746 AQUATIC PHYCOMYCETES 



the sporangium; resting spore asexually or sexually formed, upon ger- 

 mination functioning as a sporangium. 



Parasites of fresh-water and marine algae, aquatic Phycomycetes, 

 ascocarps of Discomycetes, and saprophytes on dead plant material 

 and insect remains. 



KEY TO THE FAMILIES AND GENERA OF THE HYPHOCHYTRIALES 



Thallus holocarpic, endobiotic, zoospores formed within or outside the 



sporangium Fam. Anisolpidiaceae, p. 746 



Zoospores formed within the sporangium; parasites of marine algae 



Anisolpidium, p. 747 

 Zoospores formed outside the sporangium; parasites of the fresh- 

 water algae Stigeoclonium and Drapamaldia. . . Canteriomyces, p. 750 

 Thallus eucarpic 



Thallus monocentric, zoospores formed outside or within the spo- 

 rangium Fam. Rhizidiomycetaceae, p. 751 



Zoospores undergoing cleavage at the orifice of a narrow dis- 

 charge tube Rhizidiomyces, p. 751 



Zoospores formed within the sporangium 



Sporangium epibiotic on the oogonia of water molds, apophy- 



sate, with an apical pore Rhizidiomycopsis, p. 757 



Sporangium resting on the egg of Vaucheria; nonapophysate, 



with a broad lateral pore Latrostium, p. 758 



Thallus polycentric Fam. Hyphochytriaceae, p. 759 



( H YPHOCH YTRIUM) 



ANISOLPIDIACEAE 



Thallus endobiotic, holocarpic, without a specialized vegetative sys- 

 tem, converted as a whole into a zoosporangium or resting spore; 

 zoospores formed within or outside the sporangium, anteriorly uniflag- 

 ellate, with a more or less refractive globule or granule, discharged 

 through one or more tubes; resting spore thick-walled, endobiotic, 

 asexually or sexually formed, germination not observed. 



Only three marine and one fresh-water fungus can be regarded as 

 valid members of the family. Karling (1943) included the fresh-water 

 Reessia (p. 764), but Fisch's (1884a) contradictory and unconfirmed 

 accounts of his fungi inspire no confidence in the accuracy of his obser- 

 vations. 



