1912. Browne — Aquatic Coleoptera of S.E. Ireland. 11 



The extreme range of this group is from Antrim round 

 the east and south (^oasts to Clare, and the accompanying 

 " symbol " map indicates the :counties and vice-counties 

 for which any of the species are f-ecorded. A large proportion, 



6 out of 16, of these 

 species are maritime, 

 QQ viz., A. co7isj)ersus, Ph. 

 maritimus, H. Mtd- 

 santi, 0. viridis, marinus 

 and auriciilatus, yet so 

 far as is at present 

 known the extreme 

 hmit of Irish distribu- 

 tion of these halophiles 

 is from Antrim to Clare, 

 this extreme range only 

 being recorded for Ph. 

 ^ ^ t .. .u 4. maritimiis, the others 



Extreme range of the south-eastern ' 



„j-Q^^ not extending north 



beyond Down, or w^est 

 beyond Mid Cork. Some of the species in the hst have 

 so far only occurred in a single county, e.g., H. oblongus, 

 Rh. Grapii and H. nanus and most of the others are well 

 within the extreme limits of the group. 



The distribution of the species of this group in Britain is 

 interesting, as with the exception of B. mimdissimus which 

 belongs to Watson's " Atlantic " type, all the others belong 

 to the " English " tpye which includes those species con- 

 concentrated in the south. 



Just as these south-eastern Irish water-beetles have a 

 southern English distribution, so have the south-eastern 

 Irish plants, ^ and those land and fresh-water snails which 

 in Ireland show an eastern and south-eastern distribution 

 also tend to occur chiefly in the south of England. 



The question naturally arises, is this south-eastern group 

 a distinct element or t3'^pe in the Irish fauna, or is it a chance 



^ Praeger, R.Ll., On types of Distribution in the Irish Flora, 

 Proc, R. I, Acad,, xxiv.. Sect. B.. 1902, 



