88 THE NORTH AMERICAN SLIME-MOULDS 



ering to the Physarum auriscalpium Cke. as found in New York. 

 Under this caption a specimen was later sent to Mr. Lister, who has, 

 as we see, consistently regarded the thing as a variety of P. virescens 

 Ditmar, P. nitens List. 



Meantime in 1898 Colorado material from Professor Bethel 

 reached the University. This did not recall any of the materials sent 

 from Ellis. Diderma albescens had meanwhile come again from 

 California, and been recognized as Diderma niveum Rost. 



Accordingly, in A''. A. S. the latest arrival from Colorado was 

 described as a new species, and with some temerity perhaps, offered 

 as a second species of the hitherto monotypic Leocarpus, all on ac- 

 count of the peculiar capillitium. Sometime after publication our 

 most valued correspondent Mr. Bilgram called attention to the re- 

 semblance between the Colorado and Louisiana material already 

 referred to. The University specimens as stated were small, broken, 

 and in every way poor, but enough remained to indicate the evident 

 justice of our correspondent's suspicion. Further investigation of the 

 Holway material in Philadelphia showed that it too was entitled to 

 consideration! Inasmuch as the Holway sending was all from one 

 Plasmodium, all difficulties vanished at once. The Iowa gathering 

 showed two phases: one at the University represents P. nitens, phy- 

 saroid, single-walled ; while the Philadelphia part of the gathering 

 corresponds, poorly it is true, but in fact, as now appears, to the 

 form coming in perfection from Colorado; leocarpine in structure, 

 published as Leocarpus fulvus; P. fulvum Lister. Since the combi- 

 nation P. fulvum is already in use, synonym of P. rubiginosum, it 

 seems better to write the name suggested by Ellis; Physarum al- 

 bescens never having been published, because Diderma albescens, as 

 noted took care of itself. 



Since Rostafinski w^e separate all these physaroid forms chiefly by 

 capillitial characters : capillitial structure separates genera. Physarum 

 diderma is a physarum despite its double wall. And so here Leo- 

 carpus was set out by its differentiating capillitium. In good speci- 

 mens of the present species a large part of the capillitial net is en- 

 tirely free from lime, so that when the peridium first opens at the 

 summit, sometimes no trace of lime appears; the calcareous deposits 

 are below, and tend to occupy not the nodal intersections as in 



