142 



Mycetozoa of North America 



ties, the more common ones are included in the analysis of the 

 genus as centers around which the forms may be grouped. 



Spores reticulate. 



Spores reticulate with spines or warts. 



Sporangia large, dark; spores more or less promi- 

 nently reticulate. 

 Sporangia small, pale, appearing superlicially like 

 Comatricha typhoides; spores faintly reticulate. 

 Spores reticulate with raised bands. 



Sporangia brown, usually on wood in small groups; 



spores pale, uniformly and regularly reticulate. 

 Sporangia almost black, in small clusters but large 

 developments on leaves and moss; spores dark, 

 often imperfectly reticulate. 

 Spores not reticulate. 



Sporangia confluent, small, black, in small clusters. 

 Sporangia not confluent. 



Meshes of the surface-net usually large. 

 Spores free. 



Spores clustered, adherent. 

 Meshes of the surface-net small. 



Sporangia brown, often on leaves in large tufts; 



surface-net smooth, even along the edge. 

 Similar to S. herbatica but sporangia on wood, 

 erect and in small tufts; surface-net paler and 

 uneven. 

 Sporangia usually on leaves and stalks, reddish ; 

 surface-net spinose and with expansions in the 

 capillitium; spores pale, 7-9 /*• 

 Sporangia on wood, reddish; surface-net smooth; 

 spores nearly colorless and smooth, 4-6 tx. 



1. S.fusca 



2. S. hyperopia 



3. S. virginiensis 



4. S. trechispora 



5. 5. confluens 



6. S. splendens 



7. 5. uvifera 



8. 5. herbatica 



9. S. pallida 



10. S. flavogenita 



11. 5. axifera 



1. Stemonitis fusca Roth, Mag. Bot. Roemer & Usteri 1 (2): 

 26. 1787. 



Stemonitis dictyospora Rost. Mon. 195. 1874; Rost. Mon. App. 27, 1876; 

 Macbr. N. A. Slime-Moulds ed. 2. 161. 1922. 



Plasmodium white (Lister). Total height 5 to 20 mm. Spo- 

 rangia cylindrical, obtuse, stalked, brownish purple or almost 

 black, usually in large clusters, sometimes scattered. Stalk 

 black, shining, 1 to 4 mm. high, rising from a brown, membranous 

 hypothallus. Columella reaching nearly to the top of the spo- 

 rangium. Capillitium of dark brown threads springing from all 

 parts of the columella, combined into a loose network, the ulti- 

 mate branches forming a delicate smooth or spinose surface-net 

 with angular, unequal meshes, varying from 6-16 /x wide. Spores 



