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TRANSACTIONS. 
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TEREDO NAVALIS (THE SHIPWORM), 
BY 
MR. SIBERT SAUNDERS. 
Read APRIL 5, 1882. 
The so-called ‘‘ Ship-worm,”’ although its appearance would 
seem to justify its popular name, is in reality a molluscous animal, 
ranking with the conchifera. Looking at the long, worm-like body, 
extending through the whole length of the tubular cavity which 
the creature has formed by boring into the wood in which it has 
found a habitation, it is indeed difficult to recognize its claim to be 
classed with the bivalve molluscs; and Godfrey Sellius in 1738 
was the first to discover that, notwithstanding the remarkable 
modifications of structure rendered necessary by the conditions 
under which the animal has to live, its true relationship is with 
the molluscs, and not with the annelids, and that it is very closely 
allied to the Pholades, whose curious excavations in stone are well 
known. 
On opening the tubular chamber containing a Teredo, the 
animal is seen as a soft, thin, vermicular body which is, for the 
most part, an extension of the mantle enclosing the riband-like 
branchiz and the two long siphonal tubes, through one of which 
water is taken in for respiration and food, while through the other 
the exhausted water is discharged. The extremities of these 
tubes are very small, just fitting ‘the opening in the surface of the 
timber through which the embryo first entered, and which, 
originally minute, becomes somewhat enlarged as the animal 
grows ; partly by the wearing away of the surface, and partly by 
the friction of the siphons—the tips of which are somewhat 
roughened. The external orifice in the wood, however, never 
becomes so large as to attract attention, until the surface becomes 
actually broken through, either by rough treatment from outside 
or the decay of the wood. The posterior extremity of the body is 
also furnished with two opercula, formed of calcareous matter, and 
these when brought together, close the external orifice, the siphon- 
tubes being then retracted. The body gradually increases in size 
towards what may be termed the head, which has a small, well- 
