62 THE NORTH AMERICAN SLIME-MOULDS 



p. 8, he changed the name, writing P. ditmari, on the ground that 

 virescens was descriptive of a character to which the species in question 

 occasionally refuses to conform. Most authors since Rostafinski have 

 simply accepted his suggestion, so that the species is often entered 

 P. ditmari Rost. P. virescens is certainly to be preferred. N. A. F., 

 2692. 



Canada, New England, New York, Pennsylvania, Ohio, Iowa, 

 Black Hills, South Dakota. 



15. Physarum rubiginosum Fries. 



1817. Physarum rubiginosum Fries, Symb. Gast., p. 21. 



Plasmodium scarlet. Sporangia globose or cylindric, sessile or some- 

 times narrowed to a stem-like base as if short-stipitate, olivaceous 

 brown with sometimes a flush of red ; the peridium simple, thin rugu- 

 lose or plain, the calcareous scales few, or apparently included; 

 columella none ; capillitium dense, the nodules rather large, angular, 

 rusty brown; spores dull violaceous, gently roughened, about 10 /x. 



A beautiful well-marked species, but evidently rare in North Amer- 

 ica. Our only typical specimens are from the gatherings by Mr. 

 Wingate, part of which is by Lister referred to this species, Myce- 

 tozoa, 2nd ed., p. 82. 



P. rubiginosum Fr. in the N. A. S., 1899, is based on certain west 

 coast specimens now known as Badhamia decipiens Berk. 



In Colorado there occurs a plasmodiocarpous form of the species. 

 It has the characteristic spore and capillitium but in form and habit 

 differs very decidedly. The fructification is a delicate netted plas- 

 modiocarp, the tubule about .5 mm., bright red ; the peridium simple, 

 cartilaginous, dehiscent from above, and flecked with just here and 

 there a red calcareous scale. 



Collected at Palmer Lake ; Professor Bethel. 



16. Physarum instratum Macbr. n. s. 



1899. Physarum thejoteum Macbride, A'^. A. S., p. 36, not Fries, as cited. 

 1911. Physarum virescens Ditmar, Lister, Mycetozoa, 2nd ed., p. 83. 



Sporangia very small, closely crowded on a delicate, more or less 



