GLOSSARY. ix 



Decollated, having the spire or upper part of the shell 



truncated transversely. 

 Decussated, intersected by striae 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, {see 

 'plate Q'fig. 5.) 



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 of a 

 shell are exactly similar. 



Equivalve, (applied to Multivalves), when the two prin- 

 cipal valves have the same form, size, and position : (to 

 Bivalves), when the tvi'o valves are exactly similar. 



Exserted, very thin or slender. 



Fissure, a notch or slit, {see plate 4^. fig. 57.) 



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 dis- 

 tended. 



Gibbosity, a swelling. 



Gibbous, swelled. 



Glabrous, smooth. 



