37 2 LAKES AND STREAMS 



the banks of streams, in woods and hilly countries, occurs the large dragon-fly 

 (JSsch na grandis), a species from 2A- to 2f inches in length, with a T-shaped spot on 

 the forehead, a yellow or reddish brown-spotted body, two yellow streaks on the side 

 of the thorax, and blue spots on the back between the wings and on the side of 

 the hind part of the abdomen. Another kind is the beautiful Cahpteryx virgo 

 about 1J inches long, and common everywhere, with the body of the male metallic 

 blue, and that of the female metallic green; the broadly rounded wings of the 

 former being bluish black, and those of the latter reddish brown. 







DEMOISELLE DKACOK-FLY. 



The day-flies, en- May-flies, which belong to the same group, are 

 more remarkable from their number than from their size. These 

 insects have rudimentary mouth-organs, small or rudimentary hind-wings, and two 

 or three slender bristles or tail-like appendages at the end of the body. They are 

 remarkable in their development and mode of life ; the fully-developed insect, unlike 

 any other, casting its skin twice, and pairing in the air, after which it often dies in 

 the space of a few hours without having once taken food. The cast skins are left 

 in numbers on plants along the margins of water; and some species appear during 

 August, towards evening, in such numbers on the banks of streams that their 

 bodies have been \ised as manure. The larva?, which are provided with leaf-like 

 breathing-organs, live from two to three years in the water, passing through a 



