1 877.] The Loess of the Rhine and the Danube. • 77 
and only those that could withstand the severe winters would 
survive. 
The Diirnten lignites, which, like the Cromer Forest bed 
and the Mosbach beds, are characterised and have their 
geological horizon fixed by the presence of Elephas antiquus 
and Rhinoceros etniscus, have been shown by Prof. Heer — - 
from a study of the flora preserved in them — to have cer- 
tainly been formed in as cold and possibly a colder climate 
than the present. I may remark that Prof. Heer himself 
correlates the lignites with the Mosbach gravels and the 
Cromer pre-glacial beds ;* and if the arguments that have 
been used to prove, from the existence of the former, that 
there have been interglacial warm periods, are of any weight, 
which I do not admit, then the glacial period that is supposed 
to have prevailed before the formation of the Diirnten 
lignites is one of which we have no traces in the British 
Islands, as it belongs to an epoch anterior to the growth of 
the Cromer Forest, which is older than any of our English 
glacial deposits. 
Resting on the Mosbach sands and gravels, as well as on 
gravels of more recent age, and everywhere distinctly super- 
imposed upon them, lies the loess. We have seen that in 
the gravels of more ancient date the climate was probably 
colder, or at any rate the winters were more severe than 
now. The fauna of the loess indicates a still colder climate. 
The hippopotamus, the southern elephant, and the southern 
rhinoceros are no more found. The mammoth abounds, 
and is now accompanied by the woolly rhinoceros. The 
reindeer and the Canadian elk are much more abundant than 
in the earlier period. Fresh-water shells occur but rarely, 
and belong to species such as Lymnczus truncatalus (the only 
one found near Wurzberg), which probably lived not in the 
water from which the loess was deposited, but in marshy 
spots above it. River shells are unknown : I have never 
seen even a fragment of one in the loess. The most abun- 
dant land shells are either those now ranging far to the 
north, or which, from their wide distribution, must be able 
to accommodate themselves to extremely varying circum- 
stances. Thus the most characteristic of all the shells — 
the Succinea oblonga, which I have gathered in the loess of 
the Rhine, the Main, the Danube, and the Steppes of 
Southern Russia, and which Prof. Morris finds in the 
patches of loess preserved in fissures of the chalk near 
Maidstone— is, though widely ranging, essentially a northern 
* The Primaeval World of Switzerland (Eng. ed.), pp. 171 and 176. 
