332 AQUATIC PHYCOMYCETES 



high by 9-10 u. in diameter; zoospores spherical, 4-5 ;x in diameter, 

 with a prominent eccentric colorless globule and a single flagellum, 

 liberated successively through a fairly large apical pore; resting spore 

 sessile, spherical, 12 u. in diameter, with a smooth thick wall, contents 

 with a large colorless centric globule, rhizoidal system stout, branching, 

 arising from a subsporangial apophysis, germination not observed. 



Parasitic on Spirogyra sp., Great Britain. 



The formation of a single, relatively stout, rhizoidal axis, which 

 arises laterally from the apophysis segregates the species from Phlyc- 

 tochytrium lagenaria. 



Phlyctochytrium vernale (Zopf) de Wildeman 

 Bull. Soc. Roy. Bot. Belg. (Mem.), 35: 48. 1896 



R/iiziclitim vernale Zopf, Nova Acta Acad. Leop. -Carol., 47:234, pi. 21, 



figs. 12-20. 1884. 

 Rhizophydium vernale (Zopf) Sparrow, Mycologia, 24: 277, text fig. 2f. 



1932. 



Sporangium sessile, subspherical, with a slightly flattened apex, 

 wall somewhat thickened, smooth, colorless; rhizoids coarse, sparingly 

 branched, not extensive, arising from a main axis which is slightly 

 expanded beneath the inner face of the host wall, forming a small 

 apophysis; zoospores rather quickly formed, spherical, with a single 

 prominent colorless globule and a flagellum, emerging through a fairly 

 wide subapical slightly protruding pore; resting spore not observed. 



Parasitic on Chlamydomonas sp., Germany. 



No text and no sizes or magnification of the figures are given by 

 Zopf. The first formal description of the species is in Fischer (1892: 

 108) and is derived, as is the present one, from Zopf's figures. 



The fungus reported as "Rhizophydium vernale'"' on the zygospore of 

 Spirogyra (Sparrow, 1932b: 277, fig. 2f) possessed an apical or nearly 

 apical papilla on the sporangium, which was 20-25 \i in diameter. 

 Further observations are desirable before deciding finally whether or 

 not it should be included in the present species of Phlyctochytrium. 



Phlyctochytrium lagenaria (Schenk) Domjan 

 Folia cryptogam., 2 (1): 18, pi. 1, figs. 45-46, 48, 52-55, 62-63, 67, 69. 1936 



