446 



FOSSIL TURTLES OF NORTH AMERICA. 



In fig. 603 we have a view of the dermal armor that covers the end of the tail. This con- 

 sists principally of about 12 polygonal bones which are suturally joined. Around these are 

 arranged smaller bony scutes which are less closely joined, and which evidently permitted a 

 bending of the skin. The lower border of the fragment here figured rested on the upper sur- 

 face of the hinder border of the plastron, doubtless just in the position occupied during life. 

 On another fragment (fig. 604), belonging higher up on the tail, there are other ossicles and 

 a conical bony spur. This spur is 38 mm. long, 18 mm. in diameter at the base, and some- 

 what curved. The coat of mail found on and around the tail resembles that found in T. 

 osborniana. Its purpose was evidently to close up effectually the space between the feet when 

 these were withdrawn into the shell. 



There can scarcely be a doubt that the dermal bones and the ungual phalanx described 

 as cited in the synonymy, by Professor Cope, under the name Caryoderma snovianum and 

 thought by him to belong to a glyptodont, belong in reality to this species. Entirely similar 

 bones are among the specimens of T . ortlwpvgia collected for this author and described by him 

 in 1878. Dr. S. W. Wilhston first made the observation that these supposed Edentate bones 

 were those of a turtle and referred them with doubt to Testudo undata. The types of Caryo- 

 derma snovianum are in the University of Kansas and were found in the Loup Fork deposits 

 of northern Kansas. 



601 



Figs. 601-603. 



602. 

 -Testudo orthopygia. 



Femur and tail. X* 



603. 



No. 



1325 A. M. N. H. 



601. Two caudal vertebra.', lower side. 602. Proximal end of femur, ventral surface, with dermal bones. 



603. Tail, upper surface, covered with an armor of dermal ossicles. 



In Cope's description of his Xerobates cyclopygia three specimens appear to have been 

 studied. In his table of measurements these are designated as "No. I," "No. 2," and "No. 3." 

 His "No. 1 " is identified by the present writer as No. 1322 (plate 19, fig. 6) of the American 

 Museum of Natural History, since there is no other in the Cope collection that comes so near 

 answering the requirements. The length of the hinder lobe is said to be 140 mm., and the 

 width 240 mm.; but the latter is really 270 mm. With this specimen are many fragments of 

 the carapace. The anterior lobe of the plastron is missing. A portion of the entoplastron is 

 present, but not enough to determine its dimensions. The bottom of the plastron is quite flat, 

 there being only the slightest concavity in front of the hinder lobe. The form of the hinder lobe 

 is that of the type of T . orthopygia. The notch in the hinder border has a width of 76 mm. 

 The hyoplastra occupied 112 mm. of the midline; the hypoplastra, 122 mm.; the xiphiplastra, 

 86 mm. The notch has a depth of 32 mm. The sutures separating the hyoplastra from the 

 xiphiplastra are extremely coarse. The sulcus which runs lengthwise thru the middle of the 

 plastron is very wide and deep. The humero-pectoral and the pectoro-abdominal sulci are like- 

 wise deep but narrow. The pectoral scutes are extremely narrow, not more than 4 mm. wide 

 at the midline but widening right and left. The abdominal scutes meet along the midline 

 190 mm.; the femoral scutes, 57 mm. The femoro-anal sulci are angulated about the middle 

 of their length. The areas occupied by the abdominal scutes are broadly grooved. These 

 grooves indicate the stages of growth of the scutes. 



