No. 505] THE CANADIAN OYSTER 35 



furnished with a linen rim in which was tied the neck 

 of a wide-mouthed bottle. To the towing line, in front 

 of the net, was fastened a sinker and the whole was 

 dragged through the sea-water, behind the little steamer 

 Ostrea, under reduced speed, for about a mile, when the 

 net was hauled up, the contained water carefully drained 

 through one side, after which it was dipped several 

 times right side up into the sea and raised so as to wash 

 all the plankton material down into the bottle. The 

 bottle could then be removed and corked, the net washed 

 by throwing it overboard again open, and other bottles 

 used for different places or different depths on the same 

 excursion. 



In such a manner may be procured a wealth of plank- 

 ton material, but slight modifications in mode of operation 

 may be employed, depending upon the nature and object 

 of one's research. The older bivalve larvae are compact, 

 heavy, well protected, so that they will stand compar- 

 atively rough usage. By the time one reaches the labo- 

 ratory the great mass of the copepods may be dead and 

 sunk '.towards the bottom of the bottle, but underneath 

 this mass one can see the darker, granular, more sand-like 

 bivalves. These may be withdrawn by a glass tube and 

 emptied into a watch glass, the more superficial, lighter 

 things being again removed by a pipette. In this way 

 bivalve larvae may be obtained, sometimes by thousands, 

 and almost entirely free from admixture with other ani- 

 mals, while among them, if collected at the proper time 

 and place, will occur oyster larva?. 



At Malpeque the full-grown, free-swimming, pelagic, 

 or more or less abyssal, or creeping larva of the oyster 

 (Figs. 3, 7, 8, 9) possesses a characteristic brownish-red 

 color— suggestive of the soil of its native island shores— a 

 shade which enables it to be immediately distinguishable 

 from every other bivalve larva with which it is associated. 

 The shell (prodissoconch) is asymmetrical, inequivalve 

 and inequipartite, the left valve being larger, more con- 

 vex and with a large umbo, the right one smaller, flatter 



