MUSCLE, DRAGONET. 169 



shell grows to a considerable size, and is of a circular and 

 flattened shape, with a straight hinge. The substance of 

 the shell, when cut and polished, forms the mother-of-pearl 

 of commerce ; and by the petrification of the cartilaginous 

 hinge behind, is formed the very rare and beautiful fossil 

 androdamas. The pearls are found attached either to the 

 shell, or the body bf the animal : and are supposed to be 

 extraneous exudations from the latter. A hundred or 

 more are sometimes found in one large shell ; their value 

 depends upon their size, colour, form, and lustre. They 

 are generally white, but vary to blackish, yellowish, and 

 reddish ; they are rarely found of any considerable size. 

 The pearl fishery is performed by divers, and is dangerous, 

 difficult and unwholesome. The most considerable pearl 

 fisheries are those of Ceylon and the Persian Gulf. Pearls 

 are formed by many or most of the Testacea. 



THE EATABLE MUSCLE 



Is one of the most abundant and general of shells, furnish- 

 ing an abundant, nutritious, and agreeable food. Very 

 pernicious effects have sometimes ensued from the eating 

 of Muscles, but this is attributed to the incautious swal- 

 lowing of a minute crab, which often introduces itself into 

 the shell of the Muscle. This shell is of a pleasing form, 

 and exhibits, upon the removal of the epidermis, a splen- 

 didly disposed purple colour. It has, in common with all 

 its tribe, the power of locomotion, by means of a tongue or 

 foot, capable of elongation and retraction, which is marked 

 with a longitudinal furrow, and enveloped in a sheath of 

 purplish fibres. When the Muscle wishes to attach itself to 

 any particular spot, it employs this bre in weaving silky 

 threads by which it fastens itself to the rock. 



The Muscles are distinguished by having a hinge 

 with no tooth, but a hollow longitudinal line, and the 

 silky beard by which the animals attach themselves to any 

 substance. 



THE DRAGONET. 



THE common dragonet, for there are three species, is 

 sometimes fonnd a foot long. The body is slender, round, 



Q 



