As winter approaches, the hair grows long, and lightens considerably in hue. Frequently, indeed, individuals may be seen in a herd with coats of the palest fawn colour--almost white. The muzzle is entirely covered with hair. The fur is brittle, and though in summer it is short, in winter it is longer and whiter, especially about the throat. The hoofs are broad, depressed, and bent in at the tip. The full-grown bucks shed their horns, and it is seldom that they are seen in a herd after Christmas. The female reindeer, however, retains hers during winter. Several theories have been advanced to account for this. There seems no doubt, however, that the object is to enable the female to protect her fawns from the males, who are apt to attack the young and destroy them. The cariboo is gregarious, and males, females, and young herd together at all seasons; and by this provision of Nature the females are able to defend the young, who would otherwise be subjected to injury. In another respect these animals are wonderfully provided for the mode of existence they are compelled to pursue. Not only have they to cross wide snow-covered districts, but frequently to pass across frozen expanses of water. To enable them to do this in the winter, the frog of the foot is almost entirely absorbed, and the edges of the hoof, now quite concave, grow out in sharp ridges, each division on the under surface presenting the appearance of a huge mussel-shell, and serving the office of natural skates. So rapidly does the shell increase, that the frog does not fill up again till spring, when the antlers bud out. With this singular conformation of the foot, it has a lateral spread; and an additional assistance for maintaining a foothold on slippery surfaces is given by numerous long, stiff bristles which grow downward at the fetlock, curving over entirely between the divisions. The cariboo is thus enabled to proceed over the snow, to cross frozen lakes, or ascend icy precipices, with an ease which places him, when in flight, beyond the reach of all enemies, except perhaps the nimble and untiring wolf.