792 THE AMERICAN NATURALIST. [VoL. XXXII. 
The plankton of the Balaton is peculiar in its entire lack of 
Dinobryon and Difflugia. The fauna seems to be relatively poor in 
Rotifera and Entomostraca and rich in Nematoda and Protozoa, espe- 
cially Flagellata. For these last particulars much credit must be 
given to the excellent reports of Daday and Francé. Of the Protozoa 
191 species were found, 92 belonging to the oft-neglected group of 
Mastigophora. ‘I'he bottom ooze yielded an unusual number of new 
forms. 
With regard to the distribution of Protozoa, Francé concludes that 
it is not so much influenced by climatological and meteorological 
conditions, as by the hydrological environment and the associated 
vegetation. Thus he distinguishes several characteristic habitats, 
each having its peculiar protozoan fauna wherever found, such as 
(1) the peat swamp where desmids and Protococus abound, and the 
green flagellates as Euglena are plentiful ; here we find the Rhizopoda 
With patterned shell, such as Euglypha and Nebella, which feed upon 
the green forms mentioned ; (2) decaying vegetation, where Stentor, 
Parameecium, and craspemonads occur; (3) the rush-bordered shore, 
where diatoms abound, and the diatomophagous Protozoa, such as 
Ameeba, -the Euglenidce, Chilodon, Holophrya, and Amphileptus, 
abound ; (4) the bottom ooze, resembling the shore but not so densely 
populated, where Ameba verrucosa, Arcella, and Difflugia, and small 
monads are to be found ; (5) the sandy shore, marked by the sand 
building Rhizopoda, as Difflugia, and Orbulinella ; (6) the rocky shore, 
where filamentous alga cover the rocks and afford food and shelter: 
for the algophilus Infusoria, such as Glaucoma and Colpoda, and for 
the thalamophorous Rhizopoda ; (7) the open water with its typical 
plankton forms, stich as the Perjdinide, Codonella, Synura, and the 
passive limnetic Mpistylis and Tokophrya. It is of interest to note 
that Daday finds these same habitats characterized each by its pecu- 
liar crustacean fauna. He also mentions the avoidance of the upper 
layers of water by the Entomostraca in the daytime and on moonlit 
nights, and discusses their movements with respect to light. 
An interesting case of “synoikOsis” is reported by Vangel in 
which a bryozoan, /yedericella sultana, is associated with a sponge, 
Spongilla lacustris ox fragilis. There is a marked and constant agree- 
ment in the color of the two forms, the bryozoan being of a grayish, 
brownish, or greenish tinge according as the sponge is colored. 
The author suggests that the similarity in color affords mutual pro- 
tection, that the tentacles of the bryozoan create currents which 
bring more food to the sessile sponge, and that by reason of its 
