336 APPENDI . 



Another oyster from San Diego, about two inch ; long, narrow and moderately widening, 

 slightly sigmoid in form, its margins simple and th extremity somewhat truncate and undulate 

 or dentate, with four or five radiating grooves ; shell compact, upper valve purplish. It occurs 

 in clusters intimately grouped, much like the parasitic oysters of Carolina, but more elongate, 

 less digitate at the end, less cavernous under the beak, and less black within. 



Locality. San Diego. 



