FRESH-WATER ALGAE. 321 
FRESH-WATER ALGAE. 
TuHE plants belonging to this section are but meagrely repre- 
sented in Guernsey, and the only list of species hitherto published 
is the one I made out in 1894. Many unrecorded forms have 
occurred in my gatherings, but not in a condition to be identified 
with certainty. Only nine Desmids have been observed, although 
repeated gatherings were made in many likely spots, including 
Grande Mare, the most promising locality in the island. Further 
research will undoubtedly add to the number, but the Fresh-water 
Algae will always remain relatively the weakest section of the 
Guernsey cryptogamic flora. 
Besides the 9 Desmids, 44 species are now recorded. 
CHLOROPHYLLOPHYCEAE. 
Pleurococcus vulgaris, Meneg. 
Common on tree-trunks, wooden fences, and shaded walls, 
Gloeocystis rupestris, Rab. 
On moist rocks at foot of the cliffs, Petit Port. 
Porphyridium cruentum, Nag. 
Common on damp ground and at the base of walls, forming 
patches resembling blood-stains. 
Rhaphidium falcatum, Rab. 
Abundant in a gathering from one of the pools at Grande Mare. 
Protococcus viridis, Ag. 
Common on damp walls, trees, and fences. Probably an unde- 
veloped state of some of the higher algae. 
Chlorococcum Gigas, Grun. 
In some of the Grande Mare gatherings. 
Scenedesmus obtusus, Meyen. 
Grande Mare, in pools, but only sparingly. 
Scenedesmus quadricauda, Breb. 
Abundant in a water-tank in my greenhouse. 
Pediastrum ellipticum, Ralts. 
Grande Mare: not common. 
