278 THE MYXOMYCETES 



This genus has been carefully studied by Miss Baskerville (1932) 

 and the following treatment is based in part upon her findings. 



KEY TO THE SPECIES OF OLIGONEMA 



a. Spores warted 1.0. fulvum 



a. Spores reticulate b 



b. Elaters usually rough, spirals sinistrorse, indistinct 2.0. flavidum 



b. Elaters nearly smooth, with faint dextrorse spirals and scat- 

 tered rings 3. 0. nitens 



1. Oligonema fulvum Morgan 



Jour. Cin. Soc. Nat. Hist. 16 : 36. 1893. 

 PI. XVIII, Figs. 486, 487. 



Sporangia olivaceous brown, sessile, clustered, subglobose, tending 

 toward plasmodiocarpous, up to 1 mm. in diameter; peridium light 

 olivaceous yellow, fugacious, marked with clear, straight lines arranged 

 at various angles and suggesting clusters of needle-shaped crystals, 

 and with warts; capillitium tawny yellow, scanty, the elaters simple or 

 branched, smooth or with faint spirals or occasional rings, half-rings or 

 barbs, occasionally swollen, 40-300 n in length, 3-5 ju wide; spores 

 globose, light yellow, distinctly warted, 12-14 jx. 



According to Lister, this species is to be included in Trichia scabra. 

 The complete lack of reticulation on the spore walls, together with the 

 other characters, seems to rule this out. 



Rare, known only from Ohio. 



2. Oligonema flavidum Peck 



Rept. N. Y. State Mus. 31 : 43. 1879. 

 PL XVIII, Figs. 482, 483, 484, 485, 488. 



1874. Perichcena flavida Peck, Rept. N. Y. Mus. 26 : 76. 



1889. Oligonema minutulum Massee, Jour. Roy. Micr. Soc. 348. 



Sporangia yellow, sessile, densely clustered, globose, subglobose, or 

 elongated by pressure, 0.5-0.8 mm. in diameter; peridium thin, opaque, 

 papillate, opening irregularly; capillitium scanty, of rather short, 

 simple or occasionally branched elaters, 100-300 n long and 3-4 /x wide, 

 irregular, swollen in places and with scattered depressions on the sur- 

 face, sculptured with minute warts arranged so as to form indistinct, 

 sinistrorse spirals, the apices generally blunt, sometimes ending in one 

 to several points; spores globose, irregularly reticulate, 11-14 ji. 



Distinguished from O. nitens chiefly by the uneven, roughened sur- 

 face of the elaters and the direction of the spirals. The reticulations on 

 the spore walls are usually more regular and the pitting, if present, 



