TERMS FOR PARTS OF MULTIVALVES. 9 



called goose-barnacle, of which so many strange 

 and silly tales have been told in former times. 

 (Plate 2, Lepas anatifera.) This species is 

 furnished with a kind of stem, like a bladder, and 

 is called the peduncle, (c) and is fastened to other 

 bodies. The feelers (d) are feathery projections, 

 which the animal keeps in continual motion, for 

 the purpose of catching its food. Here is a group 

 of another kind ; (Plate 2, Lepas tintinnahii- 

 lum ;) these are without a peduncle, and are 

 called sessile. The base {a) is that part of the 

 shell by which it is fixed to other bodies : (a) the 

 operculum is formed of four small valves on the 

 summit. (6) 



*' In the shells of the second division, Bivalves, 

 we shall find a greater number of parts. Valves 

 are the different pieces that compose a shell. 

 When both the valves are alike in form, the shell 

 is called equivalve: when the valves are different 

 in the same shell, it is called inequivalve. Mya^ 

 Solen, Te/^mft, are equivalves : Ostrea,Anomia, 

 Pinna, &c. are inequivalves. 



'' The hinge is formed by the teeth of one valve 

 inserting themselves between those of the other 

 valve, in some genera ; in others, by the teeth 

 fitting into the cavities of the other valve 

 (Plate 3. a.) When the teeth are placed in the 

 centre of the hinge they are called cardinal teeth. 



b5 



