BIVALVES. 63 
proofs of new and appropriate mechanism. The 
generic appellation of the Donax is derived from a 
Greek word, signifying a reed; and a flying reed is, 
by one ancient writer, used for an arrow. The name, 
therefore, aptly describes the shape of the Donax, 
which resembles the head of a javelin. This species 
delights to burrow in the sand, or among loose 
pebbles on the sea coast, and is found in almost 
every part of the known world. 
The Chama, Camp, or Gaper, signifying a gaping, 
an hiatus, an opening, produces occasionally large 
and costly pearls, and is believed to be thus named 
from the gaping observable in two of the species, 
of which the C. gigas, or Giant-Clam, is the largest 
shell in the order Testacea. We are informed by 
Linnezus, that a specimen once weighed four hundred 
and ninety-eight English pounds; that the inhabitant 
furnished one hundred and twenty men with provi- 
sion for a whole day, and that the sudden closing of 
its valves was sufficient to snap a cable asunder. 
A manuscript in the library of the late Sir Joseph 
Banks, also notices the dimensions of a specimen 
brought from Sumatra, and preserved at Ano’s Vale, 
in Ireland: the weight amounted to five hundred and 
seven pounds; the largest valve measured four feet 
six inches in length, two feet five inches and a half 
in breadth, and one foot in depth. A shell of the 
