3 22 



FOSSIL TURTLES OF NORTH AMERICA. 



few millimeters, then begins to expand and becomes wider than at the base. At the hyoepi- 

 plastral suture the lobe narrows again and passes rapidly to the lip. This is relatively narrow, 

 47 mm., is notcht at the midline, and is furmsht on each side with a blunt tooth. The epiplas- 

 trals thicken toward the lip and become 20 mm. thick. For some distance on each side of the 

 symphysis of the bones the thickness is reduced to 15 mm. The lateral expansion of the anterior 

 lobe and the lip form the most distinctive characters of this species. 



The bridge has a width of about 138 mm. 



The hinder lobe is 114 mm. long and 156 mm. wide. It is notcht behind, as in the other 

 species of the genus. The beveled surfaces (fig. 417) on the upper side of this lobe are 33 mm. 

 wide at the hypoxiphiplastral sutures. The posterior buttresses (fig. 418) are wide, beginning 

 to rise from the floor of the plastron at a line nearer to the midline than to the free border of the 

 lobe. They are articulated to the fifth and sixth costals and rise to a height of 65 mm. above 

 the floor of the plastron. 



The gulars have a length of 54 mm.; the humerals, 31 mm.; the pectorals, 68 mm.; the 

 abdominals, 83 mm.; the femorals, 51 mm.; the anals, 49 mm., at the midjine. The axillary- 

 scute has not reacht the fifth marginal, nor the inguinal the sixth. 



As in other species of this genus the posterior buttresses articulate with the fifth and 

 sixth costals. Fig. 419 represents the anterior lobe of the plastron of No. 1077, American 



420. 



Fics. 419 AND 420. Echmatemys septaria. Anterior lobe of plastron. X i- No. 1077 A. M. N. H. 



419. Lower surface. 420. Upper surface. 



Museum of Natural History. It will be observed how this expands in front of the base. Fig. 



420 presents a view of the same bone seen from above. The width of the lip is indicated, also 



the backward extension of the thickening of the epiplastrals. 



No. 10303 of the collection at Princeton University is to be referred to this species. It 



lacks only a small portion of the rear of the carapace and the tips of the xiphiplastra. It was 



collected in 1878, at Twin Buttes, Wyoming, in the Bridger beds, belonging to level C or D. 



The carapace was close to 335 mm. long. The interior of the shell is cleaned out, so that all 



parts are exposed. The sides of the anterior lobe are 

 hatchet-shaped, as is peculiar to the species. The horn- 

 covered areas on the upper side of the hinder lobe are 39 

 mm. wide. 



The vertebral scutes are narrow at the ends, wide 

 in the middle, the measurements being given in the 

 accompanying table. 



These scutes are much wider in proportion to their 

 length than in Cope's type and other specimens studied. 



The sulci are broad and deeply imprest. It is possible that the specimen belongs elsewhere. 



Nos. 10073 and 10304 of the Princeton collection are likewise referred to E. septaria. 



In the Philadelphia Academy collection is the specimen which Leidy described as Emys 



wyomingensis (Contrib., etc., pp. 148, 152, 153, No. 14). It is regarded by the present writer 



as belonging to E. septaria. The sulci are deeply sunken and the surface of the carapace is 



corrugated. The axillary and the inguinal scutes are well develop!. 



