194 THE NORTH AMERICAN SLIME-MOULDS 



cence, stipitate; stipe short, black, tapering rapidly upward, annulate 

 with the persisting base of the peridium ; columella short, thick, trun- 

 cate, and widened at the top; hypothallus well developed, brown or 

 purple ; capillitium dense, made up of dark brown branches, numerous 

 and rather slender, repeatedly branched and anastomosing toward the 

 surface to form a slight delicate network with abundant free ends; 

 spores dark purple brown, rough, 14-16 fi. 



This species in outward appearance resembles L. physarotdes, from 

 which it is easily distinguished by the much greater diameter of the 

 globose sporangium, 1 mm, or more. The persistent base of the 

 peridium is also characteristic, very prominent sometimes, and visible 

 to the naked eye. The capillitium is also unlike that of L. physa^ 

 roides; resembles more nearly that of L. violaceum. From the latter 

 species L. robustum is distinguished by the color of the peridium, and 

 by the larger, darker spores and generally different capillitium. In 

 our former edition this is called L. sauteri Rost. That much-quoted 

 author distinguished L. violaceum and L. sauteri; the English authors 

 make the last named a variety only of the former. This our Amer- 

 ican species is not. 



It is, as presented in our western mountains, clear-cut, well defined, 

 not a variety of anything. The original name is therefore restored. 



Lamproderma arcyrioides (Somm. ) Morgan is probably a form of 

 L. columbinum. The original L. arcyrioides has not yet been cer- 

 tainly identified in North America ; see following species. 



Colorado, Oregon, Washington, California. 



3. Lamproderma columbinum (Pers.) Rost. 



1796. Physarum columbinum Pers., Obs. Myc, I., p. 5. 

 1875. Lamproderma columbinum Rost., Mon., p. 203. 



Sporangia scattered, gregarious ; rich violet or purple with metallic 

 iridescence, globose, stipitate; the stipe long, three-fourths the total 

 height, slender, subulate, black ; hypothallus scant, purplish or brown ; 

 columella small, one-third the height or less, tapering or acute, black; 

 the capillitium brown throughout, not dense, arising from nearly all 

 parts of the columella, freely branching and anastomosing to an open, 

 large-meshed network; spore-mass black, spores by transmitted light 

 dark brown, rough, 10-12 fi. 



