DES C RI PTI ON. 141 



Lister Conch, tab. 206. fig. 40. 



Specimen white, orange towards the margin, 

 pectinate with knotted ribs on the upper valve, 

 lower one tuberculate and rough, obhquely pecti- 

 nated. 



Inhabits the Mediterranean, Red, Indian, and 

 American seas. 



The varieties of this species are extremely nu- 

 merous ; those which are furnished with spines are 

 considered the most valuable, and increase in esti- 

 mation in proportion to the length and beauty of 

 the appendages. 



PLATE VIII. 

 Fig. 1. Hinge of Chama Gigas. 



Fig. 2. Chama Gigas, 



Shell folded, ribs with arched scales ; posterior 

 slope gaping. 



Lister Conch, tab. 351. fig. 189. 



Specimen clear white ; gape of the posterior 

 slope lanceolate, the circumference of which is 

 tumid and crenate ; margin of the shell deeply 



