Lying upon the very crown of the continent, Yellowstone Lake receives no tributaries of any considerable size, its clear cold water coming solely from the snows that fall on the lofty mountain ranges that hem it in on every side. In the early part of the day, when the air is still and the bright sunshine falls on its unruffled surface, its bright green color, shading to a delicate ultramarine, commands the admiration of every beholder. Later in the day, when the mountain winds come down from their icy heights, it puts on an aspect more in accordance with the fierce wilderness around it. Its shores are paved with volcanic rocks, sometimes in masses, sometimes broken and worn into pebbles of trachyte, obsidian, chalcedony, cornelians, agates, and bits of agatized wood; and again, ground to obsidian-sand and sprinkled with crystals of California diamonds. Here and there hot-spring deposits show wave-worn bluffs of the purest white; and in sheltered bays, clay-concretions and casts from mud-puffs strew the beach with curious forms, that exploring trappers mistook for the drinking cups, stone war-clubs, and broken idols of some extinct race. Vegetation is abundant in the lake as well as around it. Several species of plants grow far out into the deep waters, living thickly on rocks twenty feet below the surface. After a severe storm their uptorn stems strew the beach like kelp on the seashore, and the water is discolored with vegetable matter for several yards from the shore. The water swarms with trout, but there is no other kind of fish, no shells, no shell-fish,--nothing but trout. Of these, Mr. Carrington, the naturalist of the Geological Survey, reports the following interesting observations: