94 THE NAUTILUS. 



Several specimens have been collected at Nantucket and Martha's 

 Vineyard ; it is not very rare at New Haven, but I have never found 

 anything in our bay excepting single valves. Mr. John Ford, of 

 Philadelphia, while on a visit to Providence, a few years ago, obtained 

 several live specimens among the oysters dredged off Bullock's Point. 



Family MYTILID^E. 



The mussels inhabit all shores in great numbers. Some species 

 inhabit deep water and others frequent near high water mark, being 

 uncovered nearly all the time and moistened by the salt water only 

 once every twelve hours. Woodward says, " The members of this 

 family exhibit a propensity for concealment, frequently spinning a 

 nest of sand and shell fragments, burrowing in soft substances or 

 secreting themselves in the burrows of other shells." In speaking of 

 the animals, he says, " Animals marine or fluviatile attached by a 

 byssus." There are no fluviatile members of this family, although 

 one species, which will be spoken of hereafter, seems to live equally 

 well in either fresh or salt water. 



Genus Mytilus Linne, 1758. 



The mussels are easily recognized by their triangular or wedge- 

 shaped shells, which are pointed at the anterior end and broad and 

 rounded at the posterior ; the hinge is either toothless or in some 

 species with very minute teeth. There are sixty-five species distrib- 

 uted world wide, one of which inhabits Rhode Island. 



202. Mylilus edulis Linne. 



Mytilus vulgarif Da Costa ; Mytilus borealis Lam., De Kay, Midd.; 

 Mytilus pelhicidus De Kay ; Mytilus notatus De Kay (young). 



Shell ovate-triangular, solid ; beaks pointed, situated at the an- 

 terior end ; hinge margin rising in a straight line at an angle of forty- 

 five degrees from the basal margin, which is also straight ; posterior 

 widened and rounded, the broadest part of the shell being directly 

 opposite the centre of the basal margin ; surface covered by a dark, 

 shining, bluish-black epidermis, under which the shell is violet; in- 

 terior silvery in the centre, with dark violet margins. Length of 

 large specimens two and a half inches, height one and three-tenths, 

 breadth one inch. 



This species, the common edible mussel, inhabits the whole of the 

 ocean shores of the northern hemisphere, being extremely abundant 



