bo 
Ss) 
FRESHWATER ALGA. 
In its habitat D. antaretica resembles D. mucicolu F. Hustedt (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 neater to D. montana W. and G. 8. West; the cells of this species are 
however appreciably larger, are more pronouncedly spindle-shaped, and the species is 
not endophytic. The cells in PD. montana also appear to be more regularly arranged 
than in D. antaretica (cf. G. 8. West, Brit. Freshw. Aloe (1904), p. 348, fig. 1624). 
A form like D. antarctica approaches very near to an Aphanothece. 
Genus Giaocarsa Kiitz. 
21. GLGOCAPSA RUPICOLA. 
Gleocapsa rupicola Kiitz., Spec. Alg. (1849), p. 221; Rabenhorst, Fl. Europ. Alg., ii. (1865), p. 43. 
Diam. cell. = 4-52; diam. colon. usque ad 30 p. 
fab.—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. shuttleworthiana Kiitz.) is recorded by Messrs. West (op. cit., p. 296). 
Genus APHANOTHECE Nagell. 
22. APHANOTHECE PRASINA. 
Aphanothece prasina A. Braun in Rabenh. Alg. No. 1572; Rabenhorst, Fl. Europ. Alg., ii. (1865), 
pp- 65-66. 
Hab,—I\ce-wall, five feet above present level of river-like pond, “ Penknite ice,” 
McMurdo Strait, September 13th, 1902. 
Small, but otherwise typical colonies, attached to Phorimidium glaciale. This 
species is generally free-floating. 
Genus Microcystis Kiitzing. 
23. MiIcROcCYSTIS CHROOCOCCOIDEA. 
(Pl. IL., figs. 102, 103.) 
Microcystis chroococcowea W. and G. 8. West, op. cit., p. 296, Pl. XXVI., figs. LO7-114. 
Diam. cell. = 4 p. 
fab.—Gap pond, Winter Harbour, December 15th, 1903. 
Occasional colonies of this interesting form were found on the Phoriidiwn-sheets 
from the above-mentioned locality. They agreed well with the description published 
by Messrs. West, except that the cell-contents appeared homogeneous. 
VOL, VI. K 
