122 



OBOVATE, nearly oval. 



OBSOLETE, obliterated. 



OBTUSE, blunt pointed. 



OPERCULUM, (in Multivalves,) the stellu- 

 lar valves which shut up the superior orifice: 

 (in Univalves,) the part Avhich exactly 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 stria?. 



PEDUNCLE, a tendinous substance be- 

 longing 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- form. 



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. 



SESSILE, low, dwarf. 



SINUOUS, waved. 



SINUS, a deep cut, as in the lip of the 



Murex Babylonis. 

 SLOPE, the side from the beak. 

 SPINOUS, having prickles or thorns. 

 SPIRE is formed by the whole of the upper 



whorls. 



STRIDE, lines flat, or slightly raised : they 

 are called longitudinal, when they run 

 from hinge to margin ; transverse, when 

 in a contrary direction ; and concentric, 

 when they form segments of circles. 



SUBCORDATE, approaching the form of a 

 heart. 



SUBPELLUCID, not quite clear. 



SUBULATE, tapering. 



SUPERIOR, see Margin. 



SUTURE, a toothed joint. 



SYPHON, a prolonged tube, running 



through the partitions of chambered 



cells. 



TEETH, (in Univalves.) angular plaits, as 

 on the pillar lip of Volutes: (in Bivalves,) 

 pointed protuberances within the hinge by 

 which the valves are united: they are 

 called alternate, when the teeth of one 

 valve are received between the teeth of 

 the other valve ; articulated, when the 

 tooth is received into a corresponding 

 cavity in the opposite valve ; cardinal, the 

 central tooth or teeth of the hinge ; com- 

 pressed, when flattened; erect, perpendic- 

 ular to the plane of the hinge ; forked, 

 having the point divided into two; longi- 

 tudinal, when it extends along the margin. 



TUBERCLE, a protuberance or knob. 



TUBERCULATED, having elevations re- 

 sembling warts. 



TUBULAR, (applied to Multivalves,) when 

 the greater part of the shell is cylindrical. 



TURBINATED, when the belly of the 

 shell is large in proportion to the spire, 

 which seems to proceed from the centre. 



UMBILICATED, having a hole in the base 



of a pillar. 

 UMBO, the summit. 

 UNDULATED, waved. 



VALVES, the different pieces which com- 

 pose the shell. 



VARIiE, Varices, longitudinal elevations 

 or ribs, formed by the junction of the dif- 

 ferent additions the shell has received. 



VENTRICOSE, bellied. 



VERMIFORM, having the form of worms. 



VERTEX, the top or point of a shell. 



WHORL, a spiral convolution. 



