500 AQUATIC PHYCOMYCETES 



p. 260). Whether or not the fungus found by Pringsheim (reported in 

 Braun, 1856a: 33, pi. 2, figs. 9-11) on Stigeoclonium was a Chytridium 

 or a Rhizophydium cannot now be determined, since no discharge of 

 the zoospores was observed. 



Chytridium microcystidis Rohde and Skuja 

 Symbolae Bot. Upsalienses, 9 (3): 382, pi. 39, figs. 26-27. 1948 



Sporangium sessile on the colonial sheath of the host, erect or some- 

 what tilted, ovoid or obpyriform, becoming urceolate after discharge, 

 with a prominent broad apical papilla surmounted by a strongly convex 

 operculum, 13-23 \x long by 8-12 \i in diameter, with a delicate system 

 of simple or branched rhizoids which emerge from one or several places 

 on the base which is in contact with the colonial sheath of the host; 

 zoospores spherical or ovate, about 3 \x in diameter, with an eccentric, 

 hyaline colorless globule and long flagellum, escaping after dehiscence 

 of the operculum ; resting spore not observed. 



Parasitic in Microcystis aeruginosa, M. viridis, M.flos-aquae, Sweden. 



Said to be similar to Chytridium papillatum Sparrow but to differ in 

 being larger and in having the rhizoids develop from several places on 

 the base of the sporangium. 



In general appearance and rhizoid origin, this fungus recalls a species 

 of Rhizophlyctis. The species is placed next to Chytridium papillatum 

 (even though the technical description states the sporangium is some- 

 times obpyriform), because of the remarks of the authors. 



Chytridium rhizophydii Karling 

 Mycologia. 40: 333, figs. 1 1-20. 1948 



"Sporangia hyaline, smooth, elongatelycitriform or obpyriform, 10-18 

 [A x 22-32 ;jL, oval, 8-16 x 12-22 u, or elongate; operculum persistent, 

 shallow saucer-shaped, 8-15 \x diam. Zoospores spherical, 2-2.8 \i, 

 with a minute hyaline refractive globule; flagellum 12-14 u. long. 

 Rhizoids unbranched, tapering and needle-like or finely branched, 

 4-10 \l long. Resting spores unknown" (Karling, he. cit.). 



Parasitic on Rhizophydium nodulosum, United States. 



The fungus appeared to be restricted to Rhizophydium and did not 



