WELWITSCH'S AFRICAN FRESHWATER ALG.E. 243 



cells then appearing like beads on a string. These connecting 

 threads are not visible in living plants, but in becoming dry the 

 protoplasm shrinks away from the minute canal along which it 

 passes through the septa, and on soaking again does not reattain 

 its natural position. 



1. S. ocELLATUM (Dillw.) Thur. in Ann. Sc. Nat. 6e ser. Bot. i. 

 380 (1875). Conferva ocellata Dillw. Brit. Conferv. 60-1, Supp, 

 pi. D (1809). Sirosiphon ocellatm Kiitz. Spec. AUjar. 317 (1849); 

 Tab. Phijc. ii. (1850-2), 11, t. 37, f. ii. 



A small form ; crass, fil. 27-38-5 jx ; in small quantity amongst 

 Zygnema sp., growing on tufts of Scytonema Mijochrous var. choru- 

 (fraphicKm, on rocks on the northern and western sides of Pedra 

 Songue ; April 1857. No. 153. 



Forma major. A large and finely- developed aquatic form ; 

 crass, fil. 45-61 /x. 



Huilla. Inter Utrmilariam, Morro de Lopollo ; April 1860. 

 No. 179. In paludibus exsiccandis ; April 1860. No. 176. 



2. S. flexuosa, sp.n. Filis aquaticis, inter algas varias repertis, 

 elongatis, flexuosis et sparsim ramosis ; ramis solitariis, exacte 

 patentibus et filo primario diametro fequalibus, apicibus rotundatis 

 et non attenuatis ; vaginis amplis, achrois (raro flavescentibus), 

 hyalinis, vix lamellosis ; cellulis in serie singula, rotundato-quad- 

 ratis, feruginosis, inter se subdistantibus (stepe i^-f diametri cellulfe 

 seorsum) ; heterocystis raris, lateralibus. Crass lil. 18-25 [x. 



Huilla. Inter Hapalosi phonem luteohiin et i\licrosporam Lnfgrenli, 

 &.C., in uliginosis editioribus prope Humpata, Empalanca et Lopollo, 

 plagas spongiosas unacum Eriocauloneis, Xyridibus, et Utriculariis 

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

 1860. No. 182. 



This is distinguished from .S'. panniforme (Ag.) Born. & Flah. by 

 its habit, its very different branching, its almost colourless sheath 

 with smooth exterior, and by the round apices of the branches, as 

 well as by its somewhat smaller size. 



3. S. MiNUTUM (Ag.) Hass. Brit. FresJnv. Ahj. i. 230; ii. t.lxvii. 

 f. 3, 4 (1845); Born. & Flah. in Ann. Sci. Nat. 7e serie, Bot. v. 

 72-74 (1887). Scijtonema ininutum Ag. Synop. AJtjar. Scandin. 117 

 (1817). Crass, fil. prim. 26 /x ; crass, ram. 17 /x. 



Huilla. In graminosis paludibus juxta rivulum de Lopollo ; 

 April 1860. No. 180. 



4. S. INFORMS Kiitz. Spec. Ahjar. 319 (1849) ; Tab. PIu/c. ii. 

 (1850-2), 11, t. 38, fig. iii. ; Born. & Flah. I.e. 75-77 (1887,). 

 Crass, fil. prim. 44-71 /x ; crass, ram. 36-39 /x. 



Puugo Andongo. Inter Scylunema Myochruus var. choroyraphicuin, 

 in summis rupib. ; Febr. 1857. No. 6. 



(To be continued.) 



R 2 



