CHYTRIDIALES 167 



Environment and age of the host, no doubt, will also have some in- 

 fluence on whether or not infection takes place. 



KEY TO THE SPECIES OF ROZELLA 1 



Thallus monosporangiate, that is, giving rise to one sporangium or 

 resting spore 

 Parasitic in fresh- water Phycomycetes 



Parasitic in filamentous Phycomycetes and Blastocladia 

 Parasitic in the hyphae of Monoblepharis 



R. MONOBLEPHARIDIS-POLYMORPHAE, p. 168 



Parasitic in the sporangia of Araiospora 



R. rhipidh-spinosi, p. 168 

 Parasitic in the sporangia and immature resting spores of 



Blastocladia R. blastocladiae, p. 169 



Parasitic in the sporangia of Apodachlya 



R. APODYAE-BRACHYNEMATIS, p. 169 



Parasitic in Pythium 

 Resting spore smooth 



Resting spore pale yellow R. cuculus, p. 170 



Resting spore hyaline R. laevis, p. 171 



Resting spore spiny R. irregularis, p. 171 



Parasitic in members of the Chytridiales or Lagenidiales 

 Parasitic in chytrids 



Parasitic in monocentric chytrids 

 Parasitic in operculate chytrids 



Parasitic in species of Chytridium .... R. canterae, p. 172 

 Parasitic in species of Chytriomyces 



R. CHYTRIOMYCETIS, p. 172 



Parasitic in species of Endochytrium 



R. ENDOCHYTRU, p. 173 



Parasitic in inoperculate chytrids 



Parasitic in species of Polyphagus .... R. polyphagi, p. 173 

 Parasitic in species of Rhizophlyctis 



R. RHIZOPHLYCTII, p. 174 



Parasitic in species of Rhizophydium 



R. RHIZOPHYDII, p. 174 



Parasitic in species of the polycentric chytrids Nowa- 

 kowskiella, Cladochytrium, and Septoehytrhtm 



R. CLADOCHYTRII, p. 174 



Parasitic in cells of Lagcnidiitm (? and in Myzocytiwn) 



R. PSEUDOMORPHA, p. 175 



1 Note that this key is not wholly dichotomous. 



