Barnacles. 117 



exposed rocks, drift wood, and any other substance. 

 Some of tlie mollusks affix themselves to the bodies 

 of whales,, others form a lodgment in the hollows 

 of corals and sponges. Once fixed they remain so 

 dmuno- life, taking: their chance of such saitablo 

 food as may come within their limited sphere of 

 action. At an earlier stage of their existence, 

 both their shape and habits are very different, 

 being lively little creatures, swimming about hither 

 and thither like water- fleas. They are about the 

 tenth of an inch long, and of most grotesque 

 appearance, having six-jointed legs set with hairs, 

 the whole being so arranged that they act in con- 

 cert, and striking or flapping the water, send the 

 little body along in a series of bounds ; then the 

 creature has two long arms, each furnished with 

 hooks and a sucker, and a tail tipped with bristles, 

 which is usually folded up under the body ; its pair 

 of large staring eyes are pedunculated, that is, set 

 upon foot-stalks; it has a house on its back, like a 

 bivalve shell, into which it can collect its scattered 

 members when occasion requires. 'Wh.en of suffi- 

 cient age to settle itself in life, and become a staid 

 member of submarine society, it fixes itself to some 

 convenient object, throws away its eyes as no longer 

 useful, gets rid cf its preposterous limbs, enlarges 



