106 THE SAPROLEGNTACB^ OF THE UNITED STATES 



guish it from S. monoica. Its hyphse are also rather slenderer and more flaccid than 

 those of the latter. 



The description of S.ferax given by Schroeter ('86) is clearly not applicable to 

 that species, but very well characterizes the present one. It must be considered, 

 therefore, that this author's S. ferax belongs here as a synonym ; and, if so, then 

 also his 8. dioica, which he quotes ('86) as a synonym of his 8. ferax. Fortunately, 

 the name 8. dioica had been used for another jDlant by Pringsheim ('60) and there- 

 fore cannot be retained for this one, although Schroeter's use of it antedates DeBary's. 



Saprolegnia FERAX (Gruith.) Thuret ('oO). 



Syn. : S. ferax A.\xci. p.p. 111. : Tliuret, '50, PI. XVI. 



Aelilya prolifera Pringsli. ('51). Pringsheim, '51, PI. XLVI-L. 



S. Thureti DeBary ('81). Pringsheim, '74, PI. XVIII, Figs. 5 and 11. 



DeBary, '81, PI. V, Figs. 1-10. 



Rothert, '88, PI. X, Figs. 1-13. 



PI. XVI, Figs. 43-45. 



Hyphae of medium size. Zoosporangia clavate-cylindrical. Oogonia terminal 

 oi- sometimes intercalary on main hyphse or lateral branches, globular or not rarely 

 cylindrical, their walls very thickly and conspicuously marked by large pits. An- 

 theridial branches and antheridia never developed or extremely rare. Oospores up to 

 twenty in an oogonium, or sometimes more (" 40 to over 50, " DeBary), centric, their 

 average diameter about 26,«. 



Massachusetts — Amherst : Wisconsin — Madison, Trelease : Missouri — St. Louis, 

 Trelease : Kentucky — Lexington, comm. Keller. Europe. 



In Wisconsin this species was obtained by Prof Trelease from Algie collected 

 in a ditch, and at St. Louis it grew spontaneously on flies in water. The Kentucky 

 specimen sent by Dr. Keller was obtained from Algae, chiefly Hydrodictyon, collected 

 in a pool in a cemetery at Lexington. I have never obtained it in Amherst from 

 open-air materials, but have found it on flies thrown in water taken from the room 

 for ti'opical aquatics in the plant house of the Massachusetts Agricultural College. 

 This specimen was a reduced form in all respects, although undoubtedly of this 

 species. 



This plant seems, then, to be more common in the Western than in the Eastern 

 States. The absence of anthei'idia, the rather common occurrence of cylindrical 

 oogonia, and the very conspicuous pitting of all the oogonia mark the species unmis- 

 takably. It was first sharply distinguished and characterized by DeBary ('81), who 



