CLASSIFICATION OP INSECTS. 229 



very strong, and used in the water as antennjE ; 

 the form oval, the sides and baclc very convex, 

 the surface glabrous. Inhabits water, swimming 

 with ease, the feet being moved alternately ; 

 female covers her eggs with silk, forming a kind 

 of cocoon, which she carries about with her in the 

 manner of some spiders. Feeds on the decaying 

 leaves of water-plants. Spercheus, Hydrophilus, 

 Ilydroiis, Hydrobius, Berosus. 



764. Diving-bell beetles {Helophorites). Larva 

 less elongate ; sluggish ; margins of the segments 

 fringed with hair. Inhabits duckweed, and other 

 plants on the surface and banks of ponds, also the 

 surface of stones, mud, &c. Pupa changes some- 

 times in the same situations, but mostly in the 

 earth. Imago with antennaj more or less 

 clavated, short, and generally concealed ; the 

 maxillary feelers being employed as antennae ; 

 form elongate. Inhabits the banks of ponds and 

 rivers, among aquatic plants, on which it feeds ; 

 enclosed in a bubble of air, it crawls on water- 

 plants and on the surface of water, with the back 

 downwards, but does not swim. Hydrcena, 

 Helophorus, Hydrochus, Geonjssus, Elmis, Parnus, 

 Heterocerus. 



765. Water -fleas (Gyrinites). Larva with 

 strong arcuate mandibles ; a long fleshy process, 

 fringed with hair, rising from both sides of each 

 segment ; carnivorous, aquatic, natatory. Pupa 

 changes at the edge of ponds. Imago with 



