CONTAINING FLINT IMPLEMENTS, AND ON THE LOESS. 
281 
It is evident that if we had to depend only upon the organic remains for decisive 
evidence of the nature of the climate of the period under inquiry, we might fail to 
arrive, on the present data, at any exact or positive conclusion. All the recent species 
are such as are now to be found within the limits of the temperate zone, but they 
appear to agree better with the fauna and flora of its northern than of its southern 
provinces; the Fossil Mammalia may also, from their general association and distri- 
bution, be considered to have inhabited cold countries ; so that there is a balance in 
favour of the probability of a severer, but not of an extreme climate. On the one 
hand, we are restricted in the degree of mean winter cold by the presence of trees, and 
more especially of the Oak ; on the other, we are restricted in the degree of heat by 
the range of the Reindeer and the absence of southern forms. 
If, further, we take these indications in conjunction with the physical features before 
described, the conjoint evidence has more weight and preciseness. Limited as the evi- 
dence of the organic remains is, it is at all events in accordance with the physical 
evidence in favour of a considerable winter cold. It is possible even to attempt some 
approximate limitation. Thus a climate where the Oak, the Yew, and the Fir (and 
the Bilberry) throve, where Reindeer lived, where Deer, Horse, and Ox abounded, and 
where the rivers were subject to periodical floods, and froze so as to transport large 
boulders for considerable distances, presents conditions which would probably accord 
with a mean winter cold of not less than 20°, while it may have been as low as 10° or 
even lower. This would he from 19° to 29° under that which now obtains in these 
regions, taking the winter temperature of the S.E. of England and N. W. of France at 89° 
— a difference, under normal conditions, equal to that of from 10° to 20° of latitude on 
one meridian. 
Low Levels. — The organic remains of this series are more numerous and afford better 
evidence of climatal conditions. 
Mollusca. — Of the 36 species of shells enumerated in the high-level gravels, 31 occur 
also in our lower gravels, together with 20 species which have not yet been found in the 
higher series of these districts, making a total of 51 species belonging to the beds now 
in question*. In the present state of the inquiry I attach little weight to the pre- 
sumed absence of 5 high-level gravel species ; while it remains to be seen how many of 
the additional 20 species may be found in higher beds elsewhere. Amongst the addi- 
tional species are the Carychium minimum and Helix fruticum. The former has a wide 
range in England and over every part of the Continent ; the latter, on the contrary, is 
a temperate and north European species, but does not live in England. The Helix 
arbustorum is also of the small variety characteristic of cold or alpine regions, while 
the H jgygmea is likewise a northern species. On the other hand, several other species 
of Helix (see Appendix) found in these beds range through central and southern Europe 
only. The other species to be noticed in these newer beds, are the Pomatias obscurus, 
* The lists from the low levels of Abbeville and Bedford are given in the Appendix. The latter are from 
Mr. Wyatt’s descriptions of the sections at Harrowden and Summerhouse Hill. 
2 Q 2 
