times to have an aversion to water, they now swim across any lakes or rivers that come in their way. In this operation many of them lose their lives, for they require smooth water for their navigation, and the least breeze ruffling the surface suffices to send hundreds of them to the bottom. In this way they gradually arrive at the cultivated regions, where they do so much damage to vegetation, that in olden times a special form of prayer and exorcism was in use against them. Their march is accompanied by great numbers of carnivorous beasts and birds of all sorts. Wolves, Foxes, and Wild Cats, and the smaller quadrupeds of the family Mustelidæ, Eagles, Hawks, and Owls, all prey upon them with avidity--even the Reindeer is said to stamp them to death; and the story of his eating them, long discredited, has been confirmed on good authority, while man, with his Dogs and Cats, is not behindhand in the work of destruction. Nevertheless, a great multitude survives all these dangers, and, strange to say, the termination of this painful migration is always the sea, into which the survivors of the march plunge, and, apparently, voluntarily commit suicide. Mr. Crotch, who has published several papers on the Lemming and its migrations, says that in Norway these animals always proceed from the central backbone of the country in an east or west direction, and that in either case the survivors of the march drown themselves, those that go westward in the Atlantic, those that go eastward in the Gulf of Bothnia. His notion is that the migration is in obedience to an inherited instinct acquired at a time when there was land where the sea now rolls; but there are many difficulties in the way of such a hypothesis. [Illustration: LEMMING.] Besides the Scandinavian Lemming above noticed, several other species occur in the northern parts of the world. Three species (_Myodes lagurus_, _obensis_, and _torquatus_) inhabit Siberia; the latter two are found in North America, the last also in Greenland. In this species, which has been placed in a distinct genus under the name of _Cuniculus torquatus_, the third and fourth toes of the fore feet are much larger than the second and fifth (the thumb being rudimentary), and their claws become periodically enlarged to double their ordinary size by an enormous growth during winter of horny matter on the lower surface.