50 Origin of the British Flora. 



nothing but thousands of seeds belonging to half a dozen 

 aquatic plants, which were already quite well known. As 

 an example, we may take the flora of the Cromer Forest- 

 bed, which is still a small one, for the deposits belonging 

 to it are parts of a wide>spread alluvial plain, with shallow 

 pools and broads. Yet the* collection of the plants has 

 given me ten times the trouble that was needed to obtain 

 a much larger number of species at West Wittering. This 

 latter deposit is of estuarine origin — it therefore contains 

 mingled fresh-water, estuarine, and sea-coast plants ; it is 

 the deposit of a very small stream — the proportion of dry- 

 soil species is therefore exceptionally large, and their seeds 

 are unusually well preserved ; moreover, the stream within 

 a mile crossed the edges of a most varied series of strata, 

 including chalk, stiff clay, loose sand, marl, loam, and 

 gravel — the flora is therefore as good an epitome of that 

 of the surrounding district as could be obtained by the 

 examination of several- deposits, each of which only fulfils 

 some of these conditions. It may be added that, while the 

 best fossiliferous deposits in the Forest-bed are commonly 

 stiff clays or peaty-beds, difficult to take to pieces without 

 injury to the fossils, the strata at West Wittering are 

 sandy loams, which, when dried and placed in a sieve in 

 water, quickly fall to pieces and leave the seeds un- 

 injured. 



Deposits like that just mentioned, though giving the 

 best general view of the flora of a district, are unsatisfac- 

 tory in certain respects; for they seldom yield well- 

 preserved leaves, and many species having soft seeds can 

 only be recognised by the leaves. In order to discover 

 leaves of any plants, other than the small tough-leaved 

 Arctic ones, it is commonly necessary to split up laminated 

 lacustrine clays, or masses of bog-iron ore ; but, unfortu- 

 nately, Pleistocene clays are seldom sufficiently firm to 



