THE VICTORIAN NATURALIST. 71 



Length, 132 ^i ; breadtli (maximum), 112 ;u; breadth of polar 

 lobe, 65 ^ ; breadth of isthmus, 19 n. Fig. 4. 



Habitat. — Whanregarwen, Victoria; in lagoon of the Upper 

 Goulburn River. 



The great reduction of the inferior lateral lobules gives this 

 variety a somewhat peculiar aspect. 



MiCRASTERIAS HARDYI, Sp. n. (G. S. WeSt). 



Cells moderately large, a little longer than broad, very deeply 

 constricted, sinus widely opened and acute angled, at the 

 extremity very narrow, semi-cells 3-lobed ; polar lobe large and 

 slightly extended, inferior part narrow, with sub-parallel margins, 

 within each of which is a series of about 7 small teeth, apex with 

 2 emarginate warts and with two small, short, emarginate 

 processes disposed asymmetrically, angles produced into long 

 denticulate, upwardly diverging processes ; lateral lobes pro- 

 foundly bi-lobulate, lobules large, elongate, denticulate, and 

 diverging ; apices of lobules and of processes of polar lobe 

 quadridentate ; with a series of minute teeth within the lateral 

 lobules and the processes of the polar lobe. 



Length, 200-220 /.i ; breadth, 163-202 }.i ; breadth of isthmus, 



16.5-17.5 A*- Fig- I- 



Habitat. — Yan Yean Reservoir, Victoria ; abundant in the 

 plankton. 



This species belongs to the section of Micrasterias, in which 

 the polar lobe is furnished with accessory processes. It is, 

 however, at once distinguished from the species of this section, 

 such as M. amerlcaua, M. mahabuleshwarensis, &c., by the great 

 length and divergence of the lateral lobules and of the processes 

 of the polar lobe. There is at the same time a great reduction 

 of the two accessory asymmetrical processes of the polar lobe. 



CoSMARiUM TORTUM, Lagerh. et Nordst. in Wittr., Nord. et 



Lagerh. Alg. Exsic, No. 1,486, 1903 ; Jascicuhts 35, p. 



16, 17 {cum fig.); forma triyona (G. S. West). 



Cells from the vertical view rounded trigonal, angles very 



slightly produced (sub-mamillate) ; cell wall very delicately 



punctate. 



Length, 21-24 A' ; breadth, 15-16 ^ ; breadth of isthmus, 10 /<. 

 Habitat. — Yan Yean Reservoir, Victoria ; very abundant in the 

 plankton. 



CoSMARiUM CAPITULUM, Roy and Biss. in Journ. Rot., 1886, 

 p. 195, t. 268, f. 9; var. australe, var. n. (G. S. ^Vest). 



Lower margin of semi-cells less convex ; capitulate angles 

 slightly upwardly divergent. 



Length, 16-19 ^t J breadth, 20-23 /" J breadth of isthmus, 5.5-6 ytt; 

 thickness, 8.5-9 ^. 



