GREEN HYDRA 72 Photo: J. J. Ward, F.E.S. DIAGRAM ILLUSTRATING THE BEGINNING OF INDIVIDUAL LIFE 72 EARTHWORM 72 Photo: J. J. Ward, F.E.S. GLASS MODEL OF A SEA-ANEMONE 72 Reproduced from the Smithsonian Report, 1917. THIS DRAWING SHOWS THE EVOLUTION OF THE BRAIN FROM FISH TO MAN 73 OKAPI AND GIRAFFE (_Coloured Illustration_) 74 DIAGRAM OF A SIMPLE REFLEX ARC IN A BACKBONELESS ANIMAL LIKE AN EARTHWORM 76 THE YUCCA MOTH 76 Photo: British Museum (Natural History). INCLINED PLANE OF ANIMAL BEHAVIOUR 76 VENUS' FLY-TRAP 77 Photo: J. J. Ward, F.E.S. A SPIDER SUNNING HER EGGS 77 Reproduced by permission from _The Wonders of Instinct_ by J. H. Fabre. THE HOATZIN INHABITS BRITISH GUIANA 82 PERIPATUS 83 Photograph, from the British Museum (Natural History), of a drawing by Mr. E. Wilson. ROCK KANGAROO CARRYING ITS YOUNG IN A POUCH 83 Photo: W. S. Berridge, F.Z.S. PROFESSOR THOMAS HENRY HUXLEY (1825-95) 86 Photo: Rischgitz. BARON CUVIER, 1769-1832 86 AN ILLUSTRATION SHOWING VARIOUS METHODS OF FLYING AND SWOOPING 87 ANIMALS OF THE CAMBRIAN PERIOD 90 From Knipe's _Nebula to Man_. A TRILOBITE 90 Photo: J. J. Ward, F.E.S. THE GAMBIAN MUD-FISH, PROTOPTERUS 91 Photo: British Museum (Natural History). THE ARCHAEOPTERYX 91 After William Leche of Stockholm. WING OF A BIRD, SHOWING THE ARRANGEMENT OF THE FEATHERS 91 PICTORIAL REPRESENTATION OF STRATA OF THE EARTH'S CRUST, WITH SUGGESTIONS OF CHARACTERISTIC FOSSILS (_Coloured Illustration_) 92 FOSSIL OF A PTERODACTYL OR EXTINCT FLYING DRAGON 94 Photo: British Museum (Natural History). PARIASAURUS: AN EXTINCT VEGETARIAN TRIASSIC REPTILE 94 From Knipe's _Nebula to Man_. TRICERATOPS: A HUGE EXTINCT REPTILE 95 From Knipe's _Nebula to Man_. THE DUCKMOLE OR DUCK-BILLED PLATYPUS OF AUSTRALIA 95 Photo: _Daily Mail_. SKELETON OF AN EXTINCT FLIGHTLESS TOOTHED BIRD, HESPERORNIS 100 After Marsh.