A "boreal province" corresponds with a similar faunal region upon the European shore. The mollusks which compose this fauna are about three hundred in number, and range along the New England coast from the Gulf of St. Lawrence to Cape Cod. It is a somewhat remarkable fact that many of these species are identical with English and French forms. The striking genera upon the American side are /Purpura/, /Littorina/, /Polynices/ (/Lunatia/ and /Neverita/), /Acmæa/, /Margarita/, /Chiton/, /Doris/, /Æolis/, /Mytilus/, /Modiola/, /Thracia/, and /Nucula/. THE TRANSATLANTIC PROVINCE Cape Cod has been regarded, until very recently, as a sharp divisional point between the boreal and the transatlantic provinces, the latter faunal area extending down the Atlantic coast of the United States to southern Florida. At Cape Cod the Labrador current is deflected from the coast, and the warmer shore waters south of that point are unfitted for the development of the boreal forms, though some of them, as we shall see, have passed the [pg310] barrier and maintain themselves very successfully at Martha's Vineyard and in Long Island Sound. Some of the species whose natural habitat is south of Cape Cod are also to be found north of that point, but they do not reach their full development in the colder waters of Massachusetts Bay. The long stretch of coast-line from Cape Cod to Florida is easily susceptible of faunal subdivision at Hatteras, below which locality a decided mixture of Antillean species is apparent. Between Long Island Sound and Hatteras the littoral molluscan fauna is disappointing to the collector, for the number of species is relatively small, and few even of these are entitled to any claims to beauty of shell. The nature of this coast, virtually a great sweep of exposed sand-beach, is not conducive to a varied or rich fauna. But if this portion of the transatlantic province is lacking in interest to the shell-collector, it is anything but disappointing to the army of men employed in the oyster- and clam-fishery. It is only within this faunal area that the American oyster, /Ostrea virginica/, the best of the edible shell-fish, finds its natural home, and here the oyster-culture is most extensively carried on. After storms the Jersey beaches are frequently strewn with /Mactra/, /Tagelus/, /Arca/, and /Ensis/; in more sheltered places /Fulgur/ and /Polynices/ (/Lunatia/) are commonly met. These may be accepted as the most characteristic genera of this province.