Lemming (Myodes), a genus of rodents, nearly allied to voles, but with much shorter ears and tail, larger and stronger claws, and a heavier body. The most noted species is M. lemmus, an animal about the size of a rat, with variegated black and tawny fur, an inhabitant of the northern Scandinavian mountains, where it ordinarily feeds on reindeer-moss and other lichens, grass, catkins of birch, &c. Breeding several times in the course of a year, and producing four or five at a birth, it multiplies so much that, periodically, vast troops migrate from their native mountains. They proceed persistently in a straight line (according to some always westwards), swimming rivers, crossing mountains, entering towns, devouring, breeding, and dying as they hurry on. They move chiefly in the night or early morning. Bears, wolves, foxes, lynxes, hawks, and owls follow and prey upon them, and most of the survivors finally drown themselves in the sea, thus pitifully readjusting the balance between population and subsistence. For ingenious theories and curious details about the migration, see Romanes, Mental
Evolution in Animals (1883). In times of prevalent superstition lemmings were often exorcised by the priests, and the peasantry of Norway supposed them to fall from the clouds. During the Ice Age the lemming extended as far south as the Alps, but it now is distinctly arctic. An allied species (M. obensis) occurs in Siberia and North America. Another quite distinct 'lemming' (Cuniculus torquatus), inhabiting the arctic regions of both hemispheres, turns white in winter.