the Shells of Maine. 339 



Genus Margarita. Leach. 



All the species of this genus are pelagic, and from nume- 

 rous observations I am of opinion they all inhabit similar lo- 

 calities in the bosom of the great deep. Most of the small 

 species of pelagic shells are found mixed with mud ; these 

 are found, generally, mixed with sand, or gravel, or small peb- 

 bles. 



M, cinerea. Couth. This occurs in Casco Bay, rarely. It is 

 more abundant in the Gulf of St. Lawrence, where it is much 

 larger. 



M. obscura, Couth. Rare in Casco Bay, more plentiful far- 

 ther north. 



M. undulata, Sowb. This species was found rather plenti- 

 fully in Casco Bay, in 1840, but very rarely since. It attains 

 a much larger size in the Gulf of St. Lawrence. An imper- 

 fect specimen now before me is .7 inch across the base. 



M. arctica, Leach. Mature specimens are rare. I have 

 found very small specimens of a bright red color, (which I 

 suppose to be the young) quite plentiful. 



M. argentata, Gould. Frequently found. 



31. acuminata, Sowb. Hab. Gulf of St. Lawrence. I have 

 obtained only a single specimen. 



M. varicosa, Migh. Only two specimens of this species 

 have been found ; they accompanied the preceding. 



Genus Trochus. Lin. 



T. occidenfalis, Migh. Pelagic. Hab. Casco Bay, in 

 great depths of water. Very rare. 



Genus Littorina. Ferus. 



L. (Turbo) ruclis, Donovan. (Turbo obJigatus, Say.) 

 L. (Turbo) tcuebrosa, Mont. (Turbo vestitus, Say.^ 

 L. (Turbo) palliata, Say. These three species of Litto- 

 rijia occur in the greatest profusion, covering the rocks and 

 marine plants on the whole coast from Piscataqua to Passama- 

 quoddy, but how much farther north and east, I am unin- 

 formed. 



