578 AQUATIC PHYCOMYCETES 



several points on the base of the stalk, extending over a radius of 100- 

 1200 \x; spindle shaped swellings 8 x 12 jjl-20 x 30 [i, rarely lacking 

 entirely" (Karling, loc. cit.). 



Saprophytic in decaying vegetable debris, Karling (loc. cit.), onion 

 skin and bleached grass leaves, from moist soil, Karling (1942c: 621; 

 1948c: 509), cellulose, Couch (1939a: 212), Whiffen (1941b: 329, pi. 8, 

 fig. 13), R.M. Johns (comm.), Crasemann (1954), United States; cell- 

 ulose substratum, Shanor (1944: 331), Mexico. 



It is probably this fungus, not Macrochytrium, whose nutritional re- 

 quirements Crasemann (1954) determined. 



Shanor (loc. cit.) described the resting spores as nearly spherical, 

 tbick-walled, smooth, with light-brown or amber-colored walls, and 

 with a large yellow globule in the contents. 



TRUITTELLA Karling 



Amer. J. Bot., 36:454. 1949 



(Fig. 32 A, p. 554) 



"Thallus predominantly monocentric, eucarpic; sporangia, rhizoids 



and resting spores developing from the germ tube or an outgrowth of 



the zoospore; sporangia operculate, variable in size and shape; rhizoids 



usually arising at several points on the surface of the sporangium; 



resting spores formed by encystment of segments of the rhizoids" 



(Karling, loc. cit.). 



Saprophytes on cellulosic substrata. 



Resembling Catenochytridium but differing in that the rhizoids arise 

 from several places on the sporangium and the sporangium develops 

 from the tip of the germ tube of the zoospore and not from the body of 

 the spore. 



Truittella setifera Karling 



Amer. J. Bot.. 36: 455, figs. 1-44. 1949 



"Sporangia spherical (22-70 u.), oval (20-35 x 28-65 \i), angular, 



irregular or lobed with a smooth, hyaline to light brown, 1.8-2.3 \x, 



thick wall, and a low exit papilla; operculum saucer- or bowl-shaped, 



10-17 u. diam. Zoospores spherical (4.2-6 u.) with a conspicuous 



