They were in the Eskimo country now, for the Koyukuk River forms the dividing line between Indian and Eskimo hunting grounds. The Alatna and Upper Kobuk Eskimos, while as typically Eskimos as their brothers of the sea coast, have many of them never seen salt water. Nevertheless, they are as truly maritime in their habits as though they dwelt upon the treeless tundras of the coast. Living in a country that is replete with caribou, ptarmigan, and rabbits, they rarely eat game, contenting themselves with fish which they take in vast quantities from the rivers and inland lakes, and with seal oil that is carried up river and traded by the coastal Eskimos. It is the same with their housing. Living as they do where timber for cabins is plentiful, they build no cabins, but live in igloos built half underground and their clothing consists of sealskin, also an article of trade, instead of caribou skin which abounds within their own territory. For two days the trail held to the river. Each night they pitched their tent close beside an igloo, Lou after one glance into the reeking interior of the first of these huts, declining as gracefully as possible, the urgent invitations of the occupants to share their hospitality. On the high plateau of the Alatna-Kobuk portage they experienced the first difficulty in following the trail. Rim Rock’s map showed that it held straight west for nearly fifty miles, but a new fall of snow had obliterated every vestige of trail. The timber on the plateau was exceeding sparse and consisted of straggling patches of stunted spruce widely separated by level stretches of snow. One not versed in Arctic winter trailing would think that the exact location of the trail under such circumstances would be a matter of small moment, but the sourdough who does the winter traveling knows differently. Once off the trail, he must fight the deep snows of all the winter which means intolerably slow travel with no footing for the dogs. No matter how deeply buried under new snow, where the old trail is there will be found a hard bottom which furnishes the footing that is necessary for the dogs to exert any traction. And no amount of trail breaking without the old trail underneath will afford anything like a bottom.