ALGOLOGICAL NOTES 



83 



Hah. In swamp, Kota Kota, Lake Nyasa. 



This small Micrasterias agrees more closely with M. Itzigsohnii 

 than any other described form. It resembles to some extent 

 M. incisa Breb., 1848, but is without doubt most closely related 

 to M. truncata (Corda) Breb., of which it might perhaps be best to 

 regard it as a small and delicate variety — var. Itzigsohnii (Bveh.) nov. 

 comb. — with a tendency to irregularity in the lateral lobulation." 



13. CosMARiuM GRANATUM Breb. var. subgranatum Nordst. 

 Hab. Albert Nyanza. 



14. CosMARiUM suBCONSTRiCTUM Schmidlo. Hab. Albert 

 Nyanza. 



Fig. 3. — A, Micrasterias truncata (Corda) Breb. var. Itzigsohnii (Braun) 

 G. S. West (= M. Itzigsohnii Braun), x 500. B and C, Staurastrum tridens- 

 Neptuni W. & G. S. West, x 500. 



15. Staurastrum tridens-Neptuni W. & G. S. West, " Welw. 

 Afric. Freshw. Alg.," Journ. Bot. 1897, p. 177, t. 369, f. 7. This 

 Desmid was described and figured from specimens obtained by 

 Welwitsch at Huilla in Angola, W. Africa. In working out some 

 of Stuhlmann's East African collections, Schmidle t remarked that 

 it should be placed as a form of S. subtrifurcatwn W. & G. S. 

 West. It has already been stated \ that distinctions from the 

 latter species were fully enumerated at the time S. tridens-NepUtni 

 was described. In order to test the validity of the species I have 

 again examined some of the original material, and made further 

 drawings. I find the characters of S. tridens-Neptuni very con- 

 stant, and of such a nature that one cannot regard it as having 

 any close affinity with S. subtrificrcattim. The latter has a 

 triangular vertical view, with bluntly rounded angles, whereas the 

 former has a pentagonal vertical view with sharp angles. Both 

 species are provided with three long spines at each angle of the 

 semicell, but in S. tridens-Neptuni the spines are stouter and 

 placed vertically over one another in one plane, as compared with 

 the disposition of the spines in a triangle at each blunt angle of 

 S. suhtrifurcatum. Fig. 3, B and C, represent front and vertical 

 views of S. tridens-Neptuni. 



* Bulnheim's forms figured under the name of " Micrasterias Itzigsohnii " 

 (cf. Hedivigia, ii. 1862, t. 10, I. f. 5) are merely reduction forms of M. pinnati- 

 Jida (Kiitz.) Kalfs. 



t W. Schmidle in Engler's Botan. Jahrbiich, xxxii. 1903, p. 73. 



J W. & G. S. West in Ann. Roy. Bot. Gard. Calcutta, vol. vi. part ii. 1907, 

 p. 215. 



