PHYSARUM 57 



it is here associated, it is a physarum with the outer seeming of a 

 diderma. It occurs in Europe, therefore it is safe to assume that 

 Rostafinski saw it. So well marked it is that any good description will 

 define it, and Rostafinski describes it perfectly, adequately. 



Mr. Lister having used for another species the name we here apply — • 

 see under P. bitectum — referred this present form to P. didermoides 

 Rost. Professor Sturgis, convinced that such reference was at least 

 doubtful, gave to our American gatherings the distinctive name above, 

 citing specimens from Massachusetts, from Colorado, and from Cali- 

 fornia. Curiously enough he also includes specimens of P. didermoides 

 var. lividum List., sent from England. 



As stated, Mr. Lister first applied the name P. diderma to a plasmo- 

 diocarpous form occurring in England and near P. bivalve. Later, 

 Mycetozoa, 2nd ed., 78, he adopted a new specific name, P. bitectum, for 

 the English specimens, and entered P. diderma as a probable synonym 

 for P. lividum Rost. There is really no more merit in this later com- 

 parison than in that discarded. The species P. diderma is not P. li- 

 vidum, but stands as originally delimited, and will, doubtless, again 

 appear in Europe. 



Rare. Certainly rare in Europe and so far seldom seen in the United 

 States, though widely distributed. Specimens are before us from 

 Maine, New York, Ohio, Michigan, Iowa, Oregon. Reported from 

 Montana. 



21. Physarum alpinum G. List. 



Jour. Bot. 48 : 73. 1910. 

 PI. IV, Figs. 62, 63. 



Sporangia globose and sessile, or plasmodiocarpous, dull yellow, 

 smooth or scaly; peridium double, the outer wall densely calcareous, 

 separating irregularly from the membranous inner wall; capillitium 

 densely calcareous, the nodes large, more or less branched, yellow; 

 spores purple-brown, closely and minutely warted, 9-14 n. 



This species is based by its author upon a gathering made in Cali- 

 fornia by Dr. Harkness and named by Phillips, who received it in 

 England, Badhamia inaurata. He seems not to have described it. 

 Since its first appearance, the form has been found repeatedly in the 

 Juras, whence Meylan reports pale yellow or whitish forms with, 

 however, the typical yellow capillitium. Specimens from Mt. Rainier 

 are believed to be the same. The more strongly marked plasmodio- 

 carpous habit and yellow capillitium separate this from the related 

 P. contextum and P. mortoni. 



California, Washington ; Europe. 



