266 FRESH-WATER BIOLOGY 



176 (175) 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 M. Pond water, often attached to various Entomostraca. 



FIG. 443. Chlorangium stentorinum. X 375. (After Stein.) 



177(170) Cuticle separated from body mass v .- . ; . . . 178 



178 (179) Cuticle smooth Haemotococcus Agardh. 



179 (178) Cuticle rough Coccomonas Stein. 



180 (169) Forming colonies 181 



181 (186) Colonies plate-like with flagella upon one face only. . . . . 182 



182 (185) Colonies in a four-sided plate with envelop closely adherent. 



Cells four or sixteen Gonium Muller . . 183 



183 (184) Four cells. . Gonium sociale Dujardin 1838. 



184(183) Sixteen cells Gonium pectorale Muller 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 plwoialis 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; D, colony of eight cells. 

 A X 1325; 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 



