This family comprises about five hundred species, which are distributed 

 throughout the whole world, and are found ranging from between tides, 

 to several hundred fathoms beneath the surface of the water. 



" The family Cardiidce, the heart-shells, or cockles, comprise some 

 of the largest and most attractive of Pelecijpods. The name Cardium, 

 signifying a heart, is given to them because of the close resemblance 

 to that organ when the shell is viewed from the anterior end. These 

 animals live in sandy or muddy bays, and generally congregate in 

 thousands. In England, the edible cockle, Cardium edule, is considered 

 quite a delicacy, and annually, thousands are used for food. In our own 

 country they are not generally eaten, except by the poor in Florida and 

 in some places along the Gulf of Mexico. The waters of Florida furnish 

 some very handsome species, among them the rich, red Cardium isocardia, 

 and the large Cardium magnum, the latter attaining a length of five 

 inches, and being ornamented by beautiful color patterns of brown and 

 yellow. The foot of the Cardium is very peculiar, being shaped like 

 a sickle, which enables the animal to pull itself along at a lively gait. 

 A California cockle, Liocardium elatum, grows to a diameter of seven 

 inches, and would furnish a meal for several people. Members of the 

 Cardium family are found in all parts of the world, from the Arctic 

 regions to the Tropics, and they number several hundred species. 



" In the family Tridacnidce, which we find in this case, size seems 

 to have reached its limit. This specimen of Tridacna giyas, which 

 is so nicely mounted, lives in the Indian Ocean, grows to a length 

 of nearly six feet, and weighs as much as eight hundred pounds. It 



is recorded that a pair of these shells, which 

 are two feet in diameter, and weigh five hun- 

 dred pounds, are used as benetiers in the church 

 of St. Sulpice, Paris. In some parts of the 

 Indian Ocean, where pearl and sponge fishing 

 are carried on, this clam, which is known as the 

 giant clam, is a source of great danger to the 

 divers, many losing their lives by having either 

 hands or feet caught between the great valves 

 of the shell. Many a diver has amputated 

 a finger, hand, or foot, and thus saved his life at the expense of one 

 or more of these members. 



"Let us now give our attention to this case of tellen shells," con- 

 tinued the Professor. "This family, the Tellinidce, numbers among its 

 five hundred or more species some of the most beautiful of the bivalves. 

 What could be handsomer than this tablet of specimens of the sunrise 



70 



Tridacna squamosa. A rela- 

 tive of the giant clam of the 

 Pacific Ocean. (Woodward.) 



