Nr. 1] SUBAERIAL ALGAE FROM SOUTH AFRICA oo 



Myxophyceae. 



Microcystis amethystina (Filarszky) Forti, Syll. Mvx. 1907, 

 p. 89. 



var. vinea nov. var. [PI. XIV, Fig. 337—341]. 



Difjert a formå typica praecipiietegiimento communi rubri vini 

 colore simili, non lamelloso, extrorsiim certe et distincte terminato. 

 Celliilis 3,5 — 5,5 jli diametro latis, glaucis, vacuolis carentibus. 



This small Microcystis, which is very charaoteristic by ils 

 beautiiful, wine-red calour of the gelatinous investments, is frequent- 

 ly to Ije met with in some of the samples. It is further characte ristic 

 by ils rather small, oommonly spherical colonies, measuriiig up lo 50 

 jii m diameter, tlie exteaiial surface of which is surrounded by a 

 comparatively thick and solid cutiole. The gelatinous envelope itself 

 has no slratification. The oells are 3,5 — 5,5 u in diameier, globose or 

 ellipsoid just before the divisions, bluish-green, withoul pseudo- 

 vacuoles. This alga is no doubl closely related lo Microcystis 

 amethystina, growing on damp rocks, but from which it differs 

 especially by ils wine-red colour and smaller colonies. 



GoUected on decayed wood and on Ihe bark of trees in the 

 environs of Durban (28 and 85). 



Nostoc spec. 



In a sample of bark from la tree near Umbilo River (no. 69), I 

 have found young A^osfoc-oolonies logelher wilh Tolypothrix 

 byssoidea. The specimens were too young for an adequale deter- 

 mination of species, however, 



Atractella nov. gen. 



Fila breuiiiscula, simplicia, altero apice adhaerentia, erecta vel 

 basi interdum adscendentia, anguste fiisiformia, ad iitrumque 

 apicem sensim attenuata, neqiie vero in setam producta. Tricho- 

 mata ex serie conslant simplici cellulanim 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. [PI. XIV, Fig. 313—316]. 



Filis breviusculis, vulgo 100—150 fi longis, ad 9—12 u latis, ex 

 niimero 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 sensini crassitudine decrescente, achroa, 

 haud lamellosa. Vaginis adulterioribus interdum pallide cano- 

 violaceis. Filis erectis vel curvatis, rigidis, vulgo constipatis. 



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