Illustrations xi 



FACING 

 PAGE 



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 Mall. 



SKELETON OF AN EXTINCT FLIGHTLESS TOOTHED BIRD, HESPERORNIS . 100 

 After Marsh. 



Six STAGES IN THE EVOLUTION OF THE HORSE, SHOWING GRADUAL 



INCREASE IN SIZE .......... 101 



After Lull and Matthew. 



DIAGRAM SHOWING SEVEN STAGES IN THE EVOLUTION OF THE FORE-LIMBS 

 AND HlND-LlMBS OF THE ANCESTORS OF THE MODERN HORSE, BEGIN- 

 NING WITH THE EARLIEST KNOWN PREDECESSORS OF THE HORSE AND 

 CULMINATING WITH THE HORSE OF TO-DAY ..... 104 

 After Marsh and Lull. 



WHAT is MEANT BY HOMOLOGY? ESSENTIAL SIMILARITY OF ARCHI- 

 TECTURE, THOUGH THE APPEARANCES MAY BE VERY DIFFERENT . . 105 



AN EIGHT-ARMED CUTTLEFISH OR OCTOPUS ATTACKING A SMALL CRAB . 116 



A COMMON STARFISH, WHICH HAS LOST THREE ARMS AND is REGROWINO 



THEM 116 



After Professor W. C. Mclntosh. 



THE PAPER NAUTILUS (ARGONAUTA), AN ANIMAL OF THE OPEN SEA . 117 

 Photo: J. J. Ward, F.E.S. 



A PHOTOGRAPH SHOWING A STARFISH (Asterias Forreri) WHICH HAS 



CAPTURED A LARGE FISH . . . . . . . .117 



TEN-ARMED CUTTLEFISH OR SQUID IN THE ACT OF CAPTURING A FISH . 118 

 GREENLAND WHALE . . . . . . . . . .118 



MINUTE TRANSPARENT EARLY STAGE OF A SEA-CUCUMBER . . .119 



AN INTRICATE COLONY OF OPEN-SEA ANIMALS (Physophora Hydro- 

 statica) RELATED TO THE PORTUGUESE MAN-OF-WAR . . .119 

 Photo: British Museum (Natural History). 



