THE LARGE MILK-GIVERS WHICH HAVE CONQUERED THE WORLD BY STRENGTH AND INTELLIGENCE 256 PICTURE-HEADING--Animals which lived in Europe during the warm periods before the Glacial Cold. On the right, _Deinotherium_, _Mastodon_; in background, _Helladotherium_, ancient giraffes; on the left, _Hippopotamus_, _Tapir_, _Rhinoceros_, _Hyæna_; in the tree, _Pithecus pentelicus_. All these animals, except the giraffe, were living in England in the late Tertiary Period. (From various sources.) CHAPTER XI. HOW THE BACKBONED ANIMALS HAVE RETURNED TO THE WATER, AND LARGE MILK-GIVERS IMITATE THE FISH 299 PICTURE-HEADING--An ideal scene of Europe in the Glacial Period with the “Hairy Mammoth” in the foreground. CHAPTER XII. A BIRD’S-EYE VIEW OF THE RISE AND PROGRESS OF BACKBONED LIFE 333 PICTURE-HEADING--Man as he lived in caves after the Glacial Period, among animals of species many of them now extinct--the cave bear (_Ursus spelæus_), cave lion, cave hyæna (_Hyæna spelæa_), elk, musk-sheep (_Ovibos moschatus_), mammoth (_Elephas primigenius_), and the sabre-toothed tiger (_Machairodus_), fighting with the man. LIST OF ILLUSTRATIONS. PICTURE-HEADINGS described under “Contents.” _Frontispiece._ FISH OF THE DEEP SEA--1. Chauliodus, one foot long; 2, 9, 10, 11. Harpodon or Bombay Duck, six inches; 3. Plagiodus, six feet; 4. Chiasmodus, one foot, with Scopelus in its stomach; 6. Beryx, one foot and a half; 8. Scopelus, one foot. PAGE The Lancelet, _Amphioxus lanceolatus_ 11 Sea-Squirt or Ascidian 14 Lamprey and Ammocœtes 16 Structure of Minnow and Living Fish 23 The Blue Shark 29 The Sturgeon, _Acipenser sturio_ 31 The Sturgeon’s Head and Feelers 32 The Ceratodus of Queensland 34 Remoras clinging to a Shark 51 Flying-Fish pursued by the Dorado 54 The Fishing Frog, _Lophius piscatorius_ 59 The common Sole, _Solea vulgaris_ 61 The Hippocampus or Sea-Horse 63 Sticklebacks and their Nest, _Gasterosteus aculeatus_ 65 Metamorphosis of the Frog 72 The common smooth Newt, _Lissotriton punctatus_ 78