PHYSARUM 59 



In such a position the slime mold covers, as with a sheath, the entire 

 substratum. The outer peridium, especially its upper part, is entirely- 

 evanescent. Not rare in summer and autumn. 



New England to Washington and Nicaragua, also West Indies; 

 Europe, India. 



24. Physarum mortoni Macbr. 



N. A. Slime-Moulds ed. 2. 58. 1922. 

 PL V, Figs. 72, 73. 



1925. Physarum contextum Pers. var. mortoni G. List., Mycetozoa ed. 3. 60. 



Sporangia gregarious, clustered but distinct, sessile or with short 

 stipe, 0.7-0.8 mm. in diameter, bright ochraceous yellow to pallid; 

 peridium double, the outer layer rough, breaking up into rather few 

 large deciduous scales, the inner whitish, ochraceous or olivaceous, 

 nodular-calcareous, both persisting below to form a distinct cup; 

 capillitium lax, the nodes white, large, angular; columella none; hy- 

 po thallus scanty, colorless; spores dark purplish brown, rather coarsely 

 warted, 11-13 fi. 



A very distinct species, related, no doubt, to P. contextum, but 

 different in habit, character of peridium and with darker, more coarsely 

 warted spores. It is never crowded, is only rarely plasmodiocarpous 

 and the outer peridium is generally deciduous except at the base and 

 falls in flakes. 



Colorado, Oregon, Washington. 



25. Physarum brunneolum (Phill.) Mass. 



Mon. 280. 1892. 

 1877. Diderma brunneolum Phillips, Grev. 5 : 114. 



Sporangia scattered or gregarious, but not crowded, globose, tur- 

 binate or subdepressed, rarely plasmodiocarpous, 0.6-1.7 mm. in 

 diameter, sessile or with a short stipe; peridium double, thick, smooth 

 or polished, yellow-brown without, stellately dehiscent, the segments 

 reflexed, white within; stipe, when present, short, stout, rugose, lime- 

 less, red-brown; columella none, but pseudocolumella sometimes pres- 

 ent; capillitium dense, the nodes numerous, large, irregular, white, 

 the internodes thin, short, colorless; spores globose, lilac, clearly 

 echinulate, 8-10 \x (Lister), 6-7 n (Massee). 



What seems to be an otherwise typical specimen has spores aver- 

 aging 12.5 ijl. 



This form was first described by Phillips as a diderma. Later 

 students of the specimens preserved by Phillips agree that it is not a 



