18. The chimpanzee, walking 52 19. The chimpanzee, sitting 53 20. The gorilla 55 21. Median sections of the heads of a young gorilla and of a man 56 22. Side view of a human brain of high type 57 23. Outlines of typical human and prehuman brains (side view) 58 24. Outlines of typical human and prehuman brains (top view) 59 25. Map--Europe during the Second Glacial Stage 65 26. The musk-ox 66 27. The giant deer (_Megaceros_) 68 28. The sabre-tooth tiger (_Machærodus_) 70 29. Restoration of _Pithecanthropus_, the Java ape-man 73 30. Discovery site of _Pithecanthropus_ 74 31. Section of the volcano of Lawoe and the valley of the Solo River 75 32. Map--Solo River and discovery site of _Pithecanthropus_ 75 33. Section of the _Pithecanthropus_ discovery site 76 34. Skull-top of _Pithecanthropus_, top and side views 77 35. Head of chimpanzee, front and side views 78 36. Restoration of _Pithecanthropus_ skull, side view 79 37. Restoration of _Pithecanthropus_ skull, three views 80 38. _Pithecanthropus_, the Java ape-man, side view 81 39. _Pithecanthropus_, the Java ape-man, front view 82 40. Side view of a human brain of high type 83 41. Outlines of human and prehuman brains, side and top views 84 42. The hippopotamus and the southern mammoth 92 43. Merck's rhinoceros and the straight-tusked elephant 93 44. Map--Geographic distribution of Merck's rhinoceros, the hippopotamus, and the straight-tusked elephant 94 45. Section of the Heidelberg discovery site 96 46. The sand-pit at Mauer, discovery site of the Heidelberg man 97 47. The Heidelberg jaw 98 48. Jaws of an Eskimo, of an orang, and of Heidelberg (side view) 99 49. Jaws of an Eskimo, of an orang, and of Heidelberg (top view) 100 50. Restoration of Heidelberg man 101 51. Map--Europe during the Third Glacial Stage 105 52. Chronological chart of the last third of the Glacial Epoch 108 53. Map--Pre-Chellean and Chellean stations 109 54. Map--Europe during the Third Glacial Stage 110 55. Excavation at Chelles-sur-Marne 111