64 Mycetozoa of North America 



ter, scanty, or lacking entirely. When the sporangia have little 

 lime, and are clustered besides, it is often difficult to distinguish 

 them from P. confertum, but the latter species often has irregu- 

 larly ovoid sporangia, which helps somewhat. P. vernum Somm., 

 which has not yet been found in North America, is related to 

 P. cinereum. It forms robust sporangia and large, long, plasmo- 

 diocarps, with thick walls densely charged with lime, and has 

 darker spores. There are phases of P. cinereum with larger and 

 darker spores, but I have seen none from North America that have 

 the massive sporangia and plasmodiocarps of P. vernum. P. ses- 

 sile, as separated by Brandza from a yellow form, is a phase of 

 P. cinereum. 



41. Physarum confertum Macbr. N. A. Slime-Moulds ed. 2. 64. 

 1922. 



Plasmodium yellow or white (Lister). Sporangia subglobose 

 or irregularly obovoid, 0.2 to 0.4 mm. diam., sessile, confluent, 

 clustered, or heaped, dull violet-brown or dark gray, often veined 

 with white or sprinkled with white spots; sporangial wall mem- 

 branous, pale purplish, with scanty deposits of lime. Capillitium 

 a sparse network of hyaline threads with small, angular or branch- 

 ing, white lime-knots, often limeless. Spores pale brownish 

 violet, minutely warted, 10-13 /x diam. 



Type locality: North America. 



Habitat: On dead leaves and wood. 



Distribution: Maine, Massachusetts, New Brunswick, New 

 Hampshire, New York, Ontario, Pennsylvania, Quebec, Virginia. 



Illustration: Lister, Mycetozoa ed. 3. pi. 64. 



This species is practically identical in appearance with P. 

 virescens, only in the latter, the color is yellow or greenish yellow. 

 It is closely related to P. cinereum, but the small sporangia are 

 always heaped in numerous, little clusters. The spores are usu- 

 ally paler and larger than those of P. cinereum, and the lime in the 

 capillitium is scanty, although gatherings with more lime and 

 darker spores are not uncommon. The wall is often entirely 

 limeless, but this is rather a result than a character. The lime is 

 formed on the outside of the wall, and if development takes place 

 in moist places or during wet weather, it may be washed off, so 

 that the sporangia may appear almost black, and more or less 

 imperfectly developed. 



