324 Our Food Mollusks 



swimming organ, or velum, disappears, a large foot is 

 developed. Soon afterward the creature settles to the 

 bottom. It was found that for some time the habits of 

 the young Venus were almost precisely similar to those 

 of Mya of the same age. A byssus gland is present at 

 the beginning of the creeping period, and the young qua- 

 haug attaches itself to objects on the bottom by a byssus 

 thread. This is cast off at will, the creature creeps about 

 for short distances, and then reattaches itself. Finally 

 it is large enough to burrow, and immediately, on cov- 

 ering itself, spins a byssus which it attaches to sand 

 grains or pebbles in the burrow walls. As in Mya, the 

 object of this is to prevent the animal from being washed 

 away from the point where it is lodged. The byssus 

 gland remains as a functional organ until the quahaug at- 

 tains a length of at least nine millimeters. In larger in- 

 dividuals it seems to have disappeared. 



The first experiments made on the growth of Venus 

 were conducted in 1901 on the north shore of Long 

 Island. In order to obtain as much security as possible 

 against trespassers, permission was obtained from an 

 oysterman to use a portion of an oyster bed that could be 

 watched. Though growing oysters were thickly planted 

 on the surrounding bottoms, there appeared to be an 

 abundance of food, and the rate of growth obtained 

 probably represents fairly the powers of increase pos- 

 sessed by the quahaug on ordinary bottoms near a beach 

 line. 



As many and as diverse conditions as circumstances al- 

 lowed were selected in placing the beds. Some were made 

 on the beach between tide lines, and others where they 

 would be continually submerged. Several observations 

 have made it seem probable that, as might be expected, 



