TESTACEA. 65 



of the site, if not deposited there by the parent ; and the same sense of 

 security leads to their association in thousands, though they were able 

 to separate. 



Mussel beds are sometimes very remote from each other. Therefore, 

 the fishermen dwelling on parts of the coast where none are found, some- 

 times resort to places forty or fifty miles distant, for a cargo, to be de- 

 posited within high water mark, in their own district, whence they are 

 removed for bait as required. Possibly, sufficient attention is not paid to 

 the freshness of the bait, and to this the failure of fishing may undoubt- 

 edly be often ascribed. Many creatures utterly reject animal substances 

 as food if stale. 



The practice of transporting cargoes of mussels having prevailed very 

 long in the same places, it does not appear that they are so favourable as 

 to admit the growth of colonies there. 



Small pearls, of sufficient purity, such as those technically called 

 seed pearls, frequently occur in the edible mussel. 



The surface of the shell, when the epidermis is removed, is of a 

 beautiful blue, and receives a fine polish, preparing it for various orna- 

 mental toys, as made by persons residing on the coast of England. 



Plate XII. 



Fig. 1 . BrancMa of Mytilws edulis. 



Mytilus pellucidus. — Plate XII,, Fig. 2. 



Extent fifteen lines. Shell smooth and thin ; stripes of yellowish 

 hue and other colours radiate from the smaller extremity ; a fringe pro- 

 jects from the broad extremity. As the shell gapes muddy matter is 

 absorbed, and it is discharged, but not in rolls, as by the Ascidia. A slen- 

 der irregular byssus affixes the shell to solid substances. Some naturalists 

 consider this only a younger stage of the Mytilus edulis ; and certainly 

 corresponds much with it in form and habits. Others deem it a variety. 

 ' It is comparatively rare. 



Plate XII. 



Fig. 2. Mytilus ■pellucidus. 



