BIOLOGY OF THE SCOTTISH LOCHS 
279 
Ph YTOPL AN KTO N 
The number of vegetable organisms in the plankton collections 
is much greater than that of animals, and it is much more difficult 
to assign them their true positions, whether true plankton organisms 
or casual. It is not intended to give full lists here, as these would 
almost coincide with the lists in the " Census of Species."' 
All the Chlorophyceas in the list (about 150 species, of which 
about 120 are Desmids) were obtained in the plankton nets. A large 
proportion must be casuals, washed out from the peat-bogs, etc. 
These figures may be compared with those given by Messrs W. and 
G. S. West,^ who have recorded nearly 200 Chlorophyceae for the 
Scottish lochs, about 150 being Desmids. 
As I cannot pretend to the knowledge necessary to select from 
our long list the true plankton Desmids, Messrs West's list of 44 
species is here transcribed. I would be inclined to somewhat extend 
the list. 
Desmids. — Gonatozygon monotwnium, De Bary. 
Geniculcma elegans^ West. 
Closter'mm kutzingii^ Nag. General. 
Euastrum verrucosurn^ Ehr. General. 
Micrasteria.s mahahulesliwarensis^ Hobson. Very local. 
Cosrnarium contractum^ Kirchn. 
C. depixssum (Niig.). 
C. abbreviatum^ Racib. 
Xanthidium aiitilopeum (Breb.). General. 
Jl. subhastife?'u??i. West. Local. 
X. controversum^ West. Local. 
Arthi^odesviiis mc?^^ (Breb.). General. 
A. quiriferiis^ West. 
. A. crassus^ West. 
A. triangularis, Lagerh. 
Staurastrum dejechtvi (Breb.). Local. 
>S'. curvatum. West. Local. 
S. jaculiferuin, West. General. 
S. megacanthuyn, Lund. Local. 
S. cuspidatimi, Breb. 
S. inelegans, West. 
S. longispinum (Bail.). Local. 
S. hrtsiliense, Nordst. Local. 
S. grande, Buln. Local. 
S. brevispimmi^ Breb. 
1 Trans. Roy. Soc. Edin., vol. xli. pp. 477-518, 1905. 
