114 HANDBOOK OF PROTOZOOLOGY 



reproduction is anisogamy. The zygotes are usually brownish 

 red in color and their outer coverings may be smooth or spinous. 



Volvox glohator Leeuwenhoek (Fig. 39, c). Monoecious. 

 About 700 microns in diameter. Common in European waters. 



Volvox perglohator Powers. Dioecious. Diameter up to 1 

 mm. Common in American waters. 



Volvox aureus Ehrenberg (Figs. 25; 39, d). Dioecious. Cy- 

 toplasmic threads are relatively thin. Diameter 200 to 800 

 microns. 



Volvox spermatosphara Powers. Monoecious. Without any 

 cytoplasmic connections between the cells. Diameter up to 600 

 microns. 



Volvox tertiiis Meyer. Dioecious. Without cytoplasmic 

 connections in mature state. 



Family 4 Polytomidae Poche 



These are colorless saprozoic Phytomonadida. Reserve 

 amyloid material may occur. With two flagella located at the 

 anterior end. Body form resembles in general way that of 

 Chlamydomonas. 



Genus Polytoma Ehrenberg. Body ovoid ; colorless. Stigma 

 if present red or pale-colored. Saprozoic, but numerous starch 

 bodies are present in the posterior half of the body. Asexual 

 reproduction in the motile stage. Sexual reproduction is 

 isogamy. Zygotes are spherical, with a smooth wall. In in- 

 fusion or stagnant water. 



Polytoma uvella Ehrenberg (Fig. 39, e). Body oval to pyri- 

 form. Stigma may be absent. Widely distributed in water 

 containing decaying organic substances. 



Genus Parapolytoma Jameson. Anterior margin obliquely 

 truncated, resembling a cryptomonad, but colorless. Stigma 

 and starch absent. Division into four individuals within the 

 envelope occurs. 



Parapolytoma satura Jameson (Fig. 39,/). In fresh water. 

 About 15 microns long. 



Family 5 Phacotidae Poche 



The thick shell is typically composed of two valves. Two 

 flagella protrude from the anterior end. Stigma and chromato- 



