64 CONCHOLOGIST’S COMPANION. 
same species, forms the baptismal fort at the church 
of St. Sulpice at Paris; it was presented by the 
Venetians to Francis the First. 
Ancient artists engraved a variety of figures on 
different species of this interesting genus. Availing 
themselves of the colours infused by nature into the 
strata of the shell, they accurately expressed by the 
depth of their incisions, the delicate tints of the 
finest white or red complexion, or blue and yellow 
drapery, according to the kind of Chama which they 
selected for the purpose. Several specimens are 
still extant, and to these we owe, most probably, the 
first idea of that kind of engraving which is termed 
a cameo. 
Large pearls are occasionally found in the Chama 
gigas. One, exhibited at Sir Joseph Banks’s, in 
June, 1804, was valued at two or three hundred 
pounds. The colour of this extraordinary shell is of 
a dirty white, or yellowish or reddish brown. The 
hinge is furnished with a cartilage of a dull brown 
colour; but when cut and polished, is as beautifully 
irridescent as the opal. 
Lhave previously had occasion to observe, that the 
component parts, or superficies, of many animals are 
highly ornamental, and that the properties by which 
they are so rendered do not apparently conduce to 
any other purpose. In shells and flowers, the 
