504 AQUATIC PHYCOMYCETES 



tapering; zoospores subcylindrical or subcuneate, ejected upon the 

 dehiscence of an apical convex smooth operculum. 



In Vaucheria sessilis and V. geminata, coll. Eaton, Kerguelen Island. 



Shape said to approximate that of Chytridium ol/a, a statement hardly 

 borne out by the description. The lack of figures makes the interpre- 

 tation of this species difficult. 



Chytridium lagenula Braun, pro parte 



Abhandl. Berlin Akad., 1855:31, pi. 2, figs. 4-5 (sensu recent. Scherffel 

 Arch. Protistenk., 54: 195, pi. 9, figs. 57-59. 1926) 



Phlyctidium lagenula (Braun) Rabenhorst, pro parte, Flora Europaea al- 



garum, 3:280. 1868. 

 Rhizophydium lagenula (Braun) Fischer, Rabenhorst. Kryptogamen-Fl., 



1 (4): 99. 1892. 



Sporangium sessile or with a short tenuous extramatrical stalk, 

 narrowly obpyriform (pestle-shaped), with rounded apex, upright or 

 slightly tilted, with a thin smooth wall, varying in size, large specimens 

 12-14 (x long by 5.5 \x in diameter, small ones 7 u. long by 4 jx in diameter; 

 rhizoidal system not seen, the penetration tube stimulating the host to 

 form a protective plug of wall material; sporangium opening upon the 

 dehiscence of an arched apical operculum about 4 [x in diameter; zoo- 

 spores few, spherical, 3 ;x in diameter, with a single globule and probably 

 a single flagellum, remaining motionless for a time at the mouth of the 

 sporangium before swimming away; resting spore endobiotic, broadly 

 ovoid or nearly spherical, 6-8 by 5 fx, with a thick smooth wall and a 

 large eccentric colorless oil drop 4 jx in diameter, germination not 

 observed. 



On Tribonema bombycina, Braun (be. cit.), Germany; Scherffel (loc. 

 cit.), Hungary; Sparrow (1943: 336), United States. 



Scherffel believed his fungus to be a new species, but since he described 

 a form almost identical with Braun's plant on Tribonema and applied 

 Braun's name to it, it is here considered merely an amplification of a 

 previously inadequately defined species. He divided Braun's Chytridium 

 lagenula into two species, which differ in the size, shape, and method of 

 opening of the sporangium, in the behavior of the zoospores, and in 



