302 DR. Е. E. FRITSCH ON FRESHWATER ALG 
epiphyte (c/., however, p. 329). Rabenhorst’s figure and description of 
P. viride *, however, give no indication of any regular arrangement of 
the cells ; and the same is true of Migula’s recent description, which even 
refers to the cells as being © ordnungslos" and “nicht in Reihen” f. The 
latter's description of Protoderme also recalls the Antarctic. form, in that he 
speaks of the thallus as *sehleimig." This character is also referred to in 
Hansgirg's description {, which further contains a statement (on p. 225) as 
to the occurrence of oil-drops in the cells. It will therefore be evident that 
all the characteristic features of Р. Hrownii have already been referred to in 
the descriptions of P. viride, and it may ultimately prove to be but a form of 
the latter. For the present, however, it seems best to keep it as a distinct 
species, characterised by the irregular arrangement of the cells, the muci- 
laginous and granular character of the walls, and the frequent presence of 
fat in the cell-contents $. 
(b) CHLOROSPHÆARA ANTARCTICA, P. E. Fritsch. (РІ. 10. figs. 2-6 & 
РІ. 11. phots. 1, 3, 5, 6 C.) 
The next most abundant form is а new species of CAlorosphera, which may 
be called C. antaretica, n. sp. (Pl. 10. figs. 2-6). This is found either in the 
form of large isolated cells (figs. 2, 6) or as groups of smaller cells, commonly 
in fours or sometimes larger numbers (PI. 10. fig. 3) : the average diameter 
of the cells varies between 11 and 26 p, although smaller and much larger 
cells were also observed. The cells are provided with a well-defined rather 
thick membrane, which, especially in the сазе of the isolated cells, 1s often 
surrounded by a wide spherical sheath of transparent mucilage (РІ. 11. 
phots. 1-3), to the outer edge of which numerous small foreign particles were 
generally adhering (Pl. 10. fig. 2). The isolated cells were mostly more or 
less spherical in shape, while those forming groups were somewhat angular, 
probably as a result of mutual pressure. In many cases an almost spherical 
chloroplast could be made out in the cells without much difficulty ; this 
chloroplast is only interrupted on one side of the cell by a small circular 
aperture, through which a small round body (in all probability the pyrenoid) 
can be seen (Pl. 10. fig. 2). Starch is mostly present in small quantities in 
the smaller cells, but is often scarcely to be found in the larger ones. On the 
) p, e 
other hand, large masses of the above-mentioned fat were nearly always 
+ L. Rabenhorst, * Flora europea. algarum aque dulcis et submarine,” iii. 1868, pp. 288 
& 307. 
t W. Migula, ' Kryptogamenflora von Deutschland, Deutsch-Osterreich und der Schweiz,’ 
ii. 1 Teil, 1907, p. 747 ; cf. also Wille, zoc. cit. Teil I. Abt. 2, 1897, р. 78. 
| * Meist schlüpferig," according to Hansgirg, loe. cit. p. 224. 
$ A full diagnosis of Protoderma Brownti wil be found on p. 328. It seems very probable 
that the form shown by Wittrock (* Om snóns och isens flora," (ос. cit.) in his Ве. 17, pl. 3, 
belongs to this species, although the cells are more regularly arranged than in my form, 
c І H 5 o А о М 
