THE OYSTEE AND THE OYSTER INDUSTRY. 



39 



cable to fence the beds with chicken wire strung on posts set in the 

 bottom. 



CONCH. 



This is also a snaU-like mollusc, comprising several species, some 

 of which attain a length of from 5 to 6 inches. Busycon carica and 

 Busijcon canaliculatum (PI. IX) are the most common. The eggs 

 are deposited in flat parchmentlike capsules about an inch in diameter 

 and strung together by a cord along the side to form a loosely spiral 

 chain a foot to a foot and a half in length. This is cast free from 

 the animal and left to the mercy of the waves. It has been found '^ 

 that the conch opens an oyster by insert- 

 ing the edges of its own shell between 

 the valves of the oyster when it gapes 

 (text fig. 5) and then introducing its 

 proboscis and eating the meat. Conchs 

 do not occur, however, in sufhcient quan- 

 tities to destroy many oysters. No defi- 

 nite means of combating them are 

 employed, although those taken when 

 dredging are usually killed. 



Fig. 5. — Conch opening an oyster. About 

 one-half natural size. (After Colton.) 



Mussels, the common edible species, 

 Mytilus edulis, and other species, of the 

 Atlantic waters, and Mytilus Jiamatus 

 (PI. X, fig. 1) , of the Gulf coast, are bi- 

 valves which, shortly after hatphing from 

 the egg, attach themselves to material 

 on the bottom by a slender thread or 

 hair called the byssus. As development 

 goes on the number of hairs is multi- 

 plied and they become shorter and 

 stouter until the adult mussel, at a 

 length of 2 to 4 inches, is very firmly 

 attached by these threads. The mussels multiply rapidly, and 

 dense beds are sometimes formed over the oysters, tending to smother 

 the latter. Since the mussels feed upon essentially the same materials 

 as do the oysters, there is always danger of a greater or less exhaus- 

 tion of the food supply. 



In Long Island wSound the mussel is attacked in the following 

 manner: The mussel spawns and ''sets" — that is, attaches by the 

 byssus — perhaps a month or more before the oyster. Advantage 

 is taken of this fact, and when evidences are found of an alarming 

 number of young mussels on the oyster beds, they are ''harrowed" 

 by dragging over them an ordinary dredge with the bag removed 

 or open at the back. This process crushes and destroys the majority 

 of the tiny mussels without injury to the adult oysters. If this 

 process is carried out on a bed planted with shells to catch a set, 

 no harm is done, as the oysters have not yet spawned, and there is 

 consequently no oyster set on the shells. 



a Colton, H. S. How Fulgur and Sycotypus eat Oysters, Mussels, and Clams, 

 of Natural Sciences, Philadelphia, Vol. LX, 1908, pp. 3-10, 5 pis. Philadelphia. 



Proceedings, Academy 



