128 THE SAPROLKGNIACE^ OF THE UNITED STATES, 



as Wo7'omna. The cysts of the parasite were supposed to be the antheridia of the 

 fungus. This belief, which also led to the similarly erroneous application of the 

 name Saprolegnia dioica, was based on the supposed necessity for the existence of 

 antheridia and a sexual process in these plants. 



Adilya NowicMi Bacib. (Przyrodnik [The Naturalist] Y, 327 ; 1884) may be 

 a good species, but I have not been able to examine the original description. 



AcJilya penetrans Duncan (Proc. Roy. Soc. London, XX Y, 238 ; 1876) is 

 probably a boring Siphonaceous alga. 



Aphanoniyces DeBary ('60). 



Hyphae very slender and delicate, little branched, forming a nebulous film over 

 the substratum. Zoosporangia formed from their unswoUen ends, often a hundred or 

 more times as long as broad; secondary ones not abundant, foraied by cymose 

 branching. Zoospores cylindric-fusiform, cilia not yet observed, formed in a single 

 file in the sporangium, and escaping slowly by a terminal mouth which is formed with- 

 out the preliminary development of an oral papilla ; immediately becoming encysted 

 and aggregated into a hollow rounded group ; after resting, swarming in the laterally 

 biciliate form ; finally encysting again and germinating. Oogonia usually terminal 

 and one-spored. Antheridia commonly present. 



Key to established species. 



a. 



Parasitic on Zygnemacea ; oogonia spiny Ai^h. phycophilus. 



Saprophytic , b. 



h. Oogonia quite smooth ; antheridia always present Aph. ljevis. 



Oogonia roughened or spiny c. 



c. Spines large and prominent ; antheridia always present Aph. stellatns. 



Spines small or reduced to mere roughnesses ; antheridia often absent Aph. scaber. 



Aphaistomyces l^vis DeBary ('60). 



111.: DeBary, '60, PI. XX, Figs. 17, 18. 

 PL XX, Figs. 105-107. 



Zoosporangia very long and slender. Oogonia terminal on short lateral branches, 

 globular, with entirely smooth walls. Antheridia abundantly developed on all 



