FRESHWATER ALG.E OF THE SOUTH ORKNEYS. 127 



A full consideration of this species will be found on pp. 102-103. In sample 16 a 

 very similar form was found growing on Prasiola crispa ; the cells (cliam. 5-7 p.), how- 

 ever, lacked fat, and the cell-walls were not nearly so gelatinous. 



24. EREMOSPH^RA VIRIDIS, De Bary, Conj., p. 56, tab. viii., fig?. 26-27; Rabenl., 

 FL Europ. Alg., iii., 1868, p. '24. 



Sample 11. 



Average diameter of cells = 50 M. 



ULOTRWHACE^E. 



25. ULOTHRIX SUBTILIS, Kiitz., Spec. Alg., p. 345 ; Tab. Phyc., ii., tab. 85 ; Rabenh., 

 FL Europ. Alg., iii., 1868, p. 365 (PI. II., phots. 1, 2, 6, U). 



Samples 1 and 3 (yellow snow !), rather rare. 



CHJETOPHORA CE;E. 



26. RAPHIDONEMA NIVALE, Lagerh., Ber. Deutsch. Bot. Ges., x., 1892, p. 523, pi. 

 xxviii., figs. 15-21 (PI. I., figs. 32, 33). 



Samples 1-3 (yellow snow !), rather rare ; 4-6 (red snow !), rather common. 

 Many of the filaments were narrower than Lagerheim's form ; diara. of cells = 2-4 //. 

 See also pp. 116-117. 



(EDOGONIACE^:. 



27. (EDOGONIUM, sp. 



Samples 1 and 3 (yellow snow !), isolated. 



Diam. of cells = 20 p. ; length of cells = 56-65 M ; cells with numerous caps. 



28. (EDOGONIUM, sp. 



Sample 4 (red snow !), isolated. 



Diam. cell. = 8 // ; cells about three times as long as their diameter. 



PRASIOLACEM 



29. PRASIOLA CRISPA (Lightf.), Ay., Sp., p. 416; Kiitz., Tab. Phyc., v., tab. 40, 

 fig. 6. 



Samples 8, 9, 11, 12, and 16, abundant; numerous early stages in sample 16. 



This form is already well known as occurring in Antarctic regions. It was first 

 recorded by Hooker and Harvey (Botany of the Antarctic Voyage (Flora Antarctica), 

 vol. ii., pp. 498-499). as Ulva crispa, Lightf., as occurring in " Berkeley Sound, Falkland 

 Islands ; on moist rocks ; Cockburn Island, Graham's Land ; very abundant." They 

 add the comment : " A highly interesting species, because it is one of the very few ter- 

 restrial plants that have been gathered on the limits of vegetation both in the Northern 

 and Southern hemisphere." Subsequently it was recorded by Hariot from Cape Horn, 



