THE OYSTER. 183 



number of oysters to the square yard; second, the 

 ratio of living oysters to empty shells, and, third, the 

 ratio of mature to immature oysters. To ascertain the 

 number of oysters to the square yard, a dredge with a 

 mouth a yard wide was dragged over the bottom, for 

 a measured distance, at a definite rate of speed, and its 

 contents were then brought aboard and counted. This 

 method does not give perfect accuracy, for the dredge 

 does not, as a rule, take all the oysters ; the number 

 varying 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 comparable 

 with each other, 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 



