FEESHWATER ALG^. 5 



C. subcaudata Wille) and Chloromonas alpina Wille, are, however, as yet only 

 known to occur in the Antarctic and in the north of Europe, although it is 

 hardly likely that future investigation will fail to reveal their occurrence in 

 intermediate regions. 



Another interesting ease of distribution is that of species like Chloromonas 

 alpina Wille, and the genus Eucapsis, which have hitherto only been recorded 

 from alpine habitats. Parallel cases have long been known in the Arctic regions. 



The collections of the ' Discovery ' did not include any material of snow floras. 

 On the other hand, two samples (Cape Adare, January 9th, 1902 ; McMurdo Bay, 

 September 13th, 1902) came from the ice. It will be useful to give a list of the 

 commoner species found in these two habitats : — 



The colour of the ice in the second case was due to Microcystis parasitica 

 Kiitz. var. glacialis nov. var. The species marked with an asterisk did not grow 

 directly on the ice, but were epiphytes on the Phormidium. 



As above mentioned, the bulk of the material collected by the members of 

 the British National Antarctic Expedition consisted of Phormidium-sheets with their 

 abundant epiphytic flora. The general character of this flora is sufficiently illustrated 

 by the Table on p. 4. Only a few samples comprised free-floating forms, the more 

 important of which were as follows : — 



Ghlamydomonas subcaudata Wille. 



„ intermedia Chod. 



„ ehrenbergi Gorosch. 



Hormidium- stage and young packets of 

 FrasioIa-oeWs. 



Penium sp. (cf. pp. 20, 21). 

 Microcystis marginata (Menegh.) Kiitz. 

 Merismopedia tenuissima Lemm. 

 Eucapsis minuta sp. n. 

 Phormidium antarcticum W. and G. S. West. 



Oscillatoria tenuis Ag. and other species. 

 Nostoc disciforms sp. n. 

 „ longstaffi sp. n. 

 „ fuscescens sp. n. 

 „ sphmricum Vauch. 

 Nodularia quadrata sp. n. 

 Navicula muticopsis Van Heurck. 

 „ globiceps Greg. 

 „ shacMetoni W. and G. S. West. 

 „ cymatopleurus W. and G. S. West. 



