FOSSIL TURTLES OK NORTH AMERICA. 



Element. 



Length. Width 



the front pair ot peripherals, and the hinder peripherals are acute. The borders of the carapace 

 are nowhere notcht. The surface is smooth or relieved only by longitudinal striations. 



The nuchal bone is 53 mm. long, 34 mm. wide in front, 

 and 60 mm. where widest, the table presenting the dimen- 

 sions of the remaining median bones. 



The table below presents the dimensions of some of 

 the peripherals and of the vertebral and marginal scutes. 

 The third peripheral has a height equal to 56 per cent, 

 ot the height of the first costal, from the neural to the 

 peripheral. 



The vertebral scutes are relatively narrow and the 

 sides of the second and third are moderately bracket- 

 shaped. The interior and posterior are expanded. 



The nuchal scute is 10 mm. wide posteriorly and its 

 length is 19 mm. The costo-marginal sulci run well below 

 the costo-peripheral suture. The dimensions of five of 

 the marginal scutes are given in the table below, on the right. 



The total length of the plastron (plate 48, fig. 2; text-fig. 412) is 317 mm. The anterior 

 lobe is 88 mm. long and 126 mm. wide at the base, the length being thus 70 per cent, of the 

 width. The lateral borders run directly forward to the hyoepiplastral suture, then curve to 

 the lip. This had a width of 56 mm. and had a tooth on each side. The lip does not extend 



Dimensions of peripherals. 



Dimensions of vertebral scutes. 



Dimensions of marginals. 



as far forward as the nuchal bone. The thickening on the upper side of the symphysis of the 

 epiplastrals extended backward 25 mm. The greatest thickness of the epiplastrals is 13 mm., 

 and between these thickenings the bones are slightly channeled longitudinally. The thickness 

 of the symphysis is 13 mm. The horn-covered surface of the upper side of the epiplastron, at 

 the suture with the hyoplastron, is 18 mm. wide. The entoplastron is 47 mm. long and 57 mm. 

 wide. It is pointed in front; rounded behind. 



The bridge has a width of 136 mm. 



The hinder lobe is 105 mm. long, and 140 mm. wide at the base. The length is therefore 

 75 per cent, of the width. The buttresses arise far within the free border of this lobe. The 

 beveled surface of the upper lobe (fig. 413), at the suture with the xiphiplastrals, is 28 mm. 

 wide. The free borders of the lobe are acute. The posterior notch is about 28 mm. wide and 

 6 mm. deep. The posterior buttresses appear to have extended at their bases about half-way 

 to the midline. How high they rise has not been determined. 



The gulars are 45 mm. long; the humerals, 20 mm.; the pectorals, 63 mm.; the abdomi- 

 nals, 91 mm.; the temorals, 52 mm.; and the anals, 45 mm. 



The axillary scute is large, extending outward and backward to form contact with the 

 fifth marginal for a distance of 6 mm. The inguinal scute extends forward within 13 mm. of 

 the sixth marginal. 



From E. naomt the species differs in having a smoother shell, with less deeply imprest 

 channels for the sulci, and in having narrower neurals. The carapace ot E. stevensomana is 

 more contracted in front. E. shatighnessiana is set off by the bluntly rounded anterior border 

 of the carapace. From E. tegle the present species is distinguish! by the larger axillary scute, 

 the deep grooving of the carapace, the lower position of the costo-marginal sulci, the relatively 

 broader and shorter anterior lobe of the plastron, etc. In E. of \rrhoe the carapace is smooth, 



