230 THE MYXOMYCETES 



The operculum is distinctive. It may be doubted, however, whether 

 the distinctions between the two are of more than specific value. 

 Iowa; Austria, Poland. On coniferous and frondose wood. 



4. Orcadella Wingate 

 Proc. Acad. Nat. Sc. Phila. 1889 : 280. 



Sporangia stalked, stipes rigid, unpolished, blending above with the 

 substance of the thick unpolished walls; the operculum thin, delicate, 

 membranaceous. 



A single species: 



Orcadella operculata Wingate 



Proc. Acad. Nat. Sc. Phila. 1889 : 280. 

 PI. XVI, Figs. 399, 400. 



Sporangia scattered, gregarious, ellipsoidal, ovoid, obconical or 

 nearly globose, dull brown or blackish, 0.4-1 mm. tall, the sporangium 

 0.1-0.3 mm. in diameter; wall simple, thick, coarse, at the top replaced 

 by a delicate, thin, yellowish, iridescent, lustrous or vernicose mem- 

 brane which forms a circular, smooth or wrinkled lid, soon deciduous; 

 stipe of varying height, rough from deposit of plasmodic refuse; spores 

 in mass yellowish, colorless under the lens, globose, smooth, 8-11 /x. 

 Plasmodium deep orange. 



This curious little species, well described by its discoverer, appears 

 to be very rare. At least it is seldom collected ; perhaps overlooked by 

 reason of its minuteness. It is a stipitate licea, or a lid-covered cri- 

 braria; perhaps nearer the former. It occurs on the bark of various 

 trees, sometimes associated with Clastoderma debaryanum. 



Maine, Vermont, Pennsylvania, Iowa; Europe, Japan. 



Var. sessile, G. Lister, Mycetozoa ed. 3. 186, 1925, is, as the name 

 implies, a stalkless variety, known from England only. 



Family TUBIFERACE^E 



Sporangia cylindrical or elliptical, clustered, the clusters sessile or 

 stalked; sporangium wall membranous, without plasmodic granules; 

 pseudocapillitium and columella or true capillitium sometimes present. 



KEY TO THE GENERA OF THE TUBIEERACE,E 



Sporangia cylindrical, densely clustered, sessile or on a stalk-like 

 hypothallus 1. Tubifera 



Sporangia ovate, in a loose cluster on a common stalk; capillitium a 



tuft of bristle-like tubes 2. Alwisia 



