EXPLANATION OF TERMS. 



Depressed lines, placed at irregular di- 

 stances across some of the bivalve shells, to mark their yearly 

 growth ; as in the common cockle. 



Annulate. Marked with circular rings. 



Anterior &ide> or slope. That side of bivalve shells to which 

 the cartilage, connecting the valves, is attached. 



Antiquated. Marked with the lines or furrows of annual 

 growth. 



Aperture. The mouth or opening of univalve, and some 

 multivalve shells. 



Auricles. Small ear-like appendages placed at the sides of 

 the hinge of some bivalve shells ; as the Scallops. 



Bise. The bottom of the shell. It must be observed, that 

 the base of a spiral shell supposes it to be placed with the 

 mouth downwards, and the point or tip upwards. 



Beak. The points above the hinge in bivalve shells are in 

 this work called the beaks. In general it means any point or 

 projection. 



Bivalve. A shell with two valves only. 



Breadth. The distance from one side of a shell to the other, 

 and not from the hinge to the margin : as in some of the So- 

 lenes the breadth is three or four times as much as the length, 



Cawa 1 . An elongated hollow projection from the mouth, 

 as in most of the Murex tribe ; or an excavated groove down 

 the pillar-lip. 



Carinnle. Furnished with a keel-like elevated ridge. 



Cartilage. The tough membrane which connects the valves 

 of the shell together. 



Cartilage, szr/e, or sl<pe. That side of the shell where the car- 

 tilage is placed. 



Ciliaie, Furnished with a kind of fringe. 



Complicated. Folded together in an irregular manner. 



Compressed. Flattened in the valves. 



Concentric. Running parallel from one side to the other, 

 but not longitudinally, or from the hinge to the margin. 



c 3 Confluent. 



