"II. The later or polished Stone Age; a period characterized by beautiful stone weapons and instruments made of flint and other kinds of stone; in which, however, we find no trace of the knowledge of any metal, excepting gold, which seems to have been sometimes used for ornaments. This we may call the 'Neolithic' period. "III. The Bronze Age, in which bronze was used for arms and cutting instruments of all kinds. "IV. The Iron Age, in which that metal had superseded bronze for arms, axes, knives, etc."[1] These divisions are recognized by Lyell and Tylor. Edward Lartet has proposed the following classification: I. THE STONE AGE. 1st. Epoch of extinct animals (or of the great bear and mammoth). 2d. Epoch of migrated existing animals (or the reindeer epoch). 3d. Epoch of domesticated existing animals (or the polished stone epoch). II. THE METAL AGE. 1st. The Bronze Epoch. 2d. The Iron Epoch. This mode of division is adopted by M. Figuier, in his "Primitive Man," by the Museum of Saint-Germain in that portion devoted to pre-historic antiquities, and adhered to in essential points by Troyon and d'Archiac. Professor Renevier, of Lausanne, has proposed a somewhat different scheme, founded upon the epochs of Swiss glaciation. It is as follows: "I. _Pre-glacial Epoch_, in which man lived cotemporaneously with the elephant (_Elephas antiquus_), rhinoceros (_R. hemitæchus_), and the cave-bear (_Ursus spelæus_). "II. _Glacial Epoch_, in which man lived cotemporaneously with the mammoth (_Elephas primigenius_), rhinoceros (_R. tichorrhinus_), cave-bear, etc. "III. _Post-glacial Epoch_, in which man lived cotemporaneously with the mammoth and reindeer (_Cervus tarandus_). "IV. _Last Epoch_, or epoch of the _Pile-buildings_, in which man lived cotemporaneously with the Irish elk (_Megaceros hibernicus_), aurochs (_Bison Europæus_)," etc.[2] Westropp divides the periods of man, in respect to his stages of civilization, as follows: _Savagery_, _hunters_, _herdsmen_, and _agriculturists_. In the following pages a somewhat different classification has been adopted, and may be thus explained: I. _Pre-glacial Epoch_; that period antedating the glaciers of the post-tertiary, in which man lived cotemporaneously with the animals of the tertiary, southern elephant (_E. meridionalis_), etc. II. _Glacial Epoch_; that period of the post-tertiary when man was forced to contend with the great ice-fields and the floods immediately succeeding them, when the mammoth (_E. primigenius_), rhinoceros (_R. tichorrhinus_), cave-bear, etc., began to flourish. III. _Interglacial Epoch_; that period between the glacial and the second advance of the ice, in which man lived cotemporaneously with the animals of the preceding epoch, and the cave bear became extinct.