PINNA. 



361 



aigrette or plumelet which the Eoman soldiers attached to the helmet. 

 French naturalists name them jambonneau, from their singular resem- 

 blance to a dried ham (Figs. 166 and 167), their brown, smoky colour 

 not a little aiding the resemblance. This shell is fibrous, horny, very 

 thin and fragile, compressed, regular, and equivalve, triangularly 

 pointed in front, round or truncated behind. The hinge is linear, 

 straight, and without teeth; the ligament, in great part internal, 



Fig. 166. Pinna rudis (Linnaeus). 



Fig. 167. Pinna nigrina (Lamarck). 



occupies more than half the anterior half of the dorsal edge of the 

 shell, forming a straight elongated fossette. 



The animal is thick, elongated, with mantle open behind, presenting 

 a conical furrowed foot, bearing a considerable byssus. 



The Pinnds are found in almost every sea, and at various depths ; 

 they are constantly attached by their byssus, and in a vertical position, 

 the larger side of their shell being uppermost. They assemble on 

 sandy bottoms in considerable numbers. The byssus has in all ages 

 fixed the attention of the Mediterranean fishermen upon these curious 

 shells. With its tuft of fine silky hairs, six or seven inches in length, 

 of a fine reddish-brown hue, articles of luxury are formed, which 

 are often mentioned by the Latin writers. The threads of the byssus, 

 which are remarkable for their unalterable colour, were formed by both 

 Greeks and Komans into a fabric to which there is nothing analogous 



