AQUATIC GNAT 1ARVA. 63 



compass of a basin filled from an adjacent pond. When 

 complete,, the boat consists of from 250 to 350 eggs, of which, 

 though each is heavy enough to sink in water, the whole com- 

 pose a structure perfectly buoyant, so buoyant as to float 

 amidst the most violent agitation. What is yet more wonderful, 

 though hollow, it never fills with water, and even if we push it 

 to the bottom of our mimic pool, it will rise unwetted to the 

 surface. This cunning craft has been likened to a London 

 wherry, being sharp and high fore and aft, convex below, 

 concave above, and always floating on its keel. In a few days 

 each of the numerous " lives " within having put on the shape 

 of a grub or Larva, issues from the lower end of its own flask- 

 shaped egg, but the empty shells continuing still attached, the 

 boat remains a boat till reduced by weather to a wreck. 



Here let us leave it, and follow the fortunes of one of the crew 

 after he has left his. cabin, which he quits in rather a singular 

 manner, emerging through its bottom into the water. Happily, 

 however, he is bom a swimmer and can take his pleasure in 

 his native element, poising himself near its surface head down- 

 wards, tail upwards. Why chooses he this strange position ? 

 Just for the same reason that we rather prefer, when taking a 

 dabble in the waves, to have our heads above water, for the 

 convenience, namely, of receiving a due supply of air, which 

 the little swimmer in question sucks in through a sort of tube 

 in his tail. This breathing apparatus, as well as the tail itself, 

 serves also for a buoy, and both end in a sort of funnel, com- 



