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МК. W. WEST AND PROF. G. S. WEST ON THE 
Most of our plankton-investigations have been of a qualitative character, 
as it was thought desirable that the pioneer work should be the acquirement 
of a sound general knowlege of the British freshwater phytoplankton, an 
exact knowledge of its constituents, and the points wherein the British 
phytoplankton differs so conspicuously from that of Central Europe and 
elsewhere. By а prolonged plankton-investigation of all the British lake- 
areas during the past ten years, we have acquired this knowledge very 
thoroughly. It is only since 1907 that we have been conducting observations 
of a more quantitative character in several of the more important and 
accessible lakes with a view to obtaining a knowledge of the periodicity of the 
plankton-organisms. The more detailed quantitative work concerning the 
phytoplankton, which, so far as we cau see, in the British lake-areas will be 
quite of subordinate value, сап be done piecemeal at any time by sufficiently 
qualified persons who possess the necessary means and time. 
1. ExNERDALE WATER, CUMBERLAND, 
The most western of all the English Lakes, Ennerdale Water lies in a 
drainage-basin of its own, between mountains which rise on each side to 
2000 feet. Its situation is somewhat desolate, and the valley above the lake 
is strewn with numerous moraines. The contamination of the water must be 
very slight, as only three houses are situated near its shores. It is two and 
а half miles in length by three-quarters of a mile broad, and has an average 
depth of 62 feet, the maximum depth being 148 feet. The collections were 
made regularly from August 1908 to July 1909, and the following monthly 
statement gives a brief outline of the changes in the plankton. 
Aug. lst, 1908. Temp. of water 60° F. (=15°5° €). Mostly а Desmid- 
plankton, principally of small species, of which the most abundant were a 
biradiate form of Staurastrum jaculiferum, Arthrodesmus crassus, Cosmarium 
subarctoum, and C. abbreviatum var. planctonicum. Мапу other small species 
were more or less common, and abnormalities of most of the species, due to 
rapid divisions, were frequent. Two other Chlorophyceous alge were of 
interest and were both fairly common. One was a rather small free-floating 
species of Tetraspora in which the pseudo-cilia were very distinct. This we 
have named Tetraspora limuetica. The other was a curious species of 
Ankistrodesmus which, although very minute, reminded one most forcibly 
of the partially untwisted threads in а yarn. This we have named А. tortilis. 
Of the Diatoms, Rhizosolenia morsa was the only abundant species. Other 
common constituents were Chroococeus minutus and Peridinium inconspicuum., 
Ceratium Hirundinella was not so frequent as one would have expected, 
Rotifers were fairly common, especially Notholca longispina. 
Sept. 4th, 1908. Temp. of water 59° F. (—15? С.). This collection was a 
Desmid-plankton with an abundance of Ceratium Hirundinella. As in the 
previous mouth, the smaller species of Desmids, and especially the spiny ones, 
