202 THE NORTH AMERICAN SLIME-MOULDS 



number of sporangia produced by one plasmodium is in Iowa also 

 small. The larger specimens might be mistaken for species of Peri- 

 chaena, but are easily distinguished by the regular and lobate de- 

 hiscence. The Plasmodium is yellow. 



Dr. George Rex, in almost the last paper from his hand, gives an 

 interesting account of this diminutive species. Among various gath- 

 erings studied he found a black variety, a melanistic phase, so 

 to say, and was able to follow the evolution of the sporangia from the 

 yellow Plasmodium. The sutures by which the peridium opens, first 

 show signs of dififerentiation by change of color from yellow through 

 garnet to black. Later the entire wall undergoes similar color changes, 

 beginning next the completed sutural delimitations. Of the open 

 peridia, the reflexed segments remind one of certain didermas, as 

 D. radiatum. See Bot. Gaz.. Vol. XIX., p. 399. 



New England, New York, Pennsylvania, Iowa. 



4. LiCEA PUSILLA Schrader. 



1797. Licea pusilla Schrad., Nov. Gen. PL, p. 19, tab. VI,, f. 4. 

 1829. Physarum licea Fries, Syst. Myc, III., p. 143. 

 1875. Protoderma pusilla (Schrader) Rost., Mon., p 90. 



Sporangia scattered, gregarious, depressed-globose, sessile on a flat- 

 tened base, dark brown, shining, .5-1 mm. ; peridium thin, dark 

 colored, translucent, dehiscent above by regular segments; spore-mass 

 almost black, spores by transmitted light olivaceous brown, smooth, or 

 nearly so, 15-17 fi. 



Fries, /. c, makes this a physarum, and argues the case at length, 

 evidently with such efficiency that he greatly impressed Rostafinski, 

 who did not make it a physarum indeed, but actually gave it generic 

 place and station of its own; a physarum may do without calcium in 

 the capillitium perhaps, but not be entirely non-calcareous; so he 

 writes Protoderma (first cover) and places the species number 1 on 

 the long list of endosporous forms. Even in his 'Dodatek', or supple- 

 ment, as we should say, he refers to the thing again, but only to 

 correct the inflexional ending of the specific name ; he writes Proto- 

 derma pusillum (Schrader) Rost! 



Schweinitz reports the species for America and Morgan cites 



