THE MOLLUSKS 



2S9 



tiflcially, stakes or brush are sunk in shallow water so that the young 

 oyster, which is at first free-swimming, may escape the danger of smoth- 

 ering on the bottom. After the oysters are a year or two old, they are 

 taken up and put down in deeper water as seed oysters. At the age of 

 three and four years they are ready for the market. 



The oyster industry is one of the most profitable of our fisheries. 

 Nearly S65, 000,000 a year has been derived during the last decade from 

 suoh sources. Hundreds of boats and thousands of men are engaged in 

 dredging for oysters. Three of the most important of our oyster grounds 

 are Long Island Sound, Narragansett Bay, and Chesapeake Bay. 



Sometimes oysters are artificially " fattened " by placing them on beds 

 near the mouths of fresh-water streams. Too often these streams are the 

 bearers of much sewage, and the oyster, which lives on microscopic organ- 

 isms, takes in a number of bacteria with other food. Thus a person might 

 become infected with the typhoid bacillus by eating raw oysters. It is 

 evident that state and city supervision ought to be exercised with refer- 

 ence not only to the sale of shellfish which comes from contaminated 

 localities, but also to prevent the growth of oysters or other moUusks in 

 the neighborhood of the openings of sewers or sewage-bearing rivers. 

 / Clams. — Other bi- 

 valve mollusks used for 

 food are clams and scal- 

 lops. Two species of 

 the former are known to 

 New Yorkers, one as 

 the " round," another as 

 the "long" or "soft- 

 shelled " clams. The 

 former {Venus merce- 

 neria) was called by the 

 Indians " quahog," and 

 is stUl so called in the 

 Eastern states. The 

 blue area of its shell 

 was used by the Indians 

 as wampum, or money. 

 The quahog is now ex- 

 tensively used as food. 

 The "long" clam (Mya 

 arenaria) is considered 

 better eating by the 

 inhabitants of Massa- 

 chusetts and Rhode 

 Island. This clam was highly prized as food by the Indians. The clam 

 industries of the eastern coast aggregate nearly $1,000,000 a year. 



Round clam (Vemis merceneria) : AAM, anterior ad- 

 ductor muscle; ARM. anterior retractor muscle; 

 PAM, posterior adductor muscle; PRM, posterior 

 retractor muscle ; F, foot ; C, cloacal chamber ; 

 IS, incurrent siphon; FS., excurrent siphon; 

 BO, heart; G, gilla; M, mantle; DGL, digestive 

 glands ; S, stomach ; /, intestine ; P, palp ; R, pos- 

 terior end of digestive tract. 



