MASTIGOPHORA, CHRYSOMONADINA 265 



Genus Uroglena Ehrenberg. Spherical or ovoidal colon}', com- 

 posed of ovoid or ellipsoidal individuals arranged on periphery of a 

 gelatinous mass; all individuals connected with one another by 

 gelatinous processes running inward and meeting at a point; with a 

 stigma and a plate-like chromatophore; asexual reproduction of 

 individuals by longitudinal fission, that of colony by bipartition; 

 cysts spherical with spinous projections, and a long tubular process; 

 fresh water. One species. 



U. volvox E. (Fig. 108, c). Cells 12-20/* by 8-13/*; colony 40-400/* 

 in diameter; in standing water. 



Genus Uroglenopsis Lemmermann. Similar to Uroglena, but 

 individuals without inner connecting processes. 



U. americana (Calkins) (Fig. 108, d). Each cell with one chro- 

 matophore; 5-8/* long; flagellum up to 32/* long; colony up to 300/* 

 in diameter; when present in abundance, the organism gives an of- 

 fensive odor to the water (Calkins). Morphology, development 

 (Troitzkaja, 1924). 



U. europaea Pascher. Similar to the last-named species; but 

 chromatophores 2; cells up to 7/* long; colon y 150-300/* in diameter. 



Genus Cyclonexis Stokes. Wheel-like colony, composed of 10-20 

 wedge-shaped individuals; young colony funnel-shaped; chromato- 

 phores 2, lateral; no stigma; reproduction and encystment unknown ; 

 fresh water. 



C. annularis S. (Fig. 108, e). Cells 11-14/* long; colony 25-30/* in 

 diameter; in marshy water with sphagnum. 



Genus Dinobryon Ehrenberg. Solitary or colonial; individuals 

 with vase-like, hyaline, but sometimes, yellowish cellulose test, 

 drawn out at its base; elongated and attached to the base of test 

 with its attenuated posterior tip; 1-2 lateral chromatophores; 

 usually with a stigma; asexual reproduction by binary fission; one 

 of the daughter individuals leaving test as a swarmer, to form a new 

 one; in colonial forms daughter individuals remain attached to the 

 inner margin of aperture of parent tests and there secrete new tests; 

 encystment common; the spherical cysts possess a short process; 

 Ahlstrom (1937) studied variability of North American species and 

 found the organisms occur more commonly in alkaline regions than 

 elsewhere; fresh water. Numerous species. 



D. sertularia E. (Fig. 108,/). 23-43/* by 10-14/*. 



D. divergens Imhof. 26-65/* long; great variation in different lo- 

 calities. 



Genus Hyalobryon Lauterborn. Solitary or colonial; individual 

 body structure similar to that of Dinobryon; lorica in some cases 



