Functions of the Limnoria Terebrans. SSi 



It is probable that the animal is prevented from boring' ia 

 wood covered with iron-nails, by finding the taste of the oxide, 

 which soon covers the interspaces between the heads of the nails, 

 not suited to its palate. The near approach which it makes to 

 iron-bolts passing through wood which it has once attacked, 

 seems to indicate that rust is not absolutely poisonous to it. 

 This was proved also, (as I am informed by Mr James Leslie, 

 civil-engineer), last summer at Trinity chain-pier, when a pile, 

 which had been, sometime before, covered with scupper-nails only 

 on three sides, was taken up, and found to have the whole interior 

 eaten out, only so much of the exterior being left on the three 

 sides as had been penetrated by the nails, and the oxide of iron. 

 I may here allude to the expediency of watching the condition 

 of piles exposed to the ravages of the limnoria, even when 

 covered with iron-nails ; because the heads of the nails frequently 

 fall off, after being much oxidated, and it is very possible that 

 the coat of oxide which they have previously communicated to 

 the pile, may also be abraded, so as to leave the wood wholly 

 exposed to the enemy. The nails which fall away ought to be 

 replaced by new ones as soon as possible. 



The public prints have recently announced that Mr Stevenson 

 has found a coating of some varnish effectual in protecting wood 

 from the limnoria at the Bell Rock. It is to be feared that the 

 use of such an article could not be depended on in all situations, 

 as it is so liable to be abraded by external violence. 

 •>.;J have now only pne other instance of destruction, caused by 

 the limnoria, to allude to particularly. It is met with in cer- 

 tain fir-piles fixed along the base of a stone bulwark, on the sea- 

 shore, in front of Leith Fort. These were erected about thirty 

 years ago, with the view of breaking the waves dashing against 

 the bulwark. They are from six to ten inches square, and are 

 arranged in three lines. The lower ones only have been at- 

 tacked, and the borings are carried upwards to within three or 

 four feet of mean high-water mark. A few of the piles have 

 been so much eaten away as to have been broken off near their 

 bases by the waves, and almost all are deeply abraded. Jjt 

 would seem to be owing to these piles being so near high water- 

 mark that they have not been wholly destroyed long ere now. 

 The animals contained in them arc rather smaller, and less ac- 

 tive than those in wood situated near low water-mark. It is 



