352 AMERICAN JOURNAL 



DESCRIPTION OF A NEW SPECIES OP PSEUDODON. 



BY T. A. COXRAD. 



P. ELLIPTICUM, Conrad. — t. 25, f. 1. 



Description. — Elliptical, slightly ventricose, thin; cardinal 

 tooth distinct in each valve; ventral margin regularly rounded ; 

 epidermis pale yellowish-olive, with a broad pale green ray 

 with dark margins; umbonal slope hardly defined or ob- 

 scurely angulated ; beaks eroded. 



Locality. — Cambodia. 



Cabinets of Chas. M. Wheatley and of Geo. W. Tryon, Jr. 



Observations. — This shell, received by Mr. Tryon from Mr. 

 Wheatley under the name of P. (Monocondyloea) Cumingii, 

 Lea, var., is very different from that species: it is more ellip- 

 tical, smoother, with a regularly convex basal margin, less in- 

 flated, and lighter in color. It also differs in the absence of 

 the slight plications posteriorly, which are found on Pseudo 

 don Cumingii. 



