132 British Fitngi. 



Saprolegnia monoica, Pringslieim. (fig. 38). 



Oogonia with a terminal or lateral perforation, 

 oospores hyaline, globose, 20 /u, diameter ; antheridia 

 formed at the tips of lateral branches. 



Saprolegnia monoica, Pringsh. Jahrb. Band i. p. 

 292, t. xix. and xx. ; Sacc. Sylh vii. n. 911; Archer, 

 Proc. Dubl. Micr. Club, i. 17. 



On flies, spiders, lars'se, &c., under water. Not 

 common. 



B. Species dioecious. 



Salpro legnia ferox, Nees. 



Main stem without lateral branches ; oogonia per- 

 forated; oospores numerous, globose, 30 /x diameter ; 

 antheridia ovate, produced on the tips of special 

 filaments. 



Saprolegnia ferox, Nees, in Kutz. Phyc. Gen. p. 

 256; Sacc. SylL vii. n. 916; Cke. Hdbk. p. 639, 

 figs. 308, 309. 



Saprolegnia dioica, Schroet. 



Achlya prolifera, Pringsh. Jahrb. Band ii. 



On dead flies, fish, newts, &c., in water. Causincr 

 the well-known and destructive salmon disease. 

 Common. 



Sporendonerna musc3e, Fries., or Ernpusa muscset 

 Cohn, was at one time considered to be an imperfect 

 aerial condition of the present species, but it is now 

 known that the two are not in any way related. 



Pythium, Pringsheim. 

 Mycelium simple or branched, aseptate or with an 

 occasional septum ; walls of zoosporangia usually very 

 thin and evanescent, zoogonidia always naked, be- 



