The Freshwater Algae of Africa. 509 



Recorded from [the Hollo River. Calvinia Division, by G-. S. West ; 

 from the Cape by Beinsch. 



Var. dispar (Breb.), Brunnthaler, op. cit., pp. 168, 171 (Svn. : S. 

 dispar, Breb.) (Fig. 7. b ande). 



Sample 48 (together with the type, not uncommon). 



This certainly appears to be only a variety of 8. quadricauda. The 

 decree of development of the spines is rather variable; in some cases 

 they are so short that it is difficult to recognise them. 



4. Scenedesmus bijugatus (Turp.), Kuetz., Svn. Diat., loc. cit.. 

 p. 607. (Syn. : 8. obtusus, Meyen). 



Var. seriatus, Chodat, Alg. vertes, etc., p. 212. 

 Samples 4, 8 (here common), 9, 10. 



Var. alternans (Reinsch), Hans^irLf, Prodr. Algenfl. v. Boehmen, 

 1886, p. 114; Chodat. In,-, cit., p. 213. (Syn. : S. alternans, Reinsch). 



Samples 39, 48, 50. 



The type has been recorded from Papekuil, Ceres Division and 

 Little Namaqualand, by Gr. S. West. 



5. Scenedesmus cohaerens, n. sp. (Fig. 8). 



Coloniae maximae, e 4 vel numerosis (usque 1<!<>) cellulis quaterne 

 dispositis constantes. Cellulae obloDgo-ellipticae, polis rotundatis vel 

 paullo acutis, a vertice visae rotundae ; membrana paullo incrassata, 

 polis incrassatis ; contentus cellularum non satis cognitus, pyrenoide 

 nullo, chromatophora facile dissoluta. Divisio cellularum semper 

 perpendiculariter in axe longitudinali in 4 partes fit ; cellulae filiales 

 intra membranam maternam (quae diu visibilis est) manent et mox 

 similiter dividuntur. Qua ratione coloniae magnae laminaeformes 

 oriuntur. Cellulae filiales plerumque in planitie eadem qua cellula 

 materna dividunt, sed interdum per loci mutationem alterutrius 

 cellulae filialis altera planitierum divisionis in altera perpendicularis 

 est. Propagatio dissolutione coloniae magnae in colonias quadricellu- 

 lares seu cellulas singulas fit. 



Dimensiones cellularum: 10 x 45, 18 x 6, 20 x 9, 22 x 11, 

 24 x 12 ji; crass, cell, ca. 7 - 5/x; lat. coloniarum quadricellularum, 

 18-37 ji. 



Samples 42, 44. 



This remarkable species occurs in various forms or stages of 

 development, viz. as single cells, small four-celled colonies, and huge 

 plate-like colonies of anything up to 100 cells (cf. Fig. 8, a). The 

 development of the latter can be easily followed up. The single 

 cells (Fig. 8, c) are elliptic-oblong in shape, with rounded or slightly 



