38 TiMEHRI. 



decoration, among which special forms, such as the 

 Pearly Nautilus, the Ear-shells, the Top-shells, etc., 

 when cleaned of the outer and earthy-looking layers so 

 as to lay bare the under nacreous and iridescent sub- 

 stance, yield articles of ornament unsurpassed for 

 beauty by any other of the multitudinous produ6lions of 

 nature or of art. 



In the utilisation of the Molluscs for food, a world- 

 wide appreciation is given to the various species of 

 Oysters ; but the Whelks, Periwinkles, Sea-cars, Clams, 

 Mussels etc., are also variously esteemed in civilised 

 communities ; while among primitive races the commonly 

 occurring species of the locality furnish a normal and 

 welcome article of diet. 



Apart from their economic importance, however, the 

 group of the shells has for ages been regarded with 

 popular interest, as subje6ls for colledlion, for which 

 their varied form and colouring, their wide distribution, 

 and the ease with which they may be preserved, ad- 

 mirably fit them ; and the large prices, sometimes as much 

 as fifty pounds, which have at times been paid for certain 

 rare individual species, often of small size, will give 

 some idea of the estimation in which they were and are 

 still held by special colleftors. 



It is to the biological student more particularly, 

 however, that the group of the Mollusca presents 

 the highest degree of interest ; for not only does 

 the highly specialised plan of organisation which 

 is presented by the group, furnish him with an 

 endless field of research in its origin and history and 

 its many degrees of modification, but the occurrence of 

 special charafteristic types of structure in the various 



