64 BRITISH BEETLES. 



with great quickness, and may be often seen at the 

 surface of the water, with their tail upwards, taking in 

 air, which thus reaches the spiracles. D. punctulatus 

 (Plate III, Tig. 1) is entirely black beneath. 



When ponds, etc., are dried up in the summer, the 

 Dytiscides take to the wing, flying by night or at the 

 evening in search of fresh waters ; it is astonishing, how- 

 ever, with what a small supply of damp they will exist, 

 and the greatest "hauls" of specimens are often made 

 out of the merest cupful of muddy water, the residue 

 of some large pond, in which all the beetle occupants 

 are congregated. They have been known, in flight, to 

 dash against glass or lights, possibly mistaking them for 

 water. 



Water-beetles, as a rule, are fond of gathering round 

 reeds and water-plants in the middle of ponds; and, in 

 dragging for them, the net should be scraped along 

 banks, round any projecting wood or stones, and through 

 and under weeds. After doing so, it is a good plan to 

 go over the same water again, in a reverse direction, as 

 many specimens get dislodged, but not captured, by the 

 first operation. In running streams, the beetles often 

 congregate in little pools caused by eddies and back- 

 waters, and shelter themselves on the quiet sides of 

 arches. To show how readily they fly, it may be re- 

 marked that holes in gravel pits, when converted into 

 pools by heavy rain, are soon tenanted by the large 

 Dytisci. 



The species of Dytiscus exhibit a great family like- 

 ness, but are separated chiefly through the greater or 

 less width, length, and sharpness of the forked pro- 

 cesses of the coxse at the base of the two hinder legs. 

 They are mostly found in stagnant waters, but many of 



