128 



INTRODUCTION. 



Family 54. HYDROPHILIDiE. 



Very var iable in size (-J mm. to 50 mm.) ; antennae inserted 

 before the eyes under the front angles of the forehead, short, six- to 

 nine-jointed, with the apical joints forming a pubescent club ; 

 maxillary palpi often very long, much longer than the antennae, ; 

 mentum large, quadrate ; eyes round or emarginate, rarely entirely 

 divided (Arnphiops) ; prosternum very short ; mesosternum mode- 

 rate, often raised longitudinally, sometimes produced into a long 

 spine ; legs furnished in some species with swimming hairs ; tarsi 

 Jive-jointed, the first joint sometimes very small, sometimes (Cymbio- 

 dyta, Hydrocoiiibus) obsolete ; abdomen as a rule -with five free 

 visible ventral segments, sometimes (Limnebius) seven, very rarely 

 (Qylli&mm) four. 



This is a very large and important family, comprising about 

 1000 known species. Dr. Sharp, however, believes that this 

 is not a tenth part of the existing number, and he is probably 

 right in saying that the family is likely to prove of even 

 greater extent and importance than the Dytiscld^ : for the 

 last-named family is rich in species in the colder regions of the 

 earth's surface, while the Hydrophilidje are more numerous in 

 the warmer regions, and have as yet been very little worked in 

 comparison with the northern Dytiscld.e. They are extremely 

 variable in size, aud as a large number of the members of the 

 family are small and obscure insects, they have been much 

 neglected. They are probably abundant in 

 India, the following genera being among 

 those represented there : — Hydrophilus, 

 Hydrous, Sternolophus, Hydrobius, Philhy- 

 drus, Berosas, Brachygaster, Globaria, Arn- 

 phiops, Hydrochus, Cyclonotum, Cercyon and 

 Spjhceridium. 



A considerable number of the species 

 have the maxillary palpi very long, much 

 longer than the antennae, and on this 

 account Mulsaut and others have given 

 the name Palpicornia or Palpicornes 

 to the family ; the character is no.t, 

 however, very strongly marked in all 

 cases. 



The larvae of the group are very different, 

 several of them presenting very strange 

 characters. Schiodte in his work on the larvae of Coleoptera 

 (Naturhist. Tidsskr. 1861-1873, T. viii-ix) has described and 

 figured the larvae of eight or nine genera. The head, as a rule, is 

 small, but in Spterclieus it is very large ; in Hydrous the segments 

 are furnished at the sides with long fringed appendages (much as 



Fig. 55. 



Hydrophilus olivaceus. 



