106 BRITISH BEETLES. 



sides of rivers and ponds, and will frequently come up 

 out of the damp mud in great numbers on the collector 

 treading about ; and if the sun be shining, will fly readily. 

 Some species form galleries under stones, etc., near semi- 

 saline waters, and most of them appear to be gregarious. 



All those found in Britain have been described by 

 Mr. G. R. Waterhouse, in the Trans. Ent. Soc., vol. v. 

 n. s., part 4, 1859. 



ThePARNiD^E are aquatic or sub-aquatic in their habits, 

 and are divided into two sub-families, the Parnides and 

 Elmides, both having the head received into a prolon- 

 gation of the prosternum, and the anterior segments of 

 the abdomen soldered together; differing, however, in 

 their anterior coxae, which are cylindrical and transverse 

 in the first, and almost globular in the latter. In the 

 PARNIDES the body is clothed thickly with short hairs, 

 and the second joint of the antennae assumes a widened, 

 ear-like form : the species are found near or in running 

 water, on stones or water plants. 



The ELMIDES (which are much smaller) have the 

 antennae very little thickened at the apex, no tooth to 

 the mandibles (which are, however, bifid) ; scarcely any 

 pubescence on the body, which is often metallic and 

 frequently caked with dirt ; and the last joint of the 

 tarsi very long, with exceedingly strong claws. They 

 cling to the rough undersides of large stones in strongly- 

 running waters, especially delighting in such as are un- 

 der or close to a fall of any kind; and may be found at 

 a considerable depth from the surface. They are grega- 

 rious in habit, many examples of different species (or 

 even genera) being sometimes found together. 



The GEORYSSID^: (comprising one genus and species, 

 which is very small, apterous, and almost globular) 



