J" 



is 82 mm.; the width, 143 mm. Thus the length is only 55 per cent, of the width. The epi- 

 plastral lip is 55 mm. wide and projects but little beyond the general curve ot the lobe. The 

 beveled surface on each side of the lip (fig. 396) on the upper surface of the bone is only-15 mm. 

 wide and at the hyoepiplastral suture only 12 mm. The thickened portion of the epiplastrals 

 above the lip extends backward only 16 mm., and where thickest, just mesiad of the gular 

 sulci, only 15 mm. The free borders of the lobe are acute nearly to the lip. The entoplastron 

 is lozenge-shaped, 51 mm. long and 65 mm. wide. The bridge is 133 mm. wide. 



The posterior lobe is 98 mm. long and 135 mm. wide, the length being thus about 73 per 

 cent, of the width. The width is considerably less than the half of the length of the plastron. 

 In the type of E. jeanesi the width is close to half the plastral length. Posteriorly in No. 5988 

 there is a broad notch. The beveled surfaces along the borders on the upper side (fig. 397) 



400. 



.W- 



397- 



401. 



I"IGS. 396-401. Echmatemys u'yomingensis. Various bones. 



396. Upper surface of epiplastral lip. X}. No. 5988 A. M. N. H. 



397. Upper surface of right side of hinder lobe of plastron. X$. No. 5988 A. M. N. H. 



398. Left dentary bone, outer surface. Xij- No. 5968 A. M. N. H. 



399. Same dentary as fig. 398, seen from above. X|. 



400. Upper surface of anterior lobe. X^. No. 6010 A.M. N.H. 



401. Upper surface of free border of hinder lobe of plastron. Xj. No. 6010 A. M. N. H. 



have a width of 18 mm. at the hypoxiphiplastral sutures. Here the thickness of the bones is 

 14 mm. 



The gular scutes are 39 mm. long; the humerals, 36 mm.; the pectorals, 51 mm.; the 

 abdominals, 84 mm.; the femorals, 58 mm.; the anals, 37 mm.; all measured along the mid- 

 line. The axillary scute falls far short of reaching back to the fifth marginal; the inguinal 

 comes forward nearly to the sixth marginal. 



The posterior buttresses extend inward from the free borders of the hinder lobe little more 

 than one-third the distance to the midline. Articulating with the fifth and sixth costals, they 

 rise about 44 mm., to a point nearly half-way from the lower border of these costals to the 

 bases of the rib-heads. The anterior buttresses appear to have risen about 20 mm. within the 

 first costals. 



