Descending the precipitous slopes of the Rocky Mountains on the west, we enter on a vast plain no less than 2000 miles in length, though comparatively narrow--the great basin of California and Oregon. Its greatest width, from the Sierra Nevada to the Rocky Mountains, is nearly 600 miles, but is generally much less. The largest lake found on it is 4200 feet above the level of the sea, and is connected with the Salt Lake of Utah. The mean elevation of the plain is about 6000 feet above the sea. A mountain-chain runs across it, and through it flows the large Colorado River, amidst gorges of the most picturesque magnificence. If the scenes we have described are stern and forbidding in summer, how much more so are they in winter, when icy blasts blow through the canons, and masses of snow cover the ground. From one of the outer spurs on the east, let us take a glance over the region. Behind us rises the chain of the Rocky Mountains, the whole intermediate country, as well as the mountains themselves, except where the precipitous rocks forbid it, being covered thickly with snow. Rugged peaks and ridges, snow-clad and covered with pines, and deep gorges filled with broken rocks, everywhere meet the eye. To the east, the mountains gradually smooth away into high spurs and broken ground, till they join the wide-spreading plains, generally stretching far as the eye can reach, and hundreds of miles beyond--a sea of barrenness, vast and dismal. A hurricane blows clouds of white snowy dust across the desert, resembling the smoke of bonfires, roaring and raving through the pines on the mountain-top, filling the air with snow and broken branches, and piling it in huge drifts against the trees. The perfect solitude of this vast wilderness is appalling. From our lofty post on the mountain-top, we obtain a view over the rugged and chaotic masses of the stupendous chain, and the vast deserts which stretch away far from its eastern base; while on all sides are broken ridges and chasms and ravines, with masses of piled-up rocks and uprooted trees, with clouds of drifting snow flying through the air, and the hurricane's roar battling through the forest at our feet adding to the wildness of the scene, which is unrelieved by the slightest vestige of animal or human life. THE HORNED FROG.