72 THE VICTORIAN NATURALIST. 



Habitat. — Y din Yean Reservoir, Victoria ; common in the 

 plankton. 



The upwardly diverging angles of this variety give the semi-cells 

 a relatively straighter apex than in the type. The ventral part of 

 the body of tlie semi-cell is also much less developed. 



CosMARiUM HARDYi, sp. nov. (G. S. West). 



Cells of medium size, about i}i times longer than broad, 

 moderately constricted, sinus shortly linear, ampliated within and 

 widely open towards the e.xterior ; semi-cells sub-spherical, semi- 

 circular, apex very slightly truncate and smooth, lateral margins 

 and inferior angles broadly rounded and furnished with minute 

 granules, within the lateral margins and below the apex with two 

 or three irregular series of minute granules ; in the central part 

 of the semi-cells with crowded scrobiculations, occupying a 

 relatively large area, and disposed in oblique series. Side view 

 of semi-cell sub-spherical. Vertical view broadly elliptical, with a 

 very wide inflation on each side. 



Length, 85 /i ; breadth, 57 f.L ; breadth of isthmus, 21 ^ ; thick- 

 ness, 50 ^. 



Habitat.— Ya.n Yean Reservoir, Victoria, in the plankton. 



Staurastrum LyEvispiNUM, Bisset ; van subbrachiatum, var. n. 

 (G. S. West). 



Semi-cells with the processes narrower towards the base and 

 often emarginate-furcate at the apices. 



Length without processes 17. 18.5 /x, with processes 30-35^1*; 

 breadth 11-12 ^, with processes 30-32 /it; breadth of isthmus, 

 6.5-7 ^. 



Habitat. — Yan Yean Reservoir, Victoria, in the plankton. 



Staurastrum mucronatum, Ralfs ; var. delicatulum, var. n. 

 (G. S. West). 



Semi-cells elliptic-fusiform in outline, lateral angles sub-mamillate 

 and apiculate. 



Length, 32.5-35 fx ; breadth, 34-37 /x ; breadth of isthmus, 

 6-7 ^. 



Habitat. — Yan Yean Reservoir, Victoria, in the plankton. 



Staurastrum muticum, Breb. ; var. victoriense, var. n. (G. S. 

 West). 



Cells longer than in the typical form ; semi-cells broadly 

 elliptic ; cell wall delicately punctate. 



Length, 30 jx ; breadth, 20.5 /x ; breadth of isthmus, 7,5 /x. 



Habitat. — Yan Yean Reservoir, Victoria, in the plankton. 



Staurastrum nudibrachiatum, Borge in Arkiv for Botan. utgiv. 

 of K. Sv. Vet.-Akad. Bd. i, 1903, p. 109, t. 4, f. 20.; var. 

 victoriense, var. n. (G. S. West). 

 Semi-cells from the vertical view lo-radiate ; processes a little 



