162 
Transactions of the Society. 
Chloroph. -Flora Torfstich. zu Virnheim, Flora oder Allg. 
Bot. Zeitung, 1894, Heft 1, p. 45). 
Diam. cell. 9*5-18 p. 
Hab. Keston Common, Kent, in water-lily pond. 
Fine examples of this species were observed from the above 
locality, and the gelatinous matrix was very firm ; the old cell-walls 
were also very conspicuous. After seeing examples of this species 
(which agree well with Wildeman’s description and figures), we do 
not agree with Schmidle in placing it under the genus Tetracoccus. 
The latter genus is practically without a gelatinous matrix (when 
compared with specimens of Plearococcus nimbatus). It is certainly 
nearest to Dimorphococcus, as previously stated, when the genus was 
described. It certainly does not belong to Palmellaceae, as does 
Pleurococcus nimbatus. In the latter species the groups of four are 
arranged tetrahed rally ; but in Tetracoccus the groups of four are in 
one plane, as they were illustrated (West, Alg. of Eng. Lake District, 
Journ. Roy. Micr. Soc., Dec. 1892, p. 735, PL X. figs. 43-8). We 
replied to a pressing query from Prof. W. Schmidle in a hurry, and 
h re afraid, from what he states (Schmidle, l.c. footnote at bottom of 
p. 46), that we have accidentally made (or mixed up) a remark 
applying to Kirchneriella obesa (West) Schmidle (= Selenastrum 
obesum West) with one about Tetracoccus. The genus as first 
described and figured is quite correct , and cannot be amended in 
order to include Pleurococcus nimbatus. Fig. 46 ( West l.c.) as 
specially quoted by Schmidle does not show any tetrahedral arrange- 
ment of the groups , but simply four cells in one plane , vdiich 
have been produced by division in two directions in that plane. We 
have found Tetracoccus from several localities since the description of 
the original specimens from Bowness, and it is always in free-swimming 
colonies like Dimorphococcus. 
Genus Stichococcus Nag. 
39. S. variabilis sp. n. PI. III. fig. 14. 
S. strato molli mucosoque, obscure viridi, cellulis diametro 
2-4-plo longioribus, ssepe solitariis, ssepius binis, rarissime 
cellulis tribus concatenatis, varie curvatis (rare subrectis), 
subcylindricis, vel inflatis vel subpyriformibus (interdum 
oblongis), polis plerumque truncatis. 
Long. cell. 6*5-16 p; lat. cell. 3-6 p. 
Hab. On shady rocks subject to spray of waterfall, Horton 
Park, Bradford, Yorks. 
This is a polymorphous species, the nearest to which is S. mira- 
bilis Lagerh. (Wittr. et Nordst., Alg. Exsic., No. 1087), from which 
it differs in its much shorter cells, which are never Y* and T-shaped, 
as well as in its different habit. The pale-green parietal chlorophyll 
plate is usually in a band round the middle of the cell or towards 
one end. 
