504 MR W. WEST AND MR G. 8. WEST ON 
28. St. pseudopelagicum, W. & G. 8S. West, in Journ. Linn, Soc., bot., xxxv., 
1008) 90.0047 fs 18) xf 8. 
This species occurs in quantity in the plankton of many of the Scottish lochs. A 
specimen was observed from Loch Shubhaill, Lewis, in which one semicell was quite 
normal, whereas the processes of the other were each terminated by a single stout spine. 
29. St. paradoxum, Meyen, 1829; Ralfs, Brit. Desm., 1848, p. 138, t. 23, £ 8. 
Var. longipes, Nordst., in Acta Uni. Lund., 18738, ix., p. 35, t. 1, f. 17. 
This is one of the commonest Desmids of the British plankton. We give a figure 
of a typical specimen from Lewis (PI. 7, fig. 18); long. sine proc. 26 «, cum proce. 
77»; lat. sine proc. circ. 15, cum proc. 84-87 »; lat. isthm. 8 x. 
In the plankton of Loch Langabhat, Lewis, all the forms of this variety were very 
large, and the processes were relatively longer and more robust (Pl. 7, fig. 14); long. 
sine proc. 29, cum proc. 84; lat. sine proc. circ. 17 w, cum proc. 134-139 «; lat 
isthm. 9°5 wu. 
30. St. gracile, Ralfs, var. cyathiforme; W. & G. S. West, in Trans. Linn. Soc., 
Omecer 2 ven 1899. pei ie bo, raze 
Forma lateribus ad basin semicellularum integris (non undulatis). 
Long. 58 «; lat. cum proc. 80-83 »; lat. isthm. 8 mu. 
Hab.—lLochs Fadaghoda and an Sgath, Lewis, Outer Hebrides. 
31. St. subgracillimum, W. & G. S. West, in Trans. Innn. Soc., bot. ser. 2, V. 
1896, p. 268, t. 17, figs. 3, 4. 
Forma processibus paullo crassioribus, et denticulis minutis 3 ad apicem processuum. 
5) 
Long. (sine proc.) 15°5 »; lat. sine proc. 18 », cum proc. 55; lat. isthm. 5°5 m. 
Hab.—Small loch near Cearnabhal, Lewis, Outer Hebrides. 
The specimens seen were very like those observed from near Glenties, Ireland; wide 
W. & G. 8. West, in Trans. Roy. Irish Acad., 1902, xxxi. p. 56, t. 1, fgss2 ie 
They differ in the smaller teeth at the extremities of the processes. 
32. St. anatinum, Cooke & Wills. 
This is one of the most characteristic Desmids of both the Scottish and Irish 
plankton. It is a Stawrastrwm which is more or less covered with emarginate warts, 
and the var. grande, W. & G.S. West, is one of the handsomest Desmids of the genus. 
Var. longibrachiatum, var. n. (Pl. 7, figs. 8, 9). 
Var. corpore semicellularum infra apicem subglabra, processibus multe longioribus 
et gradatim attenuatis apicem versus. 
Long. sine proc. 37 4; lat. sine proc. cire. 29 wu, cum proc. 110-1314; lat. isthm. 
11°5 w. 
Hab.—Loch Langabhat, Lewis, Outer Hebrides. ° 
33. St. Sebaldi, Reinsch, in Abhandl. d. Naturhist. Gesellsch. zu Niirnberg, i., 
Hett2, (8670p. 1755 td tl, 
Var. productum, var. n. (Pl. 7, fig. 24). 
