Thor was on what the Indians call a _pimootao_. His brute mind had all at once added two and two together, and while perhaps he did not make four of it, his mental arithmetic was accurate enough to convince him that straight north was the road to travel. By the time Langdon and Bruce had reached the summit of the Bighorn Highway, and were listening to the distant tongueing of the dogs, little Muskwa was in abject despair. Following Thor had been like a game of tag with never a moment's rest. An hour after they left the sheep trail they came to the rise in the valley where the waters separated. From this point one creek flowed southward into the Tacla Lake country and the other northward into the Babine, which was a tributary of the Skeena. They descended very quickly into a much lower country, and for the first time Muskwa encountered marshland, and travelled at times through grass so rank and thick that he could not see but could only hear Thor forging on ahead of him. The stream grew wider and deeper, and in places they skirted the edges of dark, quiet pools that Muskwa thought must have been of immeasurable depth. These pools gave Muskwa his first breathing-spells. Now and then Thor would stop and sniff over the edge of them. He was hunting for something, and yet he never seemed to find it; and each time that he started on afresh Muskwa was so much nearer to the end of his endurance. They were fully seven miles north of the point from which Bruce and Langdon were scanning the valley through their glasses when they came to a lake. It was a dark and unfriendly looking lake to Muskwa, who had never seen anything but sunlit pools in the dips. The forest grew close down to its shore. In places it was almost black. Queer birds squawked in the thick reeds. It was heavy with a strange odour--a fragrance of something that made the cub lick his little chops, and filled him with hunger. For a minute or two Thor stood sniffing this scent that filled the air. It was the smell of fish. Slowly the big grizzly began picking his way along the edge of the lake. He soon came to the mouth of a small creek. It was not more than twenty feet wide, but it was dark and quiet and deep, like the lake itself. For a hundred yards Thor made his way up this creek, until he came to where a number of trees had fallen across it, forming a jam. Close to this jam the water was covered with a green scum. Thor knew what lay under that scum, and very quietly he crept out on the logs. Midway in the stream he paused, and with his right paw gently brushed back the scum so that an open pool of clear water lay directly under him. Muskwa's bright little eyes watched him from the shore. He knew that Thor was after something to eat, but how he was going to get it out of that pool of water puzzled and interested him in spite of his weariness.