FRESHWATER ALGA 23 



In its habitat I), antarctica resembles D. miwicola F. Hustcdt (Hedwigia, XLVIIL, 

 pp. 140-141), which also grows in the mucilage of a Nostoc, but Hustedt's species is a 

 much larger form with curved cells, having marked attenuated apices. The Antarctic 

 form is much nearer to D. montana W. and G. S. West ; the cells of this species are 

 however appreciably larger, are more pronouncedly spindle-shaped, and the species is 

 not endophytic. The cells in D. montana also appear to be more regularly arranged 

 than in D. antarctica (<;/. G. S. West, Brit. Freshw. Algae (1904), p. 348, fig. 162A). 



A form like D. antarctica approaches very near to an Aphanotkece. 







Genus GI/EOCAPSA Kiitz. 



21. GLCEOCAPSA RUPICOLA. 



Glacocapsa rvpicola Kiitz., Spec. Alg. (1849), p. 221 ; llabenhorst, Fl. Europ. Alg., ii. (1865), p. 43. 



Diam. cell. = 4-5 //, ; diam. colon, usque ad 30 fj.. 



Uali. Gap pond, Winter Harbour, December 15th, 1903 (on surface of 

 Phormidium) ; freshwater pond, Granite Harbour, January 20th, 1902 (in sediment). 



The small colonies were spherical or elliptical. The inner sheaths were deep 

 red-brown, often almost completely obscuring the cells. A closely allied species 

 (G. slwttleivorthiana Kiitz.) is recorded by Messrs. West (op. clt., p. 296). 



Genus APHANOTHEOE Nageli. 

 22. APHANOTHECE PRASINA. 



Aphanothece prasina A. Braun in Rabenh. Alg. No. '1572 ; Rabenhorst, Fl. Europ. Alg., ii. (1865), 

 pp. 65-66. 



Hah. Ice-wall, five feet above present level of river-like pond, "Penknife ice," 

 McMurdo Strait, September 13th, 1902. 



Small, but otherwise typical colonies, attached to Phormidium glaciate. This 

 species is generally free-floating. 



Genus MICROCYSTIS Kiitzing. 



23. MlCROCYSTIS CHROOCOCCOIDEA. 



(PL II., figs. 102, 103.) 

 Microcystis chroococcoidea W. and G. S. West, op. cit., p. 296, PL XXVI., figs. 107-114. 



Diam. cell. = 4 p.. 



Hob. Gap pond, Winter Harbour, December 15th, 1903. 



Occasional colonies of this interesting form were found on the Phormidittm-shseis 

 from the above-mentioned locality. They agreed well with the description published 

 by Messrs. West, except that the cell-contents appeared homogeneous. 



