EMYS OREGONIENSIS.— Harlan. 

 Plate J. 



Characters. Shell suboval, greatly depressed, serrated in front, slightly emar- 

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

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

 upper jaw bidentate. 



Synonyme. Emys oregoniensis, Harlan, Amer. Jour, of Arts and Sciences, vol. xxxi. p. 

 382, plate 31. 



Description. The shell is suboval; 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 very much 

 prolonged, its lateral margin curved, and its posterior border convex and project- 

 ing; 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, roundest, and received into the concavity of the posterior margin 

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

 ginal 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 being 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 

 Vol. II.— 2 



