lo The Irish Nafuf-altsf* January, 



of destruction in amicable association just as we find them 



to-day.^ 



The rate at which these species carrj^ on their ravages is a 



matter of great interest, no less to unpractical students of 

 marine zoology than to harbour engineers, and the following 

 information, for which I am indebted to the courtes}- of the 

 Kingstown Harbour Commissioners; ma}^ be of use in deter- 

 mining that rate. The old piles now being removed from the 

 Carlisle Pier are of oak, Memel fir, and pitch pine, and those 

 reduced to a shell w-ere driven, some about the j^ear 1868, 

 others from 1877 to 1882. One of those driven between the 

 latter years has been reduced from 18 inches square to 10 

 inches square ; and of the other piles driven in 1886-87, three 

 have been reduced as follows : — 



{a) 19 in. X iS in. reduced to 14 in. x 13 in. 

 (b) 18 in. X 16 in. „ 12 in. x 9 in. 



(r) 16-^ in. x 16^ in. ,, 11 in. x it in. 



Greenheart shows most resistance to the attacks of the 

 Chchira^ but is not entirel}^ immune. 



Further information and facilities for examining both the 

 old piles removed from the pier to the harbour yard and those 

 still in situ at the pier, but badl}^ injured, were kindl}- given 

 me by Mr. R. de Witt Gra}^ Superintendent of Harbour 

 Works. One of the old piles shown me in the yard, a pile of 

 Memel fir, i6-| inches square^, which was driven in 1886-87, is 

 of peculiar interest. Of the portion of this pile between 

 high-water mark and the surface of the harbour bottom, 

 within which limits the operations of both Limnoria and 

 Chelura are confined, one half had been thickl}^ studded with 

 iron nails, a wxll-known preservative, which acts by coating 

 the surface and impregnating the superficial la3'er of wood 

 with iron oxide, while the other half had been left unpro- 

 tected. The latter half was very badly eaten, the ravages of 

 the crustaceans extending right up to, and apparently 

 ceasing at, the first row of nails in the protected part. But 

 on stooping down, it could be seen that large deep hollows, 



1 W. Thompsou, Ediuh. Philosoph. /oiiriia/, Jan. 1833, and Ann. and Mag. 

 Nat. Hist., 1847, p 161. 



