GLOSSARY. 205 



Muscular Impressions, arc the marks made by the muscles 

 with which the animal adlicrcsto the sliell, as in the Com- 

 mon Oyster. 



Obovate, nearly oval. 



Obsolete, obliterated. 



Obtuse, blunt pointed. 



Operculum, (in Multivalvcs), the stellular valves which shut 

 up the superior orifice: (in Univalves), the part which ex- 

 actly fits into the aperture and encloses the animal. 



Orbinilar, forming an entire circle. 



PapUlarif, 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, a tendinous substance belonging to some of the 



Multivalves, by means of which they adhere to solid bodies. 

 Pillar, see Columella. 

 Pillar-lip, that side of the aperture in which the columella is 



situated. 

 Pisiform, pea-like. 



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

 Posterior, see Margin. 



Reticulated, like net- work. 



Refuse, when the lower whorls are pressed into the body. 



Rostrum, see Beak. 



Rugose, wrinkled. 



Scabrous, rough. 



Serrated, toothed like a saw. 



Semilunar, like a half-moon. 



