DiDERMA 95 



Type locality: France. 



Habitat: On dead leaves, twigs, and plant stems, occasionally 

 on wood. 



Distribution: Throughout North America; not uncommon. 



Illustration: Lister, Mycetozoa ed. 3. pi. 83, figs. a-e. 



The small colonies are not uncommon on leaf piles in company 

 with other leaf species. Sessile phases, resembling and approach- 

 ing subglobose sporangia of D. effusum, may be recognized by 

 traces of stalks, or the central attachments of the sporangia to the 

 habitat. 



3. Diderma effusum (Schw.) Morg. Jour. Cin. Soc. Nat. Hist. 

 16: 155. 1894. 



Physarum effusum Schw. Trans. Am. Phil. Soc. II. 4: 257. 1832. 

 Didymium reticulatum Rost.; Fuckel, Symb. Myc. Nachtr. 2; 73. 1873. 

 Chondrioderma reticulatum Rost. Mon. 170. 1874. 



Plasmodium white (Lister). Sporangia sessile, gregarious or 

 crowded, depressed, smooth, white or nearly so, either rounded, 

 0.7 mm. diam., or forming elongate and flat, simple or branching, 

 net-like or effused plasmodiocarps, up to 6 cm. long and 1 cm. 

 broad, or more; sporangial wall of two layers, the outer a fragile 

 crust of globular lime-granules, separating from the membranous, 

 colorless, inner layer. Columella pulvinate, depressed, brownish 

 flesh-colored, enclosing white lime-granules. Capillitium consist- 

 ing of delicate, colorless or pale purplish threads, sparingly 

 branched and anastomosing. Spores pale violet-brown, nearly 

 smooth, 6-10 /i diam. 



Type locality: Salem, North Carolina. 



Habitat: On dead leaves, sometimes on wood. 



Distribution: Common and abundant throughout North 

 America. 



Illustration: Lister, Mycetozoa ed. 3. pi. 83, fig. f. 



The method of Lister in broadening the description to include 

 all variations in form is accepted. The species as described by 

 Schweinitz is restricted to the effused and applanate plasmodio- 

 carps which are not so common, and the other phases collected in 

 greater abundance, and surely more representative, are treated 

 by other students as var. reticulatum. Similar conditions of 

 sporangia and plasmodiocarps exist in many other species, and 

 with our greater knowledge of the group, the present trend is to 



