PHYTOMONADINA 287 



colonies up to 600 m in diameter; 500-2000 cells; 2-12 gametes. 

 Europe and North America. 



V. spermatosphaera Powers (Fig. 115, f-h). Dioecious. Male colo- 

 nies up to 100m in diameter; cells, without connection, up to 128 

 microgametocytes. Female colonies up to 500 n in diameter; 6-16 

 macrogametes; zygotes 35-45/1, with smooth membrane. Partheno- 

 genetic colonies up to 650/x in diameter; 8-10 gametes; young colo- 

 nies ellipsoid, up to 100 ju in diameter. North America (Powers, 1908). 



V. weismannia P. (Fig. 115, i). Male colonies 100-150/z in diam- 

 eter; 250-500 cells; 6-50 microgametocytes; clusters of microgametes 

 (up to 128) discoid, 12-15/t in diameter. Female colonies up to 400/*; 

 2000-3000 cells; 8-24 macrogametes; zygotes 30-50ju in diameter, 

 with reticulate ridges on shell. Parthenogenetic colonies up to 400/z; 

 1500-3000 cells; 8 or 10 gametes; 40-60/x in diameter; young colonies 

 1 00-200 /x in diameter. North America (Powers, 1908). 



V. perglobator P. (Fig. 115, j, k). Dioecious. Male colonies 300- 

 450/x in diameter 5000-10,000 cells, with delicate cytoplasmic con- 

 nections; 60-80 microgametocytes. Female colonies 300-550/z in di- 

 ameter; 9000-13,000 cells; 50-120 macrogametes; zygotes 30-34/x, 

 covered with bluntly pointed spines. Parthenogenetic colonies as 

 large as 1.1 mm; three to nine gametes; young colonies 250-275/x in 

 diameter. North America. 



Genus Gonium Miiller. 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 reproduc- 

 tion through simultaneous divisions of component cells; sexual re- 

 production isogamy; zygotes reddish; fresh water. Colony formation 

 (Hartmann, 1924). 



G. sociale (Dujardin) (Fig. 116, a). 4 individuals form a discoid 

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

 lakes. 



G. pectorale M. (Fig. 116, b). 16 (rarely 4 or 8) individuals form a 

 colony; 4 cells in center; 12 peripheral, closely arranged; cells 5-14/x 

 by 10/x; colony up to 90/z in diameter; fresh water. 



G. /orraoswm Pascher. 16 cells in a colony further apart; peripheral 

 gelatinous envelope reduced; cells similar in size to those of G. so- 

 ciale but colony somewhat larger; freshwater lakes. 



Genus Stephanoon Schewiakoff. Spherical or ellipsoidal colony, 

 surrounded by gelatinous envelope, and composed of 8 or 16 bi- 



