72 THE NORTH AMERICAN SLIME-MOULDS 



28. Physarum nucleatum Rex. 



1891. Physarum nucleatum Rex., Proc. Phil. Acad., p. 389. 



Sporangia gregarious, spherical, ^ mm., white, stipitate; peridial 

 wall membranaceous, rupturing irregularly, thickly studded with 

 rounded white lime-granules ; stipe about 1 mm., subulate, yellowish- 

 white, rugose; columella none, capillitium dense, snow-white, with 

 minute, white, round or rounded nodes, in the cientre a conspicuous 

 mass of lime forming a shining ball, not part of the stipe although 

 sometimes produced toward it ; spore-mass black ; spores brown-violet, 

 delicately spinulose, 6-7 //,. 



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 capillitium. Ex- 

 ceptionally 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. 



29. Physarum wingatense nom. nov. 



Plate XVI., Figs. 3, and 9. 



1876. Tilmadoche columbina (Berk. & C.) Rost, Mon., App., p. 13 (?). 



1889. Tilmadoche compacta Wing., Proc. Acad. Nat. Sci., p. 48. 



1894. Physarum compactum List., Mycetozoa, p. 45. 



1896. Physarum compactum (Wing.) Morg., Jour. Cin. Soc, p. 91. 



1899. Tilmadoche compacta Wing., Macbr., N. A. S., p. 61. 



1916. Physarum columbinum (Rost.) Sturg., Mycologia, Vol. VIII., p. 4. 



Sporangia gregarious, or somewhat crowded, erect or cernuous, 

 stipitate, gray or brownish gray, globose; peridium thin, metallic 

 brown or bronze in color, splitting at maturity in floriform manner 

 into six to twelve segments; stipe white or yellowish white, often 

 shading to black or fuscous below, rather long, tapering upward; 

 hypothallus none; columella none; capillitium extremely delicate, 

 white or colorless, radiating from a central lime-mass or nucleus, 

 and with ordinary nodules small and few, fusiform; spore-mass 



