CHYTRIDIALES 577 



colored oil globule, emerging in a spherical mass and remaining quies- 

 cent at the mouth of the exit papilla for several seconds before swim- 

 ming away. Resting spores unknown" (Whiffen, loc. cit.). 



Saprophytic on grass leaves, Whiffen {loc. cit.), Karling (1941a: 387; 

 1942c: 620), United States. 



CYLINDROCHYTRIDIUM Karling 



Bull. Torrey Bot. Club, 68: 382. 1941 

 (Fig. 32 G, p. 554) 



Siphonochytrium Couch, nom. nud., J. Elisha Mitchell Sci. Soc. 55: 208. 

 1939. 



"Thallus monocentric and eucarpic. Zoosporangia usually stalked 

 and cylindrical, occasionally sessile, operculate. Zoospores posteriorly 

 uniflagellate, emerging fully formed and lying quiescent in a globular 

 mass at the orifice of the sporangium for a few minutes before swimming 

 away. Rhizoidal system extensive, branched with numerous catenulate 

 spindle-shaped swellings. Resting spores unknown" (Karling, loc. cit.). 



Saprophytes in vegetable debris. 



Although not mentioned in his diagnosis, Karling (1945c: 367) later, 

 in differentiating Rhopalophlyctis from the present genus, noted that 

 Cylindrochytridium is usually intramatrical, whereas Rhopalophlyctis is 

 extramatrical, save for the rhizoids. 



Whiffen (1941b: 324, pi. 8, fig. 13) points out that Siphonochytrium 

 Couch, which is undescribed, is Cylindrochytridium johnstonii. 



Cylindrochytridium johnstonii Karling 



Bull. Torrey Bot. Club, 68: 383, figs. 1-16. 1941 



"Zoosporangia hyaline, smooth, thin-walled, usually tubular, cylin- 

 drical or slightly clavate, 12-25 \x 30-800 \x, occasionally oval, pyri- 

 form and sessile; stalk or basal portion usually of the same shape and 

 diameter as the sporangium, but sometimes inflated, vesicular, irregular 

 and apophysis-like. Operculum oval, ellipsoidal, 4x6 [i-S x 10 [x, 

 spherical, 4-17 u.; remaining attached to the sporangium or lying loose 

 nearby. Zoospores spherical, 5.6-7 \l, with a large highly refractive 

 globule; flagellum 22-26 u. long. Rhizoidal system arising from one to 



