PHYTOMONADINA 199 



V. tertius Meyer. Dioecious; without cytoplasmic connections 

 in mature state; individuals about 7-8ai in diameter. 



Genus Gonium M tiller. 4 or 16 individuals arranged in one 

 plane; cell ovoid or slightly polygonal; with 2 flagella arranged in 

 the plane of coenobium; with or without a gelatinous envelope; 

 protoplasmic connections among individuals occur occasionally; 

 asexual reproduction through simultaneous divisions of com- 

 ponent cells; sexual reproduction isogamy; zygotes reddish; 

 fresh water. 



G. sociale (Dujardin) (Fig. 93, c). 4 individuals form a discoid 

 colony; cells 10-22/^ by 6-16ai wide; in open waters of ponds and 

 lakes. 



G. pectorale M. (Fig. 93, d). 16 (rarely 4 or 8) individuals form a 

 colony; 4 cells in center; 12 peripheral, closely arranged; cells 

 5-14^t by 10;u; colony up to 90/i in diameter; fresh water. 



G. formosiim Pascher (Fig. 93, e). 16 cells in a colony further 

 apart; peripheral gelatinous envelope reduced; cells similar in 

 size to those of G. sociale but colony somewhat larger: freshwater 

 lakes. 



Genus Stephanoon Schewiakoff . Spherical or ellipsoidal colony, 

 surrounded by gelatinous envelope, and composed of 8 or 16 

 biflagellate cells, arranged in 2 alternating rows on equatorial 

 plane; fresh water. 



S. askenasii S. (Fig. 94, a). 16 individuals in ellipsoidal colony; 

 cells dfx in diameter; flagella up to 30yu long; colony 78^ by 60/i. 



Genus Platydorina Kofoid. 32 cells arranged in a slightly 

 twisted plane; flagella directed alternately to both sides; fresh 

 water. 



P. caudata K. (Fig. 94, h). Individual cells lO-lSju long; colony 

 up to 165^1 long, 145yu wide, and 25^ thick; rivers and lakes. 



Genus Spondylomorum Ehrenberg. 16 cells in a compact group 

 in 4 transverse rings; each with 4 flagella; asexual reproduction 

 by simultaneous division of component cells; fresh water. One 

 species. 



S. quaternarium E. (Fig. 94, c). Cells 12-26^1 by 8-15At; colony 

 up to 60/i long. 



Genus Chlamydobotrys Korschikoff. Colony composed of 8 or 

 16 individuals; cells with 2 flagella; chromatophore; stigma; no 

 pyrenoid; fresh water. 



C. stellata K. (Fig. 94, d). Colony composed of 8 individuals 



