70 Mycetozoa of North America 



wall double, the outer densely charged with white lime-granules, 

 free and deciduous above, recurved and persistent below; inner 

 wall smooth, membranous, pale purplish, more persistent. Capil- 

 litium a network of hyaline threads, with many variously shaped, 

 large, smooth-walled, white lime-knots. Spores 10-12 n diam., 

 dark purplish brown, spinulose, often with a paler, smoother area 

 of dehiscence. 



Type locality: England. 



Habitat: On dead leaves and twigs. 



Distribution: California, Colorado, Kansas, ^Montana, 

 *Ohio, Oregon, *Puerto Rico, *Washington. 



Illustration: Lister, Mycetozoa ed. 3. pi. 51. 



This species is related to P. bivalve, associated therewith occa- 

 sionally, and connected by intermediate forms. Some of these 

 have the external appearance of P. bitectum, but the lime-knots 

 and spores of P. bivalve. In doubtful examples, where the inner 

 wall is not clearly recognizable, the lime-knots and spores are the 

 deciding characters. 



50. Physarum testaceum Sturg. Colo. Coll. Pub. Sc. Ser. 12: 18. 

 1907. (N. Y. B. G. no. 11812, cotype.) 



Physarum Diderma Macbr. N. A. Sllme-Moulds 30. 1899. Not P. Diderma 

 Rost. 1874. 



Plasmodium? Sporangia sessile, subglobose, clustered and 

 polygonal from mutual pressure, 0.7 mm. diam., white; outer 

 sporangial wall white, eggshell-like, separating from the mem- 

 branous and colorless inner wall. Capillitium consisting of 

 numerous large and small, angular, branching, white lime-knots, 

 connected by short, hyaline threads. Spores purplish brown or 

 grayish purple, spinulose, distinctly darker and more spinulose on 

 one side, 8-10 n diam. 



Type locality: Colorado. 



Habitat: On dead wood; not rare. 



Distribution: Colorado, *Iowa, Maine, *Michigan, *Mon- 

 tana, New Hampshire, New York, Ohio, Ontario, *Oregon. 



Illustration: Lister, Mycetozoa ed. 3. pi. 54. 



This species is widely distributed in North America and not 

 rare. The white, shell-like, outer wall is a conspicuous feature. 

 Occasionally, the sporangia have a large, hollow columella, 

 noticed in specimens from Colorado and Ontario. 



