576 
Notes. 
Hence for the two reasons, (i) association both in impressions 
and in petrifactions with Lyginodendron, (2) the structure of the 
tissue in which the sporangia are embedded, the claim of these clusters 
to be the fructifications of Lyginodendron is overwhelmingly strong. 
My thanks are due to Professor F. W. Oliver for the loan of several 
confirmatory slides. 
MARGARET BENSON. 
Royal Holloway College. 
ALGOLOGICAL NOTES. — 
III. PRELIMINARY REPORT ON THE PHYTOPLANK- 
TON OF THE THAMES. — Freshwater Plankton-investigations, so 
vigorously prosecuted on the continent, have received little or no 
attention in England. As far as the writer is aware no paper on 
this subject has ever been published in this country. The Plankton 
of the sea has occupied English botanists since some years, and 
systematic work in this direction is being done at some of our 
marine stations ; but we possess nothing whatever comparable to 
the inland biological stations established on the continent ; take for 
example Plon in Schleswig-Holstein, which is practically devoted 
solely to research on the Plankton of the numerous small lakes of this 
part of the German Empire. This special line of research has here 
become so proficient and prolific, as to admit of the publication of 
a separate journal 1 to embody its results. 
It was with the intention of drawing attention to this kind of work 
in our country that I commenced to investigate the Plankton of the 
Thames — the more as the Plankton of the artificial waters at Kew, 
which are fed more or less directly from the river, seemed to promise 
good results. And indeed a little over a month’s investigation has given 
such interesting results that I venture now to publish a general account 
of the Plankton without being able to say anything as to its periodicity. 
Investigations of the Plankton of rivers have not been often carried 
out as yet. Lauterborn 2 in 1893 published the results of some 
collecting, performed on the Rhine near Ludwigshafen ; his list 
consists chiefly of animals, two Diatoms being the sole representatives 
of the vegetable kingdom. It is really Bruno Schroder who first gives 
1 Forschungsberichte aus der biologischen Station zu Plon, edited by the 
Director Dr. O. Zacharias. Stuttgart. Appeared first in 1893. 
2 Beitrage zur Rotatorienfauna des Rheins und seiner Altwasser. Zoolog. Jahr- 
biicher, 1893. 
