IIYDROrniLID.E. 



437 



are hatched in about eight days. They are myriapodous in 

 form, with a pair of large, long, lateral respiratory- tilameiits 

 on each segment, much as in the larva of 

 C'orydalus. The}' become full}- grown in Au- 

 gust, crawl out of the water and spin an oval 

 cocoon, within which the pui)a remains a 

 month, and then appears as a beetle. In 0;i- 

 rinus (Fig. 380, G. boreaUs Aubc ; Fig. 381, 

 larva of a European species) the scutellum is 

 distinct ; the species of Dineutxts, of which D. 

 canus is a type, are larger, and lack the scutellum. 

 Schiodte states that the larvte of Car ab idee , 

 Dytiscidce and Gyrinidm differ from those of other Coleop- 

 tera in having double claws, while in the others the tarsus is 

 undivided and claw-like. 



Hydropiiilid^ Leach. Carnivorous as larva?, but when 

 beetles, vegetable eaters, and living on refuse and decaying 

 matter, this family unites the habits of the foregoing fiimilies 

 with those of the scavenger Silphids. They are aquatic, small, 

 convex, oval, or hemispherical beetles, in which the middle and 

 ])osterior feet are sometimes adapted for 

 swinnning ; the antenna? are short, and the 

 palpi very long and slender. The females 

 spin a silken, turnip-shaped nidus for their 

 eggs, fifty to sixty in number, which ends 

 in a Iiorny projection, serving as a respira- 

 tory- tube to supply the young larviB with 

 uir as they are hatched. Others cany the 

 cocoon about with them on the under side 

 of the body. To spin this large amount of 

 silk, they are provided with two large silk 

 glands, with external spinnerets. The larva? 

 hatch in from two to six weeks, and moult 

 three times ; when mature they are long, cy- 

 lindrical, tapering rapidl}^ towards the pos- 

 terior end, with short legs, while the head is 

 flattened above and very convex beneath, Avith the mandibles 

 elevated much as in the larva of Cicindela, enabling them to 



