550 MR. W. WEST AND PROF. G. S. WEST ON 
This is one of the most interesting of British Desmids, and 
has never been recorded since the appearance of Archer’s meagre 
description in 1869. The figure given by Cooke in his ‘ British 
Desmids,’ 1886, t. 61. f. 3, is entirely imaginary, as he possessed 
neither specimens nor figures. The specimens from the plank- 
ton agreed well with a good drawing in our possession, which 
was copied by the Jate Dr. J. Roy from Archer’s original sketch. 
Fig. 7, Pl. 14, is the first figure ever published of the species and 
illustrates the remarkable divergent character of the processes. 
We have also obtained numerous scattered specimens of this 
rare Staurastrum from bogs in western Sutherland. As in 
S. Ophiura, the upper surface of the processes is considerably 
rougher than the lower surface. 
33. SravurastruM Oputura, Lund.in Nov. Act. R. Soc. Scient. 
Upsala, ser. 3, viii. (1871) no. 2, p. 69, t. 4. f. 7. 
Long. 77-91 p; lat. sine proc. 40-46 p, cum proc. 128-169 p; 
lat. isthm. 19°5—-26 p. 
Hab. Loch Shin and Loch a Gharbh Bhaid Mhoir, Sutherland. 
Loch Laxadale, Harris, Outer Hebrides. Loch Tay, Perthshire. 
Loch Doon, Ayrshire. 
This fine Desmid appears to be a general constituent of the 
Scottish plankton, although not occurring in large numbers. Like 
S. brasiliense var. Lundellii and S. Arctiscon, it is a Desmid 
of a western type, confined in the British Islands to the western 
districts of Wales and Scotland. It is not confined to the 
plankton, and we have observed it from bogs in both Sutherland 
and the Outer Hebrides. 
Some of the specimens reached a very large size (larger than 
any others we have seen from Britain or the United States, or 
those recorded for Scandinavia), and in all cases the central ring 
of papille on the apices was composed of conical (and not 
quadrifid) warts. 
No individuals were observed which could have been referred 
to var. cambricum, West, although the apical papillae were not 
strictly in accordance with Lundell’s Swedish specimens. As in 
the Welsh variety, the 8-rayed forms were the most numerous. 
34. S. seExanGuLare, Rabenh. Krypt. Fl. Sachs. 1863, p. 621; 
Lund. 1. c. p. 71, t. 4. f. 9—Didymocladon sexangularis, Buln. 
in Hedwigia (1861), p. 51, t. 9a. f. 1. 
