194 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



After a time it grows a shell and settles down as a fully 

 formed little mussel. 



outh. 



Various 



n the growth of the mussel. (All magnified). 



The Development of the Flounder . — 

 Eggs of the flounder will be examined with the micro- 

 scope every afternoon. On the second day of the class a 

 number of eggs will be taken from several female fish, and 

 these will be fertilised by milt from male fish. A sample 

 of this batch of eggs will be examined every afternoon, 

 and the little fishes studied as they form inside the egg- 

 shell. These fish will hatch out in from seven to ten days, 

 according to the temperature of the sea-water. 



Fourth Day. 



The Tow-net and Plankton. 



Although the sea-water may look perfectly clear, yet 

 it nearly always contains great quantities of very small 

 animals and plants. These can be caught by means of a 

 tow-net, which is a small net made of fine silk, or muslin, 



