The Present Flora of Britain. 17 
plants which are confined to a few widely separated 
localities. Some of the Litiacee and Boraginee, for 
instance, though abundant where they occur, are curiously 
local, most of them being absent from extensive areas 
apparently as well suited for their growth as those in 
which they are found. In the altered state of our woods 
these anomalies are particularly difficult to understand, 
for the plants usually do not appear to group themselves 
into assemblages confined to special districts, and the 
distribution of each species has to be studied separately. 
Not one of our woodland mollusca or plants, unless the 
Arbutus be reckoned as a forest species, falls into the 
specia] groups confined to the eastern counties, to Cornwall, 
or tothe West of Ireland. It is a question whether the 
absence of Lusitanian woodland species may not be due 
merely to the destruction of forests in Cornwall and in 
the West of Ireland; but this cannot be determined till the 
sub-fossil plants of the forests buried under the recent peat 
in these districts have been collected and examined. It is 
possible that some of the difficulties may be cleared up 
when we have studied each patch of ancient woodland, 
however small; for by searching small isolated patches of 
old forest we can often find outliers of the sedentary wood- 
land mollusca and plants, such as probably once extended 
over wide areas now bare or under cultivation. 
A certain number of our plants are confined to lime- 
stone rocks or to calcareous soils; but it will be sufficient 
here to remark that none of them is characteristically 
eastern or western, and that scarcely anything is yet 
known of any of them in the fossil state. 
In addition to these classifications according to climate 
or habitat, there is yet another, certain species being 
eastern and others western. Though we have a con- 
Cc 
