A DICTIONARY OF TERMS. 



lvii 



Membrane. - A skin, or pellicle, susceptible of being inflated 

 like a bladder. The Helix janihina has a mem- 

 brane which it inflates like a bunch of grapes, 

 or soap bubbles. 



Minute. - - A term applied to shells that require a lens to 

 distinguish their several parts. 



Mollusc a. - Animals inhabiting shells, belong to the class 

 Mollusca. 



Mouth. - •- The aperture, or opening of a shell. It is gene- 

 rally round, or long ; though sometimes trian- 

 gular, and even quadrangular. 



Multilocular. Having several divisions, or compartments. All 

 chambered shells are multilocular, and abound 

 in the minute species. 



Multivalve. - Having more than two valves. The Barnacle 

 and the P kolas are multivalve shells. 



Muscle. - - A flexible, fleshy, fibrous organ, by which the 

 animals, especially of bivalves, are attached to 

 their shells. v, 



O. 



Oblique. - - Diverging from right to left, or from left to right. 

 Some shells are obliquely striated. 



Obtuse. - - Blunt pointed. The spire of the Volute is obtuse. 



Operculum. - A solid, horny, or calcareous substance, gene- 

 rally round and flat, which fits exactly into the 

 mouth of Univalves, and serves the animal as a 

 lid, or cover, with which it can shut itself into 

 its shell. Multivalves, such as the Lepas, have 

 also an operculum. 



Orbicular. - Of a round shape. 



Papyraceous. Thin as paper. The Paper Nautilus, is of this 



description. 

 Pedicle. - - A stalk. The Barnacles are raised on pedicles. 

 Pelagian. - Inhabiting the deep. 

 vol. i. e 



