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 occur 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. calif ornicus, 

 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 Avithin 

 the intertidal zone. These small mussels are occasionally found in 

 local markets, where they command a good price. The large mussel, 

 M. calif ot^nianus, 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. 



