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CHAPTER IV. 



HYDRADEPHAGA. 



WE have now completed our notices of the Geode- 

 phaga, the analogues of the land Carnivora among 

 the higher animals, and we now come to the HYDRA- 

 DEPHAGA, or carnivorous Beetles of the water the 

 whales, porpoises, and seals of the insect world. 



We know that all animals are specially adapted 

 to the life which they have to lead, and therefore may 

 naturally expect that Beetles which live in the water 

 will be formed very differently from those which 

 reside on the land, even though that land be con- 

 stantly wet. Shape, for example, is likely to be 

 altered. We know that the whales, dolphins, and 

 seals, who have to pass either the whole or the greater 

 part of their lives in the water, and to catch in it the 

 living prey on which they feed, become assimilated 

 in shape to the fishes ; and it is likely that insects 

 will obey the same laws as mammals. This is really 

 the case, the shape of all the Hydradephaga being 

 very fish-like, in order to enable them to pass more 

 easily through the water. As there is much more 

 friction in passing through the water than through 

 the air, the Water Beetles, as the Hydradephaga are 



