Cats, unlike dogs, are very fond of music. And it has been proved that their music-sense can be developed to a remarkable degree 21 A happy family of polar bears. The young cubs wrestle and tumble, as playfully as two puppies. This play has much to do with their physical and mental development 34 Dryptosaurus. The prehistoric animals, too, undoubtedly had their play time, with games and "setting up" exercises 35 The mother opossum is never happier than when she has her little ones playing hide-and-seek over her back 38 This young fox came from his home in the woods daily to play with a young fox-terrier. He is now resting after a romp 39 Naosaurus and Dimetrodon, two extinct armour-bearers who should have been well able to protect themselves 50 An armour-bearer of prehistoric times whose shield was an effective protection against enemy horns 51 To the polar bear the ice and snow of the Far North means warmth and protection. The mother bear digs herself into a snowbank, where she lives quite comfortably throughout the winter 84 The sharp claws of the ground squirrel are efficacious tools in digging his cosy underground burrow 85 The coyote can readily distinguish whether a herd of sheep is guarded by one or more dogs, and will plan his attack accordingly 94 The zebu, the sacred bull of India, in spite of its domestication, has an agile body and a quick, alert mind 95 Roosevelt's Colobus. These horse-tailed monkeys chatter together in a language exclusively their own, yet they seem to have no difficulty in making themselves understood by other monkey-tribes 112 A tamed deer of Texas, whose constant companion and playmate was a rabbit dog. Between the two, there developed, necessarily, a common language 113 Water-loving animals, like the beavers, seemingly take great pride in their toilets. Their fur is always sleek and clean 122 Great forest pigs of Central Africa. Like the common domesticated hogs, they will seek a clay bath to heal their wounds 123 The Rocky Mountain goat has many means of defence, not the least of which is his agility in climbing to inaccessible places 134 Wild boars are among the most ferocious of animals. By means of their great strength alone they are well able to defend themselves 135 Brontosaurus. The animals that seemed best equipped to defend themselves are the ones that, thousands of years ago, became extinct 144