590 Annals of the South African Museum. 



Sample 25. 



Long., 70 /x; lab., 12 /a. 



5. Navicula anglica, Rail's; Cleve, op. cit., p. 22 ; Van Heurck, op. 

 c#., p. 87, PL VIII, fig. 29. (Syn. : N. tumida, W. Smith.) 



Samples 3, 4, 5, 6. 



Long., 30-36 /x ; lat,, 12-13 /x. 



6. Navicula muticopsis, Van Heurck, Diatomees, Result, d. vov. d. 

 S. Y. Belgica, 1909, p. 12, PI. IT, fig. 181. 



Samples 32. 43. 



Long., 15-18 /x ; lat., 8-8-5 /x. 



It is interesting to find this species, which, as far as I am aware, 

 has hitherto only been recorded from the Antarctic, The specimens 

 belonged mainly to forma reducta, W. A: G S. West (Freshw. Algae, 

 Rep. Brit, Antarct. Exped., 1907-09, i, 1911, pp. 283, 284, PI. XXVI, 

 figs. 121-124). 



7. Navicula dicephala, W. Smith, op. cit., i. p. 53, PI. XVII, fig. 157; 

 Cleve, op. cit.. p. 21. 



Samples 32, 4o. 



This is certainly very close to some forms of the previous species. 



Section PINNULARIA Ehrenberg. 



1. Navicula (Pinnularid) molaris, Grim. : Cleve, op. cit., p. 74; 

 Van Heurck, op. cit., PI. VI, fig. 19. 



Samples 5, 32. 

 Long., 31 fi ; lat., 7 /x. 



2. Navicula (Pinnularia) interrupta, W '. Smith, op. cit., i. p. 59, 

 PL XIX, fig. 184 ; Cleve, op. cit., p. 76 (Fig. 40. a d). 



Samples 2, 4, 5, 14, 36 (diverse forms, cf below). 



This is obviously an exceedingly variable species, merging on the one 

 hand into P.mesolepta, Ehrenb., on the other into P. braunii, Grim., 

 and P. bicapitata, Lagerstedt, In Lagerstedt's original figure of the 

 latter species (Spetsb. Diat.. Bill. Sv. Vet -Ak. Hand]., i. 1873, Tab. I. 

 Pig. 5) the valves are shown with parallel, slightly refuse sides and 

 small capitate ends, while the striae are not interrupted at the middle 

 of the valve. Van Heurck's figure (PI. VI, fig. 14), however, shows the 

 sides as perfectly straight, although otherwise like that of La^ersteilt. 

 Cleve (op. cit., p. 76) places P. bicapitata under forma biceps of P. 

 interrupta, this form corresponding to P. interrupta. var. (3, W. Smith 

 (op. cit., ii, p. 96), which is synonymous with P. biceps, Gregory; to 

 this form Cleve also refers the specimen figured by Van Heurck. The 



