GLOSSARY. 203 



Decussated, intersected by striae at acute angles. 

 Dentated, having teetli. 

 Diaphanous, transparent. 

 Digitated, having projecting claws. 

 Divaricated, ohHquely striated. 

 Dorsal, belonging to the back. 



Ears, external projections on the sides of tlie hinge, (see plate 



U.Jig. 2.) 

 Effuse, having the lip separated by a gutter. 

 Emarginate, having the margin excavated by a canal. 

 Epidermis, the outer skin or covering of a shell. 

 Equilateral, when the anterior and posterior parts ofasliell 



are exactly similar. 

 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 ^\\i, {see plate 32. fig. 1.) 



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 wliere the valves are united, and generally 

 furnished with one or more teetli : it is said to be compress- 

 ed, when it is formed of one compressed tooth: lateral, 

 when placed on one side of the shell: rejlected, when its 

 edges are folded over the exterior margin : terminal, if situ- 



