218 AQUATIC PH YCOM YCETES 



conspicuous, apical or subapical exit papillae. Zoospores spherical 

 (2-2.9 ;jl) with a minute (0.5-0.8 [jl) refringent, hyaline globule; flagel- 

 1 n m 8-10 [x long. Rhizoid unbranched, usually thread-like or filament- 

 ous, up to 8 \x long and 0.8-1.2 u, in diameter, rarely knobbed at the 

 end, or peg-like. Resting spores doubtful" (Karling, loc. cit.). 



Parasitic on the sporangia, resting spores, rhizoids, and mycelium 

 of Rhizophydium keratinophilum, R. coronum, Rhizophlyctis rosea, Chy- 

 triomyces hyalinus, C. aureus, C. appendiculatus, Siphonaria variabilis, 

 Asterophlyctis sarcoptoides, Septochytrium variabile, Polychytrium ag- 

 gregation, Rhizidiomyces hirsutus, Thraustotheca clavata, Aphanomyces 

 sp., Achlya flagellata, Zoophagus insidious, and a species of Fungi 

 Imperfecti, United States. 



The species is remarkable for the wide range of hosts it will attack. 



Phlyctidium chlorogonii Serbinow 



Scripta Bot. Horti Univ. Imper. Petro., 24: 156, pi. 5, 

 figs. 11-17. 1907 



Phlyctidium acre Serbinow, nom. nud., Dnevnik IX Sezda Rusk. Est. 



i vz., 1901 (10): 474. 

 Rhizophydium chlorogonii Jaczewski, Opredelitel gribov.... I. Fikomit- 



sety, p. 38. 1931. 



Sporangium sessile, broadly and symmetrically pyriform, with a 

 rather small protruding apical papilla, 6-8 \x in diameter, wall thin, 

 smooth, colorless: haustorium an inconspicuous knoblike structure; 

 zoospores spherical, 1.5 u, in diameter, with a small colorless refractive 

 globule and flagellum, emerging individually by means of their own 

 motility through a small apical pore; resting spore not observed. 



On moribund and dead Chlorogonium euchlorum, Serbinow (be. 

 cit.), Russia(?); (?) Chlorogonium elongation, Scourfield (1936: 120, pi. 

 1), Great Britain. 



Scourfield's record is open to question, since the endobiotic part 

 (seen in one instance) was rhizoidal. 



The species was first mentioned in the minutes of the Ninth Con- 

 gress of Russian Naturalists and Physicians as Phlyctidium acre, but 

 for some reason the name P. chlorogonii was applied to it in the com- 

 plete description made later (1907) in Russian and German. The size 



