53 



EMYS MOBILENSIS. 



Plate IX. 



Characters. Shell oval, convex, ecarinate; convex anteriorly, depressed pos- 

 teriorly, entire in front, emarginate and subserrate behind; jaws serrated; inferior 

 furnished with a hook. 



Description. The shell is regularly oval, broadest and flattened posteriorly; 

 convex, entire in front, but emarginate and sub-serrate behind. Of the five vertebral 

 plates, the anterior is urceolate, smallest in front, with three articulating margins, 

 larger behind, and convex; the second, third and fourth are hexagonal; the third 

 slightly concave on its anterior margin; the fourth smaller and concave on its 

 posterior; the fifth is irregularly triangular, its apex rounded, and directed upwards, 

 and its basis cut into four articulating margins. The lateral plates are very large, 

 the anterior triangular, the second and third pentagonal, and the fourth quadri- 

 lateral; all these plates are longitudinally rugous. The marginal plates are 

 twenty-five in number; the nuchal is a parallelogram; the first is irregularly 

 quadrilateral, rounded posteriorly, broad and straight anteriorly; the second is also 

 quadrilateral, with its superior internal angle greatly elongated, to enter between 

 the first marginal and first dorsal plates; all the remaining marginal plates are 

 quadrilateral, the posterior and internal angle of the three last are salient, which 

 gives a slightly serrated appearance to the shell, at its posterior margin; all these 

 plates, except the intermediate and anterior, are marked with one or more con- 

 centric striae, at the junction of the lateral and vertebral plates. 



The sternum is oblong, full, and entire in front, and emarginate behind. The 



