204 GLOSSARY. 



ated at the extremity of the shell: and truncated, if the 

 beaks of the shell appear to have been transversely cut off, 

 and the teeth of the hinge fixed to this part. 

 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 dissimilar. 

 Inequivalve, when the valves are dissimilar. i 



Involute, without a spire, as in the Patellae. 



Keeled, see Carinated. 



Labium, see Lip. 



Lenticular, when the valves are round, and diminish in thick- 

 ness from the centre towards the edges. 



Lid, see Operculum. 



Ligament, amexnhranous substance which connects the valves : 

 it is both interior and exterior in the generality of Bivalves. 



Linear, when the length of the shell is greater than its breadth, 

 and its form not cylindrical. 



Linguiform, tongue-shaped. 



Lip, (in Univalves), the sides of the aperture : (in Bivalves), 

 the exterior edge of the valves. 



Lunar or Zimafe, having a crescent form. 



Margin, the edge of the shell : anterior, the space in which 

 the ligament is situated : posterior, the space on the other 

 side of the hinge: superior, the space between the anterior 

 and posterior parts. 



Marginate, {in Univalves), having the sides of the shell thick- 

 ened : (in Bivalves), surrounded with an elevated margin. 



Mouth, see Aperture. 



