110 BIOLOGY OF THE RICHMOND RIVER, 



A cell that is free, has far greater opportunities for growth than 

 one which forms part of a filament. 



Genus Pediastrum Meyen. 

 Pediastrum tetras var. integrum (Nag.). (PI. iii., f.26). 

 Coenob. long. 26, lat. 20; cell. viv. lat. 12, alt. 10 /x. 

 Lismore(13). 



In company with minute forms of P. tetras. This specimen was, 

 originally, evidently a coenobium of P. tetras of the 7 + 1 type 

 The central cell and four of the peripheral cells have died, but the 

 outer ones still retain the size and shape of the cells of P. tetras. 

 The three living cells plainly belong to P. integrum Nag. It is 

 evident, therefore, that the cells of a coenobium are in a state of 

 growth, and that the peripheral cells develop from one form to 

 another. 



Pediastrum Boryanum var. capitatum, n.var. (PI. iii., f.27). 



Cellulse exteriores ad cornua extrema globulis singulis in- 

 structse. 



Cell. diam. 32; alt. centr. 20, c. corn. 36; diam. corn ap. 3, 

 globul. 7-8 ix. 



Lismore(15). 



Genus Kirchneriella Schm. 

 Kirchneriella lunaris (Kirchn.) Mobius. 

 Cell. diam. 7, crass. 2 /x. 



Var. approximata, n.var. (PI. iii., f.28). 

 Cellulae crassae; apicibus acutis approximatis, lateribus interiori- 

 bus parallelis. 



Fam. (8 coenob., 8 cell.) diam. 80; coenob. 25, cell. long. 1 1, lat. 

 10, crass. 5 fx. 

 Lismore(ll). 



Var. aperta (Toiling). (PI. iii., f.29). 

 Cellulae crassae; apicibus aeuminatis non autem acutis, lateribus 

 interioribus planis, divergentibus. 



