506 AQUA TIC PH YCOM YCETES 



Parasitic on Melosira varians, Sparrow (loc. cit.), United States; 

 Sparrow (1936a: 437, pi. 15, figs. 12-14), Great Britain. 



The development of the sporangium has not been studied; it is prob- 

 ably similar to that of Chytridiwn schenkii. 



Chytridium melosirae, sp. nov. 1 



Sporangium narrowly ovoid to pyriform, resting directly on the host 

 cell and penetrating it with an unbranched, isodiametric rhizoid, when 

 mature 11-17 \x long, 6-8 \x in diameter at base, and tapering to 4-5 \i 

 in the neck region, wall smooth, hyaline, moderately thick; zoospores 

 broadly ovoid to subglobose, 2-2.5 [i broad by 2-3 \i long, with a 

 flagellum three to four times the body in length and a refractive an- 

 terior droplet, spores 16-48 in a sporangium, freed by the throwing off 

 of a sporangial lid; resting spore not observed. 



On Melosira ambigua, Rohde and Skuja (in Skuja, 1948:381), 

 Sweden. 



A Chytridium much like that figured by Sparrow (1936a, fig. 4, j-n) 

 on Melosira. The Swedish fungus is definitely not Rhizophydium simplex, 

 to which species it was referred by Rohde and Skuja. The empty spo- 

 rangia illustrated by them as on the same host filament possibly belong 

 to another species. 



Chytridium curvatum Sparrow 



Amer. J. Bot, 20: 69, text fig. 1 n. 1933 



(Fig. 31 G, p. 496) 



Sporangium strongly arched, broadly obpyriform or clavate, smooth- 

 walled, 8 \x in diameter tapering to 5 (jl in diameter by about 18 [i in 

 length, with an apical operculum about 5 jx in diameter, having at the 



1 Chytridium melosirae, sp. nov. — Sporangium includens 16-48 zoosporas, libe- 

 ratas per operculum dehiscens, anguste ovoideum vel pyriforme, sessile in cellulam 

 hospitis et eamdem penetrans; axe penetranti simplici rhizoidali 11-17 ;x longo, 

 basi 6-8 \x diam., sursum angustato ad 4-5 [i prope cervicem, laevi, hyalino, modice 

 crasso. Zoosporae late ovoideae vel subglobosae, 2-2.5 (J. crassae, 2-3 jjl longae; 

 flagello triplo vel quadruplo longiori quam somate; globulo refractivo anteriori 

 singulo. 



In Melosira ambigua. Species Suecica sub nomine Rhizophydii simplici, a Rohde 

 et Skuja descripta et delincata, sed valde diffcri. 



