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whence the animal throws out tentacula. The body of the shell has 
an appearance resembling stalactites, and was found filled with a soft 
gelatinous flesh : but there appeared no indication of the animal 
having adhered to any part of the internal surface of the shell, which 
was in general smooth. 
Rumphius has figured one species of this shell ; but his figure exhi- 
bits two long jointed tubes, issuing from the upper part of the exterior 
tube ; and he describes them to be found in shallow water, among the 
mangrove trees. The shell of Rumphius differs from that of Mr. 
Griffiths, in having the two tubes through which the tentacula pass, 
of considerable length, and entirely separate. 
Sir Joseph Banks, on seeing this shell, had no doubt of its being a 
Teredo ; and the truth of Sir Joseph’s opinion has been since esta- 
blished by the discovery of the two boring shells and the two flattened 
opercula, which form the decided character of teredines : these, Mr. 
Home states, were found enclosed in one of the specimens. This 
shell is therefore considered by Mr. Home as belonging to a new 
species of Teredo, which he names Teredo gigantea *. 
On examining the Teredo navalis, whilst preserved in sea-water, 
Mr. Home found that the animal threw out sometimes one and some- 
times two small tubes : one of these, about f of an inch long, the other 
only half that size. In examining the shell, while in the wood, its 
external orifice is very small, just large enough to give a passage to 
the two small tubes. The sides of the cylinder are thickest near its 
origin, becoming thinner towards the head of the animal. 
The head of the animal is enclosed between the two boring shells, 
which are united together by a digastric muscle. From the middle of 
the exposed part of the head projects a kind of proboscis, which there 
is reason to believe acts as centre bit. 
The body of the worm is enclosed in one general covering, extending 
* Description of a rare species of worm-shells, discovered at an Island lying off the North- 
West coast of the Island of Sumatra, in the East Indies. Philosophical Transactions, 1806. 
