520 AQUATIC PHYCOMYCETES 



Zoosporangia broadly obovoid, with the half-spherical rounded top 

 somewhat expanded laterally, tapering basally, mostly 6-10 \x. high by 

 5-6 [x thick, larger specimens more oblong to obpyriform, up to 10 fi. 

 by 6 [i, with a delicate smooth colorless wall, often asymmetrical when 

 several occur on the same host cell, the lower part being one-sidedly 

 expanded and appearing inclined to the substratum, operculum strongly 

 convex, usually persistent, 2-4 [jl in diameter; endobiotic part a subspo- 

 rangial spherical apophysis 4 [j. in diameter, without rhizoids, often con- 

 taining a large oil globule; zoospores emerging individually through a 

 large apical opening, body spherical (2-3 [i in diameter), with a colorless 

 eccentric globule and a single flagellum; resting spore not observed. 



On Characiopsis minuta (?) (in plankton), ScherfTel (loc. cit.), Hunga- 

 ry. 



The fungus reported in Oedogonium from England by Sparrow as 

 Chytridium schenkii (1936a: 431, pi. 15, figs. 15-16) may possibly belong 

 here. It differs in having larger sporangia and a larger apophysis provid- 

 ed with rhizoids; endobiotic smooth-walled resting spores were found 

 associated with the zoosporangia. 



Chytridium inflatum Sparrow 



Amer. J. Bot., 20: 65. text fig. 1 j-1. 1933 

 (Fig. 31 I, p. 496) 



Sporangium sessile, broadly pyriform or urn-shaped, with a promi- 

 nent apical papilla surmounted by a strongly convex operculum, wall 

 smooth, colorless; endobiotic part consisting of a spherical subspo- 

 rangial apophysis apparently devoid of rhizoids; zoospores fully formed 

 within the sporangium, uniflagellate, spherical, with a single centric 

 colorless globule, upon the dehiscence of the operculum emerging and 

 forming a temporary group with intertwined flagella before darting 

 away, movement hopping; resting spore not observed. 



Parasitic on Cladophora sp., Sparrow (loc. cit.), United States; 

 Oedogonium sp., Sparrow (1936a: 437, pi. 15, fig. 19), Great Britain. 



Two well-defined size classes were found: 



1. Sporangium 15 a in diameter by 17 u high: apophysis 9 a in dium- 



