THE YAN ҮКАМ RESERVOIR, VICTORIA. 37 
Heterokontæ.— 7ribonema bombycina, (Ag.) Derb. & Sol., forma minor, 
(Wille) G. S. West, Ophiocytium majus, Мио. 
Bacillarieæ.— Рипойа lunaris, (Ehrenb.) Grun., Navicula ` bicapitata, 
Lagerst., Gomphonema gracile, Ehrenb., Nitzschia Sigma, (Kütz.) W. Sm. 
Myxophycez.— Oscillatoria Agardhii, Gom. 
All the above species, except those belonging to the Heterokontæ, have 
heen derived from the Yan Yean Reservoir by the overflow of the waters 
during times of heavy rain. Species of the genus Ophiocytium thrive in 
pools which become stagnant and foul in hot weather. They appear to 
flourish best where there is little aëration of the water *. The dominant 
species of the pools were Ulothrix idiospora and the small form of Tribonema 
bombycina, 
SMALL POOLS IN RANA CREEK. 
The collections were made in September 1907, and the dominating Algæ 
were Zyynema sp. (sterile ; filaments very thick) and Chetophora elegans, 
(Roth) Ag. The others noticed were Volvow globator, (L.) Ehrenb., Chara- 
cium tenue, Herm., Navicula bicapitata, Lagerst., М. radiosa, Kütz., var. acuta, 
(№. 8m.) Van Heurck, Gomphonema gracile, Ehrenb., and its var. dichotomum, 
(Kütz.) Van Heurck, Nitzschia Palea, (IKütz.) М. Sm., and Chanuresiphon con- 
fervicola, А. Br. The latter was attached thickly to the leaves of Myriophyllum. 
Poors IN OTTELIA CREEK. 
Two pools of very different character were examined in September 1907. 
The first one was a stagnant pool dominated by Tribonema bombycina, ( Ag.) 
Derb. A Sol., forma minor, Ophioeytium parvulum, (Perty) А. Br., O. capitatum, 
Wolle, and Wicrothamnion Niitzingianum, Мао, The two species of Ophio- 
cytium are well-known inhabitants of small stagnant pools; Tribonema 
bombycina Ё. minor thrives best in water which is fairly well aërated, but also 
often occurs in stagnant pools; JAMierothamnion Aiitzingianum generally 
occurs in small pools, not necessarily stagnant, and it is a decided vernal 
type. In the British Islands it is seen at its best in April and Мау. Among 
the species mentioned were small quantities of the following :— 
Chlorophycee.—Ocdogoninm sp. (with developing oogonia), Oe. crypto- 
porum, Wittr., Zyguema sp. (sterile), Spirogyra quadrata, (Hass.) Petit (in 
the fruiting condition), Closterium Venus, Kütz., Pleuroteæeniunm truncatum, 
(Bréb.) Nüg., Celastrum spherieum, Niig., Ankistrodesmus falcatus, (Corda; 
Ralfs. 
Bacillarieæ.— Гилойа lunaris, (Ehrenb.) Grun., Navicula bicapitata, 
* Consult also F. 1. Fritsch in Ann, Bot. xxi, (1907) pp. 256 & 257; Fritsch gives a 
summary of the records of OpAiocytium (up to 1906) in tropical pools. 
