40 DR. б. S. WEST ON THE ALGÆ OF 
А small collection from amongst wet mosses on the Wallaby watershed 
yielded the following :—Mougeotia sp., Netrium Digitus, (Ehrenb.) Ttzigs. & 
Rothe, Navicula viridis, Kütz., N. bicapitata, Lagerst., Vanheurckia rhom- 
boides, (Ehrenb.) Bréb.. Г. ма, Bréb., Achnanthes coarctata, Bréb,, 
Surirella linearis, W. Sm. 
SILVER CREEK WEIR. 
Samples of plankton were obtained both from the outlet and from alongside 
the stone embankment of the dam. As in the ease of the material collected 
from Wallaby Creek Weir, an enormous amount of decaying organic matter 
was present, amongst which were numerous sporangia of ferns and fragments 
of Bryophytes. The dominant algal constituent was Synedra Спе, and the 
following were also present in smaller quantity :— 
Chlorophycez.— Closterium prelongum, Bréb., forma brevior, West. 
Bacillarieæ.— Melosira granulata, Ralfs, Fwnotia major, (W. Sm.) Rabenh., 
ar. bidens, (Greg.) Van Heurck, Tabellaria floceulosa, (Roth) Kütz., Navicula 
Brébissonii, Kütz., Vanheurckia rhomboides, (Ehrenb.) Bréb., Г. vulgaris, 
(Thw.) Van Heurck, Surirella robusta, Ehrenb., var, splendida, (Ehrenb.) 
Van Heurck, 5. linearis, W. Sm. 
Myxophycez.— Oscillatoria irrigua, Kütz. 
In the channel above the weir, Tribonema bombycinum forma minor occurred 
in quantity along with Synedra Ulna. 
The Wallaby and Silver Creek collections were made in July, 1907. 
IV. THE RELATIONS BETWEEN THE PLANKTON, BENTHOS, AND 
ALG.E OF THE DRAINAGE AREA. 
The phytoplankton of the Узи Yean Reservoir, т the thirteen months 
from Feb. 1905 to Feb. 1906, contained 104 species and 16 varieties, 
During the same period 206 species and 17 varieties were observed in the 
mierophytie benthos. Of these Algo, 79 species and 6 varieties were common 
to both plankton and benthos, and 23 species and 5 varieties were evelusively 
conjined to the plankton, Of the latter, the following species and varieties 
are true plankton-forms :— 
Closterium ` Kützingn, Cosmarium tortum forma trigona, Staurastrum 
muticum var. vietorieuse, ©. lævispinum var. subbrachiatim, S. patens var. 
planctonicum, S. paradoxum var. longipes, Pediastrum duplex var. clathratum, 
Closteriopsis longissima, Kirehneriella lunaris, Oocystis lacustris, O. parva, 
Lagerheimia splendens, Botryococeus Braunii, Melosira granulata var. spinosa, 
Rhizosolenia morsa, Gyrosigma elongatum var., Chroococeus limneticus var. 
subsalsus, and Dinobryon elongatum var. undulatum. 
Some species, although present in both the plankton and the benthos, are 
so much more abundaut in the former that they also must be regarded 
