oct. — dec. 1857.] The Pearl Oyster of Ceylon. 



leaving behind a strong fibre with an oval disc, of the form of the 

 groove in the foot. This whitish fibre is attached to the base of 

 the foot at one end, and to the rock, or to the shell of another 

 Oyster, at the other. In a day or two, this fibre becomes of a bronz- 

 ed greenish colour, and looks like hair, with abroad flattened oval 

 root attached to the rock. This process is again and again repeated, 

 at intervals of a few minutes, till a sufficiently strong cable is form- 

 ed. In a large Oyster, removed from the sea, upwards of fifty such 

 fibres form a thick strong cable or byssus, which is attached to the 

 base of the foot by a bifurcated fleshy root. The animal cannot de- 

 tach the byssus from the rock to which it is attached, but it has 

 the power of casting it off its own body and leaving it behind, (like 

 a ship letting slip her cable and anchor in a storm, and sailing off 

 to sea) in order to make another byssus, either on the same rock, or 

 on any other convenient place. 



I observed all this process in the aquarium at a very early period 

 of my investigations ; and was not surprised to find, that the Pearl 

 Oyster having nearly the same organs as the Mussel, should form 

 and reform its byssus. But I was agreeably satisfied in learning by 

 these observations, that Captain Steuart, in his valuable and inter- 

 esting Monograph on the Pearl Fisheries of Ceylon, was incorrect 

 in denying to the Pearl Oyster this faculty. He states, that " it is 

 not believed that the Pearl Oysters have the power to detach them- 

 selves, or to remove at their own will." I have not only satisfied my- 

 self, and many friends who have seen the Oysters in the aquaria 

 which I have established, that the Pearl Oyster can detach or unmoor 

 itself, but likewise that it walks away with its foot foremost, and the 

 shell behind ; and does not, as Captain Steuart observes, "move with 

 its hinges in advance.^ This " shuffling" movement alone attracted 

 Captain Steuart's attention, but it is an unimportant one ; as all 

 bivalves without a byssus have it, and it is independent of the will 

 of the animal, owing to the valves being opened and closed for the 

 purpose of respiration. How imperfect must Captain Steuart, a 

 candid inquirer, now say, have been his long observations, when 

 the Oyster is seen, night after night, taking a walk round the in- 

 side of a chatty, or mounting the glass side of a vivarium, forming, 

 here and there, a byssus. It is most unfortunate, that he and 



