16 P. E. FRITSCH. 



In view of the method of reproduction above described, this species should 

 perhaps be referred to the genus Chlorella ; it shows some resemblance to species like 

 CIdorella conglomerates (Artari) Oltmanns ( = Pleurococcus conglomeratus Artari) and 

 C. regularis (Artari) Oltmanns ( P. regularis Artari). 



10. PLEUROCOCCUS DISSECTUS. 



Pleurococcus dissectus (Kiitz.) Niigeli, Gatt. einzell. Algen (1849), p. 65, Tab. IV., B, fig. 3. 



Hah. Freshwater pond upon ice among eskers, four miles north of Black 

 Island, McMurdo Strait, September 12th, 1902 ; Gap pond, Winter Harbour, 

 December 15th, 1903. 



Isolated cells or flat strata on the surface of Pkormidium, as recorded by 

 Messrs. West (op. cit., p. 277).* 



PRASIOLACE.E. 



Genus PRASIOLA Ag. 

 11. PRASIOLA CRISPA. 



(Text-figures A-D.) 



Pra&iola crispa (Lighfcf.) Menegh. ; Kiitzing, Phycol. gener. (1843), p. 295 ; Eabenhorst, Flor. ourop. 

 algarum, iii. (1868), p. 308. 



Hob. Damp spot, summit of Cape Adare (1000 feet), January 9th, 1902 ; 

 under boulder, fifty feet above sea, Cape Adare, January 9th, 1902 ; probable 

 developmental stages common among the Cyanophyceous sheets from the Gap pond, 

 Winter Harbour, etc. 



There can be no doubt that this is a common form in Antarctic regions (previously 

 recorded by Hooker and Harvey, Wille, Fritsch, W. and G. S. West, etc.), as the 

 frequency of the characteristic packets of cells throughout the material demonstrates. 

 The only mature thalli were obtained from the summit of Cape Adare, while the 

 material from beneath a boulder fifty feet above sea-level at the same locality 

 consisted almost entirely of the Hormidium-stage. 



The expanded thalli were irregularly folded and bullate, the cells showing 

 ordinarily a very regular arrangement in groups of 16 or 32, separated by slightly 

 wider interspaces (text-figure B). The dimensions of the cell-contents were 

 6-7' 5 /A x 4-5 p. in surface view and 11 /A deep in section. At other points in the thalli, 

 where a formation of the cell-packets serving for reproduction was taking place, the 

 arrangement becomes far more irregular, the characteristic grouping being sometimes 

 almost completely lost. As stated in an earlier paper (Fritsch, op. cit., p. 331), this 



* A form resembling Protoderma was observed on the Phormidium-sheeks in one of the samples from the 

 Gap pond, Winter Harbour, but too little of it was seen to admit of determination. 



