258 Mycetozoa of North America 



Plasmodium white, then rosy (Lister). Sporangia stalked, 

 rarely sessile, crowded, often angled by mutual pressure, ovoid, 

 ellipsoid, or irregular in shape, 0.6 to 1 mm. high, 0.4 to 0.6 mm. 

 broad, ochraceous, yellowish or brownish; sporangial wall more 

 or less evanescent above, persistent at the sides, dividing into 

 four to six deep, rounded, membranous and papillose lobes. 

 Stalk dark brown to nearly black, short, 0.1 to 0.4 mm. long, 

 filled with spore-like cells. Capillitium a loose, slightly elastic 

 network of yellowish or flesh-colored threads 3-5 /i diam., with 

 few attachments to the sporangial wall, marked with spines, 

 warts, and low transverse ridges, often arranged in an open spiral ; 

 free ends more or less numerous, clavate, papillose. Spores pale 

 ochraceous, with a few scattered warts, 7-9 n diam. 



Type locality: Maine. 



Habitat: On dead wood. 



Distribution: *Iowa, Maine, *Manitoba, Maryland, Massa- 

 chusetts, Michigan, *Missouri, *Nebraska, *New Hampshire, 

 New York, Ontario, *Oregon, Pennsylvania, Quebec. 



Illustration: Lister, Mycetozoa ed. 3. pi. 192 (color too red). 



The description is based on the large amount of material here, 

 and dififers materially from that of other authors. I have col- 

 lected the species frequently from August to December, and 

 observed the development of the sporangia from emergence of the 

 Plasmodium through all stages to maturity, which requires several 

 days. The colors given are not due to fading. The form is 

 clearly an Arcyria and allied to A. stipata, with which it is con- 

 nected by intermediate forms, and with which it may be confused, 

 unless the dehiscence in lobes is evident. The collections during 

 cold weather, in the latter part of the season, vary in the character 

 of the sporangial wall. The colonies then are usually small, of 

 more globose sporangia on very short stalks or sessile. The wall 

 is often more cartilaginous and firm throughout, dehiscing ir- 

 regularly and without traces of the petaloid structure. In others, 

 the wall is weaker at the top, and the lobes, while indistinct, are 

 indicated by the rounded parts of the edge of dehiscence, the 

 lower part of the wall persistent as a deep calyculus. 



Genus 43. LACHNOBOLUS Fries, Fl. Scan. 356. 1837. 



Sporangia sessile, clustered; sporangial wall single, membran- 

 ous, somewhat persistent, not thickened with angular granules; 



