1038 AQUATIC PHYCOMYCETES 



monoclinous or diclinous, sometimes borne just be- 

 neath the oogonium, short stalked, clavate; oogonium 

 terminal or intercalary, spherical; oospore 15-18 y in 

 diameter, wall 0.5-0.8 u, thick; on rice bait in water 



P. pleroticum T. Ito l 



Oospore aplerotic 



Oospore single in oogonium 

 Sporangium proliferating 



Antheridium typically monoclinous, rarely diclinous, 

 one to three, usually single and hypogynous, when 

 monoclinous or diclinous, either sessile or stalked, 

 only slightly inflated, clavate, making moderate 

 apical contact with oogonial wall ; oogonia spher- 

 ical, smooth or with a short apical papilla, ter- 

 minal or intercalary, frequently catenulate, 15-28 y 

 in diameter; oospore thick-walled, 14-24 y in 

 diameter; with a single reserve globule; spo- 

 rangium acrogenous, spherical to ovoid, strongly 

 proliferous; zoospores 9-16 y in diameter when 

 encysted ; in water . . P. middletonii, nom. nov. 2 p. 74m 



Antheridium typically diclinous, rarely monoclinous, 

 one to four, irregularly expanded, 10-20 by 8-12 y, 

 making broad contact with oogonium; oogonium 

 subspherical, 23-39 (30.9 y av.) in diameter; 

 oospore subspherical, 19-33 y in diameter, with a 

 moderately thick wall (1.95 y av.) and single 

 reserve globule; sporangium subspherical or 

 asymmetrically utriform, the long axis generally 

 at right angles or less to sporangiophore; zoo- 

 spores 9-12 y in diameter when encysted; in 

 decaying water-lily leaves 



P. marsipium Drechsler, p. 75m 



Sporangium not proliferating 

 Antheridium typically hypogynous, less often monoc- 

 linous or diclinous, one to two, when monoclinous 

 often sessile or a short lateral protrusion origi- 

 nating immediately below the oogonium and de- 

 limited by a basal septum, then usually as long as 

 broad, sometimes on a somewhat longer branch, 



1 J. Jap. Bat., 20: 59, rig. 3. 1944. 



2 Syn. Pythium proliferum dc Bary, Ja/irb. wiss. Bot.,2: 180, 1860. Nan Pythium 

 proliferum Schenk, Verhandl. Phys.-Med. Gesell. Wurzburg A. R, 9:27. 1859. 



