The Shell-builders. 



and this cordage it spins ; but it spins it as one of the 

 secrets of the deep. Somehow or other, though it has 

 no hand, it contrives to intertwine this yarn which it 

 has formed among the numerous bits of coral, so as 

 firmly to bind a handful of it together. Externally, 

 this habitation is rough, and therefore better fitted to 

 elude or to ward off enemies. But though rough 

 externally, within all is smooth and lubricous ; for the 

 fine yarn is woven into a lining of tapestry, and the 

 interstices are filled up with a fine slime, so that it is 

 smooth as plaster work. When the Lima is taken 

 out of its nest and put into a jar of sea water, it is one 

 of the most beautiful marine animals you can look upon. 

 The shell is beautiful ; the body of the animal within 

 the shell is beautiful ; and the orange fringe-work 

 outside the shell is highly ornamental. Its mode of 

 swimming is the same as that of the scallop. It opens 

 its valves, and, suddenly shutting them, expels the 

 water,, so that it is impelled onwards and upwards ; 

 and when the impulse thus given is spent, it repeats 

 the operation, and thus moves on by a succession of 

 jumps. When moving through the water in this way, 

 the reddish fringe-work is like the tail of a fiery comet." 

 Many of the bivalves are miners, digging down 

 deeply into the sand, beneath which they can live safely 

 and undisturbed by hungry foes. Of these burrowers 

 the Cockle is a familiar example, living in sandy bays 

 or sand banks where digging operations can be swiftly 

 and easily performed. It is its long, strong foot which 

 the Cockle employs as a spade. Thrusting the pointed 

 tip into the yielding sand, the Cockle pushes its foot 

 down as far as it will go ; then, bending the end into 



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