Spiiaerotheca 59 



and become indistinguishable from certain forms of S. humuli. 

 Evidence on another side also points to " S. pruinosa " being only 

 a form of 5. httimdi. The form of 5. humuli on Geranium sylva- 

 ticum published by Penzig and Saccardo as "5. fugax" is de- 

 scribed as having appendages "hyalinae vel basi dilute fuligincae," 

 and it was probably on account of this character that the authors 

 considered their plant as showing affinity with 5. fruinosa. Al- 

 though in the type-specimen of " S.fugax'' the perithecia I exam- 

 ined showed more or less colored appendages, other examples 

 that I have seen of S. humuli on species of Geranium have 

 had appendages colorless and shining in the upper half quite 

 agreeing in all respects with certain specimens on Rosa from 



America. 



It may be objected that as 5. /////;///// already contains so many 

 forms which differ in slight characters {e. g., the scattered or clus- 

 tered habit, a persistent or evanescent mycelium, long or very 

 short or even rudimentar>^ appendages) it is inadvisable to include 

 under the name a form with shining white appendages. But if we 

 were to separate by means of this character, the plant on Rhus as 

 even a variety of S. humuli, we should have to recognize, it seems 

 to me, very arbitrary and unnatural limits. In the first place, 

 with regard to the specimens on Rhus, the occasional occurrence 

 of color in the appendages would have to be overlooked ; certain, 

 if not all, specimens on American roses (referred to above) 

 would have to be included in the variety, although forms on 

 species of Geranium would be found to completely connect them to 

 the type. It seems more natural, I think, to regard " 5. pruinosa " 

 as only a form of 5. humuli. We may perhaps regard this white 

 appendaged plant on Rhus together with certain specimens on 

 Rosa, as a marked form developing into a new species, but at the 

 present time too closely connected by intermediates to be separ- 

 ated systematically. 



Halsted (156) records the occurrence 



/ 



iop/. 



rescence of Rhus glabra. 



S. cakndulac (Malb. & Roumeg.), on Calendula an>ensis is S. 

 humuli, X2.x.fidiginea; the asci contain eight spores not six as de- 

 scribed. Fuckel records a fungus, observed only m the conidial 

 stage on Rubus Idauis, under the name of Erjsiphe ? rubi (Symb. 



