194 МВ, G. S. WEST ON THE FRESHWATER ALG 
Fig. 20. Pediastrum simplex, Meyen. х 500. Curious abnormal form in which the coeno- 
bium is not strictly plate-like. Some of the cells, such as a, are like those of typical 
P. simplex ; b is similar to the peripheral cells о? P. Boryanum, and c like those of 
P. Kawraiskyi, Schmidle; g., resting gonidium (aplanospore). 
21. P. simplex, Meyen, var clathratum, forma radians. х 500. Abnormal condition 
with one cell (a) of the ring deformed. 
22. P. Boryanum, (Turp.) Menegh., var. rugulosum, var. n. Xx 500. Five cells 
(2 peripheral and 3 central) from a large coenobium. 
PLATE 6. 
Fig. 1. Pleurotenium caldense, Nordst., forma africanum. х 520. 
9. Closterium nematodes, Josh., var. tumidum, var. п. x 520. 
3. Penium australe, Racib., forma brevius. х 520. 
4. » ya forma crassius. X 520. 
5. Staurastrum pilosum, (Nüg.) Arch., var. minimum, var. п. x 520. 
6. » quadrangulare, Bréb., var. attenuatum, Nordst., forma. х 520. 
7. » Cunningtonii, вр. п. х 520. 
8. » anatinum, Cooke & Wills, var. subglabrum, var. п. x 520. 
9. » monticulosum, Bréb., var. bidens, var. п. x 520. 
10. > gracile, Ralfs, var. Nyanse, var. n. x 520. 
11. „ » var. protractum, var. п. x 500. 
12. " leptoeladum, Nordst., forma africanum. x 500. 
18. Arthrodesmus Incus, (Bréb.) Hass., var. Ralfsii, W. & G. S. West, forma. х 620. 
PLATE 7. 
Figs. 1-2. Micrasterias Cunningtonii, вр. п. x 520. 
Fig. 3. Euastrum truncatiforme, sp. п. x 520. 
Figs. 4-5. , pseudopectinatum, Schmidle, forma. x 520. 
Fig. 6. Cosmarium galeritum, Nordst., var. retusum, var. n. x 620. 
7. » Cunningtoni, вр. п. х 520. 
8. > decachondrum, Roy & Biss., var. ornatum, var. п. x 520. 
9. " lacunatum, sp. п. x 520. The minute punctulations which surround 
the granules are not shown in the figure. 
10. » globosum, Buln., var. Wollet, W. & б. S. West, forma major. х 520. 
11. " Pseudobroomei, Wolle, var. compressum, var. п. x 520. 
PLATE 8. 
Fig. 1. Fragilaria ethiopica, sp. п. x 1000. 
2. Navicula distincta, sp. n. x 500. 
З. Synedra Nyanse, sp. п. х 520. 
E „ Cunningtonii, sp. п. x 250. 
5. Surirella plana, sp. п. x 500. 
0. » Tanganyike, sp. п. x 500. 
T. y» obtusiuscula, sp. п. x 500. 
8. Cymatopleura Nyanse, sp. п. x 590. 
9. Соссопета grossestriata, (О. Müll.) nob., var. Tanganyske, var. n. x 500. 
10. Gyrosigma nodiferum, (Grun.) nob. x 500. 
11. Navicula Tanganyike, sp. n. х 500. 
12. Sehizostauron Crucicula, Grun. x 520. 
18. Gomphonema africanum, sp. n. x 520. 
