2N4 AQUATIC PHYCOMYCETES 



high by 5-9 u. in diameter, usually appearing tilted on the surface of 

 the host, wall thin, smooth, colorless; rhizoids extremely delicate, 

 feebly developed, arising from a short main axis; zoospores ovoid, 

 3 (j. long by 2 [jl in diameter, with a large colorless slightly eccentric 

 globule and a long flagellum, escaping through a broad pore formed 

 upon the dissolution of an apical, subapical, or occasionally lateral 

 papilla; resting spore spherical, 5-7 u. in diameter, wall thick, color- 

 less, moderately covered with short rodlike protuberances, resting 

 on the apex or side of the companion cell, germination not observed; 

 companion cell single (rarely two), spherical or turbinate, smooth- 

 walled, 2.5-3 \x in diameter, sessile or with a short extramatrical stalk, 

 rhizoid unbranched. 



Parasitic on Tribonema bombycina, Scherffel (/or. cit.), Hungary; 

 Sparrow (1939a: 124, pi. 2, figs. 14-25), United States. 



In the American material both conjugating thalli appeared to devel- 

 op on the host wall, although in two instances the receptive thallus 

 seemed to make contact only with the "male" plant. Once the "female" 

 alone was attached to the algal cell. It was observed that the charac- 

 teristic spines appeared on the receptive thallus soon after fertilization 

 and before thickening of the wall had been initiated. 



Rhizophydium verrucosum Cejp 



Bull. Internat. Acad. Sci. Boheme, 42 (3): 4, pi. 1, figs. 9-10, pi. 2, fig. 2. 



1933 (separate) 



Sporangium sessile, narrowly pyriform or ovoid, almost citriform, 

 14-22 by 32-41 u. (high?), wall stout, its outer surface densely covered 

 by warts, with a prolonged slightly curved smooth apiculus (papilla?) 

 12 y. long by 7 [jl in diameter; rhizoidal system delicate, composed of 

 short branches; zoospores spherical, 2-3 [jl in diameter, with a single 

 globule, uniflagellate, undergoing a period of rest (outside?) before 

 swarming; resting spore subspherical, rarely irregular, 25-30 jx in diam- 

 eter, with a thick wall covered with coarse warts, contents with num- 

 erous oil globules, rhizoids not observed, germination not observed. 



On Closterium sp., Germany. 



