lxvi Journal of Proceedings.
careful search is made for them. I speak with confidence on this point
having recently found several of them. These Alga; are probably brought
to our shores by the ocean currents. Judging from the character of
the species occurring on our coasts, I have been led to the conclusion
that the warm water of the Gulf Stream brings southern weeds, including
some Mediterranean species, to our southern and western shores, its
influence extending as far as Folkestone to the east and the Orkneys to
the north. In the opposite direction a cold current, bringing with it
northern species, appears to descend from the north, and probably sinks
beneath the warm water from the south when it meets it, both currents
leaving Algae to settle and grow wherever there occurs a quiet land-locked
bay into which they can be carried by an eddy. The cold current,
apparently divided by the north of Scotland, seems to pass down both
sides of England, being probably diverted from its course by the pro-
jecting land of Wales on the west and Norfolk on the east. At least, I
have not been able to trace such northern species as Odonthalia further
south than Yorkshire, nor such southern ones as Cystoseira ericoides
further north than Anglesea. This theory seems to be corroborated by
the fact that several southern species of Lichens have been found on the
coast of Anglesea, while the Foraminifera of the north-east of Britain
have been found by Mr. H. B. Brady, F.E.S., to be identical with those
of Norway. Having traced the northern Algae as far as the Wash, and
the southern as far as Folkestone, it would be especially interesting to
ascertain the character of those found on the Essex coast on the east and
of the Welsh coast on the west, but of the Algae of these coasts there
exist, I believe, very meagre records. That an investigation of the
marine flora of Essex would prove very interesting I have but little
doubt. While looking through the herbarium of the late Dr. Lands-
borough I came across a specimen of a North American seaweed, Dasya
elegans, labelled ' Thames River, February,' but whether it was found
on the Essex coast or not was not mentioned. The plants of this genus
love muddy shores, and as this species is found also in the Mediterranean
the question anses, is it a native of Britain, or was it merely brought
here attached to a vessel which had remained some months in a foreign
part? This question an investigation of the Marine Algae of Essex might
settle. Almost the only other contribution I can offer to the Essex list of
Marine Algae is Bostrychia scorpioides, an amphibious species occurring
on the roots of Obione pedunculata and other seaside plants, sometimes,
as near the Isle of Portland, covering extensive pieces of ground. A spe-
cimen of this plant I observed in the herbarium of the British Museum
from Maldon, Essex. Although the plant occurs so abundantly, I am not
aware that the capsular fruit has ever been found in this country.*
"It may be useful, perhaps, to call attention to those groups of Algae
in which new British species are most likely to be discovered on Essex
shores. On a comparison of the French flora with the English the prin-
cipal genera which are less fully represented in this country appear
to be Lyngbya, Oscillaria, Cladophora, Callithamnion, Polysiphonia,
Ectocarpus, and Mesogloia.
"Of these genera I propose to give a brief sketch, such as may enable
anyone unacquainted with our English species to know where to look
for them, and to refer the plants to their respective genera when found.
" There are probably few persons who have botanised along muddy
creeks who have not noticed scattered here and there small patches
having the appearance of dark green or bluish green slime, sometimes
floating on marine plants and sometimes growing on the mud. If a
* Some ripe capsules lave been detected by Mr. Buffham, since this paper was written,
on specimens brought by me from Portland.