HYPHOCHYTRIALES 757 



Because of the curious lack of a cross wall between the endobiotic 

 and epibiotic parts the sporangium is two-lobed. No cross walls were 

 noted separating the rhizoids from the apophysis. In thalli forming on 

 already infected cells of Chlamydomonas the rhizoids arose directly 

 from the base of the epibiotic part, no apophysis being developed. 

 This suggests that the apophysis possibly aided the immature parasite 

 in maintaining its position on the moving host. With chloriodide of 

 zinc the walls of the sporangium turned violet, the rhizoids, golden. 



RH1ZIDIOMYCOPSIS gen. nov. 1 



(Fig. 55 M, p. 752) 



Thallus monocentric, eucarpic, composed of an epibiotic part which 

 at maturity becomes converted into a sporangium, and an endobiotic 

 apophysis from which a branched rhizoidal system arises; sporangium 

 sessile, inoperculate, without a discharge tube; zoospores completely 

 delimited within the sporangium, emerging individually, somewhat 

 ovoid with several refractive globules and a single anterior fiagellum; 

 resting spore not observed. 



Parasitic on oogonia of water molds. 



The genus is erected to accommodate a Rlu'zidiomyces-like fungus in 

 which the zoospores are completely formed within the sporangium (not 

 outside as in Rhizidiomyces) and liberated through a pore. 



Rhizidiomycopsis japonicus (Kobayashi and Ookubo), comb. nov. 



Rhizidiomyces japonicus Kobayashi and Ookubo, Rept. Osegahara Gen. 

 Sci. Surv. Comm., 1954: 573, fig. 17. 1954. 



Sporangia gregarious, epibiotic, globose, 10-15 \i in diameter, with a 

 thin, smooth, hyaline wall, at maturity forming a sessile pore, without 



1 Rhizidiomycopsis, gen. nov. Thallus monocentricus, eucarpicus divisus in partes 

 duas, primam partem epibioticam maturitate in sporangium transformatam alteram 

 partem endobioticam (vel apophysin), ramosam, ramis rhizoidalibus. Sporangium 

 sessile, exoperculatum et sine tubo efferenti. Zoosporae separatim maturantes in 

 sporangio et singulatim dispersae, ovoideae, globulis refractivis pluribus et flagello 

 uno anteriori praeditae. Sporae perdurantes nondum visae. 



Parasiticus in oogoniis mycetum aquaticorum. 



Species typica Rhizidiomycopsis japonicus. 



