204 



tillus ; and however closely allied we may acknowledge them to 

 be, those genera may be distinguished by having the posterior 

 margin arquated somewhat prominently, the apices or beaks not 

 being terminal as in Mytillus. The latter naturalist gives the fol- 

 lowing account of the animal. " Body oval, dilated ; mantle open 

 at its inferior middle only, which at its anterior extremity is 

 fringed ; foot linguiform, canaliculate, with a byssus at its base 

 and many pairs of retractor muscles ; mouth with simple lips ; two 

 adductor muscles, of which the posterior one is very small. 



Several species are eatable, and the common Muscle of Europe 

 (3/. eduUs, L.) is taken to market in large quantities for the table. 

 All the species are marine with the exception of the M. polymor- 

 phus, Gm., or ChevinitzU, which inhabits the Danube and the 

 Commercial Docks near London, but which is probably not, strictly 

 speaking, of this genus, if we may judge by the somewhat cham- 

 bered appearance of the beak cavity. 



They attach themselves by means of their byssus to rocks, 

 stones and other fixed bodies, and even to one another. The 

 species are numerous ; Lamarck enumerates thirty-seven, of which 

 two are fossil, and several have been more recently described. 

 Some species are infested by a parasitical Pinnotheres. 



Mytillus hamatus. — Longitudinally grooved; incurved at 

 base. 



Mytillus hamatns, nob. Journ. Acad. Nat. Sci., vol. 2, p. 265. 

 Mytillus striatus, Barnes. 



Obs. A very common species in the Gulf of Mexico, and i.« 

 carried to the New Orleans market in consequence of its parasitical 

 attachment to the common oyster. Hardly a cluster 6f oysters can 

 there be found unaccompanied by one or more and generally nu- 

 merous specimens of this shell, in various stages of growth. Our 

 figure represents a fine large specimen, in which the incurved tip 

 is not so remarkable as in many smaller individuals, and the form 

 is somewhat more elongated and less triangular. It seems to ap- 

 proach M. dccussatus as described by Lamarck, but in that species 

 the transverse striae are stated to be unequal, and its inner margin 

 is not said to be of a diflFerent color ; a character which in our shell 

 is veiy obvious. Barnes read a description of it to the Lyceum of 

 Natural History of New York in 1823, (see Silliman's Jouinal. 

 vol. 6, p. 3G4.) 



