442 



FOSSIL TURTLES OK NORTH AMERICA. 



The sulci of the plastron (tig. 583) are deeply imprest. The gulars extend backward on 

 the entoplastron. The humerals occupy 85 mm. of the median line; the pectorals only about 

 18 mm.; the abdominals, 200 mm.; the femorals, 68 mm.; the anals, 68 mm. 



As already stated. Professor Cope described the anterior portion of the carapace as the 

 posterior. The evidence that the portion here regarded as the anterior is such is found in the 

 fact that the buttress which ascends from the plastron is on the third peripheral from the 

 median element; whereas, the buttress at the inguinal notch ascends on the filth peripheral 

 from the hinder median element, the pygal. That Cope had this anterior rim in view is shown 

 by the fact that it corresponds exactly with his description, while the portion of the posterior 

 rim present does not so correspond. All that Cope had to say about any part of the anterior 

 peripherals was a statement of the dimensions of one of them, and these figures apply quite 

 well to the eleventh peripheral. 



The carapace was 470 mm. wide, probably rather high and vaulted, abruptly curved in 

 front of the axillary notches, somewhat concave in front, and broadly rounded behind. 



The abrupt curves in the front of the shell occur on the second peripherals. The nuchal 

 and the anterior peripherals come to an acute edge. Backward from this edge the bones 

 thicken rapidly, become concave above, especially the second peripherals, and quite convex 

 below. The nuchal bone occupied 105 mm. of the free border and its greatest thickness is 

 30 mm. At the midline, the border of the carapace apparently lackt 55 mm. ot extending as 

 far forward as the tip of the plastron. 



592. 



Figs. 591593. TestuJo ortkopygia. Epiplastral lip. X}. No. 1325 A. M. N. H. 



591. Upper surface. 592. Section at ends of gulo-humeral sulci. 593. Longitudinal section. 



The hinder peripherals flare upward somewhat as the free border is approacht. The 

 eleventh (fig. 588) occupies 80 mm. of the free border, is 34 mm. thick and 107 mm. high. 

 The pygal (figs. 588, 589) is 75 mm. wide at the free border and about 75 mm. high. 



Only unimportant fragments of the neurals and costals of the type specimen remain. 

 There was the same alternation of larger and smaller neurals that we see in the living species 

 of the genus. Likewise, the proximal ends of the costals were alternately narrow and wide. 

 Two costals, which are regarded as the third and fourth of the left side, are represented by 

 their proximal ends. The third is 75 mm. wide where it has joined the neurals, while the 

 fourth is only 44 mm. wide. The bone is 8 mm. thick. 



There is present with the type a humerus which lacks the distal end. There is no femur 

 present, altho Cope mentions one. He states that its length, estimating for the absent condyles, 

 is 170 mm. and the width of the head plus the great trochanter go mm. A perfect femur of a 

 still larger specimen, next to be described, has a length of only 150 mm. The humerus referred 

 to, allowing for the missing distal end, had a length of about 170 mm. and a thickness thru 

 the head and the ulnar tuberosity, of 85 mm. It seems evident, therefore, that Professor Cope 

 inadvertently spoke of the humerus as the femur. As the complete humerus of another 

 specimen will be described, that of the type will be passed by. 



