The food of the Eskimos of Alaska, as is the case with all other divisions of that people, is derived mainly from the sea. Their diet is almost exclusively fish, the blubber and flesh of the seal, walrus, and whales, especially the white whale or beluga, which ascends the larger streams. To these sources of supply are added the arctic hare, caribou (reindeer), and in fact any flesh that can be obtained. Vegetable diet is almost unknown, except so far as it is supplied by the berries that grow in profusion on the tundras. The necessity for salt, so marked in the case of most peoples, is absent in the far north. The coast of Alaska, where dwells the Innuit, is treeless. Inland from the margin of the sea extends the permanently frozen tundra. Wood for fires, sleds, frames for skin boats, spears, bows, arrows, etc., and in prehistoric time for producing fire by friction, is derived entirely from driftwood cast on the beach by the waves. This wood, consisting in many instances of great tree trunks from which planks two or more feet wide can be hewn, is brought to the sea by rivers heading far inland, as, for example, the Yukon and the Kuskokwim, and distributed by the wind and currents all about the coast and islands of Bering Sea. Driftwood is also carried to the Arctic Ocean by the Mackenzie, but in general is not plentiful on the borders of the ice-bound northern ocean. The houses of the Alaskan Innuit previous to the coming of the Russians, and still to a great extent, consist of a single room, usually measuring about 10 by 14 feet, situated in part below the surface of the ground and entered by means of a tunnel-like passageway. They are made of driftwood, and floored, lined, and roofed with planks hewn from the same material. On a roof of poles sods and earth are placed and rendered compact by stamping, thus forming a cover which serves to exclude water produced by the melting of the naturally added layer of snow. When spring-time approaches these partially subterranean winter dwellings are liable to be inundated, and are abandoned and tents used during summer seasons. Formerly these tents were made of skins of caribou or seal, but in these degenerate days cotton drilling bought of white traders has been substituted. During winter journeys temporary snow huts are built, of the oval, bake-oven shape, well known to most Europeans from the many pictures that have been published of similar structures made by the more northern Eskimos. On the coast of Alaska, however, when driftwood is available, the roofs of the snow houses are frequently made of poles on which snow is piled.