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 



