PLATE CXXVI1I. 



Few species of the shell tribe are more generally diffused through- 

 out the European and Indian seas than the Mytilus edulis ; and few 

 indeed exhibit such an infinite number of varieties, differing in size, 

 in form, and colour ; but which the critical Conchologist will yet 

 perceive cannot with propriety be assigned to any other species. 



On the Plate annexed to this description, one shell of the shape 

 more uniformly prevalent is figured in its natural state, and another, 

 which, having been divested of the epidermis, displays a beautiful 

 variety of irregular purple stripes : an appearance very common in 

 the uncoated shells, and in some sorts observable even when the epi- 

 dermis is upon them. The upper and lower figures are of two 

 shells, which, we are inclined to think, differ too widely from the 

 common kind to be considered as a variety : the outline appears at 

 the first sight obviously dissimilar ; and the characters in general 

 seem to mark most decidedly another species. They are both worn 

 shells, but which we have compared with perfect specimens of My- 

 tilus ungulatus, and apprehend there can be no doubt that they 

 belong to that species. 



Within the tropics, the common Muscle is known to attain a 

 much larger size than in northern climates. They are found in im- 

 mense beds, and adhere to other substances, or to one another, by 

 means of a beard of a strong and silky texture, which the fish throws 

 out. The Muscle affords a rich and palatable food ; though they 

 are not deemed wholesome by many peop/e, who after eating them 

 are sometimes afflicted with great swellings and convulsive motions, 

 with eruptive blotches, shortness of breath, and even with delirium. 

 These dreadful effects are usually attributed to some malignant poison 

 in the little pea crab which is occasionally found in the Muscle, and 



