CHAPTER XI. 



As every one knows, who has paid the least attention 

 to practical Natural History, there are very many 

 insects which can almost invariably be found in the 

 water, and very seldom elsewhere. Such, for example, 

 are to be found in the great groups of water beetles, 

 water boatmen, water gnats, water scorpions, etc., etc. 

 Now as all insects breathe atmospheric air, it is evident 

 that any insect which is found in the water must be a 

 trespasser, and therefore entitled to a notice in this 

 book. These insects are, however, so numerous, that 

 I can only select one of each kind as an example of 

 the entire group. 



Any one who has looked into a pond, or the still 

 parts of a stream, must have noticed the vast number 

 of beetles that inhabit the water; some spinning in 

 mazy circles on the surface, and seldom going below it ; 

 while others, with long oar- like legs, are perpetually 

 coming up from the depths below, and diving down 

 again out of sight. The general structure of all these 

 latter beetles is in all important points the same, and 

 so we will take one species as a representative of 

 them. 



