946 AQUATIC PHYCOMYCETES 



attached near anterior end of the spore. Resting spore consistently 

 with a companion cell, dark brown, spherical to oval, 10.68 to 45.1 \x in 

 longest diameter, spines on exospore wall up to 3.56 [jl in length, endo- 

 spore wall 0.75 to 1.32 \x thick, exospore wall 1.78 to 2.50 \x thick" 

 (Whiffen, he. cit.). 



Parasitic on Pythium sp., coll. P. Couch, United States. 



Characterized by somewhat short, straight spines. 



Not found capable of infecting other species of Pythium by Whiffen 

 (op. cit., p. 611). 



Olpidiopsis karlingiae Karling 

 Mycologia, 41 : 271, figs. 1-17. 1949 



"Sporangia hyaline, smooth, spherical, 8-120 \x, oval, 15-84 x 

 20-98 [jl, oblong and slightly curved, 6-10 x 12-28 [x, pyriform, obpyr- 

 iform or slightly angular when pressed together, with one simple, 

 rarely two and branched, short and broad, 6-12 by 14 — 18 [x, or long, 

 7 x 110 Li., discharge tubes which protrude directly through the host 

 cell wall or the exit papillae. Zoospores reniform, 6-6.5 x 10-10.8 

 \x, and containing 30 to 50 minute granules which are not particularly 

 refractive; heterocont, anterior and posterior flagella 6.5-7 \x and 1 1.6- 

 13 \x long, respectively. Resting spores spherical, 8-22 \x, oval, 9-17 x 

 15-23 \x, oblong, 7-9 X 12-20 [i. or angular when pressed together, with 

 a hyaline, smooth, 1.8-2.2 \x, thick wall, evenly but coarsely granular 

 protoplasm and one or more vacuoles ; germination unknown" (Karling, 

 he. cit.). 



Parasitic in Rhizophlyctis rosea, United States. 



Attempts to infect other chytrids with this species were unsuccessful. 



Olpidiopsis gillii (de Wild.) Friedmann 



Osterr. Bot. Zeitschr., 99: 209, fig. 6. 1952 



Olpidium gillii de Wildeman. Ann. Soc. Beige Micro. (Mem.), 20: 42. 1896. 



Sporangia one or two in a host cell, tubular, 4 20 la in diameter and 

 5-120 \x long, more or less slightly constricted in the middle, pushing 

 apart the valves of the host, discharge tube apical or subapical, up to 

 70 \x long by 4-5 \x in diameter, with a broad 8-20 \x in diameter base, the 



