790 THE AMERICAN NATURALIST. [VoL. XXXII. 
biological station under the direction of Professor Frič has had a large 
share in this work. The latest publication from this station is a paper! 
which deals with the flora and fauna of two glacial lakes in the Bohe- 
mian Forest. These lakes have an altitude of 1008 and 1030 meters, 
and a maximum depth of 30 and 35 meters, respectively. They are 
characterized by rocky shores, little vegetation, and great transparency 
of the water. As might be expected under these conditions the fauna 
is scanty, including, with the adjacent land forms, only 185 species, 
of which but 83 are referred to the aquatic fauna. ‘This is charac- 
terized by the presence of a number of cosmopolitan species, prin- 
cipally of Protozoa and Entomostraca, together with a much smaller 
number of alpine and arctic forms. The cosmopolitan distribution 
of the two groups above mentioned is shown by the fact that of 19 
species of Protozoa listed for these Bohemian lakes, 13 are known 
to occur in this continent, and of the 24 species of Entomostraca 
at least 12 are found in American waters. A further evidence of the 
similarity of the lake fauna the world over is found in the occurrence 
in these alpine lakes of Bohemia of 12 species, largely limnetic, 
reported by Forbes? from the mountain lakes of Yellowstone Park. 
These lakes of Bohemia were under observation in 1871, in ’87, 
and again from ’92~—’96 at intervals during the summer months. 
With respect to the fauna thus observed, the authors conclude that it 
is not constant but changes from year to year in response to the 
environment, predominant forms of one year disappearing the next, 
it may be to return again when conditions favor. Thus the authors 
attribute the disappearance of Polyphemus pediculus, a littoral species 
in Schwarzersee, to the accidental lowering of water level, whereby 
the winter eggs were stranded on the dry shore, and the extermina- 
tion of Holopedium gibberum from the plankton to the introduction of 
Salmo salvelinus into the lake. A single fish (32 cm.) of this species 
was taken which had eaten 3000 specimens of Holopedium. The 
plankton is remarkable for the paucity of species reported. In 
general the collections, which were not strictly quantitative, indicate 
an accumulation of the plankton in the upper layers and its scarcity 
in the deeper water, though one instance occurs of an exceptional 
abundance of Daphnia ventricosa — with summer eggs —in the 
1 Frič, A.,und Vavra, U. Untersuchungen zweier Bohmerwaldseen, des Schwar- 
zen und des Teufelssees. Archiv f. Landesdurchforsch. v. Böhmen, Bd. x (1897); 
Nr. 3, 74 PP- 33 figs. 
2 Forbes, S. A. A preliminary report on the aquatic invertebrate fauna of 
Yellowstone National Park, Wyoming, and of the Flathead region of Montana. 
Bull. U. S. Fish Com., vol. xi (1893), pp. 207-258, Pls. XXX VII-XLII. 
