260 AQUATIC PHYCOMYCETES 



ora sp., Nitella flexilis, Chara coronata, root tips of Allium cepa and 

 Narcissus, United States. 



Rhizophydium asymmetricum (Dang.) Minden 



Kryptogamenfl. Mark Brandenburg, 5: 328. 1911 (1915) 



(Fig. 17 H, p. 228) 



Chytridium asymmetricum Dangeard, Le Botaniste, 2:243, pi. 17, fig. 1. 

 1890-91. 



Sporangium sessile, ovoid, 16 ;jl high by 10 ;x in diameter, with a 

 prominent slightly oblique apical papilla, wall stout, smooth, color- 

 less; rhizoids delicate, branched, arising from a short slender main 

 axis; zoospores very small, spherical, with an eccentric colorless glob- 

 ule and a fairly long flagellum, emerging through a pore formed 

 upon the deliquescence of the papilla; resting spore not observed. 



Parasitic on Tribonema bombycina var. minor, France. 



Considered by Fischer (1892: 94) to be merely an irregular form of 

 Rhizophydium mammillatum (Braun) Fischer. Minden (loc. cit.) though 

 placing it in Rhizophydium, where, from its inoperculate type of dis- 

 charge, it unquestionably belongs, briefly discusses it under R. mammil- 

 latum. 



Because of the characteristically tilted papilla the species should 

 be retained, at least for the present. 



Rhizophydium mammillatum (Braun) Fischer 



Rabenhorst. Kryptogamen-Fl., 1 (4): 93. 1892(sensu Dangeard, Le Botaniste, 



2:242, pi. 16, fig. 32. 1890-91) 



Chytridium mammillatum Braun, Monatsber. Berlin Akad., 1855: 381 ; Ab- 

 handl. Berlin Akad., 1855: 32, pi. 2, figs. 9-12. 1856. 



Sporangium sessile, long-ovoid or narrowly to somewhat broadly 

 citriform, with a more or less prominent apical papilla, 10-33 \x high 

 by 10-22 [j. in diameter, wall smooth, colorless, slightly thickened; 

 rhizoids delicate, branched, short, arising from a slender main axis; 

 zoospores spherical or somewhat ovoid, 2-4 \x in diameter, with a 

 minute eccentric globule and a long flagellum, emerging through a 

 small apical pore; resting spore not observed. 



