374 FOSSIL TURTLES OK 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, ot 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 T estiuio. Skull unknown. Cervical vertebrae and limb bones not well known. 

 Type: Testudo corsoni Leidy. 



Without having the skull and the distal limb bones, it is not possible to say positively that 

 this genus belongs to the Testudinidae, 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 ot 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 proximallv and narrow distally. In Hadrtanus the third neural is quadrate, as in Testudo, 

 and the corresponding costals are widened proximally to come into contact each with three 

 neurals also, as in 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 Testudinidae 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 fCat. Foss. Rept. and Amphib. Brit. Mus., ill, p. 72) gives, among other 

 characters distinguishing Hadrianus, the "narrow vertebral shields and the elongated neural 

 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 figure 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. Lydekker, 

 some of the Eocene and Miocene species of Europe that have been referred to Testudo may in 

 reality belong to Hadrianus. 



Analysis of the Known Species. 



1. Wasatch. Very high peripherals. Pectoral scutes more than half as wide along midline 



as the abdominals majusculus 



2. Bridger. Peripherals of moderate height. Pectoral scutes less than half as wide on mid- 



line as the abdominals corsoni 



3. Uinta. Peripherals high. Pectoral scutes less than one-third as wide as the abdominals . . tumidus 



4. Jackson formation. Pectoral scutes one-ninth as wide as the abdominals schucherti 



Hadrianus majusculus Hay. 

 Plate 59, fig. I; text-fig. 472. 



fHadrianus corsomi, Cope, Syst. Cat. Vertebrata Eocene N. Mex., 1874, p. ?6; Append. LL. Ann. Rep. 



Chief Engineers (Wheeler's Surv.), 1875, p. 1016 (separata, p. 96) 

 Hadrianus majusculus, Hay, Amer. Jour. Sci., (4), xvm, 1904, p. 271, plate xv; text-fig. 5. 



The species here described is founded on a somewhat damaged shell which belongs to the 

 Marsh collection in Pea body 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. 



