There are many well-attested cases of an absolute enjoyment among animals that sometimes rises to the pitch of mirthfulness. One day, Dr. Kane came across a long, icy, inclined shoot, like the artificial coasting-places made by the Russians, down which a long file of white bears went sliding on their hams: at the bottom they jumped up like a crowd of boys, with evident delight, to carry their sleds back to the top of the hill. He says that the signs of pleasure among them were unmistakable.
The Canadian fish-otter (Lutra Canadensis) loves to do the same thing. He climbs to the top of a snow-ridge in winter, or of a slippery bank in summer, lies on his belly, with the fore feet bent backward, then, pushing with the hind legs, down he goes. So the Russians, with their ice-slides, are only imitating the sport of their own arctic creatures. I suppose that long ago the pleasure derived from an involuntary and accidental slide originated the habit.
Lieutenant Dall says that the beavers in Alaska engage in gymnastics for fun. If they find a smooth, miry bank, they betake themselves to sliding down it. And the Californian gray whale loves to play in the shoals where the surf breaks; keeping a wary outlook, so that it continually escapes being beached. Its pleasure is enhanced by the peril. Seals do the same thing when they find a heavy surf. They turn from side to side with half-extended fins, moved apparently by the heavy ground-swell; at times making a playful spring with bended flukes that throws the body clear out of the
