78 On the Origin and Distribution of the British Flora.
require a scientific division of the country into provinces.
This I have attempted, so far as England is concerned, in a
paper recently published by the Geologists' Association.29
We could hardly have a better guide to critical botany than
Professor Babington's 'Manual'; and for the systematic
examination of the plants of our county we are fortunate in
possessing Mr. Gibson's 'Flora of Essex.' In the appendices
to this work Mr. Gibson compares the Essex list with those
of plants found in the adjacent counties ; and similar tables
are given for Middlesex in Messrs. Trimen and Dyer's Flora
of that county. Unfortunately the subdivisions adopted by
Mr. Gibson are not the natural lines of watershed dividing
the river basins. These undoubtedly afford the most scientific
boundary lines, and in the botanical map of England in my
paper, to which I have just alluded, Essex falls partly into
three provinces—(1) the basin of the Thames and the South-
East, including in this county the valleys of the Lea, the
Roding, and the Marditch; (2) East Anglia, to which
belong the valley of the Blackwater, in which we now are,
that of the Colne and the Stour, and that of the Crouch;
and (8) a small district near Saffron Walden drained by the
great Ouse. Whilst I should not be sorry if our Club were
the means of adding to the four British species peculiar to
Essex, I should be still more glad to hear of the rediscovery
of any of those plants which Mr. Gibson enumerates as lost,
and shall be fully satisfied if my remarks are the means of
directing the attention of a small number to the geographical
relations of our plants.30
29 "On the Geological and other causes that affect the Distribution of
the British Flora," Proc. Geol. Assoc, vol. vi., No. 9.
30 Among the authorities to which I have been specially indebted are
Mr. J. G. Baker's 'Botanical Geography' (1875); Mr. Bentham's Presi-
dential Address for 1869; Professor Morris's article, "The Cretaceous
Flora" (1876) ; Professor Lesquereux's work with the same title (1874);
Mr. Wallace's 'Island Life' (1880); the various works of Professor Heer,
and of Mr. Watson ; Professor Forbes's essay; Professor Dyer's article
"Distribution" in the 'Encyclopedia Britannica' (1877) ; and Professor
Henslow's paper, with the same title as the present one, in the Watford
Society's Transactions for 1879. I have not yet seen Count Saporta's