184 
TEREDO. SHIP-JVORM. 
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 
liavalis 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 Tcignmouth, 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, tilled 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 Costas Conch ology,plate 10. 
fig. 1, 2, 3, the third figure showing the internal scmi-con- 
canrerated formation, v. v. 
2. Teredo bipennata. Feathered Ship-worm. Fig. 38, 
39, 40. 
Shell resembling the last, hut 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-sliaped valves • in¬ 
stead of which there are inclosed two slender flexible sub¬ 
stances, of a spongy rather than testaceous texture, nearly, 
four inches long and hardly the tenth of an inch in diame¬ 
ter. 
