382 Jstew Species of Fresh Water Tortoise. 



Art. XXII. — Description of a new species of fresh water Tor- 

 toise, inhabiting the Columbia River; by Richard Harlan, 

 M. D., F. L. S., &c. 



Emys Oregoniensis — (see plate.) 



Characters. — Shell suboval, moderately depressed ; dark brown 

 or olive, with bright yellow irregularly disposed lines with black bor- 

 ders ; anterior marginal plates very deep : sternum oblong, slightly 

 constricted in the middle, emarginate and bidentate anteriorly, bright 

 yellow, beautifully and curiously figured with black, with yellow 

 curved longitudinal lines ; head of moderate size, upper jaw biden- 

 tate at tip. 



Description. — Shell broadest posteriorly, about the usual height 

 of animals of this genus, rather depressed, very slightly emarginate 

 behind, more so anteriorly, there being a deep notch on either side 

 of the single anterior marginal plate, which is nearly pointed anterior- 

 ly ; the vertebral plates five in number, the first nearly square, the 

 second, third and fourth irregularly hexagonal, the posterior border 

 of the latter curved so as to admit the arched anterior border of the 

 fifth plate to project into it — the fifth plate elliptical above, and pre- 

 senting four faces at its lower border for articulation with as many 

 border plates : first lateral plate nearly triangular, connected with 

 the first five marginal plates, the two middle lateral plates form ob- 

 long squares, with each an acute angle above entering between the 

 sutures of the vertebral plates, — the last or fourth plate is pentagonal. 



Marginal plates twenty five in number, — the nuchal plate pyra- 

 midal in form, with a deep notch on either side of its apex, its pos- 

 terior margin being marked with two transverse depressed lines, the 

 two first marginal plates on either side of the single one are quadri- 

 lateral and bluntly serrate on the anterior margin, and together with 

 the third plate are unusually deep — the three following plates be- 

 come abruptly narrowed and slightly emarginate at the inferior bor- 

 der — the six posterior plates are again enlarged, nearly square, and 

 the two latter plates with each a slight notch on their inferior bor- 

 ders. 



Sternum, yellow tinged with red on its outer sides, the central 

 portions being figured with irregularly curved black bands interspers- 

 ed with interrupted yellow lines ; the second plates with each a black 

 dot in their centre : the two anterior plates triangular, with their 



