398 FOSSIL TURTLES OF NORTH AMERICA. 
A*, Lower Miocene species: 
g. Lip prominent, twice as wide as long, and nearly as thick aslong...... -. 5. peragrans 
10. Pygal convex up and down on upper side........ : _. arenivaga 
11. Lip not greatly projecting; pectoral scutes nearly ‘half as ide: on midline as 
abdominals ..... re ae vaga 
12. No 4-sided or 8-sided netrale: pectoral scutes about one-fifth as mide as slsclave 
inals ... ... emtle 
A*. Deep River and Pawnee Creek (Middle Miocene) species: 
3. Lip not projecting far; pectorals only one-seventh the width of the abdominals. . . farrt 
14. Neurals as in 7. emili@; the gulars reaching the entoplastron . . Inusttata 
15. Shell broad and deprest; lip tapering; pectorals about one-third the abdominals. . pansa 
16. Shell vaulted; pectorals one-twenty-fifth the abdominals, or less . oshorniana 
A‘. Loup Fork: 
17. Lip abruptly projecting; pectorals one-eighteenth the width of the abdominals . impensa 
18. Hinder peripherals and pygal with free border flared upward; pygal narrowing 
toward the free border ..... .. undata 
19. Pygal plane; its sides parallel : ... klettrana 
20. Lip rounded, little projecting; resembles vaga of the Lower Miocene . . ntobrarensts 
21. Strongly projecting lip; pectorals about one- -eleventh the width of abdominals.. orthopygta 
22. Skull only; consult figures. : ... gilbert 
23. First and third neurals 4-sided; second and fourth octagonal; lip prominent; 
pectorals about one-fifth the width of abdominals. 3 ede 
24. First, third, and fifth neurals 4-sided; second and fourth octagonal; lip moderately 
prominent; pectorals one-fourth the width of abdominals. : . holland: 
A’. Pliocene species: 
25. Lip prominent; all the sulci deeply sunken and wide; free borders of the peripherals 
deeply nocht by the sulci. ; . turgida 
26. Shell broad and deprest; the perce scutes voiden than long; shell thin... .. pertenuts 
27. Lip prominent; truncated; pectoral scutes nearly half as wadey as the abdominals .. cam pester 
28. Hinder peripherals thick and with very obtuse free border. . . ; obtusa 
29. Anterior lobe of plastron rapidly tapering forward; borders of lip conanued 4 in 
same lines; bones thick and heavy crassiscutata 
A*. Pleistocene species: 
30.. L ip about four-fifths as long as wide, thick behind; notch in rear of plastron four 
times as wide as deep. ; . laticaudata 
Lip rounded; notch in rear not three times as nige as , deep; borders of hinder 
lobe rapidly converging backward hexagonata 
32. Lip rounded but prominent; borders of hinder lobe slowly converging. ... atascos@ 
Testudo brontops Marsh. 
Plate 65, figs. 1, 2; text-figs. 504, 505. 
T estudo bee Marsu, Amer. Jour. Sci. (3), XL, 1890, p. 179, plate vin; Vert. Foss. Denver Basin, 
in Mon. U. S. Geol. Surv., xxvit, 1897, pp. 523, 527, figs. 95, 96.—Dana, Manual Geol., 1896, 
p- gol, fig. riba Hay, Bibliog. and Cat. Foss. Vert. N. A., 1902, p. 451; Amer. Jour. Sci., (4) 
XVIII, 1904, p. 272, figs. 6, 7. 
The type of this species is a fine large shell which was collected for Prof. O. C. Marsh, 1 
the year 1888, by Mr. J. B. Hatcher, and is now in the Peabody Museum, at Yale University. 
It was obtained in the Titanotherium beds of Indian Creek, in the southeastern corner of 
Pennington County, South Dakota. No considerable parts of the shell are missing and it has 
been only slightly crusht. The specimen bears the record “‘ Box 27, 1985.” 
In form this magnificent tortoise was broad and probably of only moderate height. The 
front of the carapace (plate 65, fig. 1; text-fg. 504) is somewhat concave in outline, the lateral 
angles broad, rounded and flaring upward. The sides were nearly perpendicular. The hinder 
border is broadly rounded, with the peripherals over the limbs considerably flaring and with 
the pygal incurved toward its free border. Where the sulci cross the free borders of the periph- 
erals the latter are somewhat notcht; and where they cross the borders of the carapace above 
the bridges they lie in grooves so deep that the interspaces appear to be strongly swollen. The 
free borders of all the peripherals come down to an acute edge. The length of the carapace 
is 711 mm.; the greatest width 1s 651 mm. 
