SNAKE RIVER
SNOW
closed by a horny structure, called the operculum. There are an immense number of land-snails in tropical countries, of considerable size and bright colors. Some are tree-climbers and secrete a thread of mucous substance, by means of which the body is suspended, like that of a spider by its thread. They are eaten as food, especially in Europe. There also are water-snails, some of which come to the surface ^to breathe air, while others are provided with gills. The common garden-snail has 135 rows of 105 teeth each, making 14,175 in all.
Snake River, the largest branch of the Columbia. It rises among the Rocky Mountains near Wyoming, and in crossing southern Idaho forms Shoshone Falls, and is a part of the northern boundary of Idaho. In southern Washington, as Lewis River, it joins the Columbia, having made a journey of 2,050 miles. It is navigable for only 160 miles.
Snakes, the largest class of reptiles, the representatives having an elongated body covered with scales. They have no limbs and no rudimentary bones representing the shoulder-arch, but there is a trace of the #rch of the hind limbs. They move by pushing the edges of the ventral scales against roughnesses, but can make no headway on a smooth surface. The bones of the skull and jaws are movable, so that the latter can be put on a stretch, which enables the snake to swallow animals larger than the normal size of the mouth and throat. Some possess poison-fangs with which their prey is killed, while others coil around their prey and crush it. They shed their skins periodically, and the deserted skins are often seen in fields and woods. Some live entirely on land, though most snakes swim well, others climb trees, and in the Indian Ocean are snakes living habitually in the water. Most of them lay eggs, but a few, including the last-mentioned ones, bring forth their young alive. The snakes naturally fall into two groups — the nonpoisonous and the poisonous ones. There are about 700 species of nonpoisonous or colubrine snakes, which are found in nearly all parts of the world They are well-represented in the United States, and include such familiar forms as garter-snakes, blue racers, grass-snakes and blow-adders, all of which are harmless. The venomous snakes are represented in the United States by the rattlesnake family. There are about 60 species in this family, all American and renowned for their venom. Besides rattlers are included the copperhead and water-moccasin, the latter being the most dangerous of our snakes. The anacondas, boas and the like are powerful nonpoisonous snakes. All snakes are more abundant in warm and tropical countries. India is noted for venomous snakes, like the cobra, and the annual number of deaths from snake-bites there
reaches nearly 25,000. See BOA, COBRA,
COPPERHEAD, MOCCASIN and RATTLESNAKE.
Snipe, a common name for a number of
favorite game-birds belonging to a group of
SNIPE
shore-birds. They grade into the sandpipers. There are about 100 species, and 30 of these visit the United States mainly during migration. A number of snipes, however, nest within the United States. Among the more widely known forms are the woodcock, jack-snipe, tip-up and Wilson's snipe. The jack-snipe is the pectoral sandpiper, and the tip-tip the spotted sandpiper. The American woodcock is about 11 inches long, and variegated with black, brown, gray and russet colors. The European wooa-cock is similar, but considerably larger. The American bird frequents low, wet woods and in the autumn visits corn-fields and wooded hillsides. They probe for earthworms with their long bills, making holes in clusters, Wilson's snipe is about n and one fourth inches long,- and is a favorite game-bird. It lives in fresh-water marshes and meadows. The tip-up or teter snipe is about seven and one half inches long, and has a white breast spotted with black. The jack-snipe is abundant during migrations. Snipes also abound in the Old World. Snow is water floating in the atmosphere in a crystallized state. When a cloud of water-vapor reaches a temperature below o° C., the process of freezing begins; and, if the air be calm, the crystals thus formed are large and regular. They are most easily observed by collecting them on a piece of black velvet and examining them with a lens. In the accompanying figure are shown the forms of some typical crystals, recently prepared from microphotographs by the United States Weather-Bureau. The whiteness of snow results from the total reflection of light, which occurs, sooner or later, when a ray of light enters any considerable body of snow from any direction. By the snow-line t sometimes called limit of per-
