occurring in Plymouth Harbour. 209 



bottom of the piers. While going round, I saw some of the 

 mooring buoys from the Sound, which were then being hoist- 

 ed in for repair, and although they had not been down more 

 than 2 or 3 years, their under surfaces were so eaten, as to 

 render them waterlogged ; from this circumstance, as well as 

 in that of the Busy cutter, it appears that the Limnoria is 

 disposed to attack floating timber as well as that which is 

 fixed. 



Having thus shown that the Limnoria at present occupies 

 every part of Plymouth Harbour, it would be an interesting 

 question to ascertain whether it be an indigenous animal, or 

 as some consider, an imported one. I am inclined to believe 

 that it is an indigenous animal, as from the mode of its ope- 

 rations, the timber might easily be supposed to be decayed, 

 and the animal overlooked ; for althogh its identity was not 

 pointed out until it was discovered by Mr. Stevenson at the 

 Bell Rock in 1807, who sent it to Dr. Leach (see Lin. Trans, 

 vol, ii. p. 370), yet I am assured by Mr. Roberts and others, 

 that its effects have been observed in this dock-yard, for these 

 forty years. Again on referring to two excellentpapers on this 

 subject, one by Dr. Coldstream, who gives a drawing and his- 

 tory of the animal, in vol. xvi. of Jameson's Edinburgh new 

 Philosophical Journal, it will be seen that after being first 

 pointed out at the Bell Rock, it was found at the Crinan 

 Canal ; Trinity Pier, Leith Fort, and recently in Torbay, be- 

 sides being noticed by Mr. Stevenson on the coasts of France 

 and the Netherlands. The other paper by Mr. Thompson, 

 in vol. xviii. of the same Journal, shews that it has been found, 

 together with the Teredo, at Portpatrick in Ayr ; at Belfast ; 

 Donaghadee ; Youghall ; Dunmore ; and Kingston Harbour 

 (Dublin). It is also known in Bridlington Harbour, and by 

 a notice at the late meeting of the British Association at 

 Liverpool, it appears to be existing at Southampton. From all 

 these observations I think it a fair inference, that both these 

 animals have long existed on the coasts of our island ; and 

 that if at any time they might have been considered as fresh- 

 ly imported, they are now so fully established as to have be- 

 come entirely naturalized as British. 



It is a matter of the greatest importance to discover the 

 best preservative against the attacks of these formidable ani- 

 mals, as the expenses annually incurred even in this dock- 

 yard, in copper, iron and labour of repairs, are sometimes 

 enormous. The use of stone, though most effectual, is not 

 always applicable, as in the dock-yard jetties, which require 

 to be built on numerous piles of timber, in order to have the 

 effect of breaking the force of the water in high winds, there- 



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