234 
ELEMENTS OF GEOLOGY. 
called Cypris in the ancient lake^ of Auvergne; and lastly 
the limestone is for the most part subordinate to the newer 
portions of both the above formations. 
It seems that, wdien the ancient lake of the Limagne first 
began to be filled with sediment, no volcanic action had yet 
produced lava and scoriae on any part of the surface of Au¬ 
vergne. 1^0 pebbles, therefore, of lava were transported into 
the lake—no fragments of volcanic rocks imbedded in the 
conglomerate. But at a later period, when a considerable 
thickness of sandstone and marl had accumulated, eruptions 
broke out, and lava and tuff were deposited, at some spots, 
alternately with the lacustrine strata. It is not improbable 
that cold and thermal springs, holding different mineral in¬ 
gredients in solution, became more numerous during the suc¬ 
cessive convulsions attending this development of volcanic 
agency, and thus deposits of carbonate and sulphate of lime, 
silex, and other minerals were produced. Hence these min¬ 
erals predominate in the uppermost strata. The subterra¬ 
nean movements may then have continued until they altered 
the relative levels of the country, and caused the waters of 
the lakes to be drained off, and the further accumulation of 
regular fresh-water strata to cease. 
Lower Miocene Mammalia of the Limagne.^ —It is scarcely 
possible to determine the age of the oldest part of the fresh¬ 
water series of the Limagne, large masses both of the sandy 
and marly strata being devoid of fossils. Some of the lowest 
beds may be of Upper Eocene date, although, according to 
M. Pomel, only one bone of a Paleotherium has been discov¬ 
ered in Auvergne. But in Velay, in strata containing some 
species of fossil mammalia common to the Limagne, no less 
than four species of Paleothere have been found by M. Ay- 
mard, and one of these is generally supposed to be identical 
with Paleotherium magnum^ an undoubted Upper Eocene fos¬ 
sil, of the Paris gypsum, the other three being peculiar. 
Not a few of the other mammalia of the Limagne belong 
undoubtedly to genera and species elsewhere proper to the 
Lower Miocene. Thus, for example, the Cainotherium of 
Bravard, a genus not far removed from the Anoplotherium, 
is represented by several species, one of which, as I learn 
from Mr. Waterhouse, agrees with Mierotherium Penggeri of 
the Mayence basin. In like manner, the Amphitragulus ele- 
gans of Pomel, an Auvergne fossil, is identified by Water- 
house with Porcatherium nanum of Kaup, a Rhenish species 
from Weissenau, near Mayence. A small species, also, of 
rodent, of the genus Titanomys of H. von Meyer, is common 
to the Lower Miocene of Mayence and the Limagne d’Au- 
