NATURAL LOCALITIES OF BRITISH COLEOPTERA. 201 



while the duller ones are found in stagnant water, the former ai-e 

 usually the best species, but this may be due to the fact that the 

 latter are more easily found, and therefore commoner. 



Almost every stagnant pool in summer contains some beetles, 

 and very often a tiny puddle will yield a more abundant harvest 

 than a large pond : the water beetles are amphibious, or more 

 than amphibious, for they can swdm in water and walk on land, 

 while their ample wings enable them to fly powerfully through 

 the air ; in consequence of their facility of movement from place 

 to place, we find quite recent pools and puddles sometimes alive 

 with beetles ; drought does not affect them, for if a pool dries up 

 they do not perish like the fish and other inhabitants, but have 

 only to seek a fresh habitation ; they are not very discriminating, 

 and are evidently guided to water by sight, for they are often 

 found on hot-bed frames, on which they have dashed them- 

 selves, mistaking the reflection of the glass for the reflection 

 of water. 



The commonest beetles in all stagnant waters are Hyphydrus 

 ovatus, Hydroporus palustris, Haliplus ruficollis, Agahus bipustu- 

 latus, Hydrohius fuscipes, and one or two Helophori and other 

 Philhydrida. There is liardl}^ a pond or ditch in which these are 

 not found, and there are many others that are almost equally 

 common ; even the rarer species as a rule are rather local than 

 scarce, and where one specimen is found many more may usually 

 be procured by closer examination. Thus Sperclieus emarginatus, 

 which used to be one of the very rarest of our British water 

 beetles, only one or two specimens from Yaxley Fen being known, 

 was rediscovered by Mr. Billups near West Ham, where Messrs. 

 Perkins and Champion found it in numbers. Not long ago Mr. 

 Harris, of Burton, found the rare Haliplus mucronatus in abundance 

 at Weston-super-Mare : there are however exceptions ; thus 

 Hydroporus ohlongus and H. Scalesianus are always rare in 

 Askham Bog, almost their only known locality, and Hydroporus 

 unistriatus, the rarest of the Hydropori, seems always to occur 

 singly at wide intervals of time. Cyhister Roeselii has been said 

 to have occurred at Walton, in Essex, and a specimen was 

 formerly in Mr. Griesbach's collection, but it is very improbable 

 that such a large beetle should have escaped notice if really 

 indigenous, and it ought certainly not to be reintroduced into 

 our list. 



