466 EARLY MAN 



knowledge more definite. Lest, however, the preceding sketch 

 of the Palanthropic age that in which gigantic men were con- 

 temporaries of a gigantic fauna now extinct should be re- 

 garded as altogether fanciful, we may proceed to consider the 

 geological facts and classification as actually ascertained. 



The Tertiary or Kainozoic period, the last of the four great 

 " times " into which the earth's geological history is usually 

 divided, and that to which man and the mammalia belong, 

 was ingeniously subdivided by Lyell, on the ground of per- 

 centages of marine shells and other invertebrates of the sea. 

 According to this method, which with some modification in 

 details is still accepted, the Eocene, or dawn of the recent, 

 includes those formations in which the percentage of modern 

 species of marine animals does not exceed 3^, all the other 

 species found being extinct. The Miocene (less recent) in- 

 cludes formations in which the percentage of living species 

 does not exceed 35, and the Pliocene (more recent) contains 

 formations having more than 35 per cent, of recent species. 

 To these three may be added the Pleistocene, in which the 

 great majority of the species are recent, and the Modern or 

 Anthropic, in which we are still living. Dawkins and Gaudry 

 give us a division substantially the same with Lyell's, except 

 that they prefer to take the evidence of the higher animals 

 instead of the marine shells. The Eocene thus includes those 

 formations in which there are remains of mammals or ordinary 

 land quadrupeds, but none of these belong to recent species 

 or genera, though they may be included in the same families 

 and orders with the recent mammals. This is a most im- 

 portant fact, as we shall see, and the only exception to it is 

 that Gaudry and others hold that a few living genera, as those 

 of the dog, civet, and marten, are actually found in the later 

 Eocene. The Miocene, on the same mammalian evidence, 

 will include formations in which there are living genera of 

 mammals, but no species which survive to the present time. 



