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CRENATED, crenulate, having blunt teeth. 

 CORDIFORM, heart-shaped. 

 CORONATED, having the apex surround- 

 ed with a row of tubercles or spines. 



DECOLLATED, having the spire, or the 

 upper part of the shell, truncated trans- 

 versely. 



DECUSSATED, intersected by stria?, at 

 acute angles. 



DENTATED, having teeth. 



DIAPHANOUS, transparent. 



DIGITATED, having projecting claws. 



DIVARICATED, obliquely striated. 



DORSAL, belonging to the back. 



EARS, external projections on the sides of 

 the hinge. 



EFFUSE, having the lip separated by a 

 gutter. 



EMARGINATE, having the margin exca- 

 vated by a canal. 



EPIDERMIS, the outer skin or covering of 

 a shell. 



EQUILATERAL, when the anterior and 

 posterior parts of a shell are exactly sim- 

 ilar. 



EQUIVALVE, (applied to Multivalves,) 

 when the two principal valves have the 

 same form, size and position: (to Bivalves,) 

 when the two valves are exactly similar. 



EXSERTED, very thin or slender. 



FISSURE, a notch or slit. 



FURROW, a gutter or groove, running 



parallel to the hinge, in Bivalves. 

 FUSIFORM, spindle-shaped. 



GAPING, (in Bivalves,) when the valves do 

 not shut close : (in Univalves,) when the 

 lower part of the lips is distended. 



GIBBOSITY, a swelling. 



GIBBOUS, swelled. 



GLABROUS, smooth. 



HINGE, the part, where the valves are 

 united, and generally furnished with one 

 or more teeth. It is said to be compressed, 



16 



when it is formed of one compressed tooth 

 lateral, when placed on one side of the 

 shell ; reflected, when its edges are folded 

 over the exterior margin ; terminal, if sit- 

 uated at the extremity of the shell. 

 HISPID, covered with hairs, as in the Helix 

 Hispida. 



IMBRICATE, when the surface is covered 

 with scales partially covering each other. 



IMPERFORATE, having no umbilicus. 



INEQUILATERAL, when the anterior 

 and posterior parts of the shell are dis- 

 similar. 



INEQUIVALVE, when the valves are dis- 

 similar. 



INVOLUTE, without a spire. 



KEELED, see Carinated. 



LENTICULAR, when the valves are round, 

 and diminish in thickness from the centre 

 towards the edges. 



LID, see Operculum. 



LIGAMENT, a membranous substance, 

 which connects the valves : it is both in- 

 terior and exterior, in the generality of 

 Bivalves. 



LINEAR, when the length of the shell is 

 greater than the breadth, and its form not 

 cylindrical. 



LINGUIFORM, tongue-shaped. 



LIP, (in Univalves,) the side of the aperture : 

 (in Bivalves,) the exterior edge of the 

 valves. 



LUNAR, or Lunate, having a crescent 

 form. 



MARGIN, the edge of the shell : anterior, 

 the space in which the ligament is situ- 

 ated ; posterior, the 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. 



MOUTH, see Aperture. 



MUSCULAR IMPRESSIONS, are the 

 marks made by the muscles with which 

 the animal adheres to the shell, as in the 

 common oyster. 



