FOSSIL TURTLKS OK NORTH AMERICA. 



Width. 



Dr. Leidy's type of the present species was found near Fort Bridger, Wyoming, and 

 probably in the level now known as B. It belongs to the U. S. National Museum and has the 

 number 109. It consists of the anterior part of the carapace. This was figured by Leidy, 



but the peripherals were omitted, having been found afterwards. 

 These have been included in fig. 404. 



From the front of the nuchal to the anterior border of the 

 seventh neural is 255 mm. The length of the nuchal is 57 mm.; 

 the width in front, 60 mm.; the greatest width, 75 mm. The 

 fourth neural is octagonal. The table shows the dimensions of 

 the neurals. 



The first peripheral measures 50 mm. along the free border. 

 The height is 48 mm. The sulcus between the costal and the 

 marginal scutes runs about 20 mm. below the upper border. The 

 dimensions of the vertebral scutes are given in the table below. 



No. 1067 of the American Museum was found by Cope in the Bridger region. Fig. 

 405 shows the carapace; fig. 407, the plastron seen from below; while plate 47, fig. 2, 



shows the plastron from above. This figure is to be 

 compared with fig. i of the same plate, E. wyomingensis, 

 especially as to the origins of the axillary and inguinal 

 buttresses. 



In the American Museum is found the specimen 

 described by Cope as belonging to this species. Its 

 number is 1072. It resembles the specimen to be 

 described below, except that the rib-heads are broader, 

 having the diameter of 12 mm. where they leave the 

 carapace. The individual was slightly larger than No. 1067, but not enough larger to 

 account for the difference. 



No. 1071 of the American Museum is a part of the Cope collection, but the exact locality 

 where it was found is not known. It came, however, from the Fort Bridger region. It belonged 

 to an individual whose shell was about 250 mm. long. The bones and sutures have an appear- 

 ance of immaturity. The features that characterize the specimens already mentioned hold 

 good here. The form was convex, as described by Cope. The fourth neural is octagonal, the 

 fifth quadrate. The vertebral scutes are proportionally wider than in the type, but this may 

 be due to less advanct age. Over the bridge the costo-marginal sulci ran very close to the 

 costo-peripheral sutures. On the costals are seen concentric grooves, which show the growth of 

 the horny scutes. On the first costal bone these are at an average distance apart of 7 mm., a 

 fact indicating rather rapid growth. The plastron is not greatly thickened, the front of the 

 hypoplastron being 11 mm. The lip has a notch in front, which cuts off a tooth on each side. 

 Behind this tooth the thickness is 1 1 mm. 



Another specimen in the American Museum of Natural History which is referred to E. 

 hayJent is numbered 3943. It consists of a shell lacking only some of the hinder peripherals. 

 It was collected in 1904, by Mr. Walter Granger, in the Bridger Eocene beds, about the middle 

 of the length of Cottonwood Creek, and therefore belongs to the lower portion of horizon B. 

 The shell is crusht laterally, so that the height is probably greater than in life, being now 182 

 mm. The length of the plastron is 370 mm., from which it is estimated that the carapace had 

 originally a length of more than 400 mm. The present width is 262 mm. 



The carapace (fig. 407) is smooth and the sulci are moder- 

 ately imprest. On the last neural and the suprapygals there is a 

 trace of a low keel. The nuchal bone has a length of 69 mm., a 

 width of 56 mm. in front, and a maximum width of about 80 

 mm. The neurals are broad. Two of these are octagonal, the 

 second and the fourth, but this is believed to be only an individual 

 variation. In the American Museum of Natural History there is 

 a specimen of Chelydra serpentina in which the same neurals are 

 octagonal. The table herewith presents the dimensions of the 

 neurals of 3943. 



Neural. Length. Width. 



