352 THE COCKLE. 
The same ingenious people are also accustomed to make curious little pearl-covered josses, 
by stamping them out in thin bell-metal, slipping them into the shell, and leaving them 
between the valves until they are sufficiently coated with pearl. 
In the THorny CLAM, a curious member of another family, the shell is covered with long 
and branching projections, something like the horns of a young roebuck. All the Clams are 
natives of the warmer and tropical seas, especially among coral reefs, and their color and 
shape are extremely variable. Mr. Broderip writes of them as follows: ‘‘The shells are 
attached by their external surface to submarine bodies, such as coral rocks, and shells have 
been observed at depths varying from points near the surface to seventeen fathoms. These 
shells appear to be subject to every change of shape, and often of color, that the accidents of 
their position may bring upon them. Their shape is usually determined by the body to which 
they are fixed ; and the development of the foliated ilaminze which form their general charac- 
teristic is effected by their situation ; and their color most probably by their food, and their 
greater or less exposure to light. The Chama that has lived in deep and placid waters will 
generally be found with its foliations in the highest state of luxuriance, while those of an 
individual that has borne the buffeting of a comparatively shallow and turbulent sea will be 
poor and stunted.’’ The Clams are generally attached by the upper valve. The animal is 
edible, and is considered a great delicacy. About fifty species of Clams are known. 
The Tridacnidze are easily known by their deeply-waved shells, with the indented edges 
fitting into each other, and the overlapping foliations of the surface. Although separated 
from the true Clams, they are popularly called by the same name. The YELLOW CLAM is 
often buried in a mass of white madrepores. A well-known species, called from its enormous 
dimensions the Giant Ciam (7ridacna gigas), was formerly rare, but is now tolerably plen- 
tiful. It attains to a gigantic size, sometimes weighing more than five hundred pounds, and 
containing an animal which weighs twenty pounds, and can furnish a good dinner to nearly as 
many persons. 
The natives of the coasts on which it is found—namely, those of the Indian seas—are 
extremely fond of this creature, and eat it without any cooking, just as we eat oysters. 
The substance of the shell is extremely thick and solid, and enables it to be used for many 
ornamental purposes. 
In former days, when this species was very rare, a magnificent specimen was presented to 
the church of St. Sulpice, in Paris, where it may now be seen, the valves being set up as 
benitiers for containing the holy water. This shell dates from the time of Francis I. It is 
evident, that the byssus by which so enormous a shell is moored to the rocks must be of great 
size and strength, and, indeed, is so strong as to require an axe for its severance. The mus- 
cles, too, by which the animal contracts its shell are enormously powerful; and it has been 
remarked by Mr. Darwin, that, if a man were to put his hand into one of these shells, he 
would not be able to withdraw it as long as the animal lived. 
The SporreD Brar’s-pAW CLAM has been placed in a separate genus, on account of a 
difference in the number of projections on the hinge, technically called hinge-teeth. The 
mouth is marked by a coronet-like circlet around it, and the foot is seen below just projecting 
from its groove. 
This animal also spins a byssus, which is, however, weak and slight compared with that 
of the gigantic species just described. 

THE family of the Cockles, or Cardiada, so called from their heart-like shape, is well 
represented by the common CocKLE (Cardium ediile). Generally, the Cockle is a marine ani- 
mal; but it sometimes prefers brackish water to the salt waves of the ocean, and a small 
variety is found in the Thames nearly as high as Greenwich, when the water is sensibly 
flavored with salt at each high tide. Another species, the Prickty CockiE (Cardium acu- 
ledtum), is found on the southern coast, and regularly brought to market. 
The Cockle is gathered in great numbers for the purpose of being eaten, although, as the 
greater number are consumed in the open air, they can hardly be said to be procured for the 
