Fresh-water Alga. 71 



Var. istriana, Grim. 



Angola. With the type form. 



52. Navicula borcalis, (Ehrenb.) Kiitz. 

 Angola. In stream in Cazengo District. 



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



53. Navicula Brebissonii, Kiitz. 



Upper (or Composite) Eegion. Holle Eiver; 10.12.08. Among 

 Tetraspora explanata in dam at Karieboomfontein ; 8.1.09. 



54. Navicula cryptocephala, Kiitz. 

 Angola. In stream in Cazengo District. 



Karoo. In sulphureous spring, Gansfontein ; 2.12.08. 

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

 Little Namaqualand. In spring at Henkriesfontein ; 11.1.09. 

 Among various algse at Dabainoris ; 11.1.09. 



55. Navicula cuspidata, Kiitz. 



Little Namaqualand. Very typical specimens in a small pool at 

 Aggenys; 6.1.09. Altitude 3,000 feet. 



56. Navicula clliptica, Kiitz. 



Angola. In stream in Cazengo District. 



57. Naviculua gibba, (Ehrenb.) W. Sm. 

 Angola. In stream in Cazengo District. 



58. Navicula limosa, Kiitz. 



Angola. In stream in Cazengo District. 



59. Navicula mutica, Kiitz. 



Karoo. In sulphureous spring at Gansfontein; 2.12.08. 

 Little Namaqualand. In dam at Henkriesfontein ; 11.1.09. 

 Among other algas on submerged stones, Dabainoris; 11.1.09. 



60. Navicula Pupula, Kiitz. 



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

 10.12.08. 



Little Namaqualand. In dam at Kamiebies ; 24.12.08. 



61. Navicula radiosa, Kiitz., var. tenclla, (Breb.) Cleve, Synops. 

 Navic. Diat. II, 1895, p. 17. 



Little Namaqualand. Among Mi/xoneiua tenue and Noduldria 

 turicensis in running water, Henkriesfontein; 14.1.09. 



62. Navicula rhynchocephala, Kiitz. 

 Angola. In stream in Cazengo District. 



63. Navicula sphcerophora, Kiitz. 

 Angola. In stream in Cazengo District. 



