In this sense our bay presents, on a miniature scale, a variety of physical and organic combinations, which may be compared to those more extensive divisions in the geographical distribution of animals and plants, called by naturalists zoölogical or botanical provinces or districts, the animal and vegetable populations of which are technically designated as their faunæ and floræ. Such organic realms, as we may call them, have long been recognized on land, and the most extensive among them are easily distinguished. No one will fail to recognize the tropical zone, with its royal dynasty of palms and all the accompanying glories of a tropical vegetation, its birds of brilliant plumage, its large Mammalia, lions, tigers, panthers, elephants, and its great rivers haunted by gigantic reptiles. Nor is the representation of vegetable and animal life less characteristic in the temperate zone, where the oak is monarch of the woods, with all his attendant court of elms, walnuts, beeches, birches, maples, and the like, where birds of more sober hues, but sweeter voices, take the place of the brilliant parrots and many-tinted humming-birds of the tropical forest; while buffaloes, bears, wolves, foxes, and deer represent the larger Mammalia. In the arctic zone, though marked by peculiar and distinctive features, vegetation has dwindled to a minimum; the birds are chiefly gulls and ducks, which go there for the breeding season in the summer, and the reindeer and polar bears are almost sole possessors of the snow and ice-fields; but this meagreness in the representation of the larger land Mammalia is amply compensated in the numbers of heavy aquatic Mammalia, the whales, walruses, seals, and porpoises of the Arctic seas. During the last half-century, since the geographical distribution of animals and plants has become a subject of more careful investigation among naturalists, these broad zones of the earth's surface, with their characteristic populations and vegetation, have been subdivided, according to more limited and special combinations of organic forms, into narrower zoölogical and botanical areas. The application of these results to marine life is however of much more recent date, and indeed it would seem at first sight, as if the water, from its own nature, could hardly impose a barrier so impassable as the land. The localization of the marine faunæ and floræ is nevertheless as distinct as that of terrestrial animals and plants, and late investigations have done much to explain the connection of this distribution with physical conditions.