FRESHWATER ALGAAS. 25 
It does not seem possible to distinguish adequately between Kiitzing’s Microcystis 
parasitica and his Microhaloa firma (= Microcystis firma). The colonies observed in 
the present material really combine the characters of the two species. 
Var. QLACIALIS var. nov. 
Cellulis minutissimis, dense aggregatis in familiis plerumque et saepe valde 
irregularibus, in muco rubiginoso involutis; contentum cellularum dilute serugineum 
esse verisimile est. 
Diam. cell. = *5 4; diam. colon. usque ad 40 pm. 
Hab.—Dull brick-coloured ice, situated in long level line as though in situation 
of former water-level, four feet above frozen water-course through ‘ Penknife” ice, 
MeMurdo Bay, September 13th, 1902. 
This form is partly, if not entirely, responsible for the colouration of the ice in this 
habitat. The minute cells are densely aggregated in a brownish-red mucus, which 
seems to be the only essential point of difference from the type. As far as could be 
made out the cells themselves have pale blue-green contents. 
Genus MERISMOPEDIA Meyen. 
27. MERISMOPEDIA TENUISSIMA. 
(Pl. L., figs. 49-51.) 
Merismopedia tenuissima Lemmermann, Beitr. z. Kenntn. d. Planktonalgen, Bot. Centralbl., lxxvi. (1898), 
p. 154. 
Diam. cell. ca. 1°5 p. 
Hab.—Damp spot, summit of Cape Adare, January 9th, 1902. 
The colonies were composed of small, generally closely placed cells, and consisted 
of sixteen or frequently thirty-two or even sixty-four cells, forming very regular 
compact plates of small dimensions. The cell-contents were pale blue-green and 
homogeneous. Wille (Antarkt. Algen, Nyt Mag. f. Naturvidenskab, x]. (1902), p. 219) 
has recorded another form of this genus (J/ glawcum (Ehrb.) Niig. var. punctatuin 
(Meyen) Hansg.) from Cape Adare, but the cells in the colonies of my material were 
too minute to belong to this species; they differed also in their frequently dense 
ageregation. 
Genus Evcapsts Clements and Shantz. 
28. HKUCAPSIS MINUTA sp. n. 
(Bim hos 147643;) 
Familiis sepe irregularibus, sed e fasciculis cubicis 8—32-128 vel plurium 
cellularum compositis, libere natantibus, cum tegumento hyalino mucoso arcto ; cellulis 
hemisphericis vel subglobosis, geminatim dispositis ut in genere Chroococeo, 
cytoplasmate plerumque dilute wrugineo (praesertim in familiis novellis), sed interdum 
K 2 
