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 
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