80 On the Origin and Distribution of the British Flora.
'Encyclopaedia Britannica' affords hardly any information
on the natural features of the county, and the drainage is
barely alluded to in Mr. Gibson's 'Flora of Essex.'
I propose to divide the county into seven Sub-Provinces,
viz.: 1, the Lea and Stort; 2, the Roding; 3, the Crouch; 4,
the Blackwater; 5, the Colne; 6, the Stour; 7, the Brook. Of
these the first two come within Province (A), that of the
Thames and its tributaries. From the direction of its mouth
and delta-deposits it seems that, were the sea-bed elevated,
the Crouch, with its tributary the Eoach, would unite with
the Blackwater rather than with the Thames. I therefore
class it in Province (B) East Anglia. The Paver Lea rises in
the Chiltern Hills in Bedfordshire ; flows south-east through
Herts, the eastern two-thirds of which is drained by it and its
tributaries, of which the Maran and the Beame are each
about eleven miles in length. It then flows south to the
Essex boundary near Roydon, where it receives the waters of
the Stort, separates us from Herts down to a little below
Waltham Cross, and then from Middlesex down to its outfall
into the Thames at Bow Creek. Its total course is about fifty
miles; but I have no information as to the acreage drained
by it and its tributaries in Essex. The Stort rises within the
Essex boundary between Little Chishall and Langley Mills,
reaches the boundary between Stanstead Mountfitchet and
Birchanger, and forms the boundary for the greater part of
the remainder of its course to Roydon, receiving at Stanstead
a stream (name?) from Chickney, giving its name to Bishop's
Stortford, receiving the Pincey brook from Hatfield Forest
near Harlow, and a Hertfordshire stream from the neighbour-
hood of Sawbridgeworth above Burnt Mill Station. Its total
course is nineteen miles. Below Roydon the Lea receives the
Cobbin River from between North Weald and Nasing, and
from Middlesex Salmon's Brook from Enfield Chase and
other streams from Hadley, East Barnet, Finchley, and
Southgate, from Highgate and Hornsey (at Tottenham), and
formerly the Hackney Brook at Old Ford. The Roding rises
at Brook End near Easton, flows south by many villages to
which it gives a name to Chipping Ongar, receiving a tributary