766 MOLLUSCA—OYSTER. 
make the furrow in 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 grooye, until 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 ONS TER? 
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. w 
The oyster differs from the muscle in being utterly unable to change ‘ts 
situation. It is entirely without that tongue which 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- 
1 The genus Ostrea, or oyster, is characterized by an adhering shell, inequivalve, irregu- 
Jar, with beaks separated, and the upper 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. 
