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. 
ALKING 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 varous 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-oecology. 
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, 
