40 Mycetozoa of North America 



scriptions of the species, is not always present, and is not charac- 

 teristic, as a similar hypothallus may often be observed in P. 

 glohuliferum. A beautiful collection made by Mr. Rispaud and 

 the author (N. Y. B. G. no. 4747) in Pike County, Pennsylvania, 

 is about as representative as can be found. 



11. Physarum tenerum Rex, Proc. Acad. Nat. Sc. Phila. 1890: 

 192. 1890. (N. Y. B. G. nos. 10905, cotype material, 6463, 

 7610, authentic material.) 



Physarum viaculatum Macbr. Bull. Nat. Hist. S. U. Iowa 2: 383. 1893. 

 Physarum simplex (?) M. E. Peck; Peck & Gilb. Am. Jour. Bot. 19: 136. 1932. 



Plasmodium primrose-yellow (Lister). Sporangia gregarious, 

 globose, 0.4 mm. diam., stalked, erect or nodding, yellow, often 

 gray; sporangial wall membranous, with closely set rounded clus- 

 ters of lime-granules. Stalk subulate, slender, straight, curved 

 or twisted, opaque, 0.5 to 1.7 mm. long, yellow and filled with 

 lime above, usually darker below from included refuse matter. 

 Columella none. Capillitium a close, persistent network of slen- 

 der, hyaline threads, with numerous, rounded, yellow lime-knots, 

 often pale. Spores brownish lilac, nearly smooth, 7-8 ju diam. 



Type locality: Philadelphia, Pennsylvania. 



Habitat: On dead wood; common. 



Distribution: Throughout North America. 



Illustration: Lister, Mycetozoa ed. 3. pi. 25. 



This species forms small colonies, rarely more than an inch 

 across. The sporangial wall frequently dehisces in petal-like 

 lobes. The amount of lime in the stalk varies, sometimes abun- 

 dant so that the stalk is erect and stiff, and at other times scanty, 

 so that it is flexible with the sporangia nodding. There is often 

 a sharp bend near the apex of the stalk. The lime in the wall 

 and capillitium is often pale, or nearly white, but the yellow color 

 of the stalk is more constant. P. citrinum is a more robust form 

 with a stout stalk, and a columella. P. simplex, from Oregon, 

 appears to be a form of the present species. 



12. Physarum Wingatense Macbr. N. A. Slime-Moulds ed. 2. 72. 

 1922. 



Didymiunt columbinum Berk & Curt., not published. 



Tilmadoche columbina Rost. Mon. App. 13. 1876. (N. Y. B. G. no. 5614, 



type material.) 

 Tilmadoche compacta Wing. Proc. Acad. Nat. Sc. Phila. 1889: 48. 1889. 



