1907. Brownr. — Cork Conference. — Aquatic Coleoptera. 295 



it is sufficient for my present purpose- to mention four wide 

 groups which are easily recognisable : — 



1. Salt marsh or brackish water species ; 



2. Fresh-water marsh species — inhabitants of ditches* 



drains, and ponds containing Eemna, Callitriche 

 etc. ; 



3. Peat-moss species ; 



4. Runnings water species. 



There are of course many species which are more or less 

 cosmopolitan, but there are very few, if any, which are equally 

 common in all four kinds of habitat, although there are also 

 very few, if any, which are exclusively confined to one of the 

 four habitats. 



Such species, for instance, as Agabus co?ispersus, Marsh., 

 Philhydrus maritimus, Thorns., and Octhebius mari?ius, Payk., 

 are typical salt marsh species ; Hydroporus pictus, F., and 

 vittula, Er., Ilybius ater } De G., and many others, are typical of 

 stagnant ditches and ponds; while Hydroporus Gy/lenkalii, 

 Schiodte, tristis, Payk., and obsczirus, Sturm, Agabus affinis^ 

 Payk., and Ilybius cenescens, Thorns., are peat-moss species ; and 

 Haliplus fluviatiliSy Aube, Deronectes depressus, F., and 

 -yi\\.-pustulatus, F., Brychius elevatus, Panz., and Platambus 

 7?iaculatus, L-> are examples of the denizens of clear-running 

 streams. 



Of the five or six localities visited during the Conference 

 there was a peat-moss at Lough Allua (W. Cork) ; salt 

 marsh at Youghal (E.) and Kinsale (Mid), and clear-running 

 water at Carrigrohane (Mid), and the Gearagh, Macroom (W.) ; 

 while what I have included as freshwater marsh was worked 

 at Ballyphehane, Carrigrohane, Kinsale, and Farrangalway 

 (Mid), Youghal and Rostellan (East), and I am inclined to 

 think that the distribution observed depends chiefly, if not 

 entirely, upon habitat. 



With a total of only 42 collections it is useless to give the 

 percentage of occurrences of each species in the different 

 habitats, because the division between these is not nearly so 

 clear in reality as it appears on paper, so that one or two col- 

 lections included in the wrong category would, in such a small 

 total, greatly affect the results. Also, as I have said, very few 

 species, if any, are confined to one habitat, so that in a small 



