The Life History of the Soft Clam 293 



byssus. Immediately on settling, the young clam at- 

 taches itself by means of this thread to shells, sea-weeds, 

 pebbles, or even to sand. It is now not much larger than 

 many of the sand grains, and its body is so light that 

 if it were not anchored in some way, it would be rolled 

 along by the action of the water. When water move- 

 ments cease, as at slack tide, it often casts off the byssus 



FIG. 56. Very small long neck clam 

 (.4 millimeter), b, byssus; /, foot; 

 s, siphon. Drawn from living speci- 

 men. 



and begins to creep by means of its foot. What the ob- 

 ject of this habit may be it is difficult to imagine, for the 

 little creature, even if in search of a more favorable lo- 

 cality, is able to move only very short distances. After 

 a little exercise of this sort, it rapidly secretes and fast- 

 ens another thread, but sometimes continues to creep 

 about to the length of its tether. 



The general appearance of this newly settled clam 

 is illustrated in Figure 56. Foot (/) and siphon (s) 

 are shown extended, and the byssus thread (b) with its 



