CHYTRIDIALES 409 



Sporangium elongate, saccate ; in slime of Chaetophora 



R. mycophilum, p. 409 



Sporangium spherical; in insect exuviae R. chitinophilum, p. 412 



Sporangium terminal on the rhizoidal axis 



Sporangium spherical, ellipsoidal, ovoid or pyriform 

 Sporangium wall smooth; zoospore globule colorless 

 Sporangium with one discharge pore 



On fresh-water algae or diatoms in salt pools 



On Haematococcus and resting cells of Chilomonas 



R. vorax, p. 413 

 On the planktonic alga Gemellicystis. R. windermerense, p. 414 



On diatoms in salt pools R. braunii, p. 414 



On insect exuviae and vegetable debris 



Sporangium spherical; on insect exuviae . R. ramosum, p. 415 

 Sporangium spherical, pyriform, ovoid or ellipsoidal; in 



slimy vegetable material R. nowakowskii, p. 416 



Sporangium with more than one discharge pore 



Resting-spore wall warty R. braziliensis, p. 417 



Resting-spore wall smooth R. laevis, p. 417 



Sporangium wall verrucose, light or reddish brown; zoospore 



globule reddish brown R. verrucosum, p. 418 



Sporangium distinctly elongate, somewhat pyriform, oval or 



irregular R. elongatum, p. 419 



Sporangium with a single rhizoidal axis but having a strong tendency 



to form several R. varians, p. 419 



Rhizidium mycophilum Braun 

 Monatsber. Berlin Akad., 1856: 591; Flora, 14: 599. 1856 



Sporangium elongate, saclike, arising laterally from near the apex of 

 the somewhat obovate, pyriform, or citriform expanded tip of the 

 rhizoidal axis, which it nearly equals in size; main rhizoidal axis 

 sometimes with lateral rhizoids, tapering distally and becoming divided 

 into delicate and repeatedly branched rhizoids; zoospores 5 u, or more 

 in diameter with a well-defined globule and long flagellum; resting 

 spore spherical, brownish, 16.5-20 [x in diameter, outer wall either 

 covered by thick protuberances or almost spiny; germination not 

 observed. 



In the gelatinous colonial envelope of Chaetophora, Germany. 



Rhizidium mycophilum is the type species of the genus. Our concept 



