422 МП. W. WEST AND PROF. G. S. WEST ON THE 
7. Loca LUBNAIG, PERTHSHIRE. 
This loch is 44 miles in length by about half a mile broad at its widest 
part, and is 405 feet above sea-level. On its western side is Ben Vane 
(2685 feet), und on its eastern side Beinn Each (2660 feet), the summits of 
these mountains being about two miles from the lake. 
The collections from this lake were also incomplete, but as they were made 
from August to October 1908 and from January to April 1909, it is possible 
to form some idea of the periodicity of the phytoplankton. 
Aug. 15th, 1908. Temp. of water 61° Е. (=161° C). The plankton 
consisted mostly of Dinobryon eylindricum and Anabena Flos-aque', amongst 
which were numerous Rotifers and much organic detritus. 
Sept. 16th, 1908. Temp. of water 54° F. (2122? €... The material con- 
sisted almost entirely of Entomostraca, Tabellaria floceulosa and Dinobryon 
cylindricum were present in small quantity, and there was a little organic 
detritus, 
Oct. 16th, 1908. Temp. of water 56° Е. (— 13:3? C.). Much organic detritus 
and broken sterile filaments of GEdogonium. Very few Diatoms, and few 
Rotifers and Entomostraca. 
Jan. 20th, 1909. Temp. of water 34° F. (=1:1° C). Plankton practically 
absent, collection consisting of organic detritus, but we doubt whether the 
material was collected in a proper manner. Two or three species of Diatoms 
were observed, and one or two specimens of Rotifers and Crustacea. 
Feb. 21st, 1909. Temp. of water 36° F. (22:2? C.). Searcely any phyto- 
plankton, but much organic and mineral detritus. А few species of Diatoms. 
No Rotifers. Defective material? 
March 16th, 1909. Temp. of water 36° F. (=22° С.). Phytoplankton 
mostly Diatoms, of which Surirella biseriata and Tabellaria flocculosa were 
most conspicuous. А few species of Desmids were also present in small 
quantity. Very few Rotifers. 
April 20th, 1909. Temp. of water 44^ Е. (=6°6° C.). Phytoplankton 
mostly Diatoms, of which Tabellaria fenestrata is dominant and T. floceulosa. 
less abundant. Synedra Ulna was common, and many of the valves were 
curiously bent and deformed. — Dinobryon eylindricum and Llothrie zonata 
were both frequent. Few Rotifers were present, and there was a great 
admixture of organic detritus. 
Altogether 37 species were observed in the phytoplankton of Loch 
Lubnaig, mostly Green Algæ and Diatoms. Most of the Chlorophycee 
occurred in the August collection, whereas the Diatoms were most numerous 
and in greatest variety in March. The data at our disposal are at present, 
however, insufficient to enable us to make any definite statement regarding 
the periodicity of the phytoplankton of this lake. 
