234 



UNIVERSITY OF COLORADO STUDIES 



Spores ferruginous or pale reddish-brown. 



Spores 8 to 9 M diameter fusca var. rufescens Lister. 



Spores 4 to 5 M diameter ferruginea Ehrenb. 



S. smUhii Macbride, which is included by Sturgis, following Lister, in 5. ferruginea, 

 is common in Boulder County, as I am informed by Mr. Bethel. The Plasmodium 

 is white or greenish-white. 



(24) Comatricha Preuss. Sporangia globose or cylindrical; no distinct surface 

 net. C. nigra (Pevs.), and var. cBqualis (Peck); C. laxaRost.; C. typhina (Wigg.); 

 C. irregularis Rex; all Boulder. 



C. nigra var. suksdorfii (Ellis and Ev.). Yankee Doodle Lake, Tolland, etc. 

 According to Macbride C. typhina should be called C. stemoniiis (Scopoli). 

 The following key is partly based on that of Macbride: 

 Capillitium very lax, the branching open. 



Spores nearly smooth; sporangium minute, ovate . . . . C. laxa. 



Spores spinulose C. irregularis. 



Capillitium dense. 



Sporangia very small, i to 2 mm. diameter, cylindric, stipitate C. stemonitis. 



Sporangia very small, spherical or ellipsoidal C. nigra. 



Sporangia larger. 



Sporangia black C. suksdorfii. 



Sporangia pale ferruginous C. aqtialis. 



(25) Enerthenema Bowman. Sporangia globose; capillitium springing from apex 

 ot columella only. E. papillata (Pers.). 



Order CRIBRARIACEM 



Sporangium wall membranous, beset with microscopic round plasmodic granules; 

 capillitium wanting; spores pallid or brown. 



Family CRIBRARIID.S 



(26) Cribraria Persoon. Sporangium wall forming a persistent irregular net; 

 sporangia stalked. C. argillacea Pers. (sporangia clay-colored) and C. mitiutis- 

 sima Schw. (sporangia brown or rufous, very small). 



Order RETICULARIACEM 



Sporangia combined into an sethaHum; their walls incomplete, perforated or form- 

 ing a spurious capillitium (Lister). 



Family RETICULARIID^ 



(27) Dictydiaethalium Rost. Sporangia columnar, their walls represented by 4 

 to 6 straight threads extending from base to apex; externally only the flattish 

 slate- or clay-colored aithalium is seen, the apices of the sporangia producing a 

 minute areolation. D. plumbeum (Schum.). Spores pale yellow, spinulose. 



(28) Enteridium Ehrenberg. Not unlike the last, but sporangium walls with 

 large round perforations. E. rozeanum Wingate (splcndens Morgan). Cortex 

 brown, smooth and shining; spores with about two-thirds of the surface reticulate. 



