PHY S ARUM 63 



visible hyphothallus, often connate, but not superimposed, sub-spheri- 

 cal, dull orange, brownish or tawny; peridium thin, violaceous, covered 

 with very minute yellow calcareous scales ; columella none ; capillitium 

 lax, sometimes almost wanting; the nodules small, yellowish or 

 brownish, occasionally confluent; spore-mass violaceous, spores by 

 transmitted light, violet-tinted, smooth or nearly so, 6-7 /x. 



Not uncommon in the Mississippi valley, where it sometimes is 

 passed by the collector as an immature form of some other species. 

 The appearance is very characteristic, unlike P. virescens in both habit, 

 size, and color. Colonies are quite often three inches in length. The 

 most common habitat seems to be rotten oak, especially fragments of 

 charred logs, etc. 



Ohio, Illinois, Missouri, Iowa, Nebraska. 



This species presents a decidedly well-marked form, so much so that 

 it may be easily recognized at sight, without a lens. It therefore re- 

 quires special discussion, and although in the spore-characters and 

 some minor but not determinative details it agrees with P. virescens 

 Ditm. to which it is by European authors sometimes referred, it 

 seems nevertheless deserving of specific recognition, since in its entire 

 habit and expression it is not only completely different but is constant 

 in its specific peculiarities, much more so than is the suggested related 

 form. 



In the first edition of this work, the form was referred to Physarum 

 thejoteum of Fries. This was the judgment of our American col- 

 league. Professor A. P. Morgan whose work in this group is widely 

 recognized. Fries admits, Syst. Myc, III., p. 142, that while he 

 deems P. thejoteum very distinct, he yet has not seen P. virescens 

 Ditm. ! Since our form apparently does not occur in Europe, speci- 

 mens which the distinguished author had before him were doubtless 

 representatives of the now commonly recognized species of Ditmar. 



For these reasons it seems appropriate to give the American type a 

 suitably descriptive title. 



17. Physarum megalosporum Sturg. 



Plate XVI., Figs, 7 and 7 a. 

 1917. Physarum megalosporum Sturgis, Mycologia, Vol. IX., p. 3. 



