25 



the camps on the shore of the bay there were several busliels ol' 

 the shells of oysters that had been opened during the past winter, 

 and each of these showed the same effect of the sponge as was 

 to be observed in the shells now on the reefs. In the living 

 oysters examined, as well as in the shells of those recently opened, 

 many of the burrows of the sponge extended entirely through 

 the shell and had necessitated an unusual secretion of limey ma- 

 terial by the oyster to close the openings on the inside of the 

 shells. This unusual drain on the vitality of the oyster would, 

 in part at least, account for their poor condition, and besides 

 the presence of the sponge protruding beyond the shell would 

 serve as a collector of sediment and also interfere with the feed- 

 ing of the oysters. 



On some of the reefs many living conchs {Purpura haemos- 

 toma) were found, and a large number of the shells of this form 

 were piled around the camps. Very few of the oyster shells, 

 however, showed the attacks of this boring mollusc, and the 

 amount of damage done by it is probably very slight when com- 

 pared with that done hy the sponge. 



The most practical way to overcome the trouble caused by 

 the sponge would be to thoroughly clean the beds of dead shells 

 by means of a dredge, so as to destroy the breeding sponges, and 

 at the same time the greater number of the snails would be de- 

 stroyed. In combatting the conchs the destruction of the eggs 

 is one of the most efficient methods. The q^^ capsules are promi- 

 nent purplish masses that are attached to the stakes and other 

 immovable bodies so that they can readily be found and are easily 

 destroyed. 



Pelican Lake, just east from Bay Wilson, w^ith which it is 

 connected by a number of passes, is some three miles long and 

 two miles wide. Along the north side of the lake the depth of 

 the water is from five to seven feet ; but over the greater portion 

 of the lake it is from two and one-half to four feet. In the south- 

 ern part of the lake there are several old reefs that are exposed 

 at low tide, while the depth of the water over many of the others 

 is not more than from six to eighteen inches. Everywhere out- 

 side of the old reefs the bottom is too soft to support seed oysters. 

 All of the natural reefs have apparently been destroyed, the only 



