PLATE IV. 



Tab. XIII. Back-swimmers: adults and nymphs. 

 Tab XV. Nepa. 

 Tab. XVI. Ranatra. 



Tab. XIV. Naucorid. The above are photographs of the plates in 

 Frisch, an old text published in 1727. Among the first published illus- 

 trations of water bugs. (Not the first, however.) 



Photo. 1. The toad bug resting upon sand. 



Photo. 2. Vential view of female Corixid. Note the peculiar beak 

 and remarkable differentiation of the limbs. 

 Photo. 3. Notonecta undulata. Say. 

 Photo 4. Bucnoa margareiacea. Bueno. 

 Photo. 5. Female Corixid — Ramphocorixa acuminata. Uhl. 



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