PHY S ARUM 65 



gated, and scantily supplied with lime; but in such case the lime is 

 yellow and the spores are small. 



This species has also been constantly referred to our confused P. 

 cinereum, P. plumbeum, etc., but Schweinitz, who certainly had seen 

 P. cinereum in Europe, since he cites it, under several forms, in the 

 Conspectus, found the species in America and proceeded in Pennsyl- 

 vania in December to find something else, very different as he thought, 

 and in fact. He called this new discovery P. atrum, "beautifully 

 reticulate" , he says "like P. cinereum but larger." 



Most American students in an effort to keep faith with their pioneer 

 mycologist, have taken cue from the specific name, looking for some- 

 thing black, heedless that in Pennsylvania almost any delicate thing 

 has 'dark looks' in the middle of the winter! Berlese in Saccardo 

 Syll. VII., p. 350, regarding P. atrum as a synonym, writes for the 

 black American specimens, P. reticulatum, emphasizing another 

 Schweinitzian descriptive adjective. But P. atrum Schw. has had 

 place in literature to this hour. 



19, Physarum melleum (Berk. &' Br.) Mass. 



1873. Dydymium melleum Berk. & Br., Jour. Linn. Soc, XIV., p. 83. 



1873. Didymium chrysopeplum Berk. & C, Grev., II., p. 53. 



1876. Physarum schumacheri Spr. van melleum Rost., Mon., A pp., p. 7. 



1892. Physarum melleum Massee, Mon., p. 278. 



1896. Cytidium melleum (Berk. & Br.), Morg., Jour. Cin. Soc, p. 83. 



1899. Physarum melleum (Berk & Br.) Mass., Macbr., N. A. S., p. 47. 



1911. Physarum melleum Mass., Lister, Mycetozoa, 2nd ed., p. 46. 



Sporangia scattered, stipitate, globose, flattened below, clear yellow 

 or honey colored ; stipe short, about equaling the sporangium, pure 

 white, somewhat wrinkled ; columella small but distinct, white ; hypo- 

 thallus none, capillitium abundant, open, snow-white, with rather 

 large angularly stellate nodes; spore-mass brown, almost black; spores 

 by transmitted light, pale violet or lilac-tinted, almost smooth, 

 7.5-10 /x. 



Easily distinguished by its white stipe, columella and capillitium in 

 contrast with yellow peridial walls. N. A. F., 1395. Massee refers 

 this number erroneously to P. schumacheri Rost. The description 



