CHYTRIDIALES 291 



spore sessile, spherical or subspherical, 10 [j. in diameter, with a thick 

 wall covered with somewhat long colorless stout spines, contents coarse- 

 ly granular, yellowish, with a large oil globule, germination not ob- 

 served. 



Parasitic on Glenodinium cinctum, France. 



There is some question as to the method of zoospore discharge in 

 this species. Fischer and Minden have considered it to occur inoper- 

 culately and have placed the organism in Rhizophydium. Dangeard 

 says of the discharge that the "... partie terminate du sporange 

 s'enlevanten forme de calotte pour la sortie des zoospores." Though 

 the word "opercule" is not used here, he clearly states that the top 

 of the sporangium is lifted up by the emerging spores, and the sharply 

 defined reflexed rim of the open sporangium gives additional evidence 

 that such has been the case. In contrast to those of most species of 

 Chytridium, however, the resting spores — if indeed they belong to the 

 fungus — are epibiotic, as in Zygorhizidium, but, unlike those of Zygor- 

 hizidium, they are apparently asexually formed. 



Possibly belonging in Phlyctidium or Chytriomyces. 



Rhizophydium ovatum Couch 

 Mycologia, 27: 168, figs. 28-55. 1935 

 (Fig. 4 B-F, p. 72) 

 Sporangium sessile, obpyriform or obovoid, broadest in the distal 

 half, with a broad apical papilla, 8.4-16.8 by 16-30 [jl (mostly 13 by 

 20-25 p.), wall fairly thin, smooth, colorless; rhizoid (possibly two) 

 very short and delicate, arising from a minute bulbous main axis; 

 zoospores (gametes?) somewhat ovoid, 3 by 4 [x, with a large colorless 

 eccentric oil globule and a long flagellum, emerging with great rapidity 

 through an apical pore formed upon the deliquescence of the papilla 

 and swimming away; resting spore spherical, 5.4-9.6 \x (mostly 8.4 p.) 

 in diameter, v/ith a slightly thickened smooth colorless wall and a 

 large slightly eccentric colorless globule, sexually formed, the motile 

 female gamete coming to rest and encysting on the upper surface of 

 an undeveloped spherical (3.6-5 \x in diameter), subspherical, or ovoid 

 (5.4-9.6 \x in diameter) male thallus, which is provided endobiotically 



