196 UTILIZATION OF MINUTE LIFE. 



much in dimensions according to their age, but often 

 attain a considerable size, and secrete a byssus more 

 than a foot long. The two valves of their shell are 

 equal, and shaped somewhat like a lady's fan half 

 open. Their byssus is not, like that of the common 

 mussel, scanty and coarse, but long, fine, lustrous, 

 and abundant. The animal lives generally half- 

 buried in the sand, being anchored to an adjacent 

 rock by its long byssus. The latter is not unlike 

 silk, though its chemical nature does not appear to 

 have been examined. It is employed in the manu- 

 factories throughout Italy. It appears that the 

 Italians cannot dye this substance, and that, con- 

 sequently, it can only be used in its natural brown 

 colour. Eeaumur called these mollusca the silk- 

 worms of the sea. The inhabitants of Palermo have 

 manufactured this byssus into various species of 

 cloth, which are usually of a high price. It takes 

 many individuals to furnish enough silky thread to 

 manufacture a pair of stockings, and the thread is 

 so fine, that a pair of stockings made of it can be 

 easily contained in a snuff-box of ordinary size. 

 The species generally sought for is Pinna nobilis, L. 

 (Fig. 24, P. marina of others), which is taken off 

 the coast of Sicily, at Toulon, etc., by means of a 

 cramp, a species of iron fork, the prongs of which 

 are perpendicular to the handle. It inhabits water 

 from fifteen to thirty feet deep. 



