Clare Island Survey— Aqwttic Coleoptera. 29 10 



tardus, Herbst. has spread along the south coast only. Hdochares pundatus 

 which is common in West Mayo and has also occurred in West Gal way 

 extends along the south coast as far as Wexford, and Odhebius viridis 

 extends from Armagh round the south and west coasts to West Mayo. 

 It seems possible therefore that the southern section of these western 

 water-beetles may be merely a squeezed-out portion of the main 

 southern group of immigrants. .On the other hand, it might be that 

 in the west of Ireland they represent a relict of the pre-Glacial temperate 

 fauna, while the English and southern Irish individuals have reappeared 

 from the south in post-Glacial times. The British distribution of P. nigro- 



SI 









01 









NS CA 





HI3 





SS 







S 



RWRE EL BF AN 

 WI EI PN AS 







M 



AM PM FF KI 







I 



DN SG PC KF 







CT 



B RE LL ED HD 

 AY LA PE BWNN 



WD ED LD AN 







WTKB DF SK RX SN 



FE TY All 



DO 





CV WLNY DM 



WM SL LE MO 







IM ML MYEY 



EM RO CV LH 







A SL WYSY LN 



WGNG LF WUME 







OR DB FT CH DY NM LS 



SG KC KD DU 







MX MG SP St LR CB WN EN 



CL NT QC CWWI 







CD RA HF WO WWSO HU WS ES 



NK LK ST KK WX 







PB CM BR GE OX BX BD HT NE 



SK MC EC WA 







GM MM GW NW BK MX SE 



AYC 







L NS SWNHSR WK EK 



ND SS DT SH WXEX 

 EC SD nv 



SC WC 



Fig. 3.— Distribution of Paiacymus nigro-neneus, Sa/tll). 



aeneus seems to favour this view. It occurs in the southern English counties 

 from Kent in the east as far north as Nottingham and it reappears in 

 western Scotland in Main Argyll, Coll and Mull (Mid-Ebudes), and Eigg 

 (North Ebudes). Its occurrence in the Isle of Man, which was entirely 

 glaciated, and where the whole fauna and flora are undoubtedly post-Glacial, 

 is not so easily accounted for unless it is one of those " ectopic " cases 



