This genus derived its name from the faculty it possesses of boring
wood. The T. navalis can penetrate the stoutest oaken planks of a ship’s
sides by means of two valves affixed to the head of the animal. The
effects produced would be much more destructive but from the fact of
their generally perforating the wood in the direction of the grain. Sir
E. Home wrote a very scientific and interesting description of a species
not mentioned by Lamarck, called the T. gigantea, found imbedded in
indurated mud in the Island of Sumatra. It is the largest species known,
some having been seen four or five feet long.
Shell thick, solid, very short or annular, open at both extremities;
equivalve, equilateral, angular and sharp anteriorly, only slightly
touching by the opposite edges; hinge obsolete; a considerable internal
spoonlike cavity; one slightly sensible muscular impression.
Tube more or less distinct from the substance in which the animal lives,
cylindrical, straight or flexuous, closed with age at the oral extremity
so as to envelop the animal and its shell; always open at the other end,
and divided interiorly into two syphons by a middle partition.
Teredo navalis.
T. palmulata.
T. gigantea.
_T. navalis._ The common Ship Worm.
Species very thin, cylindrical, and smooth; slightly twisted, white,
finely striated longitudinally.
FAMILY II.
PHOLADARIA. Two genera.