Clare Island Survey. 



44 

 LAND AND FRESH-WATER ISOPODA. 



By NEVIN H. FOSTEE, M.B.O.U. 



Read April 22. Published June 4, 1912. 

 ISOPODA TeRRESTRIA. 



The survey of the Land Isopods (Woodliee) of Clare Island shows that in this 

 group the fauna of the island does not reveal any striking difference from 

 that of the adjacent mainland. Although only one species, Cylisticus convexus, 

 which has not been taken elsewhere in Co. Mayo, was discovered on the 

 island, it is likely that this woodlouse (very sparingly found throughout 

 Ireland, although recorded from fourteen counties 1 ) has been so far overlooked 

 in this county. 



Of the twenty-seven species of woodliee known in Ireland four — 

 Trichoniscus pusillus, Philoscia muscorum, Oniscus asellus, and Porcellio 

 scaber — are abundant in every county ; and in respect of these species the 

 same obtains on Clare Island and the Clew Bay islands, as also on Caher, 

 Inishturk and Inishbofin. At least five of the recorded Irish species must 

 be regarded as introduced exotics, and none of these has been observed in 

 Co. Mayo. 



The following nine species have been found on Clare Island : — 



Ligia oceanica (Linn.). Oniscus asellus Linn. 



Trichoniscus pusillus Brandt. Porcellio scaber Zatreille. 



Trichoniscoides albidus (Budde- P. pictus Brandt. 



Lund). P. dilatatus Brandt. 



Philoscia muscorum (Scopoli). Cylisticus convexus (Be Geer). 



All the species recorded from West Mayo have been observed on Clare 

 Tsland, with the exception of one, Metoponorthus cingendus, which had been 

 noted on Achill Island. It seems probable that this species may eventually 

 be found on Clare Island, as it is by no means rare in the west of Ireland. 



1 D. R. Pack Beresfoui) and Nevin H. Foster : " The Woodliee of Ireland : their distribution 

 •and classification." Proc. R. I. Acad., vol. xxix, sect. B, No. 4, March, 1911. 



R.I.A. PBOC, VOL. XXXI. A 44 



