115 



7 



EMYS CUMBERLANDENSIS.— iZo/6roo/t. 



Plate XVIII. 



Characters. Head of moderate size; upper jaw slightly emarginate; lower 

 jaw furnished with a small hook in front; shell sub-round, indistinctly carinate, 

 shghtly notched anteriorly, and beautifully serrated posteriorly; sternum full, 

 entire in front, truncated behind. 



Description. The shell is much flattened and sub-round in form, having a 

 distinct though slightly elevated carina throughout its whole extent; the anterior 

 margin is slightly notched, while its posterior is beautifully serrated. The first 

 vertebral plate is hexagonal, elevated into a small prominence at the centre of its 

 posterior part, where the carina begins; its greatest extent is in the antero- 

 posterior direction, with its posterior margin projecting at the centre, and its 

 anterior marked by three small articulating facets; the second vertebral plate is 

 also hexagonal, with acute lateral angles, its anterior margin concave, to receive 

 the first vertebral; its posterior straight, and with its greatest extent in the trans- 

 verse direction; the third vertebral is nearly of the same form, but has a small 

 pike on its posterior margin, to be received in the fourth vertebral plate, which is 

 also hexagonal, but shorter, and has a notch both on its anterior and posterior 

 margins. These plates are smooth, except the first and fifth, which are marked 

 near the marginal plates with a few slight, concentric striae. The first lateral 

 plate is nearly an equilateral triangle, with its basis downwards and forwards, 

 and joined to five marginal; the second is pentagonal, with three facets on its 

 lower and larger border; the third is irregularly hexagonal, and the fourth quadri- 

 lateral. These plates are also slightly marked with five or six longitudinal, 

 concentric striae near their junction with the marginal. There are twenty-five 



