300 NATURAL HISTORY OF OUR SHORES 



of animals that live between the tidal zones and haunt the 

 bottom, but there is a vast and varied population that is 

 pelagic. 



During the summer months especially the sea surface 

 is pretty well a living mass of gyrating, darting forms of 

 microscopic size, usually transparent, but sometimes so 

 coloured as to give a characteristic tint to large areas. 



An enumeration of what these are is not usually under- 

 taken, but they are generally covered by an all-embracing 

 term" Plankton." 



This pelagic fauna varies with the seasons. In early 

 spring the larval stages of the cirripedes abound, and the 

 zoea stages of many of the higher Crustacea begin to appear. 

 The larval forms of worms and eggs and larvae of fishes 

 abound. 



Later on most of these vanish and new ones take their 

 place Copepods and Ostracods, Amphipods and Isopods, 

 the Mysids and the Cumas, the Megalopa stages of the 

 crabs, and the little jelly-fish generation of the Hydroid 

 zoophytes a floating population in more than one sense, 

 ever changing, but always there. 



The way in which the naturalist obtains his gatherings 

 is by means of the " Tow Net," a method of collection that 

 is done with a minimum of trouble. 



The Tow Net may be a simple, home-made affair or a 

 somewhat mechanical arrangement. 



In laboratories, where research is made as to what forms 

 haunt different depths, etc., tow nets are employed to 

 work at varied levels, and these open and close when 

 the desired depth is arrived at and departed from, so as 

 to secure only the animals of that particular situation. 



Some nets are made of fine silk gauze, to secure the in- 

 finitely small infusorians, etc. Others have a bottle at the 

 tail end, to bottle up the captives as they come in. But I 

 am writing an outline, a little book intended as an incentive 



