576 Acton . — Coc corny xa subellipsoidea , <2 
The colonies were described as irregularly globose, of a dark-green colour, 
about one inch in diameter, and to the naked eye resembling Rivularia. 
This leads one to the conclusion that Harvey’s plant was Aphanothece 
prasina , a Blue-green Alga which occurs in precisely such colonies as he 
described. Rabenhorst 1 was also of the same opinion. Both Hassall, 2 and 
De Toni, 3 have likewise referred Palmella Mooreana to the Blue-green 
Algae. 
Thus the Alga under consideration cannot be referred to Palmella 
Mooreana , as that Alga is without doubt a blue-green one. 
The only other Alga with elongated cells which is definitely known to 
belong to the Palmellaceae is Dactylothece Braunii , Lagerh. 4 In this species, 
however, the cells are symmetrical, and the cell-division is transverse. The 
mucous envelopes of the cells are also lamellose. 
In 1901 Schmidle 5 described the genus Coccomyxa to include an 
Alga with symmetrical cells, which formed a green gelatinous stratum. 
The present Alga agrees with this genus in its general habit, its elongated 
and asymmetrical cells, and in its oblique cell-division. It differs, however, 
from Schmidle’s Coccomyxa dispav in the greater regularity in the form of 
the cells, and in the presence of pyrenoids. 
It would appear that the genus Coccomyxa occupies an intermediate 
position between the Palmellaceae and the sub-family Selenastreae of the 
Protococcaceae, and would thus include certain Algae which could not be 
placed with certainty in either of these groups. 
The present Alga can be diagnosed as follows: — Coccomyxa subelli- 
psoidea. Stratum mucous and expanded, of a dark-green colour. Cells 
commonly obliquely ellipsoid (rarely subspherical), with a single chloroplast 
in the form of a parietal plate occupying about half the cell-wall and 
containing one pyrenoid ; commonly occurring in pairs after division or 
scattered in a structureless mucus. 
Multiplication by oblique division of the cell. Reproduction by 4 
(rarely 8) non-motile gonidia, or by the formation of 2, 4, or 8 macrozoo- 
gonidia, or 8 or 16 microzoogonidia within a mother-cell. Length of cells 
6-10 11 ; breadth of cells 4-6 fx Hab. Widely distributed in British Islands, 
occurring in subaerial situations as a dark-green stratum on damp rocks and 
stones. 
In the oblique division and in the form of the cell and of the chloro- 
plast, this Alga shows a great resemblance to Oocystis submarina , Lagerh., 
as described and figured by Wille. 6 
1 Rabenhorst : Flor. Eur. Alg. iii, 1868, p. 34. 
2 Hassall : Brit. Freshw. Alg., 1845, p. 316, t. 78, Fig. 1. 
3 De Toni : Sylloge Algarum, 1889, vol. i, p. 683. 
4 Lagerheim in Ofvers. af K. Sv. Vet. Akad. Forh., 1883, No. 2, t. 1, f. 22-4. 
5 Schmidle : loc. cit., p. 20. 
6 Wille in Ber. Deutsch. Botan. Ges., Bd. xxvi, 1908, p. 812, t. 15. 
