POLYEDRIUM. 1 83 



h. Var. GIGAS, Kg. Chlorococcum gigas, Eab. 



Cells green, mucous, globose, large, either single or 

 associated in small families, always involved in a broad, 

 more or less lamellose, hyaline, tegument. 



Diameter of cells, without the hyaline membrane, 12-18 //. 

 Frequent in small ponds. 



Plate CLXI, fig. 4, single cells without tegument; figs. 

 5-11, cells divided into two ; redivided into four or eight 

 cells in a wide tegument ; fig. 12, four cells dividing ; fig. 

 13, a large tegument with sixteen cells, each redivided into 

 four. 



i. Var. WIMMERI. Chlorococcum Wimmeri, Eab. 



Cells single, globose with rather thick membrane, often 

 lamellate, colorless ; contents of cells often yellowish red ; 

 primarily green. 



Diameter of cells, 45-55 ^. 



Occurs occasionally in stagnant waters. Not a normal 

 condition ; only another phase of the polymorphous forms 

 of the present genus. 



Plate CLXI, figs. 14-20, two of the cells dividing. 



j: YESTITUS. Pleurococcus vestitus, Eeinsch. 



Cells solitary or in small loose families; green, or later 

 orange yellow ; cell membrane thick, densely invested with 

 small hairs, or spines. 



Diameter of cells, 12-22 ju. 

 Not rare in ponds. 



Syn. Acanthococcus vestitus, Lagh. 



Plate CLXII, fig. 1, a cluster of cells of this form. 



Genus 50, POLYEDEIUM, Naeg. 



Cells single, segregate, free swimming, compressed, 3-4-8 

 angled ; angles more or less produced, sometimes radially elon- 

 gated, either entire or bifid, mostly armed, rounded or rather 

 truncate at the ends. Cell membrane thin, even. Cell contents 

 green, mostly granular, sometimes with one to four reddish oil 

 drops. 



Propagation by means of gonidia, of which usually three or 

 more are formed in a maternal cell ; they escape through a 

 fissure in the membrane. 



