82 SEA-SIDE STUDIES. 



of which there are several different kinds, all curious to the 

 philosopher, but none very interesting to keep. One species, 

 the Teredo navalis (Plate II., fig. 5), is a formidable fellow, 

 unloved of shipowners, since many a ship has been known 

 to split in the open sea, no one on board having suspected 

 that the planks had been thoroughly drilled through and 

 through by this patient borer. The hardest oak, nay, even 

 teak and sissoo woods, are no obstacles to this mollusc. The 

 chemical process which protects timber against decay is no 

 protection against the Teredo. The animal alway.s tunnels 

 in the direction of the grain of the wood, and if in its course 

 it meets with another gentleman engaged in the same pro- 

 cess, it alters the direction of its course, so that a piece of 

 wood attacked by many Teredos becomes completely lioney- 

 combed. In dockyards the defence has been to cover the 

 woodwork under water with iron nails ; and you may 

 imagine how necessaiy some protection is, since not only 

 have docks been perforated, but many years ago Holland 

 was thrown into terrible alarm by discovering that the piles 

 of her embankments had been riddled by these silent mol- 

 luscs, and all Europe thought that the United Provinces 

 were doomed. Other borers choose rock for their opera- 

 tions ; and many a solid-seeming mass is so perforated by 

 them, that the da.shing of a stormy sea may scatter it in 

 fragments along the coast. The fact of boring is familiar 

 enough to every one who has noticed the Rod-nose {Saxi- 

 cava rurjosa) peering from a thousand holes in the hard 

 limestone, and squirting water as it retires on the first 

 application of the hammer ; but while the fact is imdis- 



