Shell-Bearers 



departs from the usual appearance of marine molluscs ; 

 it is greyish-white, nearly a foot long and provided with a 

 pair of very minute valves on its hinder end. The young 

 shipworm, during the first few hours of its existence, is a 

 lively little creature ; a miniature hedgehog, in fact, all 

 studded with spines. Pine, elm, oak and teak are all 

 tunnelled by this creature, and so closely placed are the 

 borings of the different individuals that the dividing walls 

 are often as thin as a sheet of paper. Each tunnel is 

 lined with a thin layer of chalky matter, and it has been 

 statedthat a piece of wood, badly attacked bythe shipworm, 

 contains as much of this deposited mineral matters as of 

 the original wood. Our common shipworm has a relative, 

 dwelling in the tropics, with the curious habit of tunnelling 

 into the husks of coconuts which have found their way 

 into the sea. 



There is a very common mollusc of our coasts which 

 deserves more than passing notice. We refer to the limpet. 

 Everyone knows the limpet, but few of us probably have 

 paid much attention to it. Astonishing as it may sound, 

 it is none the less true that this creature is possessed of 

 nearly two thousand teeth, which it uses to scrape minute 

 vegetation, as food, from the rocks on which it dwells. 

 The most extraordinary and, curiously, the most commonly 

 observed trait of the limpet is its power of adhering to the 

 surface of the rock on which it has taken up its abode. 

 Its adhesive powers are wellnigh beyond belief, and 

 experiment has shown that a moderate-sized limpet will 

 support as much as a quarter of a hundredweight for several 

 seconds before relaxing its hold. 



The most popular theory, in explanation, is that the 

 mollusc affixes itself by drawing up its body in the centre, 

 thus imitating a schoolboy's sucker. It is a theory, however, 

 which will not hold, for if a limpet and its shell be cut in 

 two, the halves will adhere as tightly as the whole. Of 

 one thing we are certain, the mollusc must have a perfectly 

 level surface to pitch its home, and to make certain of 



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