expedition 

 of 1892, in South Dakota. A drawing (fig. 493) is presented of the ulna, radius, intermedium, 

 radiale, the ulnare, the fourth distal carpal, and another (fig. 494) of a digit, including one claw 

 phalange. The limb is stouter than it is in any of the species of Testudo at hand, but resembles 

 them closely. The proximal end of the ulna is broad, and forms a prominent olecranon process. 

 The distal ends of both radius and ulna are flat for articulation with the carpals. The radius 

 forms a prominent styloid process. The terminal phalanges are much larger relatively than 

 they are in most species of Testudo, but approach nearest those ofGopherus polyphemus. They 

 differ from the latter in not being so broad and sharp-edged. From the materials at hand it 

 can not be determined whether there were two or three phalanges in the median toes; hut no 

 elongate phalanges are present. 



There are at hand the ilium and a portion of the pubis of a specimen, No. 1301, from Old 

 Woman's Creek, Wyoming (fig. 495). On comparison with the corresponding bones of 

 Testudo vaga, no differences of importance are observed, except that the flat process extending 

 backward from the upper end of the ilium is directed slightly inward, instead of outward. 

 Cope furnisht a figure of a small portion of the pelvis (Ext. Batrach, Kept., Aves N. A., plate 

 vii, fig. n). 



The femur is like that of Testudo vaga, except that the pit between the trochanters is not 

 so deep. Cope's figure of this bone has been referred to in the description of the humerus. 

 No. 1301, A. M. N. H., furnishes this bone from the left side (fig. 496). It is shown two-thirds 

 the size of nature in fig. 496. It resembles closely the corresponding bone of Gopherus poly- 

 phemus but the lower articular surface is more deeply grooved and there is a distinct and 

 sharp ridge separating the tibial from the fibular surface. 



