TESTUDINIDJE. 385 



standing Cope's statement. Its length was about 1 10 mm. The scutal sulci are very obscure 

 on this fragment of the plastron, but the gulo-humeral is distinguishable. 



An anterior peripheral has the upper surface nearly flat and the free border acute. The 

 hinder peripherals (fig. 482) are strongly flared upward toward the free border, the ninth most 

 so (fig. 484), the eleventh less so (fig. 485). The ninth has a width along the free border of 

 85 mm. and the height was about 90 mm. in a straight line. All the peripherals have a thick- 

 ness of about 18 mm. The pygal is 21 mm. thick. 



Cope states that the sulci are deeply imprest. Those of the carapace are distinct enough, 

 but those of the front of the carapace are very narrow, shallow, and indistinct. The gulo- 

 humeral sulcus is very narrow and shallow and distinguisht with difficulty. 



Osborn, Scott, and Speir's identification of this species is based entirely on two ungual 

 phalanges collected by them in the Bridger beds. 



Genus STYLEMYS Leidy. 



Testudinidae with the plastron joined to the carapace by sutures, and with inguinal 

 buttresses which pass a short distance within the carapace between the fifth and sixth costal 

 plates. No hinge in either plastron or carapace. Of the neural plates, those behind the third 

 are hexagonal and have the antero-lateral sides much the shortest. The second and third may 

 be hexagonal; or the second may be octagonal and the third tetragonal. Two or three supra- 

 pvgals; the penultimate, bifurcate. Ribs at distal ends of costal plates entering pits in 

 peripherals ot budges. Costal plates with opposite ends differing much or little in width. 

 Epiplastral lip not projecting beyond the general contour of the anterior lobe of plastron. 

 Entoplastron in front of the humero-pectoral sulcus. Supracaudal scute single. Skull and 

 limbs, so far as known, like those of Gopherus. 



Tvpe: Stylemys nebrascensis Leidy. 



The relationship of this genus has been variously regarded. It was establisht by Leidy, 

 the name being given through a misconception that the plastral buttresses were separate 

 bones. On the discovery of his error Dr. Leidy employed for a while the name Testudo for 

 the species of this genus, while in his latest work on the genus (Contrib. Ext. Fauna West. 

 Terrs.) he vacillated between Testudo and Stylemys. This procedure indicates that he recog- 

 nized the close relationships between the species with which he was dealing, S. nebrascensis, 

 and the species of Testudo. Professor Cope recognized the validity of the genus. \\ hi le 

 regarding the Emydidae and the Testudinidae as forming distinct families, he referred Stylemys 

 to the former, doubtless supposing that the digits possest three phalanges each. 



It is the opinion of the present writer that the genus in question belongs to the Testudinidae. 



Unfortunately, we are even yet not thoroly acquainted with the osteology of the species 

 of Stylemys. Probably thousands of shells of S. nebrascensis have been observed, yet we know 

 of only one skull that has been found actually associated with its shell, no undisturbed foot 

 likewise associated, and no cervical vertebrae whatever. In the collection at Princeton Uni- 

 versity there is the greater portion of a skull which is here figured as belonging to 5. nebras- 

 censis but it did not accompany a shell. In the Carnegie Museum at Pittsburg is a shell of 

 .V. nebrascensis accompanied by the skull. In the American Museum there are various bones 

 of the internal skeleton about which there need be no doubt. All the indications furnisht by 

 thes* remains point to a close relationship with our living land-tortoises. The skull has the 

 structure of that of Gopherus (Xerobates). It seems quite certain that none of the digits 

 possest more than two phalanges, but the proof is not complete. The scapula, the coracoid, 

 the humerus, the forearm bones, the pelvis, and the bones of the hinder limbs agree with the 

 corresponding bones of Testudo and Gopherus. A humerus of 5. nebrascensis (fig. 492) shows 

 that the radial and ulnar processes of the proximal end are twisted toward each other as in 

 Testudo, and in a way entirely different from what we see in the Emydidae. The form and 

 structure of the shell agree rather with that of Testudo than with that of the Emydidae. It is 

 true that in the type species, S. nebrascensis, the. neural bones and the costals have not under- 

 gone the modifications which characterize those of Testudo; but even here we meet with the 

 beginnings of these modifications; and in the [ohn Day species they become unmistakable. 

 Here the second neural is octagonal, the third is tetragonal, and the costals have become 

 wedge-shaped. A peculiarity of the hinder region of the carapace, seen rarely in the Emydidae, 



2 5 



