CLASS OF CBUSTACEA. 449 



so long as their life endures, to some submarine body, and 

 completely change their form. It is by the back that they 

 thus adhere, and their body, more or less pyriform and 

 curved on itself, is enclosed, in whole or in the greater part, 

 in a kind of shell, composed of several pieces (Fig. 435). 

 They have no eyes, and their mouth is furnished with man- 

 dibles and jaws having the strongest resemblance with those 

 of certain Crustacea; the abdominal aspect of their body is 

 occupied by two rows of fleshy lobes, having each long horny 

 appendages, furnished with cilia, and composed of a great 

 number of joints. These kinds of arms or cirrhi, numbering 

 twelve pairs, are curved on themselves, and the animal con- 

 stantly protrudes and withdraws them by the opening of its 

 sheath or case. At the extremity of this series of organs is 

 found a kind of tail, having the form of a long fleshy tentacle, 

 at the base of which is the anus. Their nervous system is 

 composed of a double chain of ganglions, disposed exactly as 

 in the other articulated animals. They have a heart, lodged 

 in the dorsal part of their body, and they breathe by branchiae 

 whose form varies. 



The cirrhipoda are divided into two families the anatifae 

 and the balani. 



The Anatifse (Fig. 435) (called also lepas anatifera) 

 are enclosed in a kind of compressed mantle, open on one side, 

 and suspended by a long- fleshy peduncle ; sometimes this 

 mantle is almost entirely cartilaginous : at other times it is 

 covered by five testaceous plates, of which the two principal 

 ones bear some resemblance to those of a muscle. The 

 common anatifa dwells in our seas, and is frequently found 

 attached to rocks, to the keels of ships, and to pieces of 

 floating timber. It has been the subject of most absurd 

 fables ; some coarse resemblance of its shell 

 to a bird, gave origin to the silly tale, that 

 from these animals came the goose called 

 barnacle. 



The Balani or sea glands (Fig. 436) abound 

 on the rocks of our seas, and are contained 

 wholly in a kind of shell, generally conical, 

 and very short, fixed by its base, and com- Fig.436.-Balanus. 

 posed of several lappets, articulated with 

 each other: the opening of this tube is occupied by two or 

 four moveable valves, between which is found a fissure des- 

 tined to give passage to the cirrhi. 



