128 INSECT LIFE. 



following label, and immediately after the water- 

 striders, for these insects also belong to the order 

 Hemiptera : — 



Family Notonectid^ (No-to-nec'ti-dae). 

 The Back- swimmers. 



An Essay on Back-swimmers (School Work).—> 

 Write an account of what you have learned regard- 

 ing back-swimmers. 



The Water-scorpions (Field and School Work). — • 

 Among the strange insects that live in ponds, but 

 come to the surface to obtain air, are the water-scor- 

 pions. These are not so com- 

 mon as the back -swimmers, 

 but as they are found in simi- 

 lar situations, there may be 

 specimens among those insects 

 in your aquaria collected by 

 sweeping the stems of sub- 

 merged plants. If not, search 

 for them in the 

 ^i. 1^^ placeswhereback- 

 -<— Ijly-^ swimmers are 



j|Hr found. 



^^^BX| There are two 



I ^H^ I quite different 



^T^ ' kinds of water- 



I scorpions in this 



• country. In one 



Fig. I02. f iv n J ^^°- '°3- 



of these, called 

 Nepa (Ne'pd), the body is flat and broad (Fig. 102) ; in 

 the othfer, called Ranatra (Ran'a-trd), the body is long 

 and very slender (Fig. 103). In both, the hind end 



