HO 



FOSSIL TURTLES OK NORTH AMERICA. 



been about 250 mm. The anterior border is truncated. The free margins are nowhere 

 notcht. The nuchal is 50 mm. long, 43 mm. wide in front, and 75 mm. where widest. Its 

 anterior border, as well as that of the peripherals of the first pair, is acute. These bones are 

 rather thin, only 1 1 mm. The anterior and the posterior neurals are relatively broad, the 

 others narrow. The dimensions ot the neurals are shown in the table. 



The fifth neural is octagonal, due doubtless to an individual variation. The first supra- 

 pvgal is 22 mm. long and 3$ mm. wide. 



The costal plates are usually about as wide at the upper end as at the distal end. However, 

 the third is 37 mm. wide proximallv and 2" mm. distally. The third has a height equal to only 



394. 



595- 



FlGS. ^04 and 395. Echmatemys wyomingensis. Carapace and plastron. Xj. 



No. 5Q8S A. M.N. H. 



V>4- Carapace. 



395. Plastron. 



41 per cent, of the height of the first costal near its hinder border. The posterior peripherals 

 |>ns.s.(ss .111 at Lite free border. The first costal bone is hardly two-thirds as wide as high. 



1 he dimensions of the peripherals are given in the table above. 



I he sulci are narrow and rather shallow. The first and fifth vertebral scutes are broad, 

 flu- others are narrow, with nearlv parallel sides. The dimensions of the vertebral scutes 

 are shown in tabular form above. 



1 he costo-marginal sulci run about in mm. below the costo-peripheral sutures. 



The plastron (plate 47, fig. 1; text-fig. 395) is 304 mm. long. It is thick, especially at the 

 crossing of the longitudinal and the hyohypoplastral sutures. The length of the anterior lobe 



