GLOSSARY. 205 
Muscular Impressions, ave the marks made by the muscles 
with which the animal adheres to the shell, as in the Com- 
mon Oyster. 
Obovate, nearly oval. 
Obsolete, obliterated. 
Obtuse, blunt pointed. 
Operculum, (in Multivalves), the stellular valves which shut 
up the superior orifice: (in Univalves), the part which ex- 
actly fits into the aperture and encloses the animal. 
Orbicular, forming an entire circle. 
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 striz. 
Peduncle, a tendinous substance belonging to some of the 
Multivalves, by means of which they adhere to solid bodies. 
Pillar, see Colwmella. 
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. 
Retuse, 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. 
