CIRRHOPODES. 



385 



Our seas produce a small spccios (Patella nnomnla, Mull.). 



The Discing;, Lam., are Orbicula; whose inferior valve is notched with a fissure.* We must also approximate to 

 the Orbicuke, 



The Cr>iiiia, Brug., whose animal has equally ciliated arms, but the shells have deep and round internal mus- 

 cular impressions, in which some have fancied they saw a likeness to the figuie of a skull. One (Anumia crunio- 

 laris, Linn.) is a native of our seas. There are many fossil species, of which M. Hceninghaus has given a beautiful 

 monograph. 



[The 7'™d«c<aof Sowerby is a fossil genus, with a shell somewhat like a Cardium in figure, and rendered re- 

 markable by the manner in which the anterior margin is produced beyond the part inhabited by the animal. The 

 species are, to a certain extent, characteristic of the strata of secondary formation, and particularly of the carbon- 

 iferous or mountain limestone.] 



THE SIXTH CLASS OF THE MOLLU.SCA. 



THE CIRRHOl'ODESt (Lepas and Trito.n, Linn.) 



In several points of view the Cirrhopodes effect a sort of connection between tliis sub- 

 kingdom and tliat of Articulated Animals. Enveloped in a cloak, and in a shell whose valves 

 oltcu resemble those of several of the Acephales, their mouth is furnished with lateral jaws, 

 and the abdomen w itli filaments named cirri, arranged in pairs, composed of a number of little 

 ciliated articulations, and representing a kind of feet or swimmers, such as we see under the 

 tail of many Crustacea. The heart is situated in the dorsal region, and the brancliia; on the 

 sides : the nervous system forms a series of ganglions in the abdomen. ITowever, it may be 

 said that the cirrhous feet are merely the analogues of the articulated appendages of certain 

 Teredines, while the ganglions are in some resjieets only repetitions of the posterior ganglion 

 of the Bivalves. The jxisition of these animals in the shell is such that the mouth is at the 

 bottom, and the cirri near the orifice. Between the two last cirri there is a long fleshy tube, 

 which has been sometimes inadvertently mistaken for a proboscis ; and at its base, near the 

 back, is the vent. The stomach is puckered u ith a number of little cavities in its parietes, 



which appear to fidfil the functions of a liver : 

 we notice besides a simple intestine, a double 

 ovary, and a double serpentine canal termi- 

 nating in the extremity of the fiesliy tube pre- 

 viously mentioned. The eggs pass through this tube, 

 and in their course are exposed to the influence of 

 the seminal fluid. The Cirrhopodes are all fi.xed. 

 Linnaeus considered them all as belonging to one 

 genus, which Bruguieres divided into two, and 

 these have recentlv been much subdivided. 



The Anatifa, Bnig. — 

 Has a compressed cloak, open on one side, and sus- 

 peiuled to a fleshy tube, varyiug greatly as to the 

 nuinber of testaceous pieces with ^^llicb it is fiirnislied. 

 The animal has twelve pairs of cirri, six on each side ; 

 those nearest the month are the shortest and thickest. 

 The hranchiffi are elongated pyramidical appendages, 

 that adhere to the external base of the whole of the 

 cirri, or of part of tliera. 



In the commonest species {Peiitala.smis, Leach) the two 

 prncipal valves have a considerable resemblance to those or 

 a Mussel ; two others serve to complete a part of the margin 

 of the shell opposite the beak ; and a fifth odil one unites the 



, l;n.— ('roup of Am 



rt'liich we sent to liir 



1 Tlic Cirrip^drt ul L:ii 



u,p..d,- ., 



