Deposits containing Fossil Plants. 51 
allow of handling in this way. Or else we must search 
the masses of tufa deposited by calcareous springs; for 
these yield beautifully preserved casts of deciduous leaves, 
and may also contain impressions of the succulent leaves 
of non-deciduous plants; they are almost useless, however, 
for the study of seeds, which are generally too small to be 
recognisable in hollow impressions in a somewhat coarse- 
grained matrix. 
Want of time has prevented me from undertaking so 
thorough an examination of the plants of the newest 
deposits as they deserve, or as has been made in Sweden: 
by Professor A. G. Nathorst and Dr. Gunnar Andersson. 
We happen, however, to possess a large series of deposits 
of somewhat earlier date than any of those found in 
Scandinavia ; it seems best, therefore, to devote attention 
more particularly to the plants contained in them. Pre- 
glacial plants are extremely rare in Europe, and the Inter- 
glacial flora has only been studied at a few localities in 
North Germany, principally by Dr. Carl Weber and. 
Professor A. Nehring. 
It only remains to add a few words as to the position 
in time of the various deposits to be described. They are 
here divided into Preglacial, Early Glacial, Interglacial, 
Late Glacial, and Neolithic. The whole of the historic 
period, from the invasion of the Romans downwards, has 
purposely been omitted, not because it is of little import- 
ance in the history of the flora as we now see it, but 
because collecting has not yet been done with sufficient 
accuracy to fix the century to which the deposits belong. 
Without this, the identification of the included plants 
would be of little value. One exception only has been 
made. A certain number of plants from Silchester are 
mentioned, as these were found in carefully selected 
material obtained by Mr. A. H. Lyell during excavations 
