48 A Monograph of the Myxogastres. 



On decorticated branches of Alnus incana. Finland. 



Aethalium variable in form, suborbicular or elongated, convex, 

 pulvinate or depressed, 2 5 mm. broad. 



I have had no opportunity of examining the present species. 

 If the spores are minutely warted all over, the species may 

 be distinct, but clustered spores with warts all over are not 

 common ; and remembering the numerous inaccurate descrip- 

 tions in the works of Karsten and Rostafinski in connection 

 with epispore marking, I am inclined to suspect the autonomy 

 of the present species. 



ORCADELLA, Wing. 



Sporangia with coarse stipes; sporangium wall likewise 

 coarse, but at the top of the sporangium replaced by a delicate 

 membrane which forms a more or less flattened deciduous lid. 



Orcadella, Wingate, in Proc. Acad. Nat. Sci. Philada., 1889, 

 p. 280. 



The present genus is considered as the type of a new family 

 of the Myxogastres, described as follows by Mr. Harold Wingate 

 in the article quoted above 



"This curious minute plant presents anatomical character- 

 istics which lead me to propose a new family of the Myxo- 

 mycetes, and which, in Dr. Rostafinski's classification, would 

 come under Order IV., Anemeae, and after Family 13, Clathro- 

 ptychiaccae. 



" Orcadellaccae, fam. nov. 



" Sporangia without columella or capillitium, and the upper 

 part of the coarse sporangium wall replaced by a delicate 

 membrane having a defined outline. 



" This family seems to bridge, to a certain extent, the gap 

 between Rostafinski's orders Anemeae and Heterodeiineae, as we 

 here have a stage between the uniform wall of Licea, Tubulina, 

 &c., and the lacerate upper wall of some species of Cribraria, 

 where the receptacle is strongly developed and covered with 

 minute granulations. The epispore seems to be absolutely 

 without thickenings even under very high magnification." 



