THE OYSTER. 149 



dredge does not, as a rule, take all the oysters. The 

 number of oysters taken by the dredge varies with the 

 weight of the dredge, the speed of the boat, the depth 

 of the water, the length of the line, the character of 

 the bottom, etc. Still examinations of this sort, made 

 upon different beds by the same dredge used by the 

 same persons in the same boat and managed in the 

 same manner, give results which are reliable, although 

 it is more difficult to compare the results of two or 

 more examiners. 



The oysters captured in this way were carefully 

 separated from the empty shells and other refuse, and 

 both oysters and debris were measured and counted. 

 The oysters of various ages were then separated into 

 four sets : large oysters, or those less than 200 to the 

 bushel; medium oysters, or those between 200 and 

 300 to the bushel ; small oysters, or those over 400 

 to the bushel and over an inch long; and young 

 growth, or those less than an inch long. 



During this work we examined sixty-one beds and 

 made three hundred and forty hauls of the dredge ; 

 and the results of this examination are here given in 

 full, together with an analysis, and a comparison of 

 our results with those which had previously been ob- 

 tained by Winslow and others. 



In 1878 and 1879 Lieutenant Winslow found that 

 there were about .419 oysters to the square yard in 

 Tangier Sound, or one oyster to every two and three 

 hundred and eighty-six thousandths square yards. 

 As the Tangier Sound beds at that time showed indi- 

 cations of exhaustion, this number, .419 to the square 

 yard, is less than it would be upon uninjured beds. 



