OF CONCHOLOGY. 13 



genera, to make the student ac- 

 quainted with the terms used in Tes- 

 taceology, as far as regards the dif- 

 erent parts of shells. 



EXPLANATION 



OF THE 



PARTS OF SHELLS. 



MTJLTITALTE. 



Operculum is four small valves on 

 the summit of the lepas, which how- 

 ever is in a certain degree stationary ; 

 and different from the operculum of 

 univalve shells, which will hereafter be 

 described. See plate 1st, fig. 1st, A. 



Base is that part of the shell by 

 which it is fixed to rocks and other 

 bodies; plate 1st, figures 1st and 2d, 

 B B B. — H is a piece of stone to which 



