124 



SEA-SHORE LIFE 



at times of low tide. This siphon may he as much as a foot in 

 length, and is pierced by two tubular openings, the one nearest the 

 hinge side of the clam serving to carry off the digested food, and 

 water from the gill chambers, while the other serves to admit water 

 into the gill chambers of the clam. There is thus a constant cur- 

 rent going into and passing out of the siphon. The shell is quite 

 thin and brittle. This clam spawns in early summer, and the eggs 



Fig. S.2; SOFT-SHELL CLAM. From lite. Aimisquam, Mass. 



develop into little free-swimming larvae which soon settle down 

 upon seaweed or other submerged objects and attach themselves 

 by means of a thread called a byssus, Avhich is secreted by a gland 

 in the foot of the little clam. Soon they free themselves and sink 

 to the bottom, where they begin to burrow when about one-quarter 

 of an inch long. They still attach themselves to particles of 

 sand, however, and often leave one burrow to construct another. 

 Finally, however, they dig a permanent burrow which they rarely 

 or never leave, and no longer ]u-oduce a byssus. 



This valuable mollusk is highly esteemed in the market. The 

 fishery in the New England States is worth more than $500,000 

 annually. 



