26 
225. 
226. 
228. 
TRANSACTIONS AND PROCEEDINGS OF THE | Szss. LXIX, 
Long. sine proc. 10-llu, cum proc. 27-40y; lat. sine proc. 
75-9 Su, cum proc. 26-50 ; lat. isthm. 4°5u. 
S.—Plankton of Neugles Water and Loch Brindister, and also 
of Loch Beosetter, Bressay. 
This variety occurred in considerable quantity, and the 
individuals varied much in the relative length of the processes. 
The cells were invariably twisted, the processes of one semi-cell 
alternating with those of the other. 
. hexacerum (Ehbrenb.), Wittr. O—Kirkwall; Hoy. S.—Near 
Lerwick ; Scalloway. Plankton of Lochs Asta and Clickhimin. 
Bressay, in ditches, and also in the plankton of Loch Beosetter. 
Var. semicirculare, Wittr. S.—Scalloway. 
. cyrtocerum, Bréb., var. compactwm, var. n. (fig. 29). 
Var. corpore semicellularum robustiori, processibus multe 
brevioribus. 
Long. 36u ; lat. cum proc. 40u ; lat. isthm. 11m. 
S.— Plankton of Loch Trebister. 
. inflecum, Bréb. O—W. of Kirkwall; Finstown; Hoy. S.— 
Scalloway. 
. affine, sp. n. (fig. 27). 
S. submediocre, paullo longius quam latum (cum processibus), 
subprofunde constrictum; semicellule  elliptico-subsemicir- 
culares, ventre valde convexo, dorso leviter convexo, angulis m 
processus crassos breves denticulato-nodulosos subdivergentes pro- 
ductis, apicibus processuum quadrispinatis ; a vertice vise tri- 
angulares, lateribus leviter convexis, angulis in processus breves 
crassos denticulato-nodulosos productis; membrana minute 
granulata, granulis in annulis concentricis circa basin processuum 
dispositis. 
Long. (sine proc.) 37-40 ; lat. sine proc. cire. 29-33, ; lat. 
cum proc. 44—55y ; lat. isthm. 10°5y. 
S.—Plankton of Neugles Water and of Loch Brindister. 
This species occurred in abundance in the plankton of the 
above-mentioned lakes. Its distinctive characters are the large 
size of the body of the semi-cells, and the short, outwardly 
diverging processes, each of which possesses two rings of den- 
ticulations and four apical spines. It is perhaps nearest to 
S. polymorphum, Bréb., but is larger, of different relative propor- 
tions, and with different processes. 
Borge has recently described a “S. subpolymorphum” (vide 
“ Arkiv. for. Botan. utgif. af K. Sv. Vet.-Akad.,” Bd. L., 1903, 
p. 107, t. 4, f. 13), but this is a smooth Staurastrum, which we are 
inclined to think is merely a South American form of 8. 
distentum, Wolle (vide W. and G. S. West, “ Some Desm. U.S,” 
ap te Linn. Soc.,” bot. xxxiii., 1898, p. 316, cum fig. xylogr., 
). 
229. S. polymorphum, Bréb, O.—Kirkwall. S.—Scalloway ; Lerwick ; 
Neugles Water. 
Var. sumplez, var. n. (fig. 28). 
Var. cellulis paullo longioribus (sine processibus) ; processibus 
leviter divergentibus cum annulo uno denticulorum ; apicibus 
processuum spinis minutis 4 preditis; membrana reliqua 
glabra ; cellule a vertice vise quadrangulares. 
Long. sine proc. 21-23y; lat. sine proc. 12°5—15u, cum. proc. 
23-28°5y; lat. isthm. 7°6u. 
S.—Near Lerwick, abundant amongst Chlorobotrys regularis, 
etc. ' 
