APPENDIX. 365 
simis, lunula nulla, extus lutescente seu albidi-olivacea, 
intus alba, marginibus tenuissime crenulatis; sinu pallii 
brevi, obtusa. 
This shell was taken in considerable numbers from 
the crop of a pin-tail duck, shot in the harbour of 
Esquimalt, Vancouver Island. 
It is a small species, of an ovate-triangular shape, a 
smooth shining appearance, and a light olive colour. 
The surface is concentrically marked with slight grooves. 
The beaks are prominent and very shining. | Internally 
the surface is white, the margins of the shell very finely 
crenulate, and the pallial impression short and blunt. 
Long. nearly + inch; lat. rather less than 4 inch.— 
Hab. Esquimalt Harbour, Vancouver Island. (Brit. 
Mus.) 
Venus rigida. (Gould.) Vancouver Island, mud between tide marks. 
Saxidomus squalidus. (Desh.) Vancouver Island, mud between tide 
marks. 
Spherium (Cyclas) tumidum. (Baird: Nov. Sp.) 
Testa ovato-trigona, tumida, olivacea, conferte 
transversim concentrice forte costata; umbonibus pro- 
minentibus, necnon erosis; interne cerulescente; mar- 
gine ventrali rotundato. 
This shell is of a tumid, swollen figure, and of an 
ovate-trigonal shape. The colour externally is dark 
olive, and it is strongly ribbed concentrically. The 
beaks are prominent, and frequently eroded. The inner 
surface is of a bluish tint. The ventral or lower margin 
is rounded. Long. 4 inch; lat. rather more than } inch. 
—Hab. Sumass Prairie, Fraser River, British Columbia. 
(Brit. Mus.) 
