51 



slate covered with a dense colony of ascidians ; in this 

 condition a great percentage of available surface is lost 

 which ought to serve for the attachment of spat. The 

 surfaces so occupied would also be comparatively clean 

 were it not for these organisms which actually become a 

 serious annoyance. They, like the oyster, affix them- 

 selves to the slates while still in the free swimming larval 

 stage, since the surfaces designed for the oyster are equal- 

 ly well adapted to them. The barnacles which also affix 

 themselves in great numbers become a nuisance for the 

 same reason. The larval barnacle is an extremely active 

 little creature and dashes about in the water with great 

 rapidity. As soon as it has completed this stage of its 

 growth, it betakes itself to some object to the surface of 

 which it attaches itself by the head end, when a singular 

 change takes jDlace, at the end of which it is found that 

 it has begun the construction of the curious conical shell 

 which it inhabits. They grow very rapidly, so that in a 

 coux^le of months the shell will already measure over half 

 an inch in diameter. In this way farther inroads are 

 made upon the room which should be taken up by oys- 

 ters. 



Of course, the larger types are not alone in taking up 

 space, since infusorious, bryoza, polyps, etc., are also cul- 

 pable, as well as algae, such as diatoms and the higher 

 forms. The only remedy for this accumulation of ani- 

 mal growths on the surfaces of the slates and other col- 

 lecting apparatus, will be to have the frames which hold 

 the slate in position so arranged that each tile, shingle or 

 slate can be removed, in order that it may be readily over- 

 hauled and these organisms removed from the surfaces 

 which it is desired shall reniain clean. This work would 

 have to be done at intervals of every two or three weeks, 

 and should be conducted with great care so as not to re- 

 move the oysters which have affixed themselves along 

 with, the other things wliicli it is the intention to destroy. 

 Tlie removal of the smaller forms from the surfaces of 



