578 Seaver : North Dakota slime-moulds 



plants and often some distance above ground, an adaptation for 



spore distribution. 



DiDYMiUM SQUAMULOSUM (Albert. & Schwein.) Fries, 



On leaves and decaying materials of various kinds. A com- 

 mon species. 

 FuLiGO ovATA (Schaefif.) Macbr. 



This is a common species and one which often attains consid- 

 erable size. One specimen collected on a rotten log in North 

 Dakota was from six to eight inches in diameter and smaller speci- 

 mens were found to be very common. 

 Physarum contextum Pers. 



Several collections were made on decaying materials of vari- 

 ous kinds in woods near Fargo. 



Tilmadoche viridis (Bull.) Sacc. 



Plants collected on rotten wood. The species is not uncom- 

 mon and has a wide distribution. 



STEMONITACEAE 



Stemonitis maxima Schwein. 



Numerous specimens were collected on bark and wood of 

 Tilia americana, for which substratum it shows a decided prefer- 

 ence. Widely distributed. 



Stemonitis Smithii Macbr. 



The specimens, collected in similar localities to the preceding, 

 were mostly larger and easily distinguished from that species, by 

 the color of the spore mass, which is ferruginous instead of pur- 

 plish black. Rather common. 



CRIBRARIACEAE 



Dictydiaethalium plumbeum (Schum.) Rost. 



Several collections on decaying wood. The plants are de- 

 pressed and spread out, becoming 1-2 cm. in diameter and recog- 

 nized by these characters and the ochraceous color. The one 

 species known to North America has a wide distribution, 



DiCTYDiuM cancellatum (Batsch) Macbr. 



One of the most variable species of the group, the plants being 

 either long- or short-stemmed and very variable in color. 



