ACIIMA 99 



Antheridia iisiialK- mi all oogonia, and arising as a rule from llio main 



threads; c^rs 4-6, their diameter about 25/i A. paffillosa (4) 



Antheridia present on about half the oogonia, arising from just below 



the oogonium; eggs I or 2 4. spi)!Osa (p. i,i;8) 



Antheridia absent A. cornuta (5) 



SfB-GENUS Euachlya: Eggs eccentric, with a large oil drop on the ]ieriphery outside of 

 the protoplasm, or subcentric, with the protoplasm nearer one side than the other 

 and surrounded or nearly so by small droplets of oil. Antheridial branches androgy- 

 nous or diclinous, usually branched and often long; antheridia elongated, their sides 

 applied to the oogonia; often branched. Oogonial walls hyaline or rarely \ellowish. 

 Sporangia typically narrowed toward the tip; s|iores with a strong tendency to form 

 a hollow sphere on emerging. 

 Prolifera Group: Eggs eccentric with a single large oil drop on one side 



.Antheridia present; oogonial wall normally without papillae or warts 



.Antheridia practicalK- all androgynous; present on all or a majority of the 

 oogonia; eggs usually more than two 



Antheridia on all oogonia, arising mainly from the main h\|ihae. bill 

 also at times from the very short oogonial stalk; oogonial wall hyaline, 



pitted but the pits not very conspicuous A. americana (6) 



-Antheridia on all oogonia, nearly always arising from the main hyphae; 

 oogonial wall yellow, with very conspicuous pits; oogonial stalk about 

 as long as the diameter of the oogonium; eggs 23-26/1 thick 



A. americana var. camhrica (p. 139) 



Antheridia on all oogonia, arising only from the main hyphae; oogonial 



walls unpitted, their stalks one to three times as long as the oogonial 



diameter; eggs 18-25^ thick A. deBaryana fp. 141) 



Antheridia practically all androgynous, present on about 75% of the oogonia; 



eggs usually I or 2, mostly 33-36M thick .1. Orion (7) 



Antheridia always diclinous or both diclinous and androgynous, usually 

 longer and more branched than in the above four species; present on all or 

 nearly all the oogonia; eggs usually more than two 

 Oogonial wall pitted 



Antheridial branches always diclinous, much branched and winding 

 like a parasite about the oogonia; eggs small (20-26^), numerous 



A. prolifera (p. 143) 

 Like the above, but eggs larger (24-31. 5^) and spores said to be 



without a swimming stage A. aplanes (p.143) 



Antheridial branches mostly diclinous, in many cases winding them- 

 selves about the main hyjihae; eggs 18-24M thick 



A. proliferoides (8) 



-Antheridia more often diclinous than androgynous, not winding 



about the hyphae and never arising from the oogonial stalks; 



eggs about 26-35/1 thick A. flagellata (9) 



-Antheridial branches about equally androg>nous and diclinous, 

 usually long and much branched but not winding about the 

 hyphae, not rarely arising from the oogonial stalks; eggs 17-23/i 



thick A. imperfecta (10) 



Oogonial wall unpitted (except in one case in certain chemicals); anther- 

 idia nearly all diclinous A. Klchsiana (11) 



