374 FOSSIL TURTLES OF NORTH AMERICA. 
scutes; hinder lobe of plastron notcht. Of the neural plates the second and third are hexagonal 
with the shortest sides directed backward; the third is quadrilateral; and the remainder are 
hexagonal, with the shortest sides directed forward. Three suprapygals, of which the penulti- 
mate is notcht behind and receives the third. Costals with no great difference between the 
widths of the proximal and distal ends. Two supracaudal scutes. Shoulder and pelvic girdles 
as in Testudo. Skull unknown. Cervical vertebra and limb bones not well known. 
Type: T estudo corsoni Leidy. 
Without having the skull and the distal limb bones, it is not possible to say positively that 
this genus belongs to the Testudinida, as limited in this work. The shell and shoulder and 
pelvic girdles, however, present many characters which indicate close relationships with the 
modern land-tortoises. We find in this genus apparently the beginnings of those modifications 
of the shell which characterize the genus Testudo. In most species of the latter the neural 
plates are alternately tetragonal and hexagonal; and the second, fourth, and sixth costals are 
narrow at the proximal ends and wide at the distal ends, while the third, fifth, and seventh are 
wide proximally and narrow distally. In Hadrianus the third neural is quadrate, as in TJ estudo, 
and the corresponding costals are widened proximally to come into contact each with three 
neurals also, asin Testudo. The other costals differ only slightly in the widths of their opposite 
ends. As in Testudo, the connection between the costals and the peripherals is a rather loose 
one; the sulcus between the costal and marginal scutes follows closely the sutures between the 
peripheral and costal bones; the epiplastrals form a conspicuous lip; the humero-pectoral 
sulcus falls behind the entoplastron; and the pectoral scutes are rather narrow. Even Stylemys, 
belonging to a later period, appears to be less advanct in many respects than Hadrianus. 
In various writings (the latest being his Vertebrata of the Tertiary Formations of the West, 
1884, p. 113) Prof. E. D. Cope assigned as the character distinguishing Hadrianus from the 
other Testudinide a divided supracaudal scute. Three species of the genus Testudo, as 
recognized by Boulenger, also have this scute divided. It seems to the author that the un- 
differentiated condition of the shell furnishes a more satisfactory basis for the genus. Mr. 
Richard Lydekker (Cat. Foss. Rept. and _Amphib. Brit. Mus., 11, p. 72) gives, among other 
characters distinguishing Hadrianus, the ‘‘narrow vertebral shields and the elongated cued 
bones which are hexagonal, with short postero-lateral surfaces” [sides]. The neurals, however, 
are not of unusual narrowness. As to their form, Mr. Lydekker cites a igure by Leidy which 
represents only the 3 anterior neurals, but another figure by Leidy in the same work (Ext. 
Vert. Fauna West. Terrs, plate xxx, fig. 1) shows that the fourth and fifth neurals have the 
antero-lateral sides short. 
So far as known at present the members of this genus are confined to the Eocene. The 
oldest-known species is H. majusculus Hay from the Wasatch of New Mexico; the most 
recent species is H. tumidus Hay, from the Upper Uinta. As suggested by Mr. ise 
some of the Eocene and Miocene species of Europe that have been referred to Te studo may 
reality belong to Hadrranus. 
ANALYSIS OF THE KNOWN SPECIES. 
. Wasatch. Very high peripherals. Pectoral scutes more than half as wide aeee midline 
as the abdominals..............0 000 ccc ccccceeeseveeeveseeveeees oo... mayusculus 
2. Bridger. Peripherals of moderate height. P ectoral scutes less than half as eee on mid- 
line as the abdominals............ Af , ; corsont 
2. Uinta. Peripherals high. Pectoral scutes less than one-third as wide as the abdominals. . tumidus 
~) 5 . . . . 
4. Jackson formation. Pectoral scutes one-ninth as wide as the abdominals. . . . a schucherti 
Hadrianus majusculus Hay. 
Plate 59, fig. 1; text-fig. 472. 
?Hadrianus corsont1, Cope, Syst. Cat. Vertebrata Eocene N. Mex., 1874, p. 36; Append. LL. Ann. Rep. 
Chief Engineers (Wheeler’s Surv.), 1875, p. 1016 (separata, p. 96) 
Hadrianus mayusculus, Hay, Amer. Jour. Scie (4), XVIII, 1904, p. 271, plate XV; text-hg. 5: 
The species here described is founded on a somewhat damaged shell which belongs to the 
Marsh collection in Peabody Museum, at Yale University. Accompanying this shell is a label 
which bears the following record: “Turtle from foot of bluff, west side of Murderer’s Gap. 
