426 



FOSSIL TURTLES OF NORTH AMERICA. 



All the tarsalia of fig. 559 (2, 3, 4, 5, of the second row) are present in the right foot 

 except the first; but this is present in the left foot. The first and the fifth are largest. By its 

 inner border the fifth articulates with the fifth tarsal; and by a part of the lower border, with 

 the fourth metatarsal. The metatarsals of the first and second digits and the first phalangeal 

 of the second digit are missing; but these are present in the left foot. The distal, claw-bearing 

 phalanges are relatively long, that of the first digit being 27 mm. long; that of the second, 35 

 mm.; that of the third, 40 mm.; and that of the fourth, 37 mm. Each claw phalange is there- 

 fore as long as, or longer than, the remaining phalanges, together with the metatarsal of the 

 same digit. In size and form the distal phalanges resemble those of Gopherus polyphemus. 



The terminal portion of the tail is greatly expanded. This portion is 75 mm. long and 

 appears to consist of 5 vertebrae. The lateral processes of these vertebras are lengthened, so 



557- 



FIGS. 557 AND 558. Testudo osborniana. Shell and femur of type. 

 557. Carapace, side view. Xj- 558. Left femur, ventral surface. Xi- 



558. 



that a broad flat beaver-like paddle is produced. Its greatest breadth is 85 mm. The terminal 

 vertebras, 10 in number, of G. polyphemus have their lateral processes similarly lengthened, 

 but in this case the processes are distinct, true caudal ribs. 



This tortoise possest the same kind of supplementary armor that we have found in T '. 

 orthopygia. The skin of the bottoms of the feet, of the lower leg, of the hinder part of the 

 thigh, the tail, both on the upper and the lower sides, and probably also of the anterior limbs 

 supported an armor composed of bones of various sizes. These bones doubtless lay each 

 beneath a horny scale such as we see protecting the limbs of many of the living species of 

 Testudo and of other genera of turtles. Fig. 559 represents the dermal bones, as well as the 

 foot bones of the right hind foot. The dermal bones evidently belonged to the bottom of the 

 foot and the hinder portion of the lower leg. The deeper surface of these bones is seen, as is 

 indicated by the pitting. The external surfaces, where seen, are smooth. In the figure the 

 tarsal bones and the phalanges are lettered. It will be observed that the dermal bones of the 

 foot and the heel are larger than those further up on the leg. How far up on the leg they 

 extended is uncertain. 



Fig. 560 shows the dermal bones which protected the upper surface of the tail and of the 

 hinder portions of the thigh. In the center of the mass is seen a considerable area consisting 

 of about a dozen bones closely articulated suturally. These overlie the expanded extremity 

 of the tail, of which the last centrum and its processes (fig. 560, //, A) are seen resting on the 

 hinder border of the carapace. On the left side of the figure the dermal bones adjoining the 



