68 
W. B. Crow 
sissimis, varie aggregatis, modo densissimis plerumque sparsis, 
sphaericis, 3-5-6-5 /x diam. pseudovacuolibus provectis. 
Loc. In aquis dulcibus, Insula Ceylonica. 
Microcystis pseudofilamentosa n. sp. 
Strato libere natante, longissimo, angusto, in locis constricto ut 
series stratorum secondariorum fiat, interdum passim dilato et vel 
perforato vel reticulato tegumento strati subdistincto. Cellulis 
sphaericis pseudovacuolibus provectis 3-7 /x diam. Strato magnitu- 
dine variabilissimo, interdum vicies saepe decies longo quam lato, 
saepe 200-300 /x longo, 20-30 /x lato; stratis secondariis saepe 20-30 /x 
longis. 
Loc. In aquis dulcibus, Insula Ceylonica. 
Microcystis pulverea (Wood) Migula. 
Var. incerta (Lemm.) nob. 
Cellulis 1-2 /x diam.: cetera ut in typo. 
Forma elongata n.f. 
Strato vel ter vel quater longo quam lato; cetera ut in var. 
incerta nob. 
LITERATURE CITED 
(1) Crow, W. B. A Critical Study of Certain Unicellular Cyanophycese from 
the Point of View of their Evolution. New Phytol. 21. 1922. 
(2) Forti, A. Myxophycese. De Toni\s Sylloge Algarum, 5. 1907. 
(3) Kirchner, O. Cyanophyceae. Englev and Pranti’s Nat. Pftanzenfam. 1. 
(4) Kutzing, F. T. Tabulce Phycologicce, 1 . Nordhausen. 1846. 
(5) Lemmermann, E. Algen. Krypt. Flora Mark Brandenburg, 3. 1910. 
(6) Ostenfeld, C. H. Phytoplankton aus dem Victoria Nyanza, 1904-5. 
Engler’s Bot. Jahrb. 41. 1908. 
(7) Smith, G. M. Phytoplankton of the Inland Lakes of Wisconsin, I. Wise. 
Geol. and Nat. Hist. Survey, Bull 57 . Sc. Ser. 12. 1920. 
(8) Tilden, J. Minnesota Algce I, Myxophycece. Minneapolis. 1910. 
(9) Wesenburg-Lund, C. Plankton Investigations of the Danish Lakes. Copen¬ 
hagen. 1904. 
Explanation of Plate I 
a. Microcystis ceruginosa Kuetz. Typical Colony from Tank Balauwewa. 
b. M. flos-aqucB (Wittr.) Kirchner. Colony from Colombo Lake with Partial 
Colonies. 
c. M. flos-aquce (Wittr.) Kirchner. Typical Colony from Colombo Lake. 
d. M. protocystis n.sp. Typical aggregation from Tank Mineri. 
e. M. pseudofilamentosa n. sp. Typical Colony from Tank Nuwarawewa. 
/. Another colony of the same, apparently showing method of division. 
g and h. M. marginata (Menegh.) Kuetz. g. Side view of typical colony; 
h. Front view of same. 
(The scale measures ioo/x and is divided into units of 10fx each.) 
