PINNA. MYTILACE.E; MUSSELS. 405 



remarkable for its suppleness and warmth. The filaments are 

 extremely fine, of perfectly equal diameter through their whole 

 extent, of great strength, and of a brilliant and unalterable red- 

 dish-brown colour. The ancients were acquainted with this sort 

 of stuff; but, in consequence of the diminution in the number oi 

 animals, it is becoming very scarce ; and, from its expensive- 

 ness, it is little more than an object of curiosity. 



SECTION D. MYTILACE^. 



1030. In all the Mollusks of this Order, there is a foot, which 

 some species employ for locomotion, whilst in others it serves 

 merely to draw out, direct, and fix the byssus. There are also 

 two adductor muscles, of which the anterior one is often very 

 small. The Mussels, properly so called, abound on the rocks of 

 our own coasts, to which they are fixed by their byssus ; and 

 they are often closely impacted together. Although in ordinary 

 circumstances they have no tendency to change of place, they 

 seem possessed of a certain degree of locomotive power. Reau- 

 mur mentions, that in the saline marshes on the sea-coast, where 

 the fishermen throw the Mussels at hazard, they are found at 

 the end of some time united into packets. By putting them into 

 glass vessels, he observed that their mode of progression con- 

 sisted in thrusting their tongue-like foot out of the shell, curving 

 it, hooking it to some adjacent body, and thus drawing them- 

 selves forward to the point of attachment. Vast quantities of 

 them are eaten, principally in the towns on the coasts, and a still 

 larger number is employed for bait ; Dr. Knapp states that for 

 the latter purpose from 30 to 40 millions are annually collected 

 in the Frith of Forth alone. Although Mussels commonly afford 

 a very wholesome supply of food, they sometimes acquire very 

 poisonous properties. How this is to be accounted for, is yet 

 uncertain. Many instances have occurred, in which a large 

 number of persons have been suddenly attacked with violent 

 symptoms, after eating Mussels from a particular bed ; and fatal. 



