cuiKimroDLS. 



. 5 



«"lnr KM produce a small species (Pa'rlta anomnln. Mull.). 



The /' h e, Lam., are OrbicuUe whose inferior valve is notched with a fissure* V7e must also approximate to 



the I IrbicaUB, 



The Of '""■ Bnig., whose auirnal has equally ciliated arms, but the shells have deep and round internal mus- 

 cular imp' in which some have fancied they saw a likeness to the figure of a ikoll. One {AnowUa cranio 

 luris, I.inii.i is a native of our seas. There are many fossil species, of which M. HoBninghaiU has given a beautiful 

 monograph. 



[The Preducta of Sowerhy is a fossil genus, with a shell somewhat like a Cardiom in figure, and rendered re- 

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

 [.peeies 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 tup: mollusca. 



THE CIRRIIOl'ODESt (Lepas and Triton, Linn.) 



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

 kingdom and that of Articulated Animals. Enveloped in a cloak, and in a sliell whose valves 

 often resemble those of several of the Aeephales, their mouth is furnished With lateral jaws, 

 and the abdomen with 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 branchiae on the 

 aides: the nervous system forms a series of ganglions in the abdomen. However, it maybe 

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

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

 of the Bivalves. The position of these animals in the shell is auch that the mouth is at the 

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

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

 back, is the vent. The stomach is puckered with a number of little cavities in its parictes, 



which appear to fulfil 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 fleshy tube pre- 

 viously mentioned. The eggs pass through this tube, 

 and in their course are exposed to the influence ol 

 the seminal fluid. The Cirrhopodes are all fixed, 

 Linnaeus considered them all as belonging to one 



genus, which Bruguieres divided into two, and 

 these have recently been much subdivided. 



Tin. Av i ri fa, Brug. — 

 Has a compressed cloak, open on one side, and 

 ; , & to a fleahj tube, varying greatly as to the 

 sr of testaceous pieces with which it is furnished. 



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



•h is,- nearest the month arc the shortest and thickest. 

 The branchiae are elongated pyramidical append 

 that adhere to the external base of the whole »i the 

 cirri, or Of part of them. 



lii the commonest Pentalatt I 



principal valves have a conalderabU wee to ti ■ 



M ; two othei - re to complete ■ part ol the n 



Of the shell ,. pp. i site the beak ; and I HMh Odd one unites the 



» v - iVr I, 



cmlrrlj- -»|..m l' '. uMafKtaallr I I 1Th«( • ' l "«- 



i r. 



I" |' of Anatifv dltuchr ! (0 • lb f't bullun 



