Mr. W. Thompson on Chelura terebrans, fyc. 163 



sixty -five hours; they were alive on Wednesday night at 12 

 o'clock and dead on the next morning at 7 o'clock. The wood 

 in which they were, was a small piece about six inches in length 

 and an inch in thickness ; it was not wetted since being received 

 on Monday, and was kept in a warm room (about 65° Fahrenheit) 

 all the time. The apparently simple fact of the species thus 

 living so long out of water has a very important bearing, for it 

 suggests to us that this species could, like the Limnoria, commit 

 its devastations in wood left dry by the ebbing of every tide. 

 Dr. Coldstream informs us that the latter species " often effects 

 a lodgment in piles very near high-water mark, where it is left 

 dry by the receding tide during the greater part of every 

 twenty-four hours*," and I have very little doubt that the 

 Chelura could play a similar part. I have not heard that the 

 extent of the damage done at Ardrossan by the destructive ani- 

 mals noticed in this communication has yet been estimated, but 

 on lately writing to my obliging friend and correspondent there, 

 requesting him to procure if possible perfect specimens of the 

 Xylophaga for dissection — the testaceous portions only had be- 

 fore been sent — he replied that the opportunity for so doing was 

 now past, M as the damaged portions of the dock-gates had been 

 replaced by sound timber." 



This may not be an inappropriate place to add the following 

 note on Teredo navalis. 



A copy of Loven's ' Index Molluscorum Scandinaviae ' lately 

 published, having been kindly sent me by the author, I was in- 

 duced, in consequence of the Teredo navalis, Linn., being there 

 considered distinct from that so called by other authors, to re-ex- 

 amine the shells bearing that name in my cabinet from different 

 parts of the British coasts. The result is that they are all the T. 

 norvegica, Spglr. (7 , .wtfi?«/2s,Turt.Brit.Biv.) as distinguished from 

 T. navalis, Linn. The localities from which they were obtained 

 are Portpatrick (Scotland) and Donaghadee (co. Down), in both 

 of which the animal was found alive — Miltown Malbay (co. Clare), 

 in drift timber — Belfast, in the bottom of a vessel arrived from 

 the tropics in 1846 : Teredo malleolus, Turt., was much more 

 numerous in this vessel — Belfast, also in blue clay (subfossil) : the 

 valves of these last are very large, being equal in size to those 

 described in my former paper as obtained at Portpatrick. I 

 allude here to specimens procured since that communication was 

 published, a portion of the bough of an oak-tree a few inches in 

 diameter, found during the excavation of a deep sewer, having 



♦ Edin. Phil. Journ. 1834. 



12* 



