WATER-BOATMEN 



i55 



(seven in Nepa, two in Ranatra), whose minute struc- 

 ture shows that they supply the egg and embryo with 

 air. The fresh-hatched larva of Ranatra has no 

 respiratory tube, and perhaps does not take in 

 o-aseous air at all. In the larvse of all Nepidae the 

 tube is short. 



The remaining aquatic Rhynchota which we have 

 to describe are the Notonectidae or Water-boatmen. 

 These Insects are very common in stagnant waters, 



Fig. io8.— Water-boatman, Notonecta glauca. 



one of them, Notonecta, occurring in profusion where 

 decaying organic matter provides subsistence for the 

 animals on which it preys. In the Water-boatmen 

 the hind-legs are developed as oars, and become 

 flattened, fringed with hairs, and useless for loco- 

 motion on land. Of the two genera most commonly 

 met with, one, Corixa, swims about like a Water- 

 beetle, with the back upwards, but the other, Noto- 

 necta, with the back downwards. Like most other 



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