CHYTRIDIALES 599 



with a small colorless centric globule and a long flagellum, escaping 

 upon the dehiscence of a convex operculum 3-5 \x in diameter; resting 

 spore broadly ovoid with truncate ends, with a thick smooth wall, 20 u, 

 long by 15 jo. wide, contents with globules, germ sporangium operculate. 



Parasitic on Elodea canadensis, United States. 



This remarkable fungus caused a pronounced discoloration and dis- 

 integration of the leaves of Elodea. 



GENERA OF DOUBTFUL AFFINITY 

 TETRACHYTRIUM Sorokin 

 Bot. Zeitung, 32: 311. 1874; Bull. Soc. Nat. Kazan, 4(3): 15. 1874 



(Fig. 38 F-M, p. 600) 

 Zoospores upon germination developing at one pole a cylindrical axis 

 which forms distally a single short reflexed lateral sterile branch and 

 three terminal ones, each of which bears a single operculate sporangium, 

 developing at the opposite pole a lobed holdfast which anchors the plant 

 to the substratum; the thallus polycentric, eucarpic, hypha-Uke; zoo- 

 spores (gametes?) four, with a central vacuole (?), posteriorly uniflagel- 

 late, matured outside the sporangium in a delicate evanescent vesicle 

 which envelops the extruded protoplasm after the dehiscence of the 

 operculum, conjugating in pairs to form a new sporangial plant; no 

 resting stage formed. 



Primarily saprophytic on submerged decaying wood and grass stems. 



TETRACHYTRIUM TRICEPS Sorokin 



Bot. Zeitung, 32: 31 1, pi. 6, figs. 23-35. 1874; Bull. Soc. Nat. Kazan, 4 (3): 15, 



pi. 2. figs. 23-35. 1874 



Thallus 39-94 { x long, main axis 19-78 \i long by 5-9 [x in diameter, 

 protoplasm bluish; sporangium spherical or subspherical, 15-17 \i in 

 diameter, with a terminal colorless operculum having a prolonged con- 

 ical umbo ; zoospores spherical, 1 1 \i in diameter, bluish with a colorless 

 centric spot, flagellum two to three times as long as the diameter of the 

 body, movement lively, never amoeboid. 



Saprophytic on wood, grass stems, and the like, cadaver of Coleop- 

 tera, European Russia (southern part). 



