didymium] didymiaceae 127 



4. D. Trochus Lister in Journ. Bot., xxxvi. 164, tab. 386, 

 fig. 1, a to c (1898). Plasmodium bright " buttercup " yellow. 

 Sporangia scattered, hemispherical or top-shaped, 0*6 to 1 mm. 

 diam., shortly stalked or sessile, rarely forming plasmodio- 

 carps, smooth, cream-coloured or white ; sporangium- wall 

 readily falling off entire and consisting of two layers ; the outer 

 layer brittle and shell-like, composed of closely compacted, 

 angular or stellate crystals of lime forming a hemispherical 

 cap fitting on to the yellow-brown thickened margin of 

 the broad convex columella ; the inner layer membranous, 

 usually adhering to the outer layer. Stalk obconical or 

 shortly cylindrical, yellowish-brown, 0*2 to 0-4 mm. high, 

 filled like the columella with stellate crystals of lime. 

 Capillitium consisting of rigid and persistent colourless or 

 purplish-brown nearly simple or branched threads, sometimes 

 expanded below into membranous vesicles filled with lime- 

 crystals. Spores brownish-purple, 9 to 10 /x diam., strongly 

 warted, paler and the warts smaller on one side of the spore 

 than on the other. — Torrend Fl. Myx., 150. 



PI. 106. — a. sporangia (Bedfordshire) ; b. capillitium and spores with fragments 

 of the crystalline outer layer of the sporangium-wall and of the columella ; c. spore. 



This species has been recorded from three English counties, Beds, 

 Bucks and Surrey, and also from Portugal, where Dr. Torrend has 

 found it on decaying leaves of Agave. In this country it has been 

 found some years in great profusion on old straw-heaps among the 

 deeper layers of the straw. To collect perfect specimens may require 

 a little care, as the shell-like sporangium-walls and often the sporangia 

 themselves are easily detached. D. Trochlea differs from D. difforme, 

 its nearest ally, in the sporangia being usually provided with a stalk, 

 in the presence of a prominent columella, and in the warted spores. 



Hab. On dead leaves and old straw. — Kitchen End, Beds (B.M. 

 1708) ; Reigate, Surrey (B.M. 2465) ; Portugal (B.M. 2466). 



5. D. complanatum Rost. Mon., p. 151 (1875) (non Sckr&d) . 

 Plasmodium lemon-yellow. Sporangia forming scattered or 

 solitary depressed plasmodiocarps, 2 to 8 mm. broad, 0*1 to 

 0-15 mm. thick, either effused, perforated and net-like, or 

 vermiform, grey ; sporangium-wall membranous, colourless, 

 with scattered superficial stellate crystals of lime. Columella 

 none. Capillitium consisting of very slender somewhat 

 branching and anastomosing pale violet threads, connected 

 with numerous subglobose vesicles 20 to 50 /j. diam. filled with 

 yellow obscurely granular matter. Spores pale violet-brown, 

 minutely warted, 7 to 9 ^ diam. — Macbr. N. Am. Slime-Moulds, 

 85. Lycoperdon complanatum Batsch Elench. Fung., i. 251 

 (1786)? Physarum confluens Pers. /3 muscigenum Alb. & Schw. 

 Consp. Fung., 61 (1805) ? Didymium Serpula Fr. Syst. My o., 

 iii. 126 (1829) ? ; Rost. Mon., App. p. 21 ; Lister Mycetozoa, 96. 



PI. 107. — a. plasmodiocarp (England) ; b. section of plasmodiocarp showing 

 capillitium with large vesicles ; c. capillitium and spores ; d. spore. 



