564 Annals of the South African Museum. 



Sample 32 (rather rare). 



I)iam. fil., 30 fx; lat. zygosp., 42-54 jx ; long, zygosp., 96-114 /x. 

 The material was rather scanty, so that a slight doubt attaches to this 

 determination. The cells were, however, invariably provided with 

 two chloroplasts, the conjugation was always lateral, and the fructify- 

 ing cells were not very strongly inflated. The dimensions of the 

 zygospore are larger than those given by Petit, but agree with those 

 recorded by Teodoresco (Fl. algol. d. 1. Roumanie, Beih. Bot. Centralbl, 

 xxi, Abt, ii, p. 194). The membrane was rather thick ami showed a 

 faint stratification. 



(Note. — Sterile, and therefore indeterminable, species of Spirogyra 

 were also observed in the following samples : 3, 5, 21, 23 (a species 

 with very wide flat cells, diam. about 150 /x, shorter than long, and 

 often not more than i as long as broad, 4-6 spirals, with several large 

 pyrenoids, describing from | to 1 turn— probably a form of 8. maxima), 

 42 (a species, with folded ends, more or less elongated cells with one 

 chloroplast in the shape of a very wide spiral, making several turns, 

 diam. cell., 41-42 /x), 25, 26, 28, 32, 34, 34a, 35). 



Genus ZYGNEMA Agardh. 



1. Zygnema ericetorum (Kuetz.), Hansgirg, Prodr. d. Algenfl. v. 

 Boehmen, i, 1886, p. 155 ; Borge, op. cit, p. 37, fig. 61. (Syn. : Zygo- 

 gonium ericetorum, Kuetz.) 



Sample 51. 



I tentatively refer this form to the above species, on account of the 

 form of the chloroplast, which is that typical for Z. ericetorum, as 

 described by West and Starkey (New Phytol., xiv, 1915, p. 205). 

 The cells were often very flat, from one-half to twice as long as broad, 

 whilst the chloroplast only occupied a small region in the centre of the 

 cell. The chloroplast had one, or more commonly two, pyrenoids. 

 The cell-membrane was moderately thickened, the specimens appearing 

 to belong to the forma aquatica. Diam. cell., 30-33 /x. There were 

 no constrictions between the cells. 



2. Zygnema steUinum (Vauch. ), Agardh, Syst, Alg., 1824, p. 77 ; 

 Borge, op. cit., p. 36, fig. 57. 



Sample 32 (abundant, with numerous immature and mature zygo- 

 spores). 



3. Zygnema (Zygogonium) spirale, n. sp. (Fig- 34.) 



Fila vegetativa cellulis rectis, li-6plo longioribus quam latis, 

 membrana vix incrassata, chromatophoris duabus stellatis formae 

 vulgaris: conjugatione scalariformi. cellulis copulantibus plus minus 



