146 THE MYXOMYCETES 



Family STEMONITACE^ 



Fructification aethalioid or of separate and distinct sporangia; 

 capillitium usually abundant, typically in the form of dividing and 

 anastomosing branches arising from all parts of the columella, the 

 latter sometimes lacking or indistinct; hypothallus membranous, often 

 common to a group of sporangia. The first two genera are of doubtful 

 affmity with the others. 



KEY TO THE GENERA OF THE STEMONITACE^E 



a. Stipe and columella calcareous, rarely waxy 1. Diachea 



a. Wholly non-calcareous b 



b. Fructification aethalioid c 



b. Fructification sporangiate e 



c. Capillitial threads unbranched, united into columnar cords 



and attached to both base and peridium; columella lacking. ... 2. Schenella 



c. Capillitium branched, dendroid d 



d. Columellas obscure or lacking; capillitium not vesicular. . . 3. Amaurochcete 

 d. Columellas distinct above, merging below; capillitium vesic- 

 ular 4. Brefeldia 



e. Tips of capillitial branches united to form a more or less com- 

 plete surface net 5. Stemonitis 



e. Surface net lacking, or scantily and imperfectly developed .... 6. Comatricha 



1. Diachea Fries 

 Syst. Orb. Veg. 1 : 143. 1825. 



Sporangia distinct, globose or cylindric, usually stipitate; peridium 

 thin, iridescent; stipe and columella charged with lime, white to orange, 

 rigid, thick, tapering upward; capillitium of delicate threads free from 

 lime, radiating from various points on the columella, branching and 

 anastomosing as in Comatricha to form a more or less intricate net- 

 work, the ultimate branchlets supporting the peridial wall. 



Rostafinski placed this genus near the Didymieae on account of the 

 calcareous columella and the non-calcareous capillitium. On the other 

 hand the structure of the capillitium and the iridescent simple peridium 

 ally Diachea to Lamproderma and the Stemonitaceae, the only dis- 

 tinction being the calcareous stem. It is simply an intermediate genus 

 to be placed here more conveniently than anywhere else in what is of 

 necessity a linear arrangement. 



KEY TO THE SPECIES OF DIACHEA 



a. Lime deposits white b 



a. Lime deposits orange, or lacking / 



b. Sporangia typically cylindrical I. D. leucopodia 



b. Sporangia ovate, globose or hemispherical c 



