240' THE FISHERIES OF THE UNITED STATES. 



In illustration, I may contrast the condition of the oysters in the pond leased by the commission at St. Jerome and 

 those dredged ofl' Toint Lookout, in twenty or thirty feet of water, on the 3d day of October, 1 880. The oysters in 

 the pond, by the middle or end of September, were in good condition as to flesh, and marketable, while those from 

 deeper water off Point Lookout, and but little later in the season, were still extremely poor, thin and watery, and 

 utterly unfit for market. These differences in condition, it seems to me, are to be attributed in a great measure to 

 differences of temperature and the abundance of food, but mainly to the latter.* 



Ground-ice— North of Long Island an enemy is found, which does not exist in the milder south, in the shape 

 of " ground-ice" or "anchor-frost ". It is little understood, though often experienced, and I was able to collect only 

 vague data in regard to it. It ajjpears that in hard winters the bottom of the bays freezes solid in great patches, even 

 at a depth of 15 or 20 feet. The mud freezes so hard that rakes cannot be pressed into it ; and if a stronger implement, 

 like a ship's anchor, is able to penetrate it, the crust comes up in great chunks. These frozen patches are sometimes 

 40 feet square and continue uuthawed for long periods. When such "anchor-frost" takes place at an oyster-bed, 

 of course the mollusks are frozen solidly into the mass, and few of them ever survive the treatment. To the Cape 

 Cod planters this is a serious obstacle to success. 



* Op. cit., pp. 19-23. 



