112 HANDBOOK OF PROTOZOOLOGY 



eight individuals arranged in a ring. Flagella upon one face 

 only. Individuals are pyriform with several processes. Asexual 

 reproduction and isogamy. Fresh water. 



Stephana sphaer a pluvialis Cohn (Fig. 38, /). Diameter 30 

 to 60 microns. Fresh water. 



Genus Pandorina Bory. Spherical or subspherical colony of 

 usually sixteen (sometimes eight or thirty-two) biflagellate 

 individuals which are closely packed within a gelatinous, but 

 firm and thick matrix. Individuals are often angular. With 

 stigma and chromatophores. Asexual reproduction through 

 simultaneous division of each of the individuals. Anisogamy is 

 preceded by division of each cell into 16 to 32 gametes. The 

 zygotes are colored and covered by a smooth wall. 



Pandorina morum (Miiller) (Fig. 38, g, h). Individuals 8 to 

 15 microns long. Colony 20 to 40 microns in diameter. Common 

 in ponds and ditches. 



Genus Eudorina Ehrenberg. Spherical or ellipsoidal colony 

 of usually 32 or sometimes 16 spherical cells. The cells are 

 widely separated from one another and arranged along the 

 periphery. Four at each pole and three groups of eight in be- 

 tween. Each cell is similar to that of Chlamydomonas. Asexual 

 reproduction is similar to that of Pandorina. Isogamy. Macro- 

 gametes green spherical bodies, 32 to 64 in number; microga- 

 metes are numerous and occur in bundles. The reddish zygote 

 possesses a smooth wall. 



Eudorina elegans Ehrenberg (Fig. 39, a). In ponds, ditches 

 and lakes. 



Genus Pleodorina Shaw. Somewhat similar to Eudorina, 

 being composed of 32, 64 or 128 ovoid or spherical cells. The 

 cells are of two types: small somatic and large generative, 

 and are located within a gelatinous matrix. 



Pleodorina illinoisensis Kofoid (Fig. 39, h). Thirty-two 

 cells: 4 vegetative and 28 reproductive individuals. They are 

 arranged in five circles: 4 in each polar circle, 8 at the equator 

 and 8 on either side of the equator. Four small vegetative cells 

 are at the anterior pole. Colony 100 to 140 microns long by 84 

 to 102 microns wide. 



Pleodorina calif ornica Shaw. 64 or 128 cells, of which from 

 one-half to two-thirds are reproductive cells. 



