BROOK INSECTS 



61 



Fig. 32. Young Stone- 

 fly ; g, gills. 



water. These in- 

 sect s arc either 

 young stone-flies 

 (fig- 3 2 ) or young 

 May-flies (fig. 33). 

 The young stone- 

 flies have two tiny 

 claws on their feet 

 (examine with a 

 magnifierj and are 

 usually more flat- 

 tened and broader- 

 bodied than the 

 young May-flies, 

 whose feet end in 

 a single small claw. 

 Take some of these 

 insects alive to the 

 school room, where 

 they can be kept in 



Fig. 33. Young May fly; 5% gillj 



a glass jar of water for a day or two. Put one of them into a 

 watch glass of water, and examine it with a magnifier. Is it a 

 young stone-fly (two claws on feet) or a young May -fly (one claw 

 on feet?) Examine the delicate gills projecting from the sides of 

 the body : the young stone- flies usually have three pairs of gills 

 on the thorax (part of the insect from which the legs arise), 

 which are tufts of short gill-hairs ; the young May-flies usually 

 have gills all along the abdomen, which may be transparent 

 thin plates, or composed of gill hairs. (For an account of the 

 way in which water insects breathe, and of the tracheal gills, 

 see the lesson, "How Insects Breathe.") Note that the legs of the 

 young stone-fly are flattened and thickly fringed with stout hairs. 

 What for ? So that the legs may serve for swimming as well as 



