IV. ADDITIONAL LIST. 
INCLUDING 
Segregates, Aliens, Casuals, Extincts, Errors and 
Ambiguities. 
PRELIMINARY EXPLANATIONS. 
This miscellaneous List is intended to include any plants 
reported to have been found seemingly wild in Britain, under 
conditions which have not been deemed sufficient to warrant 
their inclusion in the foregone ‘Synopsis of Species,’-—or, con- 
cerning the localities for which our knowledge is yet so imperfect 
that it was found practically impossible to bring them under the 
formula there adopted. The heterogeneous assemblage is divisible 
into various groups or categories, as above indicated; although 
such divisions will be found to pass one into another by almost 
insensible gradations. widely different in meaning as the terms 
used to designate them may appear to be. Just as gradually do 
they pass into the three categories of plants before treated in the 
Synopsis. These still remaining for notice, in the following list, 
are separated from those previously treated in the Synopsis, by an 
uncertain line, chiefly determined by our lack of sufficient know- 
ledge about their localities, or by our individual differences of 
opinion respecting the degree or character of their wildness in this 
country. Nevertheless, it seems desirable to classify them into 
groups, if only to obtain a series of terms to epitomize explanations 
in the List presently to follow, by the substitution of single terms 
instead of many words. The sense or meaning of the several 
terms will be rendered more familiar by the subjoined brief 
account of them. 
1. Segregates——The character of this group has been fully 
shewn in the half-dozen examples which were taken to explain 
