214 



rilOTOZOOLOGY 

 b c 



Fig. 98. a, Gonyostomum semen, X540 (Stein); b, Vacuolaria vires- 

 cens, X460 (Senn); c, Trentonia flagellata, X330 (Stokes); d, Thau- 

 matomastrix setifera, X830 (Lauterborn), 



well known. The majority possess small discoidal grass-green 

 chromatophores with a large amount of xanthophyll which on 

 addition of an acid become blue-green. No pyrenoids occur. The 

 metabolic products are fatty oil. Starch or allied carbohydrates 

 are absent. Stigma is also not present. 



Genus Gonyostomum Diesing (Rhaphidomonas Stein). With 

 grass-green chromatophores; highly refractile trichocyst-like 

 structures in cytoplasm; in fresh water. A few species. 



G. semen D. (Fig. 98, a). Sluggish animal; about 45-60ju long; 

 in marshy water among decaying vegetation. 



Genus Vacuolaria Cienkowski. Highly plastic; without tricho- 

 cyst-like structures; anterior end narrow; with 2 flagella; cysts 

 with a gelatinous envelope. One species. 



V. virescens C. (Fig. 98, h). About 50-150m long; fresh water. 



Genus Trentonia Stokes. Bi-flagellate as in the last genus; but 

 flattened; anterior margin slightly bilobed. One species. 



T. flagellata S. (Fig. 98, c). Slow-moving organism; encystment 

 followed by binary fission; about 60^1 long; fresh water. 



Genus Thaumatomastix Lauterborn. Colorless; pseudopodia 

 formed; 2 flagella, one extended anteriorly, the other trailing; 

 holozoic; perhaps a transitional form between the Mastigophora 

 and the Sarcodina. One species. 



T. setifera L. (Fig. 98, d). About 20-35^ by 15-28m; fresh water. 



