66 THE LOWER FUNGI— PHYCOMYCETES 



relationship. In any case our knowledge of its life cycle and 

 cytology is insufficient to warrant its inclusion here. 



2. Ostenfeldiella Ferdinandsen & Winge (1914: 648). 



This genus was based on material collected by Ostenfeld on the 

 coast of St. Croix (West Indies) on Diplanthera wrightii one of 

 the Potomogetonaceae. The organism was found in the con- 

 spicuously thickened internodes of the erect branches, and was 

 named 0. diplantherae Ferd. & Wge. Certain cells of the host 

 were found packed with brown, thick-walled spores. Uni- 

 nucleate amoebae were found in others. Although other stages 

 were not observed the organism was placed in the Plasmodio- 

 phoraceae by the authors of the new genus. There seems to be 

 but slight reason for including it in the group, and at best its 

 position is doubtful. The authors did not see living material. 



3. Cystospora Elliott (1916: 15). 



This genus was based by Elliott on a single species, C. batata 

 Elliott, which he found to be the cause of a characteristic disease 

 of the tubers of sweet potato called pox or soil-rot. Although 

 he assigned the genus to the Plasmodiophoraceae there is in fact 

 little in the published account to indicate relationship with this 

 group. 



Woroninaceae 



Mycelium wholly lacking; thallus intramatrical, usually 

 occurring in water moulds, in early stages existing as a naked, 

 more or less amoeboid protoplast, at maturity, in some cases, 

 forming a membrane and functioning as a single sporangium or 

 resting spore, in others, fragmenting into a number of naked 

 parts, each of which then assumes a membrane and functions 

 as a sporangium or resting spore; the sorus, thus formed, conse- 

 quently never provided with a soral envelope ; sporangia typically 

 multispored; zoospores laterally biciliate, as in the Oomycetes. 



Key to Genera of Woroninaceae 



I. Mature thallus functioning as a single sporangium or resting spore. 



A. Resting spore lacking a companion cell. 



1. Pseudolpidlum, p. 67 



B. Resting spore bearing one or more companion cell^i. 



2. Olpidiopsis, p. 67 



