766 MOLLUSCA — O VSTER. 



make the furrow ia proportion as it goes forward, it reaches out its tongue 

 that answers the purpose of an arm, and thus carries its shell edgewise, as 

 in a groove, mitil it reach the point intended. There where it determines 

 to take up its residence, it fixes the ends of its beard, which are glutinous, 

 to the rock or the object, whatever it be; and thus, like a ship at anchor, 

 braves all the agitations of the water. The beards have been seen a foot 

 and a half long; and of this substance the natives of Palermo sometimes 

 make gloves and stockings. 



THE OYSTERi 



Is formed with organs of life and respiration, with intestines which are very- 

 voluminous, a liver, lungs, and heart. Like the muscle, it is self-impreg- 

 nated ; and the shell, which the animal soon acquires, serves it for its future 

 habitation. Like the muscle, it opens its shell to receive the influx of 

 water, and, like that animal, is strongly attached to its shells both above 

 and below. The oyster respires by means of gills. The water is drawn 

 in at the mouth, which is a small opening in the upper part of the body, 

 and proceeds thence down a long canal, constituting the base of the gills, 

 and so out again, the animal retaining such a portion of air as is necessary 

 for the functions of the body. 



The oyster differs from the muscle in being utterly unable to change its 

 situation. It is entirely without that tongue Avhich we see answering the 

 purposes of an arm in the other animal, but, nevertheless, is often attached 

 very firmly to any object it happens to approach. Nothing is so common 

 in the rivers of the tropical climates as to see oysters growing even amidst 

 the branches of the forest. Many trees, which grow along the banks of 

 the stream, often bend their branches into the water, and particularly the 

 mangrove, which chiefly delights in a moist situation. To these the oys- 



' The sjenus Ostrea, or oyster, is characterized by an adherini; shell, inequivalve, irregu- 

 lar, with beaks separated, and the npper valve advanced as the animal increases in age; 

 hinge without teeth ; ligament half internal ; the hollow of attachment and the beak in 

 the lower valve increasing with age. 



