46 LIFE IN THE SEA [OH. 



appearance. The succession of the planktonic larvae 

 in any sea area is generally the same from year to 

 year, and it can be predicted. Let us take the suc- 

 cession of organisms in the sea of Liverpool Bay as 

 an example. We should notice first of all the eggs 

 of fishes, chiefly cod, plaice, whiting, dab and some 

 others, and then the larvae of these species of fishes. 

 By the end of May all these would have disappeared. 

 The larvae of barnacles appear in the water during 

 the month of March, with the larvae of numerous 

 species of crabs, and all these persist for a time, but 

 soon the barnacle larvae become metamorphosed to 

 their final stages, and the crab larvae are also trans- 

 formed to further forms. About the end of May the 

 barnacle larvae would have disappeared entirely, but 

 the later crab larvae would still persist. About the 

 end of May the larvae of shrimps would appear in 

 quantity, but would very soon leave the plankton, as 

 they take up their permanent habitat on the sea- 

 bottom. At the end of Ma} 7 and the beginning of June 

 the later spawning fishes would contribute their eggs 

 to the plankton, but by the end of August these also 

 would mostly have gone down to the sea-bottom as 

 demersal organisms. June is the season for many other 

 planktonic larvae, such as those of many marine worms, 

 sea-urchins, or starfishes, and of these some would last 

 on till near the end of the autumn, but by that time 

 most of the larvae would have left the plankton. 



