CHYTRIDIALES 345 



Sporangium subspherical or broadly urn-shaped, 10.5-23 u. high by 

 12-26 \x in diameter, colorless, with two concentric whorls of solid 

 apical converging teeth, the inner circle being composed of four minute 

 divergingly bipartite sessile ones which immediately surround the 

 discharge papilla, the outer circle, of six bipartite strongly diverg- 

 ing longer ones each of which terminates the inwardly arching tip of a 

 broad flangelike solid boss 5-7 u. long by 3 [x wide by 3-5 u, high; endo- 

 biotic system composed of a broadly fusiform sometimes spherical or 

 irregular subsporangial swelling, 10-20 \x wide by 6-10 \x high, from 

 one side or, occasionally, from opposite sides of which emerges a wide 

 rhizoid which usually branches at some distance from the swelling and 

 ramifies through one or more cells of the alga; zoospores spherical, 

 8 \x in diameter, the clear plasma containing a single large slightly 

 eccentric spherical or hemispherical oil globule, 4-5 \x in diameter, and 

 a few minute peripheral granules, with a single posterior flagellum about 

 40 \i in length; resting spores not observed. 



Saprophytic and weakly parasitic on Cladophora sp., Sparrow (1933c: 

 fig. I, 16), oogonia of Vaucheria, Sparrow (1943: 233), United States. 



Phlyctochytrium urceolare Sparrow 



Occ. Papers Boston Soc. Nat. Hist., 8:296. 1937; Amer. J. Bot., 25:491, 



figs. 31-41. 1938 



Sporangium colorless, somewhat variable in shape but predomi- 

 nantly cylindrical and expanding slightly distally until reaching the 

 first whorl, which is composed of six sessile bipartite solid upright or 

 slightly diverging teeth, where it tapers sharply toward the apical 

 discharge papilla, which is surrounded by a whorl of four minute 

 bipartite upright solid teeth, 10-14 \x high by 7-1 1 \x in diameter tapering 

 to 5-6 [x at the apex; endobiotic system composed of a narrowly to 

 broadly fusiform or occasionally spherical subsporangial swelling 3-5 

 u. in diameter by 7-10 \x in height (3-7 \x in spherical examples), the 

 swelling if narrowly fusiform generally bearing at its base a single 

 rhizoid which ultimately branches, if broadly fusiform or spherical, 

 bearing two oppositely placed rhizoids which eventually branch; 

 zoospores spherical, 4 \x in diameter, with a single slightly eccentric 



