Professor Dawkins divides that part of the Pleistocene period during which man inhabited the earth as the mid-Pleistocene and the late Pleistocene periods. Monsieur Du Pont, dividing it with respect to the form of animal life most characteristic, gives us the Age of the Mammoth and the Age of the Reindeer. M. de Mortillet, classifying it with reference to the localities which have yielded most materials for study, has made current the terms the _Chellian_, the _Mousterian_, the _Solutian_, and the _Madelenian_ epochs. The following table may serve to indicate in a general way how these various classifications are related. The reader who would like to pursue the question of classification further will find good summaries in the _Smithsonian Report of the U. S. National Museum_, 1888, p. 604; in the _Smithsonian Report of the U. S. National Museum_, 1890, p. 649; in Morgan’s _Ancient Society_, pp. 3-29, and in Dawkins’ _British Pleistocene Mammalia_. ====================+=======================+========================= The Tree-dwellers. | The Early Cave-men. | The Later Cave-men. --------------------+-----------------------+------------------------- The Age of Fear. | The Age of Combat. | The Age of the Chase. --------------------+-----------------------+------------------------- The Age of the Mammoth. | The Age of the Reindeer. --------------------+-----------------------+------------------------- Period of Extinct Animals. | Period of Migrated | Animals. --------------------+-----------------------+------------------------- Dawn of the Rough | The Paleolithic or Rough Stone Age. Stone Age. | --------------------+-----------------------+------------------------- Eolithic Epoch. | Chellian Epoch. | Mousterian Epoch. | | Solutian Epoch. | | Madelenian Epoch. --------------------+-----------------------+------------------------- Mid-Pleistocene Period. | Late Pleistocene Period. --------------------+-----------------------+------------------------- The Pleistocene Period. --------------------+-----------------------+------------------------- Climate mild and | Climate becomes much | Arctic climate. Cold equable. | colder. Great | and dry. | extremes of heat | | and cold. | --------------------+-----------------------+-------------------------