Physarum 73 



form. P. Serpula is sometimes difficult to distinguish from 

 P. sulphureum var. sessile, but the plasmodiocarps of P. Serpula 

 are usually longer, narrower, and brighter in color. 



54. Physarum aeneum (Lister) R. E. Fries, Arkiv Bot. 1: 62. 

 1903. 



Physarum murinum Lister var. aeneum Lister, Jour. Bot. 36: 117. 1898. 



Plasmodium? Sporangia sessile, subglobose, or forming 

 straight or curved, simple, branched or netted plasmodiocarps, 

 0.3 to 0.4 mm. diam., brown, yellowish brown, or bronze colored, 

 glossy; sporangial wall of two layers, the outer cartilaginous, 

 brown, brittle with deposits of lime-granules, separating and fold- 

 ing back above from the shining or iridescent, membranous, inner 

 wall. Capillitium a network of hyaline threads with numerous, 

 small, rounded or angular, dark or pale brown lime-knots, occa- 

 sionally uniting to form a pseudo-columella. Spores pale brown- 

 ish lilac, nearly smooth, 6-10 ju diam. 



Type locality: Dominica. 



Habitat: On dead leaves, twigs, etc. 



Distribution: Kansas, Louisiana, New York, Virginia, *West 

 Indies. 



Illustration: Lister, Mycetozoa ed. 3. pi. 58. 



This species is the only Physarum regularly forming plasmo- 

 diocarps and with brown lime in the capillitium. 



55. Physarum rubiginosum Fries, Symb. Gast. 21. 1818. 



Plasmodium orange-red (Lister). Sporangia sessile, grega- 

 rious or clustered, subglobose, 0.5 to 1 mm. diam., smooth or 

 rugulose, and scarlet, red, or brown; sporangial wall membranous, 

 with dense included clusters of red or orange lime-granules. 

 Capillitium an abundant network of hyaline threads with frequent 

 triangular expansions at the axils, and large, angular, branching, 

 red or brown lime-knots, occasionally white and only partially 

 colored. Spores pale violet-brown, minutely spinulose, 8-11 n 

 diam. 



Type locality: Europe. 



Habitat: On dead wood and mosses. 



Distribution: Colorado, Florida, Iowa, Maine, *New Hamp- 

 shire, New Jersey, New York, *Ohio, ^Ontario, *Pennsylvania, 

 Quebec, *Washington. 



