536 MRs W. WEST AND PROF. G. Ss. WEST ON 
Loch Humphrey is less than a mile in length, and is situated 
at an altitude of over 1000 ft. 
Loch Woodend is a small lowland loch about 260 ft. above 
sea-level. 
Peridinium tabulatum and Glenodinium cinctum were frequent 
in Loch Humphrey, and Ceratium tetraceros, Schranck, was 
present in Loch Thom. The Rotifer Anurea cochlearis, Gosse, 
was abundant in both Loch Thom and Loch Humphrey. 
III.—Systrematic ACCOUNT OF THE MOST INTERESTING 
SPECIES IN THE PRECEDING PLANKTON COLLECTIONS. 
Owing to the extraordinary richness of the Scottish plankton 
in Desmids, the following account is almost entirely concerned 
with these plants, and in it we have attempted to clear up many 
of the difficulties of their nomenclature. 
With the permission of Sir John Murray, we have included 
in this account six Desmids from the plankton of Sutherland : — 
Euastrum verrucosum, Ehrenb., var. planctonicum, var. 2. ; 
Micrasterias Murray, sp. n.; Xanthidium subhastiferum, West, 
and var. Murrayi, var. n.; Staurastrum jaculiferum, West, var. 
subexcaratum, var. n.; St. Arachne, Ralfs, var. curvatum, var. n.; 
and St. brevispinum, Bréb., var. vetusum, Borge: material con- 
taining specimens of these has been collected and kindly 
forwarded to us by Mr. J. Murray of Edinburgh, who is engaged 
on the Lake Survey (Pullar Trust). These are included because 
of the interesting comparisons they afford with other Desmids 
observed in our own plankton collections. 
Class CHLOROPHYCE. 
Order Conjugate. 
Family DeEsSMIDIACES. 
Genus Genicutaria, De Bary. 
1. G. ELEGANS, sp.n. (PI. 14. figs. 1, 2.) 
G. elongata, cellulis diametro 20-28-plo longioribus, leviter 
curvatis, cylindricis, polis leviter dilatatis et firmioribus; mem- 
brana dense et irregulariter asperulata ; chromatophoris 2, 
