6 
In preparing tlie first part of the present work, I have endeavoured, so 
far as I have been enabled by my own observations, and by the assistance 
of various notes and lists liberally furnished to the author of the “ Flora” 
and to myself, to carry out the idea of the original work up to the present 
time, by making the additions which were needful to adapt it to the 
present standard of knowledge. That is to say, I have wished that the 
“Supplement,” either taken alone or in connection with the “Flora,” 
might furnish a summary of the higher vegetation of the county, so far 
as it has been ascertained: for the use of the botanical and physical 
geographer, either to be viewed by itself, or considered in comparison 
and taken in connection with other similar comital enumerations ; and 
of the resident or travelling collector, to give him information respecting 
the species which he may expect to be enabled to add to his herbarium 
within the limits of the county, and some of the special localities of the 
rarities. 
In all scientific enumerations of the plants of a definite area, it is 
needful that a clear line of distinction should be drawn between those 
which are indubitably ascertained to inhabit it, and those, the occurrence 
of which within the limits of the district rests only upon doubtful 
authority or unconfirmed report. It is also essential, if we wish to esti- 
mate the true relations of the flora, to separate as accurately as possible 
those species which are aboriginal inhabitants of the district, so far as 
can be judged, from those which bear the appearance of having been 
introduced by human agency at some period more or less remote. Partly 
in order that we might attempt to trace these distinctions in the present 
instance ; partly because, on account of the alterations in nomenclature, 
which, as before explained, have been rendered necessary by advancing 
knowledge, confusion might otherwise have arisen; it has been judged 
desirable to repeat the complete series of names. 
For various reasons, upon which it is unnecessary here to dwell, 
especially for the sake of uniformity with the “ Oybele Britannica,” the 
catalogue of British plants published by the Botanical Society of London, 
the fourth edition of which has just made its appearance, has been used 
as an index of nomenclature and arrangement. A line or more is devoted 
to each species which the county is ascertained or reported to afford ; but 
a single line only to those species, respecting the situations and degree 
