152 THE MYXOMYCETES 



minutely echinulate spores, 8-9 ju in diameter, whose origin is not 

 apparent. 



Type collected in the Yosemite valley, California, August, 1903, by 

 T. H. Macbride. Known only from the type collection. 



3. Amaurochsete Rost. 

 Versuch8. 1873. 



Fructification asthalioid, pulvinate; peridium evanescent, leaving 

 after its disappearance a mass of irregular stalks and branches, forming 

 the capillitium complex, seated on a common, dark, membranous 

 hypothallus. Capillitium and spores usually black or dark brown in 

 mass, rarely ferruginous. 



In Amaurochaete the individuality of anything like separate sporangia 

 is not clear. The view afforded, however, by a good vertical section of 

 a well-developed colony or cushion is interestingly arborescent. 

 Ragged, dendroid stems arise, dissipated above into an intricate net- 

 work. The resemblance of the overhead net to that presented by a 

 stemonitis or comatricha is very striking. 



KEY TO THE SPECIES OF AMAUROCHiETE 



a. Capillitium rigid, irregular b 



a. Capillitium soft, woolly, circinate d 



b. Capillitium and spores brown in mass; spores 7.5-9 n, 



pale 1. A.ferruginea 



b. Capillitium and spores black in mass; spores 12.5-15 \x c 



c. Spores spinulose 2. A . fuliginosa 



c. Spores strongly reticulate 3. A. trechispora 



d. Capillitium composed of numerous stout, often columella- 



like branches, giving rise to a dense network 4. A . tubulina 



d. Capillitium composed almost wholly of slender flexuose 



threads 5. A. comata 



1. Amaurochsete ferruginea Macbride & Martin 



Jour. Wash. Acad. Sc. 22 : 89. 1932. 

 PI. XI, Fig. 241. 



iEthalium pulvinate, flat, up to 7 cm. in length and 4 cm. in width; 

 peridium fugacious; hypothallus shining, silvery, extending somewhat 

 beyond the margin of the aethalium; definite columellas lacking, but 

 capillitium branching from numerous rigid irregular branches arising 

 from the hypothallus and soon dissipated into subordinate branches, 

 the threads dark brown, bearing numerous lighter brown irregular 

 membranous expansions; spores cinnamon-drab to benzo-brown 



