152 FOSSIL TURTLES OF NORTH AMERICA. 



There is present a part of a peripheral which Cope has labeled as the tenth. The upper 

 borders of both the upper and lower faces are missing, but these faces are yet 58 mm. wide. At 

 its upper, or proximal, border, the bone is 18 mm. thick. The hinder half of the bone is lost 

 but enough apparently remains to show a part of the rib-pit, had it been present in the bone. 

 Since in C. ponderosa the eighth costal sent its rib-end into the eleventh peripheral, it is prob- 

 able that there was no pit in the tenth. If the bones regarded by Cope as the eighth, ninth 

 and tenth are really such they differ greatly from the corresponding bones of Osteopygis, 

 being, relatively to their length and height, much thicker. 



The costals are extremely interesting, but they are not well understood. There is one which 

 is nearly complete, quite certainly either the third or the fifth. It has a width of about 50 mm. 

 (fig. 188). The curvature shows that the carapace was considerably archt from side to side. 

 Cope regarded this costal as that of the right side, but there are reasons for believing that it 

 belongs to the left. One sutural border is thicker and has the suture oblique to the surface of 

 the bone in such a way that it must have been overlapt by the contiguous bone. We have 

 seen that the hinder border of the nuchal and the first two peripherals overlapt the first costal. 

 It seems improbable that from having the anterior border overlapt in the first costal a change 

 would be made, about the middle of the shell, to having the posterior border overlapt. The 

 present costal can not, however, be the first, for the proximal end of its fellow bone is present 

 and does not accurately fit to the nuchal and first peripheral. It can not be the second, for it is 

 not traverst by a sulcus separating two costal scutes. It seems probable that it is the left 

 third. The posterior sutural edge is at right angles with the surface and hence it did not overlap 

 the succeeding bone. The thickness, too, is reduced to 5 mm. The upper surface of the costals 

 is smooth. On the one described there are parts of 2 vertebral scutes, probably the second and 

 the third. On the supposed posterior border of the bone the costo-vertebral sulcus is 25 mm. 

 from the neural border. The surfaces of the peripherals are markt by zigzag vascular grooves. 



On the under side of the costal is seen a large rib-head and stout ridge proceeding from it to 

 the distal end. At the proximal end this ridge lies a little nearer to the supposed anterior border 

 and on its way to the distal end it gets closer to this border, being only 3 mm. away from it 

 finally. In his description Cope states this ridge lies near the posterior border. In front, that 

 is on the side next the beveled border of the costal, there is a rough groove, as if a rudimentary 

 first rib had been applied against the ridge. The meaning of the groove is unknown. It is 

 found in three of the costals represented. 



Not enough of the femur is present to furnish definite information regarding its structure. 

 The head is missing. The shaft has a diameter of 1 1 mm. 



What is determinable regarding the vertebral scutes has been stated above. On the 

 nuchal and the anterior peripherals the marginal scutes rise only a moderate distance above the 

 free border of the shell. On the median and hinder peripherals the costo-marginal sulci appear 

 to have followed the unossified space between the costal and peripheral bones. The nuchal 

 bone does not reach the midline, and hence we can not determine exactly what was its width 

 nor that of the nuchal and first vertebral scutes. The boundary between the nuchal scute and 

 the first marginal is believed to be where shown in fig. 185. The first vertebral scute lacks a 

 considerable space of reaching the outer ends of the nuchal bone, and was, hence, evidently 

 narrow. The first marginal rises about 28 mm. above the border of the carapace; the second 

 about 18 mm. 



Catapleura ponderosa Cope. 



Figs. 189, 190. 



Catapleura ponderosa, Cope, Proc. Amer. Philos. Soc.xil, 1871^.46; Vert. Cret. Form. West, 1875, p. 259. 

 Osteopygis ponderosa, Hay, Bibliog. and Cat. Foss. Vert. N. A., 1902, p. 441. 



I he present species is based on materials even less satisfactory than is C. repanda. They 

 consist of portions of the eleventh peripheral and the pygal, portions of about 6 costals, a 

 part of a supposed hypoplastron, a scapular arch, a considerable part of a humerus, a part of 

 a femur and a part of a lower jaw. 



The type is now in the American Museum of Natural History and has the number 1475. 

 These bones were obtained by Cope from the uppermost bed of Cretaceous greensand, at 

 Hornerstown, New Jersey. 



