THE YAN YEAN RESERVOIR, VICTORIA. 5 
quadrivalvis, Acacia melanowylon, Eucalyptus globulus, Е. citriodora, Hakea 
laurina, ete. Mr. Hardy states that the few recent (Post-pliocene) deposits of 
the catchment area of the Yan Yean carry only stunted growths, and that the 
low-lying part of the Silurian country to the north is sparsely timbered with 
several kinds of Eucalyptus, but that the timber improves with increasing 
altitude, growing taller and straighter, while the undergrowth becomes 
denser. The gullies are rich in shrubs, and the creeks afford moisture for 
numerous ferns, Of the large tree-ferns, Dicksonia Billardieri and Alsophila 
australis are common, the brown trunks often being draped with Нутепо- 
phyllum. The shade-loving Pteris incisa and P. tremula are conspicuous, 
but Pteris ayuilina is everywhere, while along the aqueduct between Wallaby 
and Silver Creeks Gleichenia circinata and species of Lomaria are abundant. 
At the weedy margins of the Yan Yean the marsh plants are chiefly the 
rush-like Heleocharis sphacelata (the flowering shoots of which attain in places 
a length of eight feet), Arundo Phragmites (only in the N.W. corner), 
Triglochin striata, Myriophyllum varüfolium, Limnanthemum exaltatum, and 
Potamogeton natans, the two latter almost monopolising small areas. Further 
out are Potamogeton obtusus, Triglochin procera, Myriophyllum elatinoides, 
Vallisneria spiralis, and a species of Nitella (about two feet in length). 
Flourishing among these larger plants there is an abundant littoral Alga- 
flora which will be considered in its relation to the phytoplankton. 
Mr. Hardy’s enthusiasm, combined with a sound knowledge of the require- 
ments of the work he was so kindly undertaking for me, caused him to visit, 
at considerable trouble and inconvenience to himself, the different parts of 
the entire drainage area. Not only was this done for the collection of Alge, 
but also for obtaining any information that might bear upon their distribution. 
He procured me samples of plankton from the Toorourong Reservoir, and 
from the dams at both Wallaby and Silver Creeks, for comparison with the 
Yan Yean plankton. In addition, he made a number of collections from 
different parts of the drainage area, especially in the vicinity of the two 
swampy inlets of the Yan Yean to which he has given the names of * Rana 
Creek? and * Ottelia Creek,’ the former owing to the congregation of multi- 
tudes of frogs, and the latter by reason of the presence of Ottelia ovalifolia 
in most of the pools. 
The present paper is divided into several chapters, of which the first three 
deal respectively with the phytoplankton of the Yan Yean Reservoir, the 
littoral Alga-flora, and the general Alga-flora of the drainage area. The Alges 
of the entire area, and the different parts of it, are then discussed in their 
'arious relationships ; the more important and interesting species are dealt 
with systematically ; and lastly, attention is drawn to the peculiarities of the 
Alga-flora of Australasian freshwaters. 
