270 welwitsch's African freshwater alg^. 



3. S. Friesii (Ag.) Gomont in Aim. Sci. Nat. 7e serie, Bot. xv. 

 316-8, t. 9, f. 1, 2 (1892). Oscillatoria Friesii Ag. Synops. Ah/ar. 

 Scand. 107 (1817). Crass, fil. 9-10 /x ; crass, trich. 4-5-5-3 [jl. ' 



Huilla. Alga gelatinosa, badio-fusca, folia Xyridearum in editis 

 de Morro de Lopollo obducens ; Febr. 18G0. No. 192. 



4. S. THELEPHORoiDEs (Mont.) Gomont, I. c. 319, 320, t. 10, 

 f. 1-4 (1892). Scijtonema? theleplioroidcs Montagne, I.e. 2e ser. 

 Bot. xii. 45 (1889). Crass, fil. 38-48 /x; crass, fil. 6 /*. 



Huilla. In paludibus exsiccandis ; April 1860. No. 170. A 

 few small examples of this species occurred in this gathering ; we 

 should like to have seen more of it, as it appears to be an aquatic 

 form of the species. 



5. S. FuscEscENs Kiitz. Phijc. Gener. 230 (1843) ; Gomont, he. 

 324-5, 1. 11, f. 4-6 (1892). Crass, fil. 12-32 /x ; crass, trich. 1-5-3 /x. 



Huilla. Freq. apud Hapalosiphonem mireum, in paludibus ex- 

 siccandis ; April 1860. No. 176. Etiam in graminosis paludosis 

 juxta rivulum de Lopollo ; April 1860. No. 180. 



Var. africana, var. n. Var. fills brevioribus ; trichomatibus 2-3 

 intra vaginam, cellulis diametro l-|-2-plo longioribus. Crass, fil. 

 15-20 /x ; crass, trich. 2-5 /x. 



Huilla. Terrestris, cum Porpihyrosiphone Notarisii, in pascuis 

 pluv. autumnalibus frequentius inundatis, demum exsiccantibus ad 

 lacum magnum de Ivantala ; March 1860. No. 18. 



6. S. natans, sp. n. S. inter alias algas aquaticas reperta, 

 plus minusve solitaria vel in crespitibus minutissimis intricatis ; 

 fills elongatissimis et in partem superiorem sparsim ramosis ; vaginis 

 firmis, crassissimis et lamellosis, marginibus parallel! s ct irregu- 

 laribus (nonnunquam subglabris), apicem versus gradatim et gra- 

 datim angustatis, apicibus interdum multe attenuatis, lamellis 

 interioribus circa trichomata Ifete rubris (subsanguineis), lamellis 

 exterioribus achrois vel pallide rubris ; trichomatibus rerugineis 1-4 

 (plerumque circiter 3, raro 5-6) intra vaginem, parallelis vel hiuc 

 inde torulosis, elongatis, ad genicula non constrictis, cellulis sub- 

 quadratis vel diametro duplo longioribus, protoplasmate granuloso ; 

 cellula apicali conica. Crass, fil. 49-61 /x (usque 92 /x) ; crass, trich. 

 5-8-6-5 fx. 



Huilla. Inter Microsporam Ldffjrenii, kc, in uliginosis editiori- 

 bus prope Humpata, Empalanca et Lopollo, plagas spongiosas 

 unacum Eriocauloneis, Xyridibus et Utriculariis constituens ; May 

 1860. No. 15. Morro de Lopollo ; May 1860. No. 182. Etiam 

 in graminosis paludosis juxta rivulum de Lopollo ; April 1860. 

 No. 180. 



The nearest species to this is <S. pur para seen s (Kiitz.) Gomont, 

 /. c. 320-1, t. 9, f. 6-8, from which it is distinguished by the much 

 fewer branches of its more elongate filaments, its diflerently coloured 

 sheaths which are much more attenuate at the apices (not acumi- 

 nate), its less numerous and more elongate trichomes not constricted 

 at the dissepiments, and in the cells never being shorter than the 

 diameter, as well as in its subsolitary free-swimming habit. 



