220 THE NORTH AMERICAN SLIME-MOULDS 



difficult to define, and the species are indeed variable. Those 

 here listed seem to offer constant features throughout our range. 



Key to Species of Oligonema. 



A. Spores reticulate. 



a. Sporangia in broad effused patches . . 2. O. brevifila 



b. Sporangia in small heaped clusters. 



i. Elaters roughened, no distinct rings or spirals, 



i . O. flavidum 

 ii. Elaters with scattered rings ; sometimes faint spirals, 



3. O. nit ens 



B. Spores warted 4. O.fnlvum 



i. OLIGONEMA FLAVIDUM (Pecti) Mass. 



1874. PerichcEiia fla-vida Peck, Rep. N. Y. Mus., p. 76. 

 1892. Oligonema flavidum (Peck) Mass., Man., p. 171. 



Sporangia crowded and superimposed, sessile in small masses 

 or clusters i cm. or less, bright yellow, shining, the periclium 

 thin but opaque, yellow ; capillitium of long, slender tubules 

 usually simple, anon branched, even, or with an occasional infla- 

 tion, the sculpture confined to warts or small, distinct spinules, 

 roughening more or less conspicuously the entire surface, the 

 apices generally obtuse, anon apiculate; spore-mass yellow, 

 spores under the lens pale yellow, irregularly globose, beau- 

 tifully reticulate, the meshes large and few, as in TricJiia 

 fazwginea, 12 14 p. 



This species is marked by its capillitium, which is abundant 

 for the present genus. The threads are longer than in any 

 other species, and not infrequently branched, smooth, or more 

 commonly, very distinctly minutely spinulose throughout, no 

 trace of rings or relief sculpture of any sort, the spirals, that 

 are to be expected, very imperfect, if discernible at all. In 

 habit the species resembles O. nitcns, but the colonies are 

 much larger, and the sporangia higher and larger, attaining 

 i mm. 



New England to Iowa and Nebraska ; south to Alabama and 

 Louisiana. 



