94 THE NORTH AMERICAN SLIME-MOULDS 



capillitium dense, persistent, the nodes frequently calcareous, elon- 

 gate and vertical, especially below, yellow; spore-mass brown; spores 

 by transmitted light, bright violaceous-brown, slightly papillose, 9- 



10 IX. 



This species is instantly distinguishable from all cognate forms by 

 its peculiar sooty color. Not less is the species structurally marked 

 by its capillitium. The latter below is exactly as in the species of 

 Tibnadoche. Indeed, the present species unites characters supposed 

 to distinguish Physariim from Tilmadoche, and would so far justify 

 those authors who bring all the species of both genera together under 

 one generic name. In any case the species is by its capillitium en- 

 tirely distinct from P. galbeum, as well as by the structure of the stipe 

 and the peridial surface. The Plasmodium, at first watery, emerges 

 from decayed elm logs and soon takes on a peculiar greenish tint pre- 

 served somewhat in the mature fruit. 



Rostafinski, Monograph, pp. 105, 106, rejects Berkeley's specific 

 name, flavicomum, because it refers to the somewhat indefinite, char- 

 acteristic color. As this is no valid reason for change, we have re- 

 stored Berkeley's specific name, which by general consent has priority. 

 N. A. F., 3299. 



Not common. New Jersey, Ohio, South Carolina, Iowa. 



52. Physarum bethelii (Macbr.) Lister. 



1899. Tilmadoclie betlielii, Macbr., Exempt, ad Herbaria. 



1911. Physarum gyrosum Rost, List., Mycetozoa, 2nd ed., p. 75. 



Sporangia scattered, globose, umbilicate below, .5—1 mm. in diam- 

 eter, iridescent blue, or sometimes tinged by the presence of delicate 

 pale yellow calcareous scales, stipitate; stipe rather short, black or 

 dark brown, equal ; capillitium dense, radiating from the black, 

 slightly intrusive summit of the stipe, and from the base of the 

 peridium ascending; the nodules not numerous, elongate, branching 

 betimes, pale yellow; spores minutely roughened, 10-12 ju. 



This beautiful delicately tinted little species is clearly tilmadochoid 

 in the Friesian sense. The capillitium persists after the fall of the 

 upper filmy peridium, adherent below to the persisting peridial base. 

 Collected thus far twice only; by Professor Bethel and by Professor 

 Sturgis, Colorado. 



