158 THE NORTH AMERICAN SLIME-MOULDS 



threads, a pseudo-capillitium ; spore-mass dark brown or umber, 

 spores by transmitted light pale, globose, reticulate, 7.5-9 /*. 



This is Siphoptychium casparyi Rost. In Bot. Gas., XV., 

 p. 319, Dr. Rex shows that the relationships of the species are 

 with Tubifera ; that the so-called columella is probably an 

 abortive sporangium, the so-called capillitial threads having no 

 homology with the capillitial threads of the true columelliferous 

 forms. It is a good species of Tnbifcra, nothing more. The 

 tubules are shorter than in either of the preceding species ; the 

 spores are darker, larger, and more thoroughly reticulate. 



The plasmodium is given by Dr. Rex, /.c., as white, then 

 "dull gray tinged with sienna color," then various tones of 

 sienna brown, to the dark umber of the mature aethalium. 



New York, Adirondack Mountains ; Allamakee Co., Iowa. 



D. ORCADELLE^E. 



Sporangia distinct, minute, long stipitate, opening above by 

 a distinct lid. 



A single genus, 



Orcadella Wingate. 



1889. Orcadella Wingate, Proc. Phil. Acad., p. 280. 



Sporangia furnished with rigid, unpolished stipes, blending 

 above with the substance of the thick unpolished walls ; the 

 operculum thin, delicate, membranaceous. 



A single species, 



i. ORCADELLA OPERCULATA Wingate. 



PLATE XII., Fig. n. 

 1889. Orcadella operculata Wingate, Proc. Phil. Acad., p. 280. 



Sporangia scattered, gregarious, ellipsoidal, ovoid, obconical 

 or nearly globose, dull brown or blackish, the wall simple, thick, 

 coarse, at the top replaced by a delicate, thin, yellowish, iri- 

 descent, lustrous or vernicose membrane which forms a circu- 

 lar, smooth, or wrinkled lid, soon deciduous; stipe of varying 



