498 MR W. WEST AND MR G. S. WEST ON 
plankton. We previously mentioned this curious feature as characteristic of the plank- 
ton of Loch a Bhursta, Benbecula (vide Journ. Linn. Soc., 1908, bot., xxxv. p. 524), 
Family DrEsMIDIACcEs. 
Genus Gonatozygon, De Bary, 1856. 
5. G. aculeatum, Hastings, in Amer. Month. Micr. Journ., 1892, p. 29; Johns, in 
Bull. Torr. Bot. Club, 1895, vol. 22,/No. 7, p. 291, t. 239, f.9. [G. aculeatum, f. minor, 
W. & G. 8S. West in Trans. Linn. Soc., bot. ser. 2, v., 1896, p. 280, t. 12, figs. 1, 2.] 
Long. 266 «; lat. in med. sine acul. 10°5 w, ad apic. 12°5m; long. acul. 7°5-7°7 u 
CEI ao uz): 
Hab.—loch Fadaghoda, Lewis, Outer Hebrides. 
This rare species has not been reported previously as being found in Europe. It 
seems distributed over certain districts of the eastern United States, and TurNER has 
figured two forms of what he termed “ G. pilosum, Wolle,” from Central India, which 
undoubtedly belong to G. aculeatum (wide Turn. in Kongl. sv. Vet.-Akad. Handi., 
Bd. 25, No. 5, 1898, p. 25, t. 20, figs. 1, 2). The Scottish specimens are relatively 
narrower than the American ones, but all the species of this genus exhibit great varia- 
tion, not merely in size, but in relative proportions. 
6. G. monotenium, De Bary, var. pilosellum, Nordst. in Wittr. and Nordst., Alg. 
Hasic., 1886, No. 750, fasc. 21, p. 48; W. & G. 8S. West, Brit. Desm., 1904, vol. i. 
p. 31. 
Long. 278»; lat. in med. 7°8 u, ad apic, 9 w (PI. 6, fig. 1). 
Hab.—Loch an Sgath, Lewis, Outer Hebrides. 
This variety is of very rare occurrence, and is characterised by the short papillate 
projections on the cell-wall. It has not previously been recorded for Scotland. 
Genus Genicularia, De Bary, 1858. 
7. G. elegans, W. & G. 8S. West, in Journ. Linn. Soc., bot., xxxv., 1908, p. 536, t. 14, 
figs; 1,2; Brot. Desm:,; 1., 19045 sp) 865 ta o,rios. 12: 
Hab.—Lochs Morar and Shiel, Inverness ; Lochs Fadaghoda and an Sgath, Lewis; 
and Loch Laxadale, Harris, Outer Hebrides. 
This species appears to be confined to the plankton of the west of Scotland. It has 
only previously been recorded from Loch nan Eun, N, Uist, Outer Hebrides. 
Genus Closterium, Nitzseh, 1817. 
8. Cl. acerosum (Schrank), Khrenb., forma minor. 
Long. 242 u; lat. 20 » (Pl. 6, fig. 20). 
Hab.—Loch Fadaghoda, Lewis, Outer Hebrides. 
9. Cl. turgidum, Ehrenb., forma glabra, Gutw., in Rospraw. Wydz. matem.-przyr. 
Akad. Ume. Krakow, xxxiii., 1896, p. 37, t. 5, f. 10. 
