24 
Transactions of the Royal Society of South Africa. 
Samples 17, 18, 23, 329 (?), 334 
Previously recorded from Little Namaqualand (G-. S. West). 
Var. concavum, Schmidle, Suesswasseralg., in F. Reinecke, Flora d, 
Samoa-Inseln, Engler s Bot. Jahrb., xxiii, 1897, p. 256. 
Forma major, margine ventrali in media parte cellulae fere recta. Long, 
cell., 520-570 /x; lat., 90-102 (Fig. 6, A). 
Sample 327. 
6. Closterium acerosum (Sclirank), Elirenb. ; W. & G. S. West, loc. ext., 
p. 146, PI. XYIII, figs. 2-5. 
Samples 22, 23, 334. 
Long., 330-405 ; lat., 34-40 /x. 
Previously recorded from South Africa (G. S. West & Fritscli'^ . ^ 
7. Closterium lanceolatum, Kuetz. ; W. & Gr. S. West, loc. cit., p. 149, 
PI. XVII, figs. 9, 10, PI. XVIII, fig. 7. 
Samples 17, 23, 334, 336. 
Long, cell., 387-405 /x ; lat., 57-66 fx. 
Eecorded from Madagascar (Fritscli), the Karoo and Little Namaqua- 
land (Gr. S. West). 
8. Closterium pritcharclianuni, Arch. ; W. & Gr. S. West, loc. cit., p. 172, 
PI. XXII, figs. 6-14. 
Forma ad var. alpinum, Schmidle (Oesterr. Boc. Zeitschr., xlv, 1895, 
p. 309, PI. XIV, fig. 19) valde accedens, sed saepe longior et latior, mem- 
brana paene achroa et subtilissime striata, apicibus plerumque magis 
recurvis quam in specimine a Schmidle depicto. Dimens., 360 x 45, 
420 X 54, 555 x 40, 660 x 45 /x. 
Samples 85, 346 (very rare in the latter). 
This form has to some extent the subparallel margins of var. mada- 
gascariense, Fritsch. The work already done on the freshwater Algae of 
South Africa shows that C. pritchardianum is very widely distributed and 
exhibits very considerable variability (cf. Fritsch, 1918, p. 547). It is 
hoped at a later date, when more data have been collected, to give an 
epitome of the different forms. 
9. Closterium psetidolibellula, F. E, Fritsch, n. sp. (Fig. 7). 
C. magnum ; cellulis aut fusiformibus margine ventrali minus convexa 
quam margine dorsali (forma fusiformis) aut saepe margine dorsali valde 
convexa margine ventrali deplanata vel (raro) exigue concava (forma 
genuina), a media parte ad polos gradatim et magis attenuatis ; polls 
truncatis et recurvis (qua nota in speciminibus biconvexis saepe indistincta 
val abest) ; membrana prhnum achroa, mox flavescens, in tota superficie 
punctis minutis numerosis irregulariter ordinatis obtecta ; chromatophora e 
