THE MARINE ALGAE OF ESSEX.
3
Desmarestia aculeata, Dictyosiphon foeniculaceus, D. hippuroides,
Asperococcus echinatus, Sphacelaria cirrhosa, Chordaria flabelliformis,
Leathesia difformis, Laminaria digitata, Saccorhiza bulbosa, Pelvetia
canaliculata, Chantransia secundata, Gelidium crinale, Gigartina
mamillosa, Callophyllis laciniata, Lomentaria clavellosa, Nitophyllum
punctatum, Ceramium echionotum, C. acanthonotum, C. ciliatum, and
Polysiphonia fastigiata, all of them common species, are "conspicuous
by their absence" from the flora of Essex. For a moment we might
be tempted to think that some at least of these species had been
passed by as too common to deserve notice, but when on comparing
the Essex marine flora with that of the neighbouring counties of
Suffolk and Norfolk we find very many of the same species also
missing there, one hardly knows what to think. Dictyosiphon
foeniculaceus, D. hippuroides, Leathesia difformis, Laminaria digitata,
Saccorhiza bulbosa, Gigartina mamillosa, Ceramium acanthonotum,
C. echionotum, and C. ciliatum have not been recorded from the
coasts of either Suffolk or Norfolk, while Pelvetia canaliculata has
been "once found by Mr. Wigg" on the coast of Norfolk, according
to Paget,3 and the only Norfolk locality for Polysiphonia fastigiata
rests on the very doubtful authority of the Rev. G. Munford.4
It is not easy to account for the absence of these species, some
of which, e.g., Laminaria digitata5 and Saccorhiza bulbosa, are too
large to escape the observation of even the most careless collector.
Most probably the absence of fixed rocks large enough to form a
safe anchorage for their roots accounts for the absence of the large
sea-weeds, but one would surely have thought that Pelvetia canaliculata
and Gigartina mamillosa could have subsisted wherever Fucus
vesiculosus and Chondrus crispus were to be found. The absence,
too, of Sphacelaria cirrhosa, Polysiphonia fastigiata, and Callophyllis
laciniata appears to me most extraordinary. Of course the large
amount of sweet water poured into their estuaries by the Thames,
Blackwater, Stour, and Orwell must to a great extent modify the
marine flora of the county. There can be no doubt, however, that
a careful search would result in the discovery of many of the missing
species, and also of a large number of brackish water species not
yet recorded from Essex.
The marine flora of Essex is southern in its character, as is shown
3 "Sketch of the Natural History of Yarmouth," 1834.
4 Botany, in White's "History and Directory of Norfolk," 1864.
5 The Fucus digitatus mentioned by Goodenough and Woodward (Linn. Trans. iii., p. 155
as occurring at Harwich before 1795 was probably a form of L. saccarhina.