312 University of California Publications in Zoology [Vou.13 
Panope generosa is the largest of the West Coast clams. This 
northern form occurs only sparingly in the vicinity of San Francisco. 
It occurs on sandy or gravelly beaches near the low tide mark, where 
it burrows deeply. 
Cardium corbis, the true cockle, is a hardy clam living under a 
variety of conditions from those of an estuary to that of the open 
ocean. It is perhaps predominantly a mud dweller, although it fre- 
quently oeeurs on sandy or gravelly bottoms. It is one of the easiest 
to procure, since it generally lies on the surface. Although this clam 
has the reputation of being tough, it is suitable for, and at present 
is bemg used, as minced clams. This species is large and lacks the 
thick, dark epidermis on the siphons, making it more desirable for 
mineing than similar sized or even larger clams, such as Saxidomus 
nuttalla or Schizothaerus nuttalli. 
The rock-boring mollusk, Pholadidea penita, occurs quite abund- 
antly in the softer rocks within the Golden Gate and along the ocean 
beach. It is said to be very palatable by those living near the rocks 
in which these, incorrectly called ‘‘roeck oysters,’’ live. As yet this 
elam has not been considered of economic importance, although it 
might well be investigated from that standpoint. 
Besides these well known edible clams there are several native 
forms that might well serve as food if means for their cultivation 
were devised. One of these, the Wacoma nasuta, oceurs very abund- 
antly on the muddy or sandy beaches along the bay. It is a very 
small elam, about the size of the native oyster, but it has a good flavor 
and is easily obtaimed, since it does not burrow deeply. The true 
“‘yazor elam,’’ Solen sicarus, is reported to be excellent. It is a 
deeply burrowing, sand-dwelling form that is difficult to obtaim. It 
probably thrives best on the sandy beaches along the ocean front. 
Spisula catillifornis is represented in the Survey collections by a few 
specimens obtained from the Golden Gate. It is a large but rare 
clam that might possibly be successfully grown along the sandy beaches 
outside San Francisco Bay. Certain species of Pecten oeeur very 
abundantly in Puget Sound at depth of several fathoms. It is pos- 
sible that the same or similar species may occur off the Golden Gate 
in quantities sufficient to have an economic significance. The dredg- 
ings of the ‘‘Albatross’’, however, failed to reveal any such beds at 
the few outside stations. 
From the above discussion it is evident that the waters of San 
Francisco Bay and immediate vicinity offer suitable habitats for a 
