64 THE NORTH AMERICAN SLIME-MOULDS 



Sporangia gregarious, sessile, or short stipitate depressed, annulate, 

 or at least umbilicate above, white or anon roseate, about .75 mm; 

 stipe, when present, short, thick, black or dark brown! hypothallus 

 none ; columella none ; cspillitium strongly calcareous, an abundance 

 of irregular white nodules burden the delicate net ; spores dark sooty 

 brown with a shade of purple by transmitted light, verruculose, 

 12-13 fji. 



This species is recognizable at once by its regular, uniform, de- 

 pressed, annulate or pitted sporangia, scattered evenly over the habitat 

 of rotten leaves or wood. It suggests a didymium in its form and 

 habit, but is near a badhamia. Colorado; Bethel, 1908. 



18. Physarum confertum Macbr. nom. nov. 



Plate XV., Figs. 1, 1 a, 1 h. 



1899. Physarum atrum Schw., Macbr., A^. A. S., p. 36. 



1911. Physarum atrum Schw., Lister, Mycetozoa, 2nd ed., p. 74. 



Sporangia small about .2-.3 mm. in diameter, gregarious, confluent, 

 clustered or heaped, dull violaceous brown ; peridium thin, more or 

 less transparent, generally limeless but sometimes lightly sprinkled 

 with minute white flecks: capillitium scanty, the calcareous nodes 

 small, rounded, elongate, white ! columella none ; spores violet-brown, 

 distinctly warted, 10-12 fx. 



Having been assured on information believed trustworthy that the 

 Schweinitzian herbarium confirmed the identity of the species before 

 us, in the first edition of this work the form was listed as P. atrum 

 Schw. Meantime in the herbarium referred to, at Philadelphia the 

 original type of P. atrum still exists. My valued correspondent, 

 Mr. Hugo Bilgram, has recently given it careful study. It is a lime- 

 less P. didermoides (Pers.) R. ! Small wonder we have had trouble! 

 Exit Physarum atrum Schw. 



The species is not uncommon, especially eastward ; has been gen- 

 erally ignored for reasons cited. 



Distinguished from everything else by the color and small size 

 of the heaped sporangia. It resembles some phase of P. virescens 

 where the sporangia are small and somewhat heaped or rather aggre- 



