PHYSARUM 55 



part of the stipe although sometimes produced toward it ; spore- 

 mass black; spores brown violet, delicately spinulose, 6-7 /A. 



This species most nearly resembles in appearance and habit 

 of growth P. globuliferum Pers., but may be distinguished from 

 it by the absence of a columella, by the central ball of lime, and 

 the very small rounded lime granules in the meshes of the capil- 

 litium. Exceptionally the lime granules of the sporangium wall 

 are sparse or absent entirely, in which case the wall has a silvery 

 or coppery metallic lustre. 



Pennsylvania, Nicaragua. 



36. PHYSARUM PENETRALE Rex. 



PLATE XV., Figs. 6, 6 a. 

 1891. Physarum penetrate Rex., Proc. PJiil. Acad., p. 389. 



Sporangia scattered, erect, stipitate, generally ellipsoidal 

 or pyriform, rarely globose ; peridium membranaceous, semi- 

 transparent, studded sparsely with rounded, pale yellow or 

 yellow gray lime granules, rupturing to the base into two to 

 four segments ; stipe variable, slender, subulate, rugose, flattened 

 laterally toward the base, translucent, dull red or golden red in 

 color ; columella four-fifths the height of the sporangium, con- 

 colorous with the stipe, acuminate ; capillitium dense, persist- 

 ent, the nodes frequently calcareous, rounded, yellow ; spore- 

 mass brown, spores, nearly smooth, brownish, 6-7 //,. 



Readily recognizable by the elongate sporangia and the length- 

 ened columella unique among PJiysarums. The capillitial nodes 

 are at first pale yellow, but soon become white on exposure. 

 The spores when highly magnified show delicate spinulescence. 



Maine, New York, Pennsylvania, Ohio, Iowa. 



37. PHYSARUM RUBIGINOSUM Fries. 



1817. Physarum rubiginosttm Fries, Symb. Gast., p. 21. 

 1829. Physarum futoum Fries, Syst. Myc., III., p. 143. 



Sporangia scattered, globose or depressed globose, bright 

 golden yellow or orange, small, 5-7 mm., sessile or short-stipi- 

 tate ; the peridium apparently double, the wall a membrane, 



