362 THE OCEAN WORLD. 



in the world. The Maltese and Neapolitans still fashion soft tissues 

 from it, but the stuffs so manufactured are pure objects of curiosity. 

 Twelve species are described as living in the several seas. Pinna 



Fig. 168. Pinna bullata (Swainson). Fig. 169. Pinna nobilis, with its byssus (Linnaeus). 



nobilis (Fig. 169), the byssus of which was employed in the ancient 

 Neapolitan industry, inhabits the shores of the Mediterranean. Pinna 

 luttata, Swainson (Fig. 168), is also a well-known species. 



Our twenty-first family, Ostreidae, contains Lima, Spondylus, Pecten, 

 Anomia, and the all-important oyster. The common oyster, Ostrea 

 edulis, is found in all seas. It is unequally valved, modified in shape 

 by the form of the submarine body to which it happens to be attached. 

 The lower or adherent valve is concave, always the largest; the 

 upper one thin, usually flat ; the shell is lamellar, rough externally, 

 and seems to be composed of broken layers, adhering slightly to each 

 other, as if the successive layers had been built up from within, and 

 each succeeding layer was an enlargement upon its predecessor. 

 The hinge which unites the valves is an elastic toothless ligament 

 .placed behind the centre, which opens the valves. 



