NATURAL HISTORY — ZOOLOGY. 225 



labouring under the idea that it could no longer subsist after being 

 thus voluntarily shut up, he considered it to be the pink of chivalry 

 and honour, in preferring to commit suicide rather than infringe on 

 its neighbour. In this inclosed state, the valves often become so 

 much altered in form, as well as in the relative proportion of their 

 different parts, as not to be easily recognisable as belonging to the 

 same species ; and one species (T. divaricata) was constituted from 

 specimens of T. Norvagica which had been so deformed. The food 

 of the Teredo consists of minute animalculre, which are brought 

 within the vortex of the inhalant siphon, and drawn into the stomach. 

 The wood which has been excavated also undergoes a kind of diges- 

 tion during its passage outwards through the long intestine. The 

 animal has been proved by Laurent and other observers to be capable 

 of renewing its shelly tube, and of repairing it in any part. It is 

 stated by Quatrefages (and apparently with truth) that the sexes are 

 separate, impregnation being effected in a similar mode to that 

 which takes place among palm-trees and other dioecious plants. 

 There appear to be only five or six males in one hundred individuals. 

 The Teredo perforates and inhabits sound wood only, but an allied 

 genus (Xylophaga) has been recently found to attack the submarine 

 telegraph cable between this country and Gibraltar at a depth of 

 from GO to 70 fathoms, and to have made its way through a thick 

 wrapper of cordage into the gutta-percha which covered the wire. 

 The penetration was fortunately discovered in time, and was not 

 deep enough to reach the wire. He gave several instances to show 

 the rapidity of its perforating powers, — one of them having been 

 supplied by Sir Leopold M 'Clintock while he was serving with the 

 author's brother in the North Pacific. 



Mr. Jeffreys then traced the geographical distribution of the 

 Teredines, and showed that at least two species, which are now 

 found living on our own shores, occurred in the post-pleistocene 

 period ; and he inferred from the circumstance of one of these species 

 having been found in fossil drift wood, that conditions similar to the 

 present existed during that epoch. Some species inhabit fixed wood, 

 and may be termed " littoral," while others are only found in 

 floating wood, and appear to be "pelagic." Each geographical 

 district has its own "littoral" species; and the old notion of the 

 ship- worm (which Linnaeus justly called " Calamilas Narium") 

 having been introduced into Europe from the Indies was contrary to 

 fact as well as theory, because no "littoral" species belonging to 

 tropical seas has ever been found living in the northern hemisphere, 

 or viae versa. It is true that some species have been occasionally 

 imported into this and other countries in ships' bottoms, and that 

 others occur in wood which has been wafted thither by the Gulf and 

 other oceanic currents ; but the fewer cases belong to littoral species, 

 and never survive their removal, while the latter may be said to be 

 almost cosmopolite. 



Every species of Teredo has its own peculiar tube, valves, and 

 pair of " pallets," the latter serving the office of opercula, and by 

 their means the animal is able at will to completely close the en- 



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