Stislfox — List of Land and Freshtvater Mollusks of Ireland. 127 



Achill Island, where it is associated with 

 P. lilljcborgi and the lacustrine form of 



WD ED LD AN 



FE TY AR DO 

 WMSL LE MO 



EM EO CV LH 

 WG NG LF WH ME 



SG KG KD PU 

 CL NT QC CW WI 



NK LK ST KK WX 

 SK MC EC WA 

 WC 



P. casertanmn, while Major Trevelyan 

 has di'edged it in several lakes in Fer- 

 managh and East Donegal. The shells 

 which Dr. ScharU has recorded as 

 Pisidmm glolulare — a synonym of the 

 present shell — are now regarded hy 

 Mr. B. B. Woodward as a form of P. 

 pusilliim. Both P. steenhuchi and P. 

 lilljeborgi would appear from their dis- 

 tribution to belong to that group of 

 migrants whicli invaded this country 

 from the north at some very remote 



period, and to which Vertigo lilljehorgi 

 also belongs. 



Pisidium lilljeborgi Clessin. 



V/D ED LD AN 



FE TY AE DO 

 WMSL LE MO 



EM RO GV LH 

 WGNG LF WHME 

 SG KG KD DU 

 CL NT QC CW WI 

 NK LK ST KK WX 

 SK MC EC WA 

 WC 



Though not discovered in this country 

 until recently, this shell has now been 

 taken in several of the western di^'isioIlS, 

 from West Donegal to Achill Island in 

 West Mayo. Its known habitats are 

 all lakes with rather scanty vegetation 

 and stony bottoms, lying in barren and 

 uncultivated districts, but it is probably 

 widely distributed in the western and 

 northern counties. 



3. List of Erroneous and Doubtful Records. 



Though many of the doubtful records iu the following list will in all 

 probal)ility he eventually verified, it has laeen considered prudent not to 

 include them in Section 2 at present, as they are mainly foimded on old records, 

 and are not backed up by existing specimens. Where a record is listed as 

 erroneous, it does not mean that the particular shell in question is necessarily 

 absent from that di\dsion, but simply that the examples on which the record 

 was foimded are now considered to belong to another species. Though 

 probably not complete, I hope the list includes the majority of the erroneous 

 and doubtful records. Many of the former are due to the earlier conchologists, 

 who evidently believed that Ireland possessed all the species found in England. 

 They were therefore careless when making inquiries as to the origin of the 

 so-called Irish examples. 



