2IO BY THE DEEP SEA. 



Limpet holds on so tightly by creating a vacuum, some say 

 under the foot, others under the shell. So ancient an authority 

 as Reaumur disproved these notions. He tested the matter 

 by cutting a Limpet in two, shell and all. According to the 

 teaching of the vacuumites, the animal's hold should then have 

 loosened ; but no, the two portions still adhered to their base. 

 Anyone by observation can testify to the truth of Reaumur's 

 explanation ; there is the same powerful hold in the foot of a 

 garden snail on a damp surface, but in that case it does not 

 seem so great, because his shell affords a better hold for the 

 experimenter. The annoying feature of the Limpet is the 

 shape of his shell, which prevents our taking hold of it. Where 

 the surface of the rock is friable, as some of our Cornish Killas 

 rocks, and the chalk rocks of the Kentish coast, the Limpet's 

 foot, when forcibly pulled up, brings with it particles of the 

 surface, which have separated from the parent rock more 

 easily than from the glue of the mollusk's foot. 



A wonderful thing about the Limpet is its power to sink a 

 shallow pit in the surface of the rock, corresponding to the 

 shape of the shell ; and this, of course, has led to much 

 theorising to explain how it is accomplished. Patent solvents 

 secreted by the animal, the carbonic acid gas given off from 

 the breathing apparatus (which strangely does not destroy its 

 own shell ! ), and so on. A little study of Nature would show 

 that the wonderful organ which enables them to scrape away 

 the surface in long zigzag lines, as they crop the minute 

 vegetation, would be equally effective if applied to the spot 

 upon which they prefer to roost, and to which they habitually 

 return after their pastoral wanderings. The action of this 

 tongue on the rocks can be very distinctly heard on the shore, 

 though possibly not in the library or the museum, where only 

 the empty shells are admitted. It is worth while dissecting a 

 Limpet, and getting out this remarkable tongue, which is a 

 ribbon-shaped organ, closely studded with minute hooks of 

 flint, to the number of nearly 2,000. A similar lingual ribbon, 

 as it is termed, will be found in most of the Gastercpods. 



