664 AQUATIC PHYCOMYCETES 



tubular, the case that encloses the resting sporangium globose to sub- 

 cylindrical. Rhizoids well developed, attached basally if sporangium is 

 extramatrical, or attached to several places on the sides if intramatrical. 

 Resting sporangia when spherical 16-342 jx thick, when subspherical 

 37-142 x 35-209 [x; stalk when present very variable in size, 30-116 

 X 39-564 [x; usually filling the case in which it is formed; wall 

 two-layered, very faintly areolate, 1.5-6.1 ;x thick, nearly hyaline to 

 dull yellow or orange brown. Germination as in the genus. Zoospores 

 uniciliate when discharged, encysting almost immediately near the 

 sporangial mouth in an irregular mass. Encysted spores (gametangia) 

 8.2-10.2 [x thick, spherical. After one to two hours each cyst gives rise 

 to four uniciliated gametes which emerge through a minute pore to 

 fuse in pairs near the empty cysts; gametes 4.1 • 4.9 fx. Zygotes bi- 

 ciliated, 6 x 8 [x, swimming for an hour or more before germinating to 

 form resting sporangia" (Couch and Whiffen, he. cit.). 

 On grass leaves, from soil, coll. Philip Couch, United States. 



Blastocladiella microcystogena Whiffen 

 J. Elisha Mitchell Sci. Soc, 62: 57, pi. 7, figs. 1-5. 1946 



"Thallus of resting sporangium sessile or stalked; spherical to ovoid, 

 12-68 fx in diameter; wall of resting sporangium smooth, hyaline to 

 light yellow brown, 1.3-4.5 fx thick. Germination of resting sporangium 

 by cracking open of wall and formation of one exit papilla, through 

 which uniflagellate zoospores are discharged. Zoospores encysting al- 

 most immediately; encysted zoospore (gametangium) spherical, 4.8-6.2 

 [x in diameter; each gametangium discharging four uniflagellate gametes, 

 2.5 x 2.9 [x, which fuse in pairs. Zygote biflagellate, encysting and 

 germinating to form a plant bearing a resting sporangium"' (Whiffen, 

 he. cit.). 



On grass-leaf bait, from soil, coll. J. N. and P. Couch, United States. 



Blastocladiella simplex Matthews 



J. Elisha Mitchell Sci. Soc, 53: 194, 1 text fig., pis. 20-21. 1937 



(Fig. 45 E-G, p. 661) 



Basal cell cylindrical, holdfasts delicate, branched, wall thin, smooth; 

 whole thallus, including rudiment of reproductive structure, 30-1005 (x 



