Each pair of tigers generally frequents the same lair, which in mountainous districts is concealed amid rocks, while in the plains the requisite shelter is afforded by reed-brakes. In winter the tigers may be completely snowed up in their retreats. As in India, the tigress is reported to separate herself from the tiger a short time before giving birth to her young; these being born in some dense thicket or rocky cleft, their number varying from two to four. At birth they are about the same size as lion-cubs, but are marked in the same fashion as their parents, although clothed in more woolly coats. In India it is generally stated that the female keeps apart from the male while the cubs are young, although both parents have been seen with their offspring. Like lions, tigers associate for the greater part of the year in pairs, and are strictly monogamous. Whether old tigers in Siberia turn man-eaters, after the fashion of their brethren in India, does not appear to be known; but in much of their range it is probable that they do not resort to this mode of livelihood, on account of the sparseness of the population. It appears, however, that throughout northern China and Siberia the natives regard the tiger with much the same superstitious awe as do the natives of Hindustan. All the Siberian natives consider the tiger as a being of high nature, although the Tunguses look upon it as an evil spirit which has come under the influence of the Shamans, or sorcerers. Fossil bones from the New Siberian Islands indicate that the Manchurian tiger once ranged beyond the Arctic Circle. THE SEAL (_Phoca vitulina_) Of all mammals except whales, dolphins, and sea-cows, the true seals, of which the common British species is the typical representative, are those which have become most completely adapted to an aquatic existence. This is shown by the spindle-shaped form of the body, the total absence of external ears, the conversion of the fore-limbs into flippers, and the backward direction of the hind pair, which are also flipper-like, and lie parallel to the short tail to form an efficient rudder-like organ. Seals are evidently descended from land Carnivora, and possibly from that long extinct group the Creodontia. When fully developed, their cheek-teeth consist of a single middle cusp, flanked by a smaller one in front and behind; and there are no teeth specially corresponding with the scissor-like pair characteristic of the modern land Carnivora. This fact, unless the teeth are degenerate, is all in favour of the direct descent of seals from creodonts.