CHYTRIDIALES 419 



Rhizidium elongatum Karling 

 Amer. J. Bot., 36: 683, figs. 27-48. 1949 



"Sporangia hyaline, smooth, rarely appendiculate, predominantly e- 

 longate (6-12 x 20-45 [x), irregular, pyriform (7-18 x 9-32 [x), oval, 

 rarely spherical (8-20 fx), with a single broad, 4-12 ;x diam. incon- 

 spicuous exit papilla. Zoospores slightly oval (4.8-5.2 x 5-6.2 y.), with 

 a spherical (1 .8-2.2 fx), hyaline refractive globule ; flagellum 28-32 jx long ; 

 usually swarming in a vesicle outside of the sporangium. Rhizoids 

 attached at base of sporangium, stiff or rigid-looking main axis up to 

 5 [i in diam., sparingly branched, and occasionally extending for a 

 distance of 200 fx. Resting spores unknown" (Karling, loc. cit.). 



Saprophytic on chitinous substrata, United States. 



This and the following species would seem better accommodated in 

 Rhizophlyctis. The frequent possession of more than one rhizoidal 

 axis and, in R. various, of more than one discharge pore argues for it. 



Rhizidium varians Karling 

 Amer. J. Bot., 36: 681, figs. 1-26. 1949 



"Thallus predominantly monocentric but often polycentric. Sporangia 

 hyaline, smooth, variable in shape, rarely apophysate, spherical (20-130 

 fx), broadly or narrowly pyriform (10-40 x 30-75 [x), oval (12-30 x 

 18-60 jx), citriform, clavate, elongate, or slightly irregular with 1-4 low 

 or prominent exit papillae or tapering necks, 5-7 ;x broad at base by 

 15-96 jx long, and filled with hyaline matrix. Zoospores spherical, 

 3.5-4 [x, with a spherical, 1.9-2.4 [x, hyaline refractive globule; swarming 

 in a vesicle outside of the sporangium. Rhizoids usually arising at base 

 of sporangium, but frequently from several points on its periphery, 

 coarse, main axes up to 17 [x in diam. at base, frequently branched and 

 extending for a distance of 500 [x. Resting spores predominantly spheri- 

 cal (8-22 [x), oval (10-15 x 12-18 ;x), with a smooth, 1.8-2.4 ;x, thick 

 wall, which becomes light brown with age, and filled with coarse, angu- 

 lar refractive bodies ; functioning as prosporangia in germination" (Kar- 

 ling, loc. cit.). 



Saprophytic in cellulosic substrates, United States. 



Both a Rhizidium-typQ and an Entophlyctis-type of development were 



