Nr. 1] SUBAERIAL ALGAE FROM SOUTH AFRICA 90 
Myxophyceae. 
Microcystis amethystina (FiLarszky) Forrtr, Syll. Myx. 1907, 
p. 89. 
var. vinea nov. var. [P1. XIV, Fig. 337—3411. 
Differt a forma typica praecipue tegumento communi rubri vini 
colore simili, non lamelloso, extrorsum certe et distincte terminato. 
Cellulis 3,5—5,5 u diametro latis, glaucis, vacuolis carentibus. 
This small Microcystis, which is very characteristic by its 
beautiful, wine-red colour of the gelatinous investments, is frequent- 
ly to be met with in some of the samples. Itis further characteristic 
by itts rather small, commonly spherical colonies, measuring up to 50 
u in diameter, the external surface of which is surrounded by a 
comparatively thick and solid cuticle. The gelatinous envelope itself 
has no stratification. The cells are 3,5—5,5 u In diameter, globose or 
ellipsoid just before the divisions, bluish-green, without pseudo- 
vacuoles. This alga is no doubt closely related to Microcystis 
amethystina, growing on damp rocks, but from which it differs 
especially by its wine-red colour and smaller colonies. 
Collected on decayed wood and on the bark of trees in the 
environs of Durban (28 and 85). 
Nostoc spec. 
In å sample of bark from a tree near Umbilo River (mo. 69), I 
have found young Nostoc-colonies together with Tolypothrix 
byssoidea. The specimens were too young for an adequate deter- 
mination of species, however. 
Atractella nov. gen. 
Fila breviuscula, simplicia, altero apice adhaerentia, erecta vel 
basi interdum dadscendentia, anguste fusiformia, ad  utrumque 
apicem sensim attenuata, neque vero in setam producta. Tricho- 
mata ex serie constant simplici cellularum cylindricarum confor- 
mium, heterocystis nullis, vagina achroa, crassiuscula et firma ad 
utrumque apicem sensim decrescente circumdata. Fila libera, non 
conglutinata. Multiplicatio cellula apicali angusta et longiuscula in 
transversum divisa. Propagatio hormogoniis. 
Atractella affixa nov. spec. [P1. XIV, Fig. 313—3161. 
Filis breviusculis, vulgo 100—150 u longis, ad 9—12 u latis, ex 
numero vario cellularum, vulgo 15—20, conformium, cylindricarum, 
3—5 u latarum, aeque longarum vel usque ad duplum longiorum, 
vacuolis nullis constantibus. Parietibus transversariis crassiusculis. 
Vagina crassa ad apices sensim crassitudine decrescente, achroa, 
haud lamellosa. Vaginis adulterioribus interdum pallide cano- 
violaceis. Filis erectis vel curvatis, rigidis, vulgo constipatis. 
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