CHYTRIDIALES 237 



Sporangium symmetrical, not angular or with humplike lobes 

 Sporangium narrowly ellipsoidal to cylindrical ; not on diatoms 

 Sporangium large (48-54 \x by 17-22 fx); rhizoids arising from 

 a stout main axis; zoospores pale rose-colored; on Cla- 



dophora R. messanense, p. 296 



Sporangium small (4.5-15.5 \i by 2.5-5 ;jl); rhizoidal axis deli- 

 cate; zoospores colorless; on Hyahbryon R. hyalobryonis, p. 297 



Sporangium fusiform ; on diatoms R. fusus, p. 298 



Sporangium angular or irregularly gibbose 



Sporangium angular with one to fifteen prominent discharge pa- 

 pillae ; on keratinized substrata R. nodulosum, p. 299 



Sporangium irregularly gibbose, with humplike lobes: on algae 



and rotifer eggs R. gibbosum, p. 299 



SECTION I 1 



Rhizophydium globosum (Braun) Rabenhorst 



Flora Europaea algarum, 3:280. 1868 (sensu strictu Cohn, Nova Acta 



Acad. Leop.-Carol., 24:142. 1853) 



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

 handl. Berlin Akad., 1855:34, pi. 2, figs. 14-18. 1856. 



Phlyctidium globosum (Braun) Sorokin, Arch. Bot. Nord. France, 2: 19, 

 fig. 12. 1883 (separate). 



Sporangium sessile, completely spherical, 12-50u. in diameter or 

 over, wall double-contoured, smooth, colorless, with from two to 

 four protruding discharge papillae on the upper half; rhizoidal system 

 branched, fairly extensive, arising from a short stalk or directly from 

 the tip of the penetration tube; zoospores very numerous, somewhat 

 ellipsoidal, 2-3 \x in diameter, with a flagellum about 20 u, long, es- 

 caping individually through one apical pore or through from two to 

 four sessile or slightly elevated pores on the upper half of the spo- 



1 See also the following imperfectly known species of Rhizophydium: 



R. caudatum, p. 300 R. hyalothecae, p. 304 



R. chrysopyxidis, p. 309 R. marinum, p. 307 



R. decipiens, p. 301 R. v. mindeni, p. 304 



R. digitatum, p. 302 R. multiporum, p. 304 



R. discinctum, p. 306 R. oedogonii, p. 305 



R. dubium, p. 302 R. parasitans, p. 308 



R. epithemiae, p. 303 R. sporoctonum, p. 305 



R. fallax, p. 303 R. tranzschelii, p. 309 



R. gelatinosum, p. 307 Rhizophydium spp., pp. 310-312 



