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THE YAN YEAN RESERVOIR, VICTORIA. 
Long. cell. 28-38 ш; lat. cell. 75-9 ш; long. set. 13-26 и. 
Hab. Yan Yean Reservoir, in the plankton (Feb. 1906, scarce). 
This large and conspicuous Lagerheimia possesses cells which are almost 
three times the size of those of any other species. The outward form ot 
the cells, with conical poles, is also quite distinctive. The bristles are most 
distinetly tubereulated at the base, the flattened tubercles being closely 
applied to the sloping sides of the poles and never at the extreme apex. 
The number of bristles attached to each pole is either three or four, and not 
uncommonly three are present at one pole and four at the other pole of the 
same individual. The bristles are readily detached from the cells, the 
tubereulated base leaving а minute scar on the conical pole from which it 
has become detached. The cell-wall is delicately marked with a few decus- 
sating spiral striations, which ean be seen very well in some of the empty 
cells. "There is a single parietal chloroplast, which only covers part of the 
wall of the cell, and, so far as could be ascertained, it contained no pyrenoids. 
Genus OOCYSTIS, Nav. 
59. Oocysris SUBMARINA, Lagerh. in Botan, Notiser (1886), p. 45, fig. 1. 
Forma major: long. cell. 23-25 p; lat. cell. 775-8 р. 
Hab. Yan Yean Reservoir, at the weedy margins (Mar. 1905). 
О. submarina was described by Lagerheim from brackish ditehes in Sweden. 
In the form of the cells the Australian plant exactly agrees with it, but the 
dimensions are larger. The colonies observed consisted of either two or four 
cells. 
Family PALMELLACEÆ. 
Genus TETRASPORA, Link. 
60. ТЕТВАЗРОВА LACUSTRIS, Lemm. in Botan. Centralbl, (1898) Ixxvi. ; ir 
Forschundasber. Biol, Stat. Plön, vii. (1899) р. 22, t. 1. fig. 13. 
I have for some time regarded Tetraspora lacustris, Lemm., as most 
probably merely а stage in the life-history of Splurrocystis Schrótevi, Chodat 
(vide Treat. Brit. Freshw. Alg. 1904, p. 242), and the Yan Yean plankton- 
collections furnish much evidence in support of this view. From February 
to September the plankton contained colonies of a green Alga which is 
unquestionably referable to Spherocystis Sehroeteri. These colonies reached 
their maximum abundance from June to July, and best exhibited the charac- 
teristic features of Splerroeystis from May to June. In July the larger 
colonies became mostly dissociated into the component smaller groups, which 
then developed more conspicuous gelatinous coats with much firmer outer 
