^Ijz Irislj JJaturalist. 



VOL XXVII. 



PORCELLIO RATHKII 



A WOODLOUSE NEW TO THE IRISH FAUNA. 

 BY WALTER E. COLLINGE, D.SC, F.L.S. 



In their very thorough account of the Woodhce of Ireland^ 

 Messrs. Pack-Beresford and Foster remark, under the genus 

 PorceiUo, " The two species {Rathkii and Ratzehurgii) which 

 have not yet occurred in Ireland are, however, included in 

 the following table, as they are very likely to be eventually 

 taken here." 



In the preparation of my forthcoming Monograph on the 

 Woodlice of the British Isles, I have sought the aid of 

 various friends and correspondents in obtaining examples 

 of Irish specimens, and in a small collection recently obtained 

 from a garden near Dublin, I was pleased to find two 

 examples of Porcellio Rathkii, Brandt, which has not 

 hitherto been recorded for Ireland. 



I have elsewhere pointed out^ that this species may 

 easily be confused with forms of P. pictiis, Br. The lateral 

 cephalic lobes, however, in P. pictus are larger than in 

 P. Rathkii and terminally more truncate ; the median 

 lobe is less prominent and broadly rounded, and the 

 proximal joint of the fiagellum of the antenna is the longer 

 one. 



^ Proc. Roy. Irish Acad., 1911, vol. xxix., pp. 165-190, pi. viii 

 * ^coit. Nat., 1917, p. 137. 



