152 



BRANCH ARTHROPODA 



The carnivorous water beetles (Dylic'idce), of which there are three 

 hundred species, are found everywhere in streams and ponds (Fig. 123). 

 They vary in length from I to 1 } inches. The diving beetle projects the tip 



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Fig. 122. — Ground beetle (Calosoma), similar to C. scrutator; below, a 

 Carabus. (Brehm.) 



of its abdomen through the surface film to breathe. It raises the elytra a 

 little, and the air which is caught under them is held by the fine hairs on the 



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n 





Fig. 123. — Carnivorous water beetles. (Brehm.) 



back, where the spiracles are situated. Thus, it carries a supply of air 

 which enables it to breathe under water. These beetles make interesting 

 aquarium specimens. 



