SUPPLEMENT ON CIRROPODA. 427 
mantle of the animal, which lines their interior, and opens 
anteriorly by a longitudinal cleft, as in the bivalves. The 
base of the shell is united to a fleshy tube more or less long, 
fixed by its other extremity to the rocks, to the timber 
of vessels, to fuci, to gorgons, and even to the sandy 
bottom of maritime coasts. ‘This tube is composed of three 
strata of fibres, of a circular form in the two external strata, 
and much harder, and more consistent than in the internal 
stratum. ‘The fibres of which this last is formed extend in a 
parallel manner, from one extremity of the tube to the other. 
It is by its base, or its posterior and inferior part, that the 
body of the anatifa adheres to the tube. The mouth, placed 
towards the middle of the belly, is directed forward, when the 
animal extends itself out of its shell, and upwards when it is 
folded back. It presents a very remarkable apparatus of 
organs. Six parallel thin leaflets, of a form almost triangular, 
denticulated at their lower edge, which is free, surround it 
superiorly, and on a part of the sides. The two external 
leaflets are attached a little to another organ, situated at the 
inferior part of the mouth, hard, very projecting, of a triangular 
form, and which much resembles a lower jaw. A pointed 
proboscis, at the base of which a small aperture may be ob- 
served, protected on each side by two triangular lamelle, 
terminates the upper extremity. Between it and the mouth, 
are, on each side, five or six trunks, which support an equal 
number of pairs of tentacula, of a corneous substance, whose 
length augments in proportion as they are removed from the 
mouth, composed of numerous articulations, ciliated and 
curved forwards. ‘The animal puts them forth from its shell 
and agitates them at every instant. It cannot be doubted, 
that it endeavours by this manceuvre to attract towards its 
mouth the alimentary corpuscula. It has an intestinal canal, 
which runs along the back, and ascends towards the pro- 
boscis, and two tubes winding at its sides, which hold the 
