570 



SCIENCE. 



[N. S. Vol. XI. No. 276. 



exclusively Eurasiatic history, so far as we 

 know. These are, among animals related 

 to the horse and tapir, the Palseotheres and 

 Lophiodon ; among ruminants the Tragu- 

 line deer and Muntjacs ; among inseetivores' 

 the hedgehogs ; among primates, the An- 

 thropoid Apes and the lemurs. The latter 

 are peculiar to the Malagasy and Ethiopian 

 regions. At the same time America ex- 

 clusively raised the Titanotheres,* the Hy- 

 racodontidce or cursorial rhinoceroses, the 

 pouched rodents or Geomyidce, all the early 

 families of Tylopoda, the peccaries. It is 

 paradoxical that so many animals which 

 we are wont to consider typically American 

 came from the Eurasiatic region, while so 

 many others which we always associate with 

 Asia and Africa came from this country. 

 Herein lies the necessity of a paleontolog- 

 ical basis for zoogeography. 



PLEISTOCENE DIVISIONS IN EUEOPE. 



The Pleistocene Quaternary or Glacial 

 Age is the period in which the present dis- 

 tribution of animals and plants was de- 

 termined. In this period the fulness of 

 European investigation is in strongest con- 

 trast with the indecisive results of Amer- 

 ican work and in no other period can we 

 anticipate more weighty inductions from 

 Holarctic correlation. It is especially im- 

 portant to determine the relative antiquity 

 of the first recorded traces of man in the 

 two continents. 



It is true the Pleistocene history of 

 Europe is still in a formative stage, but it 

 is absolutely evident that a final and posi- 

 tive time scale and subdivision of the early 

 Age of Man is not far distant and that the 

 vast labors of geologists, botanists, zoolo- 

 gists, paleontologists and anthropologists 

 will be rewarded with a harmonious theory 

 of all its phenomena. 



Combined attack by geological and bi- 

 ological methods has nowhere produced 



* A Titanothere is reported in Eoumania. 



more brilliant results. The unaided testi- 

 mony of the rocks and soils fails to tell us 

 of the successive advances and retreats of 

 the ice but where, owing to the obliteration 

 of surface deposits, geology is in confusion, 

 plant and animal life' serves both biology 

 and meteorology like a vast thermometer 

 actually recording within a few degrees the 

 repeated rise and fall of temperature. 

 This record consists of the invading and re- 

 treating life waves of river, forest, field, 

 barren ground, steppe, tundra and arctic 

 types, with increasing cold, or the reversed 

 order, with diminishing cold, in the same 

 localities or geographical areas. There 

 seems to be sufficient evidence for a main 

 division of the Pleistocene as follows : 



Upper Pleistocene^ Postglacial. 



f Upper 1 

 Middle Pleistocene { Middle y Glavial. 



L Lower J 

 Lower Pleistocene^ Preglacial. 



Briefly the prevailing views in Europe as 

 to the glacial age are told in Chart V. 



(1) The preglacial stage presents a min- 

 gling of south temperate, temperate and 

 northern forms of mammals. 



(2) The long first glacial advance was 

 followed (Pohlig) by the Rixdorf stage, 

 intermorainal, colder than the succeeding 

 Mosbach and Thuringian stages which have 

 a more temperate facies in the recurrence 

 of some of the Forest Bed Fauna. 



(3) The faunal evidence for a colder 

 mid-glacial period is conclusive. The evi- 

 dence for a second or mid-glacial advance, 

 between the first and last great glacial 

 stages, is mainly biological, that is, sub- 

 arctic are followed by more temperate life 

 forms, as we gather largely from studies of 

 the rodent fauna by Nehring, Studer and 

 others. The hypothesis of three distinct 

 glacial advances and of two inter-glacial re- 

 treats rests therefore upon a combination 

 of geological and biological evidence which 

 is not as yet conclusive. 



