1NJJA- 



SEA WING. 193 



OBSERVATIONS ON THE SHELL AND ITS 

 INHABITANT. 



The Pinna seems to form the connecting link 

 between the univalves and bivalves, for though 

 it is composed of two valves, yet it is incapable 

 of moving on its hinge. It is generally found at a 

 short distance from the shore, fixed in the mud 

 at its smaller end, and standing erect. The ani- 

 mal forms abyssus, the fibres of which are ag- 

 glutinated, to the sand, gravel, roots of marine 

 plants, broken shells, or any matter within its 

 reach. The byssus of the Pinna is much more 

 fine and delicate than that of the muscle ; the 

 filaments are long, silky, and of a bright lustre ; 

 the natural colour is of a rich golden brown, but 

 it readily receives any tint. The animal pos- 

 sesses a kind of tubular instrument, furnished 

 with a gland which secretes a glutinous sub- 

 stance : by means of a slight pressure, a drop 

 of this liquid is deposited on the spot, to which 

 the byssus is to be attached ; by the retraction 

 of the foot, a silken filament is drawn out, and 

 this operation being repeated some thousands of 

 times, a beautiful tuft of silky fibres, is pro- 

 duced. The Pinnae are much sought after on 

 the coasts of Sardinia and Corsica for the sake 

 of the byssus; they are fished up with an instru- 

 ment which consists of two semicircular bars of 

 iron fastened together at each end, but three 

 o 



