72 Annals of the South African Museum. 



Karoo. In sulphureous spring at Pappekuil ; 2.12.08. 



Upper (or Composite) Kegion. On drying mud in Holle Eiver ; 

 10.12.08. 



Little Namaqualand. In dam at Pella ; 8.1.09. In running water 

 at Henkriesfontein ; 1-4.1.09. In pool at Aggenys ; 6.1.09. On sub- 

 merged stones at Dabainoris ; 11.1.09. Among Spirogyra varians 

 in spring at Kamiebies ; 24.12.08. In dam at Eozynbosch ; 9.1.09. 



This species was certainly the most abundant Diatom observed in 

 the collections. It occurred in a great variety of situations and 

 exhibited a considerable amount of variation in the shape of the 

 valves. Great variation in outward form was shown by this Diatom 

 in another African area. O. Midler has described and figured a very 

 interesting and continuous series of forms from the saline lake 

 El Kab in Upper Egpyt (vide Hedwigia, Bd. xxxviii, 1899, pp. 300- 

 305, t. 12, f. 1-15). 



64. Navicula viridis, Kiitz. 



In stream in Cazengo District. 



65. Navicula sp. 



I have not succeeded in identifying this species, and it may 

 possibly be new. It agrees with those species which were formerly 

 placed in the genus Scliizouema in its absolutely transverse stria- 

 tions. These striations are very delicate (27 to 29 in 10 p), rather 

 more so than in a species of the section Schizonema, and they are in 

 no way divergent. Long. valv. 26-28 /j.; lat. valv. 5"3-5"5 fx. 



Great Namaqualand. Attached to the concrete walls of a cattle- 

 trough at Griindoorn ; 4.2.09. 



66. Stauroiieis anceps, Ehrenb. 



Upper (or Composite) Eegion. Holle River ; 10.12.08. 



Var. linearis, (Ehrenb.) Cleve, Synops. Navic. Diat. I, 1894, p. 147. 

 Long. valv. 47 p ; lat. 8p,; striis 24 in 10 /./. 



Little Namaqualand. Abundant in dam at Henkriesfontein ; 

 14.1.09. 



67. Gyrosigma Spencerii, (Quek.) O.K., var. exilis, Grun. 

 Angola. In stream in Cazengo District. 



Family GOMPHONEMACEiE. 



68. Gomphonema gracile, Ehrenb. 

 Angola. In stream in Cazengo District. 



Karoo. In sulphureous spring at Gansfontein ; 2.12.08. 

 Upper (or Composite) Region. Holle River; 10.12.08 In dam 

 at Karieboomfontein ; 8.12.08. 



