nomenclature. 49 



Valv^. Valves. 



cBquilaterce , ^Equilateral ; where the anterior and 

 posterior sides of the valve are equal and 

 similar. — Inaequilateral ; the reverse. 



cBquivalves. iEqui valve ; where one valve is per- 

 fectly similar to the other. 



dextrce et sinistrce. Right and left. If the shell be 

 placed upon its base, with the area in front, 

 and the valves be then divided, the right valve 

 will be opposite the left hand of the exami- 

 ner, and the left valveopposite his right hand, 



lacunoscB, Lacunous j marked with a longitudi- 

 nal depression. 



prominentes . Prominent ; when one valve pro- 

 trudes in any part beyond the other. 



succentiiriatcB , Accessory; those smaller irre- 

 gular shells, which are annexed to the 

 hinge of the Pholades. 



Umbones. Bosses ; the swelling parts near the 

 beaks, the highest extreme of which, or 

 that point furthest removed from the base, 

 we consider as the summit. 

 fornicatus. Arched ; inwardly much excavated, 



E 



