314 AQUATIC PHYCOMYCETES 



lar, slightly curved and attenuated at one end, its long axis parallel 

 or nearly so with that of the host filament, wall smooth, thin, colorless; 

 endobiotic part not observed; zoospores (quiescent) spherical, with 

 a small colorless globule, escaping through a broad pore formed at 

 the narrower end of the sporangium ; resting spore somewhat elongate 

 and irregularly starlike, 12(x long by 6-9 u, high, the outer surface 

 of the thickened wall bearing prominent blunt conical solid refractive 

 outgrowths 3 \l high by 3 \x broad at the base, contents with a few 

 large or numerous smaller colorless oil globules, rhizoids (seen once) 

 numerous, delicate; companion cell spherical, smooth-walled, 2 u. in 

 diameter, directly attached at various points to the resting spore. 



Parasitic on Tribonema bombycina, Hungary. 



The resting spore, as Scherffel points out, is shaped very much like 

 the sporangium of the incompletely known Chytridium cornutum Braun. 

 Only quiescent zoospores within the sporangium were observed by 

 Scherffel. 



? Rhizophydium barkerianum (Archer) Rabenhorst 

 Flora Europaea algarum, 3: 281. 1868 

 Chytridium barkerianum Archer, Quart. J. Micro. Sci. (N.S.), 7: 89. 1867. 



Sporangium sessile, strongly flattened, with a concave upper sur- 

 face from the center of which arises a slender stalk terminating in a 

 small swelling, deeply three- to four-lobed, the lobes of equal size, 

 with rounded apices and radiating in one plane; rhizoids, where ob- 

 served, rootlike; zoospores escaping from the open ends of the lobes; 

 resting spore not observed. 



On Zygnema sp., Ireland. 



This curious species, said by its author to be related to Rhizophydium 

 cornutum (Braun) Rabenhorst and R. transversum, is of doubtful valid- 

 ity. The peculiar central stalk terminating in a knob is difficult to 

 interpret unless it be the cyst of the zoospore. If so, the fungus would 

 have a type of development like that of the Scherffeliomyces. 



