120 BOTANICAL RESULTS OF THE SCOTTISH NATIONAL ANTARCTIC EXPEDITION. 



ing fluid. This deeply-coloured mucilage made details of the enclosed cell difficult 

 to determinej but so much could be seen that it has a moderately thickened wall and 

 granular contents ; a pyrenoid (?) was only very rarely visible. Numerous small particles 

 were generally adhering to the surface of the mucilage, and this still further obscured 

 the enclosed cell. The resting-cells of the second type were far less numerous than 

 those of the first. They appear to correspond to cells observed by Lagerheim, 1 and 

 referred by him to Chlamydomonas, sp. ; similar cells were noticed by Wittrock. 2 I 

 am unable to add to our knowledge of these cells, and have consequently merely 

 described them in the systematic portion of this paper as Chlamydomonas, sp. (?). In- 

 asmuch as these cells are of about the same dimensions as the smaller resting-cells of 

 the first type (described above), and as the two kinds of cells occur side by side, they 

 may be merely different stages of the same organism. 



Apart from the forms hitherto mentioned, the only other constituents of the red 

 snow from the South Orkneys are diatoms, which are, however, found only as isolated 

 individuals (Melosira sol, Kiitz., Coscinodiscus radiatus, Ehrb., etc.). It seems 

 probable that only the red restiug-cells above described and the Raphidonema are 

 true components of this flora, and that the remaining forms are introduced by the 

 agency of wind and (?) animals (possibly the penguins). The Scotiella is perhaps an 

 introduction from the yellow snow flora (which is sometimes not very far separated 

 from the red snow, cf. p. 99), while the diatoms (which are in great part marine forms) 

 probably come from the seashore. 



The complete list of algse found in the red snow from the South Orkneys is 

 as follows : 



Chlamydomonas nivalis (Sommerf.), Wille (?). Melosira sol, Kiitz. 



sp. (cf. above). Coscinodiscus radiatus, Ehrb. 



Scotiella antarctica, F. E. Fritscb. Navicula borealis (Erhb.), Kiitz. 



Raphidonema nivale, Lagerh. Amphora ovalis, Kiitz. 



(Edogonium, sp. Triceratium, sp. (T. ardicum, Bright?). 

 Zi/gnema, sp. (one filament). 



D. SYSTEMATIC ENUMERATION OF FRESHWATER ALG^E 

 FROM THE SOUTH ORKNEYS. 



A. ISOKONT^]. 

 CHLA MYDOMONADA CE^E. 



1. CHLAMYDOMONAS CAUDATA, Wille, Algol. Not., xi., Nyt Magazin f. Natur- 

 videnskab, xli., 1903, pp. 115-118 and 135-136, pi. iii., figs. 4-11 (PI. 1., figs. 35-40). 

 Samples 10 and 11, abundant ; also as a rare form in the yellow snow. 

 This and the following species are the only forms found in the material from the South 



1 Lagerheim, Ber. Deutsch. Bat. Ges., x., 1892, pp. 523, 529, pi. xxviii., fig. 10, 



2 Wittrock, " Om snbns och isens Flora," loc. cit. 



