Prof. James Geikie’s Address. 473 
In place of them we meet with a more or less Arctic fauna, and a 
high-Alpine and Arctic flora, which, as we all know, eventually gave 
place to the flora and fauna with which Neolithic man was contempo- 
raneous. ‘As this is the case throughout North-Western and Central 
Europe, we seem justified in assigning the Thiede beds to the 
Pleistocene period, and to that inter-Glacial stage which preceded 
and gradually merged into the last Glacial epoch. That the steppe- 
fauna indicates relatively drier conditions of climate than obtained 
when perennial snow and ice covered wide areas of the low ground 
goes without saying; but I am unable to agree with those who 
maintain that it implies a dry-as-dust climate, like that of some of 
the steppe-regions of our own day. The remarkable commingling 
of Arctic and steppe-faunas discovered by Woldrich in the Bohmer- 
- wald! shows, I think, that the Jerboas, Marmots, and Hamster-rats 
were not incapable of living in the same regions contemporaneously 
with Lemmings, Arctic Hares, Siberian Social Voles, ete. But when 
a cold epoch was passing away the steppe-forms probably gradually 
replaced their Arctic congeners, as these migrated northwards during 
the continuous amelioration of the climate. 
If the student of the Pleistocene faunas has certain advantages in 
the fact that he has to deal with forms many of which are still 
living, he labours at the same time under disadvantages which are 
unknown to his colleagues who are engaged in the study of the life 
of far older periods. The Pleistocene period was distinguished above 
all things by its great oscillations of climate—the successive changes 
being repeated, and producing correlative migrations of floras and 
faunas. We know that Arctic and temperate faunas and floras 
flourished during inter-Glacial times, and a like succession of life- 
forms followed the final disappearance of Glacial conditions. A 
study of the organic remains met with in any particular deposit will 
not necessarily, therefore, enable us to assign these to their proper 
horizon. The geographical position of the deposit, and its relation — 
to Pleistocene accumulations elsewhere, must clearly be taken into 
account. Already, however, much has been done in this direction, 
and it is probable that ere long we shall be able to arrive at a fair 
knowledge of the various modifications which the Pleistocene floras 
and faunas experienced during that protracted period of climatic 
changes of which I have been speaking. We shall even possibly 
learn how often the Arctic, steppe-, prairie-, and forest-faunas, as 
they have been defined by Woldrich, replaced each other. Even now 
some approximation to this better knowledge has been made. Dr. 
Pohlig,” for example, has compared the remains of the Pleistucene 
faunas obtained at many different places in Europe, and has presented. 
us with a classification which, although confessedly incomplete, yet 
1 Woldrich : Sitzungsb. d. kais. Akad. d. W. math. nat. Cl., 1880, p. 7; 1881, 
p- 177; 1883, p. 978. 
2 Pohlig: Sitzungsb. d, Niederrheinischen Gesellschaft zu Bonn, 1884; Zeitschr. 
d. deutsch. geolog. Ges., 1887, p. 798. For a very full account of the diluvial 
European and Northern Asiatic mammalian faunas by Woldrich, see Mém. de l’Acad. 
des sciences de St. Pétersbourg, viie. sér, t. xxxv. 1887. 
