162 Zoological Collections, 



** An interesting debate followed as to the mode of action of the valves of 

 the Teredo; in the course of which Mr Wilcox observed, that he thought 

 Dr Turton, in his observations relative to Sir E. Home's opinion on the 

 modus operandi of this animal, had mistaken tlie action of the double nosed 

 auger, and had described it as a centre bit ; but that their opinions of the 

 method of boring admitted of being reconciled ; the mode appearing to 

 be, that, by a secretion from its body, the decomposition of the material 

 is effected and reduced to a species of soft mud or pulp, which is mecha- 

 nically removed, and a fine polished surface left. This idea, while it 

 agrees with many of the statements, does not invalidate the experiments 

 made on the charcoal produced by burning the excreraentitious matter, 

 and meets the difficulty which at first appears as to the possibility of such 

 fragile animals piercing materials of so hard a texture- 



" At the conclusion of this lecture, the curator of the museum drew a 

 comparison between the recent Teredines and the fossil remains of that 

 animal, as exhibited in specimens of wood from the London clay of Sheppy ; 

 showing, that, though the identity of these could not now be ascertained, 

 yet such identity was very probable, as their operation and effects appear 

 to have been the same. He also produced specimens of the Mytilus litho- 

 yhdgus, M. Fholadis, and M. rugosus, the two former penetrating ma- 

 drepores, the latter limestone. 



" Having pointed out the structure of the animals, and the formation of 

 the valves, he concluded, that, possessing no apparent means of producing 

 their perforations by a mechanical operation, this tribe at least might be 

 considered as producing this effect by a chemical solvent, which, as the 

 substances acted upon were calcareous, was probably an acid ; although 

 he admitted that the action of tests had not made the presence of such se- 

 cretion satisfactorily apparent,— recommending a prosecution of observa- 

 tions and experiments, as the subject had excited much attention." 



iVo/e.— On the subject of boring marine animals, and their means of 

 perforating wood and rocks, see this Journal, vol. v. p. 98, and vol. vi. 

 p. 270. The assumption of a chemical solvent by Mr Wilcox is, in the 

 present state of our knowledge, entirely gratuitous, as the most delicate 

 tests have failed in detecting any such solvent or acid fluid. In supposing 

 the LepismcB also to burrow in submerged timber, we suspect Mr W. 

 labours under a misiake. It is more probable that the animal he alludes 

 to may be congenerous with the one which has committed similar depre- 

 dations on the piles of the Chain Pier at Trinity near Edinburgh, and of 

 which a notice follows. 



3. Destruction of the Piles at the Chain Pier by the Limnoria terebrans. 



As a sequel to the preceding observations the ravages of the Limnoria 

 terebrans on the piles of the Chain Pier at Trinity may be noticed. These 

 piles were on examination found to be perforated through a great part of 

 their thickness by a marine animal, in a very short time, and thus render- 

 ed unserviceable. The extension of the eastern pier at Leith, which was 

 proposed to be chiefly a wooden erection, induced Mr Day, one of the Dock 



