CHYTRIDIALES 529 



base, 2-3 \i in diameter which is an unexpanded portion of the cyst of 

 the zoospore, sessile or on an extramatrical stalk up to 10 jx long, 

 without an obvious papilla or operculum; rhizoidal system delicate, 

 branched; zoospores spherical, 2.2-3.0 \x in diameter (av. 2.5 \x), with 

 an anterior oil globule 1 .0 u, in diameter and a posterior oscillating granule 

 and flagellum 12-14.6 \i long, emerging in a mass upon the dehiscence 

 of a terminal or lateral portion of the sporangium wall, after which 

 the sporangium collapses; resting spore not observed. 



Parasitic on Rhizidium richmondense, Rhizophlyctis sp., Entophlyctis 

 sp., hyperparasitic on Chytridium urceolatum, and Septosperma rhi- 

 zophidii (Herb. I.M.I., No. 60444), Great Britain. 



Chytridium parasiticum somewhat resembles C. rhizophidii Karling 

 in its structural features and its hosts (other chytrids). As Willoughby 

 points out, however, there are significant differences between them in 

 the shape of the sporangium and operculum. Chytridium parasiticum 

 does closely approximate the diatom parasite C. surirellae. 



Note that in attacking Septosperma this species is parasitizing a 

 chytrid which is parasitic on another chytrid which in its turn is a 

 saprophyte! 



Chytridium suburceolatum Willoughby 

 Trans. Brit. Mycol. Soc, 39: 132, fig. 4. 1956 



Sporangium suburceolate, 4-16 \i high, with a colorless thin light- 

 brown wall; rhizoidal system of variable extent, not clearly evident in 

 host, of limited extent; zoospores spherical, 2-2.5 u, in diameter, with 

 a lateral oil droplet, 0.6-0.8 jj. in diameter, and a 14 \). long flagellum, 

 escaping rapidly upon the dehiscence of a terminal (rarely two) oper- 

 culum, movement hopping; resting spore not observed. 



Parasitic on sporangia of Rhizophlyctis richmondense (Herb. I.M.I., 

 No. 60443), Great Britain. 



The species was hyperparasitized by Chytridium parasiticum Wil- 

 loughby (see p. 528). 



Chytridium turbinatum Kobayasi and Ookubo 

 Bull. Nat. Sci. Mus. (Tokyo), (N.S.), 1 (2) No. 35: 69, fig. 8. 1954 

 "Sporangium gregarious, ovoid or ellipsoid, apically with one coni- 



