THE YAN YEAN RESERVOIR, VICTORIA. | 63 
straighter apex than in the type. The ventral part of the body of the semi- 
cel] is also much less developed. 
It is interesting. to note that a stout northern variety of this species 
(var. grænlandieum, Bürgesen) occurs in the plankton of certain lakes in 
Seotland and in the Faeroé Is. 
29. Cosmartum Murray, Playfair, in Proc. Linn. Soc. №. S. Wales, xxxii. 
part i. (1907) p. 195, t. 5. fig. 19. 
The specimens of this Desmid observed from Victoria were not in strict 
agreement with either the description or figure given by Playfair. The sinus 
was rather deeper, and the projeeting apex, although widely truncate, 
possessed somewhat rounder angles and a pair of minute median undulations. 
From the vertical view the semicells were broadly elliptic, and every indi- 
vidual showed а very small, somewhat faint protuberance at the middle on 
each side. This minute protuberance is situated nearer the apex than the 
base of the semicell and is rather more evident in the side view. Тһе basal 
angles of the semicells are also slightly thickened and projecting, a fact which 
although faintly indicated in Playfair's figure, is omitted from his description. 
Long. 20-21 р; lat. 17-18 ш; lat. isthm. 5p ; crass. 10w. (PI. 4. fig. 5.) 
Наб. Yan Yean Reservoir, among weeds at the margin (Nov. 1905). 
- 30. CosMARIUM QUADRATULUM, (F. Gay) Де Toni, Syll. Alg. (1889) p. 934. 
—Euastrum quadratulum, F. Gay, Monogr. loc. Соп). Montpellier (1884), 
p. 58, t. 1. fig. 15. 
Long. 12:5-14:5 р; lat. 112-1277 р; lat. isthm. 8-84 p. (PI. 4. fig. 12.) 
Hab. Yan Yean Reservoir, at the weedy margins (Nov. 1905 to Jan. 1906; 
abundant). 
This minute Desmid was observed in great abundance, and as its characters 
were remarkably constant I think it is best retained as a species. The some- 
what peculiar angularity of the semicells and the widely retuse apices are 
features which at once distinguish it from C. norimbergense or any of the 
forms of C. Meneglinii, 
31. COSMARIUM TRACHYPLEURUM, Lund. in Act. В. Soc. Sci. Upsal. ser. 3, 
viii. (1871) p. 27, t. 2. fig. 12. 
Var. sUBGLABRUM, var. п. (Pl. 4. fig. 11.) 
Var. angulis basalibus semicellularum subrectangularibus, granulis in 
centro semicellularum nullis. 
Long. 46 ш ; lat. 40 р; lat. isthm. 144 ; crass. 23-24 p. 
Hab. Wallaby Creek Weir, in the plankton (July 1907). 
This variety differs from all other described forms of C. trachyplevrum in 
the entire absence of the central granules. 
