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general bearing of the whole epoch on Hvolution so far as its 
plant-remains go. The most beautiful leaf-beds belong to 
the Upper Miocene, and are best seen at Oeningen, in the 
valley of the Rhine, between Constance and Schaffhausen. 
They have been explored by the late Professor Heer, whose 
noble work on the Tertiary Flora of Switzerland will form an 
imperishable monument to his name. At this spot there seems 
to have been a lake, probably fed by springs with water 
unusually charged with carbonate of lime. Along the margin. 
of this lake a series of very fine marls were deposited, often 
as thinly laminated as the pages of a book. In these strata 
an astonishing number of leaves, fruits, and insects have been 
preserved. A small collection of them is to be seen at the 
British Museum, now in South Kensington. _ To give some 
idea of the completeness of the record for this particular 
epoch, it may be pointed out that of a kind of camphor-tree 
(Prinos Lavatert) distinct sprays are found with flowers, fruit, 
and leaves; that the well-known key-fruit of the maple 
abounds, together with countless leaves ; that on some remains 
leaf-fungi can be detected just as they now are developed in 
autumn ; and that the time of year when the deposit was made 
can often be inferred from the shoot being in its vernal or 
autumnal state, and from the ants having their wings or not. 
What, then, was the vegetation that surrounded this Swiss lake 
at a time before the Alps had undergone their last elevation ? 
First of all, not one plant of the present Swiss flora has been 
found. Secondly, the vegetation was very rich in trees, and on 
the whole had a resemblance to that of Florida, Mexico, Aus- 
tralia, and Japan. The number of woody plants was very great 
for so small an area. About 180 are known. ‘These include 
swamp cypresses, evergreen oaks, laurels, elms, maples, 
acacias, liquidambar, and seven kinds of palms, including 
one (Sabal) similar to that now growing in the valley of the 
Mississippi. On the surface of the lake floated water-lhes, 
around its margin were reeds and rushes. ‘The ferns are pre- 
cisely the same as our recent ones, only of a sub-tropical type, 
such as Lygodiwm, a climbing fern, and Osimunda lignitum. 
But it would be tedious to give anything like a complete list 
of the still-existing genera which are found in these strata. 
Every one who examines the remains must be forcibly struck 
by the extreme distinctness of the generic type; for, great 
as must be the interval which separates us from these suc- 
cessive Miocene floras, all the genera are obviously as distinct 
from each other then as now. 
More than this, so great is the constancy of type in.many 
eases that Professor Heer gives a list of plants in which 
