GLOSSARY. Xm 



M'hich the ligament is situated : posterior, tlie space on 

 the other side of the hinge: superior, the space be- 

 tween the anterior and posterior parts. 



Marginate, (in Univalves), having the sides of the shell 

 thickened ; (in Bivalves), surrounded with an elevated 

 margin. 



Mouthy see Aperture. 



MuscUy a fleshy, flexible organ by which the animal 

 is attached to its shell. 



Muscular Impressions, are the marks made by the mus- 

 cles with which the animal adheres to the shell, as may 

 be seen in the common oyster. 



Obovate, nearly oval. 



Obsolete, obliterated. 



Obtuse, blunt pointed. 



Operculum, (in Multivalves), the four stellular valves 

 which shut up the superior orifice: (in Univalves), the 

 part which exactly fits into the aperture and encloses 

 the animal. 



Papillary, having the apex rounded. 



Papyraceous, of the thinness of paper. 



Patulous, gaping. 



Pectinated, when the longitudinal ribs on the anterior 

 surface form acute angles with the transverse striae. 



Peduncle, is a tendinous substance belonging to some of 

 the Multivalves, by means of which they adhere to so- 

 lid bodies. 



Pillar^ see Columella 



Pisiform, pea-like. 



Plaited, when the columella is toothed, as in Volutes. 



Posteriorf see Margin, 



