107 



EMYS OREGONIENSIS.— iZar/an. 



Plate XVI. 



Characters. Shell sub-oval, greatly depressed, serrated in front, slightly 

 emarginate behind; sternum broad, oblong, serrated anteriorly, emarginate 

 posteriorly; with a large black blotch extending to all the plates. Head small, 

 elongated; upper jaw bidentate. 



Stnonyme. Emys Oregoniensis, Harlan, Amer. Jour, of Arts and Scien., vol. xxxi. p. 

 382j plate 31. 



Description. The shell is sub-oval; broadest behind, and very slightly emar- 

 ginate; anteriorly it is narrowed, and presents a serrated border; it is greatly 

 depressed, almost flattened along the vertebral line. Of the five vertebral plates, 

 the anterior is irregularly quadrilateral, with its two anterior angles much pro- 

 longed, its lateral margin curved, and its posterior border convex and projecting; 

 the second is hexagonal, with its anterior margin concave, to receive the 

 posterior border of the anterior plate; the third and fourth are also hexagonal; 

 the latter with its posterior margin concave; the fifth is heptagonal, its anterior 

 margin shortest, rounded, and received into the concavity of the posterior margin 

 of the fourth, and with its posterior border more extensive, and joined to four 

 marginal plates. Of the lateral plates, the anterior is irregularly triangular, with 

 its basis rounded, directed forwards, and joined to five of the marginal; the second 

 and third are pentagonal; the fourth is nearly quadrilateral. The marginal plates 

 are twenty-five in number, those in front are longest; the nuchal, or intermediate, 

 is elongated, narrowed posteriorly, and projecting anteriorly; the first are quadri- 

 lateral, broadest behind, and serrated in front; the second and third are also 



