16 



POPULAR CONCHOLOOT. 



scarcity of food. But this opinion can only be satisfac- 

 torily proved or disproved when shells are better known. 

 Mr. Gray has the following remarks on the subject: — 

 " The thickness, roughness, or smoothness of shells appears 

 to depend in a great degree on the stillness or agitation 

 of the water which they inhabit. Two specimens of the 

 same species of shell will often be found very different 

 in appearance, according to the situation in which they 

 have been placed. For instance, the common Buccinum 

 of our coast is thick, solid, and heavy, when found in a 

 rough sea, and thin, light, and smooth, when found in the 

 still water of harbours. Boring shells are generally in- 

 fluenced in regard to their size, thickness, and form, by the 

 hardness or softness of the rock in which they are found. 

 Land shells are much influenced, as regards their size, by 

 the temperature, altitude, and abundance of food. The 

 shells of Helix nemoralis, and Helix hortensis found near 

 London, are not above two thirds of the size of those 

 which occur in Portugal and the south of France."* 



Of the uses and benefits derived by man from shells and 

 their inhabitants, a hasty mention may be made. First, 

 as to their inhabitants; amongst civilised nations many 

 species are highly prized as articles of food, such as the 

 oyster, mussel, &c. ; and among savage nations, particularly 

 those inhabiting the coasts of TTestern Africa and Xew 

 Holland, a great part of their food is derived from Mollusca 

 of various kinds. Their principal use, however, in this 

 respect appears to be 5 the serving as food for the classes of 

 animals more immediately above them in the scale of 

 organization, such as the amphibious mammalia, sea-birds, 

 and fish, which in a great measure live upon them, de- 

 stroying such vast quantities, that it is their extraordinary 



* Philosophical Trans. 1833. 



