THE BAY OF BISCAY. 225 



of wood, that had been perforated by wide and deep 

 galleries. I at once recognised the work of the 

 Teredo, and having soon discovered the animals 

 themselves, I was fully reassured as to the future 

 success of my expedition, and I felt that two or three 

 months would scarcely be too much to devote to the 

 thorough investigation of this singular and too cele- 

 brated Mollusc. 



The Teredo is an Acephalous Mollusc belonging 

 to the same class as the Oyster, Mussel, &c., and yet 

 at first sight there seems to be no resemblance be- 

 tween them. Imagine to yourself a kind of worm of 

 a somewhat greyish white colour, which is sometimes 

 as much as a foot in length, and from six to eight 

 lines in diameter, one extremity of which terminates 

 in a sort of rounded head, whilst the other is like a 

 bifurcated tail. Such is the aspect of a perfectly 

 developed Teredo when removed from its tube. The 

 part which I have called the head consists of two 

 small valves, something like two halves of a deeply 

 notched nut shell. These valves are immoveable, 

 and only protect a small part of the body properly 

 so called. The liver and the ovaries lie in contact 

 with one another, very far back and behind the 

 rudimentary shell, whilst the branchiae are placed in 

 the posterior part of the body. The mantle, forming 

 a sort of fleshy case, envelopes all the viscera, and 

 afterwards divides into two tubes, which the animal 

 extends or contracts at will. One of these tubes 

 serves to introduce the aerated water, which bathes 

 the branchiae, and carries to the mouth the organic 

 molecules, which are necessary for the nutrition of 



VOL. II. Q 



