144 THE MYXOMYCETES 



7. Leptoderma G. Lister 

 Jour. Bot. 51 : 1. 1913, 



Fructification sporangiate, the walls membranous above, thickened 

 with dark granular deposits below; calcareous deposits restricted to 

 scales embedded among the basal granules; capillitium netted; spores 

 purplish gray. 



A single species: 



Leptoderma irtdescens G. List. 



Jour. Bot. 51 : 1. 1913. 



Sporangia scattered or loosely clustered, subglobose, sessile or rarely 

 short-stalked, grayish purple, glossy, iridescent, 0.5-0.8 mm. in di- 

 ameter; sporangium wall nearly hyaline above, purplish below, where 

 it is thickened with granular deposits and refuse material, often in- 

 cluding crystalline flakes of lime 2-15 li in diameter; stalk, when pres- 

 ent, stout, dark, spreading below into a dark hypothallus; columella 

 present or absent, dark and convex when present; capillitium a persist- 

 ent network of arching or flexuose dark purple threads radiating from 

 the base, the tips and bases colorless or pale, the latter often expanded 

 or tubular and sometimes enclosing granular matter; spores purplish 

 gray, spinulose, 10-11 fx. Plasmodium gray or drab. 



Certain collections from Oregon and California possibly represent 

 somewhat aberrant forms of this species. The fructifications vary 

 from subglobose sporangia to short plasmodiocarps. The lime is re- 

 stricted to the basal portion or even to the hypothallus, but does show 

 occasional crystalline plates. The spores are a trifle large, 11-13 fx. 



Oregon? California? Europe. 



Order STEMONITALES 



Fructification wholly non-calcareous, except in a single genus 

 (Diachea) in which the stipe and columella, but neither the capil- 

 litium nor the peridium, are calcareous; capillitium threadlike, of 

 anastomosing branches either arising from a well-developed columella 

 or radiating from the base; spores in mass usually black or purple- 

 brown, less commonly ferruginous. 



TCF. V TO THE FAMILIES OF THE STEMONITALES 



a. Outer wall of peridium gelatinous; sporangiate; columella 



lacking Collodermace^e 



a. Peridium membranous, often early fugacious; aethalioid or 



