432 
BATHYMETRICAL SURVEY OF 
Mr. Scourfield as D. laticeps) is somewhat small and pale in colour. 
In other districts, and especially in hill lochs, it is of larger size and 
brighter colours — blue or occasionally red. There is some doubt as to 
the identity in all cases, and naturalists have given different identifica- 
tions of the Loch Ness animal. 
B. laciniatus, in contrast to D. laticeps, was only found to the west 
of the Glen, in lochs high above the sea. To the east, though it was not 
in any of the lochs surveyed, it was in some lochans at a great elevation 
on Carnahoulin. 
Desmids. — The conspicuous plankton desmids, which constitute 
probably the most distinctive feature of the western Scottish plankton 
are not very well represented in the lochs of the Ness basin. There are 
few species, but they include several of the largest and most beautiful. 
They show no marked preference for the one side of the Glen more than 
the other, but the greatest number of species is in Loch Aslaich, which 
lies west of Loch Ness. 
Micrasterias apiciiJata^ var. fimhriata, was in Loch Aslaich, and the 
var. hrachyptera was found only once in Loch Ness. 
J/. radiata, Hass (4/. furcata ). — This very local species was in Loch 
Aslaich. 
Stcmrastrum furciyerum, Breb. — In Loch Bran, at Foyers. 
S. lotuyispinuni (Bail.). — In Loch Aslaich and several neighbouring 
lochs. 
S. opliiura, Lund. — ^Loch Ness and Loch Aslaich. 
S. sexangulare (Bulu.). — Loch Garth, near Foyers. 
S. hrasiliense, Nordst. — Loch Aslaich. 
Euastrum verrucosum, Ehr., Micrasterias papillifera, Breb., 
Xanthidium antilopeum (Breb.), Staurastrum gracile, Bolfs, Stauras- 
trum lunatum, var. pJanctonicum, West, and one of the beaked Closteria, 
which I identify as C . setaceum, Ehr., are the most generally distributed 
desmids in the basin. 
Crustacea . — Apart from the Calanidae, a few of the Crustacea appear 
to be local in the district. 
Sida crystallina. — Only seen in Loch Ness and Loch Aslaich. 
Diaphanosoma hrachyurum . — Only noted in the lochs of the Great 
Glen and some lochs to the west. The eastern lochs were doubtless 
surveyed before its season. 
Holopedium gihherum. — Noted in scarcely half the lochs, but those 
on both sides of the Glen and at all elevations. 
Leptodora was only seen in the lochs of the Glen and Loch Tarff ; 
P olyphemus in the Glen and some lochs to the west ; Bythotrephes in 
the Glen and Lochs Tarff and Buthven to the east. 
Rotifera. — Conocliilus unicornis was generally distributed; C. volvox 
only in Lochs Ness, Laide, and Knockie. 
Floscularia pelagica . — Lochs Ness, Oich, and Uanagan. 
