288 MOLLUSCA. 



CLASS VI. 

 CIRRHOPODA. 



[LEPAS and TRITON, Lin."] 



The Cirrhopoda, in several points of view, are intermediate be- 

 tween this division and that of the Articulata. Enveloped by a 

 mantle, and testaceous pieces which frequently resemble those seen 

 in several of the Acephala, their mouths are furnished with lateral 

 jaws, and the abdomen with filaments named cirri, arranged in pairs, 

 composed of a multitude of little ciliated articulations, and corres- 

 ponding to a sort of feet or fins similar to those observed under the 

 tail of several of the Crustacea. Their heart is situated in the dor- 

 sal region, and the branchiae on the sides; the nervous system forms 

 a series of ganglions on the abdomen. These cirri, however, may 

 be considered as analogous to the articulated appendages of certain 

 species of Teredo, while the ganglions in some respects are mere 

 repetitions of the posterior ganglion of the bivalves. The position 

 of these animals in the shell is such, that the mouth is at the bottom 

 and the cirri near the orifice. These animals are always fixed. 

 Linnaeus comprised them all in one genus, LEPAS, which Bru- 

 gieres divided into two, that have in their turn been subdivided. 



ANATIFA, Brug. 



A compressed mantle, open on one side and suspended to a fleshy tube, va- 

 rying greatly as to the number of testaceous pieces with which it is furnish,- 

 ed; twelve pair of cirri, six on each side, those nearest to the mouth being 

 the thickest and shortest. The branchiae are elongated pyramidal appen- 

 dages that adhere to the external base of the whole of the cirri, or J tjj|rpart 

 of them. 



The two principal valves, of the most numerous species (F ITTALASMIS, 

 Leach), resemble those of a Mytilus. The Anatifse adhere to rocks, piles, 

 keels of vessels, &c. 



BALANUS, Brug. 

 The principal part of the shell of the Balani consists of a testaceous tube 











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