2 WELWITSCH S AFRICAN FRESHWATEE ALG^. 



than any hitherto described. The species are localized under the 

 various districts of the region, exactly as indicated by Welwitsch 

 on his herbarium labels. 



FLOEIDE^. 



I. — Batrachosperme^. 



1. Batrachospermum Eoth (1800). 



1. B. angolense, sp. n. Lemanea anf/oIejisis'Welw.'M^. Name 



with observation on gross characters of living plant ; the following 



description is ours : — 



B. subcartilagineum, fronde base scutatim radiata, vivum viridi- 

 Cferulescens, gracillimum, mox flaccidum, more Floridearum non- 

 nullis viscoso-collapsum, chartte parum adh^erens ; fila primaria 

 5-8 cm.; ramis numerosissimis solitariis biuisve (raro ternatis), 

 ramis ordinis secundi tertiique numerosis et delicatissimis ; axe 

 primario e serie singula cellularum magnarum formato et seriebus 

 multis cellularum appressarum multe minor um vestito ; ramulis 

 lateralibus densissimis et per axem totum regulariter dispersis, e 

 cellulis elliptico-globosis circiter 3 formatis, ramulis sublongioribus 

 ad nodos subnumerosos, ramis juvenibus cum ramulis principaliter 

 ad nodos approximatos. Diam. fil. prim. (c. ramul. lat.) 150-158 /x, 

 ad nod. 266-308 jj. ; diam. ax. fil, prim. 62 /x, ad nod. 100 fj.. 



Pungo Andongo. Freq. ast unico loco ad rupes submersas in 

 rivulo de Cabondo socialis cum Podostemaceis ; med. Febr. 1857. 

 No. 1. 



This may well be taken at first sight for a Lemanca with very 

 numerous nodes, the short lateral branches which clothe the axes 

 of the filaments being so very dense and of such uniform length 

 that a surface view appears almost parenchymatous. The filaments 

 are not much thicker at the nodes than between them. 



2. B. nigrescens, sp. n. B. l^ete viride in vivo, exsiccata 

 nigrescens ; fila primaria circiter 7-10 cm., ad saxa graminumque 

 culmos demersas adnata base radiata ; ramis solitariis, binis 

 ternisve, subpenicillatis, numerosissimis et ordinum trium, ultimis 

 delicatissimis; axe primario ut in B. amiolense sed seriebus exteri- 

 oribus cellularum numerosioribus ; ramulis lateralibus brevissimis, 

 e cellulis rotundato-quadratis 1-3 formatis, longioribus et confertis- 

 simis ad nodos numerosissimos, uodo superiori ad nodum inferiorem 

 gradatim brevioribus. Diam. fil. prim. (c. ramul. lat.) 137-141 /x, 

 ad nod. 216-233 //; diam. ax. fil. prim. 86 /x, ad nod. 112 /x. 



Pungo Andongo. Freq. ast unico loco in brachio lateral! flum. 

 Cuanza prope ejus cataract, ad Condo ; Mar. 1857. No. 2. 



This is a rather noteworthy species, being so much branched 

 that in well-developed specimens the branches aggregate to form 

 narrow pencils ; the plant when dry is almost black, and looks like 

 some of the marine Floridea. 



8. B. gracillimum, sp. n. B. multe gracillimum et delicatis- 

 simum, non radiatum, viridi-flavescens in vivo, subcferuleo-viride 

 exsiccata, basi nudiusculum ; fila primaria 10-15 cm. (interdum e 

 filo breviori et crassiori nata) ; ramis ordinum duorum, iis ordinis 



