Contributions to Our Knoivledge of the Freshwater Algae of Africa. 21 
(0 CONJUGATAE. 
(1) MESOTAENIACEAE. 
Oenus CYLINDEOCYSTIS Menegh. 
1. Gylinclrocystis hrehissonii, Menegh. ; W. & G-. S. West, Monogr. Brit. 
Desm., i, Eay Society, 1904, p. 58, PI. IV, figs. 23-32. 
Sample 36. 
Long., 51 fx ; lat., 17 /x. 
Var. minor, W. & G-. S. West, loc. cit., p. 59, PI. V, fig. 11. 
Sample 36. 
Long., 36 /x; lat., 12 ft. 
(2) DESMIDIACEAE. 
GrENTJS PENIUM Br^bisson. 
1. Penium margaritaceum (Elirenb.), Breb. ; W. & Gr. S. West, loc. cit., 
p. 83, PI. VIII, figs. 32-35. 
Var. irregularius, W. & Gr. S. West, Freshw. Alg. Orkneys and Shetlands, 
Trans, and Proc. Bot. Soc. Edinburgh, xxiii, 1905, pp. 14, 15, fig. 23 (fig. 
nostr. 6, 0). 
Sample 327 (not uncommon). 
Long, cell., 141-204 /x; lat., 22-25 /x. This form has already been 
recorded by F. E. Fritsch from the Cape, whilst the type is known from 
Madagascar. The specimens in the present sample were rather larger, but 
still appreciably smaller than those originally described by Messrs. West 
from the Orkneys and Shetlands. Another difference lies in the small size 
of the granules (Fig. 6, C). 
2. Penitim mimdum (Ralfs), Cleve ; W. & Gr. S. West, loc. cit., p. 83, 
PL X,figs. 1, 2. 
Var. ^roductum, F. E. Fritsch, nov. var. (Fig. 6, D). 
P. multo brevior et paullo latior quam typo ; cellulis in media parte 
constrictione exigua late aperta praeditis et paullo ante polos rotundato- 
truncatos levissime constrictis ; membrana glabra, hyalina. Long., 63-65 fx ; 
lat., 18-20 fx. 
Sample 36 (rare). 
This variety comes near to var. tumidtim, Wille (e/. W. & Gr. S. West, 
loc. cit., p. 104, PI. X, fig. 5), in which, however, the median constriction is 
more pronounced and the subapical contraction is absent ; the latter feature 
gives the ends of the cells of var. productum. a protruded appearance. The 
sides of the semi-cells, however, in both cases converge towards the ends, so 
that the greatest width is a little way above the base. Borge ("Alg. erst. 
EegnellschenExped.,ii,Desmid.," ' Arkiv.f. Bot.,' i, 1903, Tab. I, fig. 4) has 
figured specimens of this species under the name of var. crassum. West in 
