212 MYXOMYCETES. 



D. umbilicatum. Schrod. 



Sporangia, umbilicate, veins parallel, jointed by others 

 which are transverse ; spores purplish brown ; about the size 

 of a large pin's head, pendant, stipitate, stipe glossy. 



Common on old stumps. 



Genus VI DIDYMIUM. 



Sporangium with a membranaceous inner peridium, bursting 

 irregularly ; externally clothed with a crust-like outer perid- 

 ium, which breaks into furfuraceous scales. 



D. furfuraceum. Fr. Scurfy Didymium. 



Sporangia, floccose, whitish, columella none, stem short, 

 whitish, even ; spores blackish. 

 Common on oak branches lying on the ground. 



D. xanthopUS. Fr. Yellow-stem Didymium. 



Sporangium, globose, brown, whitish ; stipe elongated, 

 even, yellow ; columella also stipitate into the sporangia. 

 On dead oak leaves. 



D. cinereum. Fr. Ash-grey Didymium. 



Sporangia, sessile, globose, whitish, covered with an 

 ashy grey scurf ; spores black. The size of a pin's head. 

 Common on fallen oak leaves. 



Genus VII. I,YCOGAI,A. Mich. 



a^thalium semiglobular, covered with a double membrane, 

 persistent, bursting irregularly at the apex, externally warty 

 or furfuraceous. Flocco adnate to the wall of the peridium. 



