WITH NOTES ON OTHER SPECIES. 113 



Leptolegnia DeBary ('88). 



Differs from Saprolegma in that the oogonium contains a single oospore which 

 completely fills it. 



Leptolegnia caudata DeBary ('88). 



111. : DeBary, '88, PI. IX, Fig. 5. 



The single known species of this genus has narrow sporangia, ovate oogonia on 

 short racemose branches, and antheridia, usually one to each oogonium, on branches 

 of diclinous origin. It was obtained by DeBai'y from two different cultures from 

 German mountain lakes, and is known only from these. 



Pythiopsis DeBary ('88). 



Hyphse slender, much branched. Zoosporangia formed from their tips, globular, 

 oval, ovate, or short-clavate, the later ones arising by cymose branching of the 

 hyphse, either sessile or on long branches. Zoospores ovate, apically biciliate, 

 escaping by a usually terminal mouth at the apex of a distinct papilla, and swarm- 

 ing separately ; after encystment germinating without a second swarming stage, ^. e., 

 monoplanetic. Oogonia and antheridia abundantly developed. 



Pythiopsis ctmosa DeBary ('88). 



111.: DeBary, '88, PI. IX, Fig. 1. 

 PI. XVII, Fig. 60-68. 



Hyphge slender, short. Zoosporangia from globular to short-clavate. Oogonia 

 commonly terminal and globular, their walls unpitted, sometimes with a very few 

 blunt outgrowths. Antheridia clavate, one, or rarely more, on each oogonium, 

 usually arising just below its basal wall, rarely of diclinous origin. Oospores single, 

 or very rarely two, in the oogonium, excentric, with several oil-globules, their 

 average diameter about 18^. 



Massachusetts — Amherst. Europe. 



The present interesting species, previously known only from DeBary's account, 

 and obtained by him from a snow-water pool in the Yosges mountains, appeared in 

 two of my cultures in March, 1892. Both were obtained from Algse consisting 

 chiefly of Spirogyra sp. One, from a ditch, had been kept in a jar in the laboratory 

 since the preceding November, and had yielded A. apiculata, Aph. scaiet^ and Die- 



