766 AQUATIC PHYCOMYCETES 



three times as long as the body, remaining for a short time at the mouth 

 of the discharge tube, motion lively; resting spore spherical, with a 

 double wall, the outer thin and cuticularized, the inner refractive, con- 

 tents with from one to two large globules and a peripheral bright spot, 

 upon germination producing zoospores. 



In cells of Lemna minor, L. polyrrhiza, Fisch (be. cit.), L. trisulca, 

 coll. Hieronymus, Schroeter (1885: 181), Germany. 



EXCLUDED GENUS OF THE HYPHOCHYTRIALES 



* CATENARIOPSIS Couch, nom. nudum 

 Amer. J. Bot., 28: 707. 1941 

 Mentioned only by name. Considered by Karling (1943) as probably 

 a Hyphochytrium. 



SPECIES OF DOUBTFUL AFFINITY 



? Chytridium mesocarpi (Fisch) Fischer 



Rabenhorst. Kryptogamen-Fl., 1(4): 126. 1892 



Euchytridium mesocarpi Fisch, Sitzungsber. Phys.-Med. Soc. Erlangen, 

 16: 101. 1884. 



Sporangium epibiotic, flasklike, resting on the broad base, the upper 

 part prolonged into a short tube, with a brownish stout smooth wall; 

 rhizoid delicate, extending to the middle of the host cell, rarely branched ; 

 zoospores somewhat large, with the fine granular plasma containing an 

 oil droplet, not over eight formed in a sporangium, with a single anterior 

 flagellum attached to the somewhat narrower forward end of the body, 

 emerging suddenly from the tip of the sporangium after the dehiscence 

 of a circular operculum, after a period of swarming coming together in 

 pairs and fusing at the flagella-bearing poles; the zygote containing two 

 oil globules which fuse into one, its motion slow, soon coming to rest 

 on the surface of the host and penetrating it by means of a small out- 

 growth, through which the content of the zygote is discharged into the 

 host, where it enlarges, eventually surrounds itself with a double wall, 

 and becomes a resting spore; the resting spore germinating after a 

 short period, producing zoospores which penetrate other host cells and 

 form new sporangia. 



