53 



and open into tlu' mantle cavity of the oyster. The presence of 

 the sponge has also a detrimental etl'ect on the appearance of 

 the oysters when they are exposed for sale in the markets aud 

 lessens their vahie for canning. 



The mussel {Mydilus homatus) is found among the oysters 

 on most of the natural reefs, and to a less extent among the 

 planted oysters. Usually the number of the mussels is compara- 

 tively small, so that the damage is practically nothing. On some 

 of the natural reefs, however, the oysters are practically cov- 

 ered with the mussels, so that all of the water has to pass through 

 among the mussels before reaching the oysters. As the food of 

 the oyster and of the mussel consists of the same kinds of 

 microscopic plants, the presence of large numbers of the mus- 

 sels necessarily cuts down the amount of food that is available 

 for each, so that oysters taken from the badly "musseled" reefs 

 are always very poor. When the oysters are being taken for 

 market it is very difficult to cull off the mussels so as to make good 

 appearing stock, and when taking seed an extra amount of 

 culling is necessary or else a good part of the load will be made 

 up of the mussels which are not only useless as seed, but also 

 positively detrimental to the well-being of the oysters that are 

 being planted. 



The conch, snail', or borer {Purpura haemostonm) is found 

 on the oyster beds in practically all parts of the parish ; but i.-5 

 most abundant where the salinity of the water is highest. Al- 

 though considerable damage is attributed to the attacks of this 

 enemy, the evidence of its depredations is very meager. Some 

 few small oyster shells are found with a hole in one valve such 

 as might be made by this snail, but the number of shells attacked 

 in this way is always small -and there is no first hand evidence 

 that the borings were made by the Purpura. Siniee we lack any 

 conclusive evidence in this matter it is safe to consider this form 

 an. an enemy and to destroy them Avhenever possible. A great 

 deal can be accomplished toward their eradication by destroying 

 the egg capsules, which are conspicuous, brightly colored bodies, 

 attached to the stakes, and other pieces of wood, about the oyster 

 beds. Large numbers of the adult snails are taken up when the 

 beds are being worlccd in winter and if these were destroyed 

 instead of being thrown l)ack with the cullings, the number of 

 any bed would be materially reduced. 



