288 



PROTOZOOLOGY 



flagellate cells, arranged in 2 alternating rows on equatorial plane; 

 fresh water. 



S. askenasii S. (Fig. 117, a). 16 individuals in ellipsoidal colony; 

 cells 9/x in diameter; flagella up to 30/t long; colony 78/* by 60/z- 



Genus Platydorina Kofoid. 32 cells arranged in a slightly twisted 

 plane; flagella directed alternately to both sides; dioecious; fresh 

 water. 



P. caudata K. (Fig. 117, b). Individual cells 10-15/t long; colony 

 up to 165m long by 145ju wide, and 25/u thick; dioecious; anisogamy; 

 macrogametes escape from female colonies and remain attached to 



Fig. 116. a, Gonium sociale, X270 CChodat); b, G. pec- 

 torale, X670 CHartmann). 



them or swim about until fertilized by microgametes; zygotes be- 

 come thickly walled (Taft, 1940). 



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. 117, c). Cells 12-26/x by 8-15/i; colony 

 up to 60ju long. 



Genus Chlamydobotrys Korschikoff. Colony composed of 8 or 16 

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

 pyrenoid; fresh water. Species (Pascher, 1925); culture (Schulze, 

 1927). 



C. stellata K. (Fig. 117, d). Colony composed of 8 individuals 

 arranged in 2 rings; individuals 14-15m long; colony 30-40/1 in 

 diameter; Maryland (Bold, 1933). 



