GLOSSARY. 3 



Decussated, intersected by striae at acute angles. 

 Dentated, having teeth. 

 Diaphayious, transparent. 

 Digitated, having projecting claws. 

 Divaricated, obliquely striated. 

 Dorsal, belonging to the back. 



Eai's, external projections on the sides of the hinge, {see 

 plate Q,fig. 5.) 



Effuse, hadng 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 princi- 

 pal 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, {see plate ^^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. 



Hinge, the part where the valves are united, and gene- 

 rally furnished with one or more teeth : it is said to be 

 compressed, when it is formed of one compressed tooth : 



