184 TEREDO. SHIP-WORM. 



primary valves, from the hinge to the pointed margin, about 

 three-quarters of an inch ; diameter not quite so much. 



Sir Everard Home, in his minute account of the Teredo 

 navalis and its inhabitant, observes, that the smaller end of 

 the tube, or that which protrudes outwards from the wood, 

 is contracted but not divided into two canals, as in that of 

 the T. gigantea ; and has taken no notice of the semi-con- 

 camerated formation of the tube below the spoon-shaped 

 valves. There is on the wharf at Teignmouth, at the time 

 we are writing these remarks, a tree of British oak, iden- 

 tified by its marks as having been some years since lost 

 in the bay, lately trawled up, rilled with these animals in 

 a living state, exhibiting a proof that they are natives of 

 our own climate, and at the same time offering a fine study 

 of the species. The surface of this tree, especially at the 

 ends, is covered over with the tubes, protruding beyond 

 the wood from a quarter of an inch to an inch and a half, 

 all of them with a double orifice and chambered internal 

 structure. If therefore it be accurate that the specimens 

 ' which Sir E. Home received from Sheerness had a simple 

 orifice, and were without the chambered partition, our 

 present species is evidently distinct, and should be deno- 

 minated Teredo concamerata. 



There is a good figure of this shell, but without descrip- 

 tion, in Humphrey's and Da Costa's Conchology, plate 10. 

 fig. 1, 2, 3, the third figure showing the internal semi-con- 

 camerated formation. ' v. v. 



2. Teredo bipennata. Feathered Ship-worm. Fig. 38, 

 39, 40. 



Shell resembling the last, but on the posterior side or 

 that which is opposite the triangular projection, and close 

 under the hinge, is an ear-shaped process of an oblong 

 shape, reflected at the outer margin, and detached ail 

 round on the under side by the longitudinal rib forming a 

 kind of sharp raised keel. 



The tube is thicker and stronger than the last, simple 

 at its outer orifice, without the spoon-shaped valves ; in- 

 stead of which there are inclosed two slender flexible sub- 

 stances, of a spongy rather than testaceous texture, nearly 

 lour inches long and hardly the tenth of au inch in diame- 

 ter, 



