408 MR. W. WEST AND PROF, G. S. WEST ON THE 
апа Sphwrocystis Schroeteri reached a considerable maximum from October to 
November. The most interesting of all the green constituents, however, was 
Elakatothria gelatinosa, one of the Protococcales only previously observed by 
Wille in the lakes of Norway*. So far as we have ascertained, this Alga is 
not only absent from all the other lakes of the English Lake District, but has 
not been observed in any other lake in the British Islands. It occurred 
sparingly during the autumnal fall of temperature, but was abundant in June 
and July during the vernal rise in temperature. 
Peridinium Willei attained its maximum in July, as in Ennerdale Water, 
but during the period of investigation it was never absent from the plankton 
and a second smaller maximum occurred from December to January. 
On the whole, the phytoplankton of Wastwater is by no means rich. А 
very minute species of Aphanocapsa was present in the January collections, 
which we have described as a new species— А. delicatissima. 
3. WINDERMERE, W ESTMORELAND. 
The phytoplankton of this body of water, the largest of the English Lakes, 
has been worked out in detail for a period of 12 months from September 
1907 to August 1908 T. It has been shown to have three fairly distinet 
phases. 
I. January-April (cold period). Melosira granulata phase. During 
February and March the phytoplankton is at its minimum. 
II. May-July (vernal rise in temperature). First maximum of Aste- 
rionella gracillima in May and June. 
ПТ. :August- December. (autumnal fall in temperature). The Desmid- 
phase extends from August to November, and is most noticeable 
in September and October. In November is a second maximum 
of Asterionella gracillima. 
One of the leading features in the periodicity is the double maximum of 
Asterionella gracillima. There is a vernal maximum in May and June, and 
an equally great autumnal maximum from November to January, both occur- 
ring at approximately the same water-temperature (19-8? С.). Melosira 
granulata attained its maximum in April with a water-temperature of 
1:79 С.). 
4. осн LOMOND, DUMBARTONSHIRE. 
This lake is of considerable size, being 21 miles in length and 5 miles in 
width at its widest part. Although situated between mountains rising to 
2000 feet on one side and 3000 feet on the other, it is only 23 feet above sea- 
* N. Wille, in Biol. Centralbl. xviii. 1898, p. 2. 
+ W.&G. S, West, in ‘The Naturalist,’ 1909, pp. 188-193, 260-266, text-figs. 3 & 4, 
und pl. 7. 
