58 ENDOSPOREyE. fPHYSARUM. 



The uncompressed sporangia with the outer wall nearly free from 

 the smooth purplish inner wall characterises this species, and dis- 

 tinguishes it from P. bivalve and P. compressum, its nearest allies. 



Hab. On dead leaves, etc. Wanstead, Essex (L:B.M.34) ; Flitwick, 

 Beds. (L:B.M.34) ; Germany (B. M. 512). 



26. P. contextum Pers., Syn., p. 168 (1801). Plasmodium 

 yellow. Sporangia subglobose, ovoid, erect, 0'4 to 0'6 mm. cliam., 

 sessile or reniform and elongated on a broad base, crowded, often 

 angled by mutual pressure, rounded or flattened above, smooth, 

 yellowish-white or ochraceous ; sporangium-wall double, the outer 

 layer thick with dense deposits of lime, often breaking away in 

 the upper part from the thin colourless inner layer. Columella 

 none. Capillitium with scanty hyaline threads and numerous 

 large irregularly branching white lime-knots. Spores dark violet- 

 brown, spinulose, 10 to 13 p diam. Host., Mon., p. 109 ; Cooke, 

 Myx. Brit., p. 13; Mass., Mon., p. 303 (in part); Macbride, in 

 Bull. Nat. Hist. Iowa, ii., p. 157. Diderma contextum Pers., Obs. 

 Myc., i., p. 89 (1796); Fr., Syst. Myc., iii., p. 111. Diderma 

 ochroleucum Berk. & Curt., in Grev., ii., p. 52. Physarum con- 

 ylomeratum Mass., Mon., p. 304. 



Plate XX.. A. a. sporangia of t\vo forms, x 20 ; b. capillitium and spores, 

 x 280 ; c. spore, x 600 (Germany : Rostafi nski's type). 



The type of Diderma ockroleucum Berk. & Curt., from Pennsylvania 

 (K. 1533), is typical P. contextum. 



Hub. On dead leaves, sticks, etc. Lyme Regis, Dorset (L:B.M.35): 

 near Birmingham (L:B M.35) ; France (K. 365) ; Germany (B. M. 418) ; 

 Sweden (K. 1277); Poland (Strassb. Herb.); Iowa (B. M. 808); 

 Mass., U.S.A. (L:B.M.35). 



27. P. conglomeration Post., Mon., p. 108, figs. 73, 79, 90 

 (1875). Plasmodium? Sporangia subglobose, sessile on a broad 

 base, densely aggregated on one plane, angled by mutual pressure, 

 4 3 to 0'5 mm. broad, yellow or brownish-white, mottled with 

 paler shades; sporangium -wall double, the inner layer of the 

 convex upper wall having translucent, pale yellow, curved, 

 thickened areas, with a vitreous fracture ; the outer layer thick, 

 consisting of easily crumbling yellow lime-granules ; the wall 

 below thin with the two layers less distinct. Capillitium of deli- 

 cate branching hyaline threads, with numerous white or yellowish, 

 branching, often confluent lime-knots. Spores pale violet-brown, 

 almost smooth, 8 to 10 /x diam. List., in Jourii. Bot. 1891, 

 p. 259, PI. cccviii., fig. 1. Diderma conglomeration Fr., Syst. Myc., 

 iii., p. Ill (1829). PJtysarum Rostafaiskii Mass., Mon., p. 301. 



Plate XX., B. a. sporangia, x 20 ; I. capillitium, with fragment of 

 sporangium-wall, showing vitreous structure (i 1 ) and spores, x 280 ; c. spore, 

 x 600 (Germany : Eostafinski's type). 



Distinguished from P. contextum by the pale, nearly smooth, and 

 smaller spores, and by the vitreous structure of the inner wall of the 

 upper part of tho sporangium. Rostafinski's type specimens of P. 

 conglomeration fiom Germany (Strassb. Herb.) and from Sikkim 



