95. Oospores 47-58^ in diameter, 47-65/u long; male filament 



the same diameter as the female ..Oe. princeps 



95. Oospores averaging smaller, 43-52/u in diameter; male 

 filament 33-40/i in diameter, smaller than the female 



(35-46m in diameter) Oe. diversum 



96. Oogonia and oospores cylindric-ovoid- Oe. mexicanum 



96. Oogonia ellipsoid or subovoid - 97 



97. Vegetative cells 19-30/u, in diameter Oe. angustum 



97. Vegetative cells larger — 98 



98. Oogonia 49-63- ( 68 )m in diameter - - 99 



98. Oogonia 63-90m in diameter - - 101 



99. Vegetative cells 36-50/^ in diameter — - -100 



99. Vegetative cells 28-37-40/n in diameter Oe. grande 



100. Oospores ellipsoid to globose, variable.- - — Oe. crassum 



100. Oospores subobovoid — Oe. mains 



101. Vegetative cells 31-40/u, in diameter. .Oe. Landsboroughii 



101. Vegetative cells 46-54^ in diameter _ - .102 



102. Oospores broadly ellipsoid, 72-85/i in diameter -Oe. amplum 



102. Oospores elUpsoid to globose, variable, 58-76/tt in diameter..... Oe. crassum 



103. Oospore wall areolate, pitted, or scrobiculate — .104 



103. Oospore wall longitudinally ridged or costate 112 



104. Oospore wall (median) areolate..... Oe. areolatum 



104. Oospore wall, outer or median, scrobiculate - 105 



105. Oospores 22-32;a in diameter Oe. moniliforme 



105. Oospores larger 106 



106. Outer spore wall scrobiculate ...107 



106. Outer spore wall smooth, median wall scrobiculate or pitted 109 



107. Oogonia 70-83^ in diameter..... Oe. taphrosporum 



107. Oogonia smaller - 108 



108. Oogonia 48-62ai long; oospores regularly 



scrobiculate, ovoid Oe. argenteum 



108. Oogonia 68-112yLi long; oospores irregularly 



scrobiculate, globose — Oe. Wijliei 



109. Vegetative cells 11-26^ in diameter — ...110 



109. Vegetative cells 28-50/^ in diameter.. -Ill 



110. Oogonia subdepressed-globose, 64-7 6/i in diameter; oospores 



globose, nearly filling the oogonia Oe. Tiffaniji 



110. Oogonia broadly ellipsoid, 56-68/^ in diameter, 



oospores not filling the oogonia Oe. verrucosum 



111. Median spore wall with 25-30 longitudinal rows of pits; 



oospores cyhndric-elHpsoid, lOSfi long... Oe. giganteum 



111. Median spore wall scrobiculate; oospores globose or 

 ellipsoid-globose, 46-56^ long...... Oe. americanum 



112. Outer spore wall smooth, median spore wall with ribs or costae 113 



112. Outer spore wall ribbed, median spore wall ribbed or not 115 



113. Vegetative cells 24-30^ in diameter.. Oe. urceolatum 



113. Vegetative cells 12-18^ in diameter 114 



114. Oospore wall with deep, coarse crenations Oe. longiarticulatum 



114. Oospore wall with fine, numerous crenulations Oe. crenulatocostatum 



115 Oospores 32-34;u in diameter, filling the oogonia laterally, 



with 18 entire longitudinal ribs Oe. orientale 



115. Oospores larger - - - 116 



[162] 



