112 



FOSSIL TURTLES OK NORTH AMERICA. 



costal of the left side, parts of the second and the fourth left costals, the distal end of the fifth 

 right costal, the entoplastron, the left hypoplastron, and a portion of the right xiphiplastron. 



The species was one of relatively small size, with a deprest carapace (fig. 103), probably 

 about 260 mm. long. The carapace is thin, the first costal being 6 mm. thick at the center; 

 the fourth at its sutural border, 5 mm. thick. The first neural has a length of 35 mm. and a 

 width of 18 mm.; the second, a length of 20 mm. and a width of 24 mm. The next two were 

 somewhat longer. The broader end of each was in front, as in the genus generally. The 

 nuchal bone was relatively long and narrow, the length being close to 67 mm., the width close to 

 60 mm. The width in front was only 28 mm. This bone resembles closely that of H ydrome- 

 dusa. Its anterior border was thin and acute. 



The first costal bone is 62 mm. wide fore and aft, and 75 mm. long and 6 mm. thick posteri- 

 orly. On its inferior surface at the distal end is an excavation for the axillary buttress. This 

 rises 30 mm. above the lower end of the bone and is 9 mm. wide. The third costal is 21 mm. 

 wide and 105 mm. long. The right fifth is 33 mm. wide distally. On its inner surface, near 

 the distal end, is an excavation for the inguinal buttress, 33 mm. long and 7 mm. wide. The 

 first and the second, and probably all the other costals articulated with the peripheral bones. 

 The rib-heads were moderately developt. 



FIGS. 104 AND 105. Taphrosphys leslianus. Portions of type. 



104. Entoplastron. X. 105. Portions of reir of plastron. Xj. 



Known bones shown by stippling. 



The first peripheral has a length of 42 mm. along the free border, and rises from this a 

 distance of 49 mm. The second is 37 mm. along the free border and 33 mm. high. The free 

 border of the first is acute; that of the second, subacute. The upper surface of each is convex 

 in all directions. The thickness of the hinder end of the second peripheral is 8 mm. A posterior 

 peripheral is 35 mm. long. It flares upward toward the free border. The latter is acute. 

 The surface of the carapace is smooth, but there appears everywhere a rather indistinct 

 reticulation of grooves, which are narrower than the inclosed spaces. 



The sulci are shallow but not difficult to trace. There is no nuchal scute. The first 

 marginals join at the midline a distance of about 30 mm. The sulcus between the first and 



second marginals is 38 mm. long; that between the second and 

 the third, 22 mm. Posteriorly the marginals rose rather high on 

 the peripherals. The intermarginal sulci are nearer the anterior 

 ends of the peripherals. The vertebral scutes have the dimensions 

 given in the accompanying table. 



The entoplastron (fig. 104) is diamond-shaped, with rounded 

 angles. The length is 30 mm.; the width, 31 mm.; the thick- 

 ness, 3.5 mm. No other part of the anterior lobe is present. 

 A considerable portion of the left hypoplastron is preserved (fig. 105). The hyoplastral 

 border makes an angle of about 60 with the free border of the hinder lobe and a right angle 

 with the median border, so far as the latter is represented. Cope appeared to think that the 



