THE ANIMAL KINGDOM. jjo 



island of Ceylon. The peculiar lustre of pearls is caused 

 by a substance called nacre, which they receive from the 

 mantles in which they are formed. Their gills are in the 

 form of plates, and hence they are called Lam&llibranchi- 

 ata. Mussels are well known to everybody. When young, 

 they can move about by means of a foot ; but later in their 

 life, a long and strong byssus, or beard, grows, and by 

 means of this they attach themselves to rocks or stones. 

 This beard in the Pinna is very long and silky. The 

 inhabitants of Sicily and Calabria gather them, and make 

 of the beard a very fine sort of cloth, which is wonder- 

 fully soft, warm, and strong ; but the animal is now 

 scarce, and hence the manufacture of the cloth is one 

 more of curiosity than of trade. 



Clams are bivalves of enormous size ; they are, in fact, 

 the largest known conchiferous mollusks. There is a pair 

 of the shells in the church of St. Sulpice in Paris, which 

 weigh more than five hundred pounds ; and as the animal 

 is commonly eaten in the localities in which it is found (the 

 shores of the East Indian and Australian seas), you can 

 imagine the quantity of food it supplies. In these the 

 beard is so strong that it is necessary to chop it with a 

 hatchet before the animal can be removed. 



Cockles form another group of bivalves. You all know 

 these, and have perhaps seen the poor men, women, and 

 children picking them out of the sand on the shore just 

 after the tide has gone out. The foot is so large, that 

 the animal uses it for boring in the sand, and, taking 

 a firm hold, it draws its body down ; by expanding this 

 member, it can jerk itself up again, and move about by 

 springs, much faster than you would think possible. 



Razor Shells. The animal inhabiting these is eaten 

 too ; it burrows deeply into the sand, but is caught by 

 dropping salt down the opening, which causes it .to come 

 up at once. 



