PROTOACIII.VA 91 



gemmae, and, from all except the Racemosa group, in the egg structuri'. 

 It differs from SaproIc'^)iia in the non-motiiity of some of the s])orcs on 

 emerging, in the predominant sympodial iiroliferation of the sporantiia, 

 and in the frequent occurrence of dictiosporangia. From Isoachlya it dif- 

 fers in the non-motihty of some of tiie spores on emerging, in the fre()uent 

 occurrence of dictiosjiorangia, in the al)sence of chained oogonia and in tiie 

 presence of antheridia on all oogonia (normally). The relationships of the 

 genus are not ohxious. Either Dictyiichus or the Racemosa grouj) of 

 Achlya seems nearest. 



I. Protoachlya paradoxa n. coml).* 



Aclilya panidoxa Cokcr. Mycologia 6: 285, pi. 146. 1914. 

 Isoachlya paradoxa (Coker) Kauff. Amer.Journ. 801.8:231. 1921. 



Plates 26, 27 and 28 

 Plant delicate; hyphae straight, slender, and little branched, the 

 larger threads having a diameter of about 37^1 below on a mushroom 

 gruli; many much smaller, the average being about io-i5;j.; sporangia 

 plentiful at all stages, narrowly cluti-shaped and largest at the distal 

 end, which is about 20-30,1 in diameter, rounded at the tip, and fur- 

 nished with a distinct but short papilla; secondary sporangia formed 

 usually by cymose branching beneath the old ones, but occasionally 

 also by proliferation through the empty ones, exactly as in Saprolegnia, 

 except that the new sporangia are formed entirely outside the old ones; 

 dictiosporangia not rare. Spores diplanctic, formed in several rows as 

 in Saprolegnia and Achlya, on emerging all ciliated, but varying greatly 

 in behavior — some swimming away as a rule, the others remaining attached 

 in an irregular group to the tip of the sporangium. Oogonia produced 

 on the tips of short lateral branches, usually near the base of the main 

 hyphae, sometimes intercalary; spherical, the diameter 32-8011 (one seen 

 looo. thick), sometimes elongated or flask-shaped especially when inter- 

 calary; their walls smooth and usually with a few pits (two or three often 

 visible in addition to the thin places where the antheridia are attached) ;t 

 eggs centric, usually two or four, often six, and rarely one or eight or ten 

 (twelve seen once); their diameter from 22-37:1, averaging about 30;i; an- 

 theridia always present, generally several and sometimes so numerous as 



* Most of the data given herewith for this species is taken from the original publication, 

 as is also plate 24 in part. 



fin the original descriinion the walls were erroneously said to be without pits. This 

 is true only for many of the smaller ones. 



