166 MR. G. S. WEST ON THE FRESHWATER ALGÆ 
Long. 60-62 ш; lat. max. 18 №; lat. min. 16 д. 
Tanganyika.—In plankton, Komba Bay (11 Oct. 1904 ; no. 135) апа near 
Kala (19 Nov. 1904 ; no. 170). 
Compare with 5. linearis, W. Sm., and S. constricta, Ehrenb. 
218. SURIRELLA TANGANYIKA, sp.n. (PI. 8. fig. 6.) 
S. parva ; cellula ut in visa aspectu valvulari elliptico-oblonga, marginibus 
lateralibus in parte mediana subparallelis, polis subconicis ad extremo leviter 
rotundatis ; pseadorhaphide recta et distineta ; costis validis paucis 2-23 т 
10 м (12-13 in margine laterali unoquoque), subbrevibus, iis in medio 
transversis, iis ad polos radiatis ; alis intra et juxta margines laterales ; valvis 
inter costos dense et valde punctata ; cellula ut in visa aspectu cingulato 
oblongo-rectangularis, angulis rotundatis. 
Long. 84-88 д; lat. 30-32 p. 
Tanganyika.—In plankton, Kituta Bay (25 Aug. 1904; no. 77), near 
Mbete (28 Sept. 1904 ; no. 105), and near Kala (19 Nov. 1904 ; no. 170). 
This species was not uncommon in the above plankton eollections. The 
coste are relatively few, although occasionally slightly irregular in their 
arrangement; and they are also short, only extending about half the distance 
from the margin of the valve to the sagittal axis (pseudoraphe). The al» as 
seen in the valve-view are marginal or just within the margin. 
valve between the coste and right up to the pseudoraphe is stron 
There is no hyaline area on each side of the pseudoraphe. 
The outward form of the valve, the few and remote costze, and the strong 
punetulations: are features which separate S. Tanganyike from any other 
species. 
The entire’ 
gly punctate. 
279. SURIRELLA STRIATULA, Turp. in Dict. Se. Nat. li. p. 508 (Suriraya) ; 
Kütz. Васі. (1844) p. 62, t. 7. fig. 6.; Schmidt, Atlas Diat, t. 24. figs. 17 & 20. 
Long. 120 ш; lat. 82 p- 
Tanganyika.—In plankton, near Maswa (14 Jan. 1905; no. 211) and near 
Baraka (24 Feb. 1905; no. 240). 
This interesting species is mostly marine and submarine in habit. 
Genus CYMATOPLEURA, W. Sm. 
280. CYMATÓPLEURA SOLEA, W. Sm. in Ann. Mag. Nat. Hist. sev. 2, vii. 
(1851) p. 12 ; Brit. Diat. i. р. 36, t. 10. fig. 78.—8Surirella Solea, Азиз. Вас.” 
(1844) p. 60, t. 3. fig. 61. 
Nyasa.—lIn plankton, Anchorage Bay (13 June, 1004 ; no. 9) and off 
Karongo (1 July, 1904 ; no. 30). { 
. Victoria Nyanza.—Among Utricularia, near Entebbe (1 May, 1905; 
по. 620). ‚ | Р 
Tanganyika.—In plankton, Kituta Bay (26 Aug. 1904; no. 81), Komba. 
Bay (11 Oct. 1904 ; по. 135), near Kirando (1 Dec. 1904 ; no. 175), and near., 
Ndauvie (7 Feb. 1905; no. 221). | 
