1228 OYSTERS, AND ALL ABOUT THEM. 



secondly, because at the period of spatting it covers the 

 cnlch, so that the spat that settle thereon is lost ; weed 

 collects mud, which smothers the spat, and generally makes 

 the ground foul. 



Sabella is a tube-inhabiting annelid, with an arena- 

 ceous covering that accumulates round the cylindrical tube. 

 Sand thus deposited is a coarse, brown, friable substance, 

 commonly called "ross." If it contains the worm, it is 

 called "live ross," if not "dead ross." It is objectionable 

 because it grows extremely rapidly on and around the 

 oysters, tending to smother them ; and when the w r orm 

 dies, it turns black and poisons the young spat. It can 

 easily be scraped off an oyster-shell, but of course increases 

 the trouble of preparing them for the market. The oyster 

 underneath the sabella will be found quite intact, proving 

 that it is not a direct enemy. 



Acorn barnacles, called in the Thames estuary " chit- 

 ters," are very small barnacles which appear to prefer cal- 

 careous substances on which to attach themselves. They 

 are the least harmful of any of the previous enemies we have 

 mentioned, but they form on the culch, and thus prevent 

 the spat from getting fairly attached. Deep-sea oysters, 

 particularly those from the Skelling banks, have frequently 

 larger sized barnacles attached to them, which are appa- 

 rently of the same nature as acorn barnacles. 



i 



ANNELIDS, POCH, POLYPS, BLUBBER, &c. 



These are all objectionable on oyster-beds, making the 

 ground foul, and if from any cause they die, decomposition 

 will set in, and the very young oysters will succumb to its 

 poisonous influence. The younger the oyster, the more 

 delicate is its constitution, and the easier it succumbs to 

 bad diet. 



