OF THE THIRD TANGANYIKA EXPEDITION. 149 
Order PENNAT/E. 
Family FRAGILARIACEJE. 
Genus FRAGILARIA, Lyng). 
196. FnAGILARIA virescens, Лаз, in Ann. Nat. Hist. ser. 1, xii. (1843) 
p. 110, t. 2. fig. 6; Rabenh. Fl. Furop. Alg. i. (1864) p. 119. 
Nyasa.—In shore-pools, Nkata Bay (23 June, 1904 ; no. 22). 
197. FnaGILARIA ÆTHIOPICA, sp. п. (Pl. 8. fig. 1.) 
Cellula ut visa aspectu valvulari subanguste elliptica, polis rotundatis, 
pseudorhaphide distincta sublata in centro stauriformi, costis lateralibus 
crassis glabris 11 utrobique, costa mediana brevi et rotundata; ut visa 
aspectu cingulato quadrato-rectangularis, apicibus truncatis, lateribus levissime 
retusis in medio et cum costis crassis 11. Cellulæ ut visse solitarie. 
Long. valv. 17-19:5 u ; lat. уму. 75-8 p. 
Tanganyika.—On stones, submerged roots, grasses, eto., Niamkolo (1 Aug. 
1904 ; no. 44). 
This species is readily distinguished by its few, broad costee. The valve- 
view is somewhat narrowly elliptic, and there are eleven broad smooth costze 
on each side, extending towards the central line, but leaving a fairly broad 
pseudoraphe. In the centre the pseudoraphe widens out forming a stauros, 
the median costa on each side being correspondingly short. The coste are 
not transverse, but exhibit a decided radiation near the median part of the 
valve. In the girdle-view the cell is quadrate-rectangular and the созбе 
show very plainly along each lateral margin. 
F. æthiopica belongs to the section * Staurosira, Ehrenb.’ 
Genus SYNEDRA, Ehrenb. 
198. Synepra Nyaxsæ, sp. п. (РІ. 8. fig. 3.) 
Cellula ut visa aspectu valvulari robusta, linearis, diametro 64-134-plo 
longior, marginibus lateralibus parallelis, subiter attenuata apices versus, 
apicibus produetis et subcapitato-rostratis, pseudorhaphide recta magna et 
conspicua (usque 4 ш lata), striis 14-15 т 10 ш; ut visa aspectu cingulato 
linearis, apicibus rectangularibus. 
Long. valv. 91-150 ш; lat. valv. 10-13 и; lat. apice. 3°2-3°8 д. 
Victoria Nyanza.—A mong Algw on rocks below the water-level, Bukoba 
(17 Apr. 1905 ; no. 248). 
This species resembles in outline S. Ulna, (Nitzsch) Ehrenb., and 
S. oayrhynchus, Kütz., but differs. in its much finer striations, its broader 
and more conspicuous pseudoraphe, as well as in the absence of the clear 
space in the median part of the valves. 
In its general proportions it was somewhat variable, and some very short, 
robust individuals were observed. 
