THE GAPER SHELL. — THE LIMPET. 
57 
extremity, the aperture at the other end is scarcely capable of 
receiving the little finger. The walls of this tube are very thin 
and membranous, and it is more or less retractile, carrying 
within it the siphons through which the mollusc respires and 
takes nourishment. 
The Gaper Shell inhabits sandy and muddy shores, and to an 
inexperienced eye is quite invisible. The shell itself, together 
with the actual body of the mollusc, is hidden deeply in the 
mud, seldom less than three inches, and generally eleven or 
twelve inches from its surface. In this position it would be 
unable to respire, were it not for the elongating tube, which 
projects through the mud into the water, and just permits the 
extremities of the siphons to show themselves, surrounded by 
the little radiating tentacles which betray them to the experienced 
shell-hunter. These tentacles or fringes are never seen in the 
dried specimens, and can only be partially preserved by plunging 
the animal into spirits of wine, glycerine, or other antiseptic 
liquid. The Gaper Shell is esteemed as an article of food by 
man, beast, and bird ; for not only do human beings dig it up 
with tools, cook it, and eat it, but the wolves and the arctic fox 
scratch it out of the mud and eat it raw, and the various sea 
birds peck it out with their beaks, prize the shell open, and 
devour the contents. 
The well-known Limpet is a kind of borer, though the holes 
which it excavates are of very trifling depth, and are probably 
made by the mechanical friction of the shell and foot against 
the rock, without any intention on the part of the animal Those 
who have been accustomed to wander along the sea-shore must 
have noticed that the Limpet shells always sink more or less 
into the rocks on which they cling, and that in very old speci- 
mens which are covered with algae and barnacles, the shells are 
often sunk fully half their depth into the solid rock. Grooves, 
too, of various depths may be seen in the same rock, showing 
the slow and tedious track which the Limpets have made over 
its surface, until they finally settled down into some convenient 
situation. 
