280 THE FRESH-WATER LOCHS OF SCOTLAND 
S. hmahim, Ralfs. General. 
>-S'. aversmn^ I^und. 
*S*. suhnudibrachiatuvi^ West. 
S. teliferum, Ralfs. 
S. erasum, Breb. 
S. pseudopelagicum, West. Local. 
S. paradoximi^ Meyen. General. 
>S'- gracile^ Ralfs. General. 
S. anatinum^ Cooke and Wills. Local. 
S. ophiura, Lund. Local. 
S.Jui'cigeruifi, Breb. Local. 
S. sejcangulare (Buln.). Local. 
yS. arctiscon., Ehr. Local. 
Spo7idylosium pulchrum (Bail.). 
Desmidium graciliceps (Nordst.). 
D. coarctatuyn^ Nordst. 
D. occ'identale, West. 
Hycdotheca mucosa, Ehr. General. 
H. neglecta, Racib. 
Several of these are not in the survey list, and it is to be noted 
that in many cases the species occurs in the plankton under special 
varieties, not here specified, as it is only intended to indicate what 
species are, under some form, to be regarded as naturalised in the 
plankton. 
Other Chlorophycese. — 26 species (Messrs West 44 species). 
Myxophycese. — 10 species (Messrs West 21 species). 
Peridiniaceae. —Peridinmm sp. 
Glenodinium sp. 
Ceratium liiriindinella. Mull. General. 
C. cormdus (Ehr.). Local (or casual). 
Flagellata. — Mallomoiias sp. General.^ 
D'mohryon. Several forms common. 
Diatoms. — The list of Diatoms is very poor, numbering only 
some two dozen species, whereas Messrs West found about ()0. Most 
of these they regarded as casual, and the small list of true plankton 
species, here transcribed, only numbers about 20 species. 
Tabellariafenestrata (Lyngb.). General. 
T.Jioccidosa (Roth.). General. 
Fragilaria crotonensis {A. M.. Yidw.). Local. 
Asterionella formosa, Hass. General. 
A. gracillima, Heib. General. 
Eunot'ia pectinalis (Kutz.). 
