266 



176 (i7S) 



177 (170) 



178 (179) 



179 (178) 

 j8o (169) 



181 (186) 



182 (i8s) 



183 (184) 



184 (183) 



FRESH-WATER BIOLOGY 



Elongate, spindle-shaped; chroma tophores two, ribbon-shaped; 

 eye-spot obscure. , Chlorangium Stein. 



Representative species. 



Chlorangium stentorinum Ehrenberg 1838. 



Flagella terminal, subequal. Attached during the sedentary stage by a 

 short, thick pedicel, singly or in groups up to ten or twelve zooids. Length 

 24 ju. Pond water, often attached to various Entomostraca. 



Fig. 443. Chlorangium stentorinum. X 37s. (After Stein.) 



Cuticle separated from body mass. . .178 



Cuticle smooth. Raemotococcus Agardh. 



Cuticle rough. Coccomonas Stein. 



Forming colonies. . 181 



Colonies plate-like with flagella upon one face only. . . . 182 



Colonies in a four-sided plate with envelop closely adherent. 

 Cells four or sixteen. , Gonium Miiller . . 183 



Four cells. 

 Sixteen cells. 



Gonium sociale Dujardin 1838. 

 Gonium pectorale Miiller 1773. 



In this species each of the sixteen cells of the colony produces a 

 daughter colony of sixteen cells. As the daughter colonies develop, a 

 secondary shifting of the cells takes place resulting in individuals of 

 the adult colonies lying in one plane. 



Fig. 444. Gonium pectorale. X 350. (After Stein.) 



185 (182) Colonies in a rounded plate with envelop swollen, oval, or spherical. 



Stephanosphaera Cohn. 

 Representative species. . . Stephanosphaera pluvialis Cohn 1853. 



Cells four or eight, ovoid or spindle-shaped, 

 with numerous processes. ' 



This form represents a transition from a 

 rosette arrangement of cells to a spherical 

 aggregate, the units being arranged in a 

 rosette but surrounded by a common gelati- 

 nous envelop. 



Fig. 445. Stephanosphaera pluvialis. .4, copula- 

 tion of gametes; B, spore formation; C, cells with 

 protoplasmic processes; Z), colony of eight cells. 

 A X 132s; B,C,DX 425- (After Hieronymus.) 



186 (181) Colonies spherical, ellipsoidal, or flattened, with flagella not confined 



to one face 187 



187 (190) Colonies with cells crowded together 188 



