CHYTRIDIALES 505 



their hosts: (1) Rhizophydium lagenula (Braun) Fischer, on Melosira, 

 which has a somewhat fusiform inoperculate sporangium, 30-33 jj. long 

 by 8 [x in diameter, and a zoospore with a very small globule, escaping 

 at once from the sporangium; and (2) Chytridium lagenula Braun sensu 

 Scherffel, on Tribonema, which has a more clavate operculate spo- 

 rangium, 12-20 [x long by 5.5-8 \i in diameter, the zoospore having a 

 larger globule and resting for a time before the mouth of the spo- 

 rangium before assuming motility. He did not think Rhizophidium fusus 

 Zopf is synonymous with R. lagenula (Braun) Fischer, but gave no 

 reasons (see R. fusus, p. 298). Schenk (1858a: 236) reported it on 

 Stigeoclonium in Germany, but the report seems doubtful. 

 See remarks under Chytridium versatile. 



Chytridium cocconeidis Canter 

 Trans. Brit. Mycol. Soc, 31: 104, fig. 8., pi. 10, figs. 1-3. 1947 



"Thallus monocentric, eucarpic, sporangium extramatrical cylindrical 

 15-29 u, in length, 5 6 jjl in diameter, dehiscing by an apical lid, and 

 containing 12-30 zoospores. Zoospores spherical 2-3 \i in diameter, 

 with a colourless globule and single posterior flagellum. Extramatrical 

 rhizoidal system simple or branched 2-9 \i in length, rarely absent. 

 Intramatrical rhizoidal system not observed. Resting spores not observ- 

 ed" (Canter, be. cit.). 



On living cells of Coeconeis pediculus, Great Britain. 



Chytridium appressum Sparrow 

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

 (Fig. 31 F, p. 496) 

 Sporangium sessile, narrowly to broadly obpyriform, slightly con- 

 stricted toward the base, 10-17 fx long by 6-10 jx in diameter, the long 

 axis parallel with that of the algal filament, with a smooth colorless 

 wall; endobiotic part consisting of a highly refractive narrowly cylin- 

 drical unbranched tube about 3 jx long; zoospores spherical or slightly 

 subspherical, 3-5 [x in diameter, with a single colorless eccentric oil 

 globule and a long flagellum, escaping upon the dehiscence of a convex 

 terminal operculum, movement hopping; resting spore not observed. 



