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-dse). 

 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 

 ^iw ^^ places whereback- 

 •^^^lily^- swimmers are 



J^K found. 

 ^^^^^S| There are two 



I ^^m I quite different 

 ' y ^ kinds of water- 

 I scorpions in this 



' country. In one 



of these, called 

 Ne/>a {Ne'pd), the body is flat and broad (Fig. 102) ; in 

 the other, called Ranatra {Ran! a-trd), the body is long 

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



