544 Annals of the Smith African Museum. 



I believe this form is referable to Wittrock's P. conspersum, of 

 which, however, T have seen no figure. It tallies with the description 

 of this species, except in the fact that the semicells almost constantly 

 exhibit a more or less marked inflation, some little distance above the 

 base, so that the cell is narrower at its middle than further towards the 

 poles (Fig. 21). Moreover, the membrane is colourless. Each ehloro- 

 plast had two pyrenoids, and there was often a conspicuous mass of 

 fat at either end of the cell. The extremities of the cells vary consider- 

 ably in the degree of rounding. 



Nordstedt (Desm. arctoae, Of vers. K. Vet.-Ak. Foerhandl, 1875, 

 No. 6, p. 14) also describes the membrane as colourless, and Schmidle 

 (Alg. Brasilien, Hedwigia, xl, 1901. p. 47) does the same for var. 

 americanum, Nordst., in which, however, Schmidle figures (loc. cit., 

 Tab. Ill, figs. 1, 2) the granules as being much less densely arranged 

 than in the type or the variety above established. 



Genus CLOSTERIUM Nitzsch. 



1. Closterium parvulum, Naegeli, Gatt, einzell. Algen., 1849, p. 106, 

 Tab. VI. C, tig. 2 ; W. & G. S. West, op. cit., i, 1904, p. 133, PL XV. 

 figs. 9-12. 



Samples 2, 8, 52. 



Distances between apices, 108-126 \>. ; lat., 12-13 p.. 



2. Closterium leibleinii, Kuetz. ; W. & G. S. West, op. cit., i, 1904, 

 p. 141, PI. XVI, figs. 9-14. 



Samples 5, 25, 48. 



Some of the specimens had only two pyrenoids in the one chloro- 

 plast or the other. The species has been recorded from Little Naniii- 

 qualand by G. S. West. 



3. Closterium moniliferum (Bory), Ehrenb.; W. it G. S. West, op. cit, 

 i, 1904, p. 142, PI. XVI, figs. 15, 16. 



Sample 24. 



Recorded from Little Namaqualand by G. S. West, 



4. Closterium malinvemianum, De Not. ; W. & G. S. West, op. cit., 

 i, 1904, p. 145, PI. XVII, figs. 5, 6. 



Forma major, nov. form. (Fig. 22). 



Differt a typo polis paullo plus incurvatis, inflatione ventrali indis- 

 tincta, margine ventrali fere recta usque ad apices incurvatos. Apici- 

 1ms inter se distant ibus. 600 ,/ ; kit. cell., 112 fi. 



Sample 24 (rare). 



