CHYTRIDIALES 215 



papilla, wall smooth, colorless, double-contoured, endobiotic part a 

 short distally expanded peg; zoospores at first spherical, later pyriform, 

 with a colorless globule and a long flagellum, 6.5 \x in diameter, en- 

 larging during swarming to 16.3 fj., moving within the sporangium 

 and escaping through a broad apical pore, surrounded by an evanes- 

 cent layer of slime; resting spore subspherical, 16.3-26 \x in diameter, 

 with a thick brownish outer wall and a thin wavy inner one, endobiotic 

 part like that of the sporangium, germination not observed. 



On vegetative cells and heterocysts of Anabaena flos-aquae, Russia. 



This species is based on the fungus misidentified by Raitschenko 

 (1902) as Rhizophydium sphaerocarpwn. 



The broad orifice of the discharge sporangium characteristically 

 bore remnants of the inner wall around its margin. Examples of inter- 

 nally proliferated sporangia were frequent. New sporangia were formed 

 in this "false proliferation," from a zoospore which had failed to emerge 

 or from a zoospore which had swum into an empty sporangium. The 

 remarkable increase in size and shape of the zoospore during motility 

 appears to be borne out by the figures, but confirmation of this unique 

 phenomenon is needed. 



Phlyctidium olla Sparrow 

 Mycologia, 25: 517, fig. 1, 14. 1933 



Sporangium sessile, urn-shaped, smooth-walled, 13-15 \l high by 

 1 5-1 7 u. in diameter, with a broad apical papilla; haustorium unbranch- 

 ed, inflated, tubular, about 2 jj. in diameter by about 12 \x long; 

 zoospores emerging through a broad pore after the deliquescence of 

 the papilla, ovoid, 5 \l long by 3 a in diameter, posteriorly uniflagel- 

 late, with a single globule; resting spore not observed. 



Parasitic on Spirogyra sp., United States. 



In its symmetrical urceolate sporangium this species resembles Rhi- 

 zophydium sphaerocarpwn (Zopf) Fischer. The inflated character of 

 the haustorium, however, distinguishes it as a species of Phlyctidium. 

 P. olla differs from P. megastomum primarily in the smaller size of 

 its sporangium (15-17 \x in diameter compared with 16-70 [x) and in 

 the long tubular rather than short clavate haustorium. If Raitschenko's 



