ECONOMIC IMPORTANCE OF THE GROUP 193 
used as food, but the soft-shelled clam, Mya arenaria (mi'a 
ar-en-a'ri-a), is eaten extensively near the seashore. The 
soft-shelled clam has a long siphon which may be extended 
several inches beyond the valves (Figure 178). 
The scallop (skol'lup) is another mollusk that is eaten near 
the shore more extensively than elsewhere. This mollusk 
has but one adductor muscle, which is the edible portion. 
Figure 181. — Barnacles and Clams Growing on Oysters. 
Clams and oysters are raised artificially and regularly 
planted on natural feeding grounds. Care is taken to 
have such natural enemies as the starfish removed, and, in 
the case of oysters, brush and shell are added that they 
may fasten to these rather than sink to the bottom, where 
they become covered with mud. 
The culture of oysters and clams near the mouths of 
rivers contaminated with sewage is unsanitary, and dis¬ 
ease may be caused by eating such mollusks raw. This 
is one reason for the laws regulating the disposal of sewage, 
and for government inspection of the feeding grounds. 
