54 THE NORTH AMERICAN SLIME-MOULDS 



forms opening at first to display an inner peridium; forms globose 

 with narrow base, but apex cleft, and forms ellipsoidal, yet compressed, 

 opening like the gaping of some tiniest bivalve; did not Persoon say 

 P. bivalve! all are bivalvular at the last! Nay; but what are these? 

 Here are some of the shorter forms become suddenly obovate, and 

 are actually mounted on stipes! Surely variation in the same Plas- 

 modium can no farther go!^ 



Not rare. Colorado to the Pacific Coast. Evidently a western- 

 American variation of Bulliard's European type. The latter occurs 

 abundantly in Iowa on the shores of Lake Okoboji; otherwise not 

 common. 



6. Physarum bogoriense Racib. 



1898. Physarum bogoriense Raciborski, Hedw., XXXVIL, p. 52. 



Sporangia sessile, elongate, creeping but not reticulate, semicircular 

 in transverse section, sometimes globose or depressed globose ; peridium 

 double, the outer thick coriaceous, yellow or brown, dehiscing stellate- 

 ly into persistent more or less triangular reflected lobes, remote from 

 the thin, colorless inner wall; columella none; capillitium feebly de- 

 veloped, the nodes white, large, isodiametric ; spores bright violet, 

 smooth, 7-8 fx. 



This species is not uncommon in the mountains of Colorado where 

 it has been taken at various stations by Bethel. It is reported from 

 Pennsylvania and South Carolina. Raciborski describes it from Java. 



In habit it is very much like some forms of P. sinuosum but differs 

 in the depressed, rather than compressed sporangia, and in the brown 

 color of the outer peridium. 



7. Physarum alpinum G. List. 



1910. Physarum alpinum G. Lister, Jour. Bot., XLVII., p. 73. 



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 



1 See also Inauff. Diss., H. Ronn, Schr. d. Naturiv. Ver. f. Schl. Hoist., XV., 

 Hpt. I., p. 55, 1911. 



