THE COAST-FLORA OF THE CLACTON DISTRICT. 199
are few in number, and although they are in all probability
composed of Carboniferous limestone, yet the absence in most
cases of Crinoids makes the determination macroscopically some-
what doubtful.
The boulders of quartz and rhyolite found at Beggars' Hill,
Great Baddow, etc., are similar to those found in Mid. Herts,
and are probably derived from the west (cf. Proc. Geol. Assoc.
Vol. xix p. 21).
More evidence is required before any more definite hypothesis
can be formulated. I hope this paper will have the effect of
arousing interest in the subject and leading to the accumulation
of more evidence.
The specimens obtained while preparing this paper have
been deposited in the Essex Museum.
THE COAST-FLORA OF THE CLACTON
DISTRICT.
By F. SAXER.
WALKING along the sea-shore, it is easy for anyone to
perceive that the plants offer both floristic and
morphological peculiarities. Moreover, it will at once be noticed
that they grow in certain sharply defined associations. Nothing
could be more striking than the difference between the vegeta-
tion of the littoral sand dunes and that of the muddy flats
and creeks. It is again a very pleasant and not at all a difficult
matter to determine the constituent species of the various associa-
tions. Nor is it any more difficult to find the chief conditions
of soil and air which seem to determine the peculiarities of
growth and structure. One cannot help perceiving, after this,
that certain plants only grow within narrowly circumscribed
limits, determined apparently by physical and chemical pro-
perties of the soil. Gradually the idea of zonation must press
itself on an observer, even though he never in his life had heard
of plant-ecology.
It is a much more difficult matter and a much more laborious
task to determine accurately and in unimpeachable scientific
terms the factors that govern the economy of every species or
formation. Many things have to be taken into consideration,