X 



WATER-BOATMEN 



355 



(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 

 gaseous air at all. In the larvae 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. 108. 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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