J30 Mr Thompson on the Teredo navalis. 



were painted remained uninjured. The plan successfully prac- 

 tised in some places against the Teredo, of studding the timber 

 exposed to it, so closely with broad-headed nails, that the rust 

 exuding from them soon covers all the wood, has been quite ef- 

 fective here when used against this animal. Mr Stephen states 

 that the Limnoria is very destructive at Leith*, but it is un- 

 known at Dundee. Can we attribute its absence from the latter 

 place to the comparative freshness of the water there, as at the 

 Bell Rock situated so near, the destruction it caused was so 

 great as to be the means of first bringing the species to light. 



In March 1834, I saw in the collection of Robert Ball, Esq. 

 of Dublin, a specimen of wood pierced by the Limnoria, which 

 my friend informed me he procured at Yougal, in the county of 

 Cork, four or five years previously ; specimens of the Teredo 

 navalis, also shewn me by Mr Ball, were found by him in con- 

 junction with the former species, in the timber of a sluice exposed 

 to the influence of the sea. Mr Ball states, that about eight 

 years ago, he saw several pieces of timber from the harbour of 

 Dunmore,^ county of Waterford, that were perforated by the 

 Teredo, which caused great destruction there at that time. 



When on my way to England on the 27th March, I examined 

 the jetty at Kingston (Dublin Bay), which I am informed has 

 been seven years constructed, and observed that some of the tim- 

 bers, originally about eight inches thick, and two feet in breadth, 

 have been at the base, or where most under the influence of the 

 sea, entirely eaten away by the Limnoriae ; and that in others, 

 large nails project for nine inches from the present surface of the 

 wood, thereby shewing that the intermediate space has fallen a 

 prey to its ravages. During the two hours I remained there, 

 which were those immediately before and after the extreme of ebb- 

 tide, the part of the jetty which had most suffered, was left dry. 



• The entire of this paper (excepting the note on the Teredo, as observed 

 on the western coast of Ireland), was written previous to the publication of 

 DrColdstream'sexcellen', article on the subject of the Limnoria terebrans, in 

 the Edinburgh New Philosophical Journal for April 1834, in which the de- 

 struction produced by this animal at Leith, is particularly mentioned, as Well 

 as (on Mr Stevenson's authority) its occurrence on tlie coast of France and 

 the Netherlands. 



