1918] Packard: Quantitative Analysis of Molluscan Fauna 311 
to capture it. This species occurs most abundantly at the low water 
mark and might be expected to oceur sparingly along the low sandy 
beaches within the middle division of the Bay. It is known as the 
‘‘Washington’’ or ‘‘horse clam’’ in the Puget Sound region, where 
it is now being utilized for clam nectar. 
The mussels, represented by Mytilus edulis and M. californicus, 
are a sea food that has not as yet received the attention it deserves. 
Mytilus edulis occurs in varied environments wherever suitable sup- 
ports abound. It is found attached to the rocks or piles mainly within 
the intertidal zone. These small mussels are occasionally found in 
local markets, where they command a good price. The large mussel, 
M. californianus, is seldom found in the markets, although it is used 
locally by people living near the beds. It comprised an important 
article in the diet of the local Indians, as is attested by the extensive 
shell mounds along the coast. Unlike the smaller mussels, this form 
lives only along the shores of the open ocean, attached to the rocks 
at or near low tide mark. It develops best at those places along the 
rocky shore where the waves are continually breaking over them. 
These mollusks can be easily harvested at extreme low tide by pulling 
them off the rock or scraping them off by means of a suitable tool. 
Such an industry properly regulated would add a considerable amount 
of sea food to the states of California, Oregon, and Washington. 
Siliqua nuttalli, incorrectly named ‘‘razor clam,’’ occurs sparingly 
within the middle division of San Francisco Bay. It occurs typically 
within the pure sands along the open ocean. No record is available 
of this species occurring in commercial quantities in the vicinity of 
San Francisco, although it might be grown on almost any gently 
sloping outside beach, on which but little shifting of the sand occurs. 
The eastern and the native oysters occur within San Francisco 
Bay. The former, Ostrea elongata, does not reproduce within these 
local waters. Therefore seed oysters are brought from the Atlantic 
Coast to replenish the beds depleted by harvest. The principal oyster 
beds located within the lower division of the bay are now being in- 
vestigated by the United States Bureau of Fisheries, and therefore 
will not be further considered. The small native or ‘‘Olympia oyster,”’ 
Ostrea lurida, is a hardy species having a general distribution within 
the bay as well as in shallow waters outside of the Golden Gate. In 
places within the lower division of the bay these oyster shells literally 
pave the bottom. This small oyster is now extensively used through- 
out the coast. 
