DIDYMIUM.] DIDYMIACE.E. 99 



capillitium may vary from white to purplish-brown in the same group 

 of sporangia, and the colour of the stalk and columella is also inconstant. 

 The specimen B. M. 885, from Ravenel, S. Carolina, has some 

 sporangia with dark brown and others with deep orange ; stalks and 

 columella on the same leaf, representing the forms a and (3. D. 

 eximium Peck and D.fulvellum Mass, have orange-red stalks, with the 

 columella orange or pale buff. The type of D.proximum Berk. & Curt. 

 (K. 1493) has also orange-red stalks and a buff columella. The type 

 of D. pertusum Berk. (K. 463) has orange stalks and a white columella; 

 it corresponds with the description of D. xantliopus of Fries in all 

 essential characters, for the shape of the columella referred to by 

 Berkeley is a varying feature. D. elegantissimum Mass. (K. 1) is the 

 same variety. These forms blend into one another so completely that 

 they are here united under D. mgripes. 



Hob. On dead leaves. a. Lynton, Devon (L:B.M.76) ; a. Lyme 

 Eegis, Dorset (L:B.M.76) ; y. Batheaston, Somerset (B. M. 59, 101) ; 

 y. Edinbro' (K. 440) ; a. France (Paris Herb.) ; Germany, a. & y. 

 (Strassb. Herb.) ; /3. (B. M. 436) ; a. Switzerland (B. M. 555) ; y. Sey- 

 chelles (Paris Herb.) : Ceylon, a. (B. M. 561) ; /3. (B. M. 559) ; y. (B. M. 

 577) ; y. Australia (B. M. 562) ; /3. New Jersey (B. M. 566; ; y. New 

 York (B. M. 564); S. Caronila, a. & /3. (B. M. 884, 885) ; y. (B. M. 

 857) ; a. Brazil (K. 319) ; a. Chili (Strassb. Herb.). 



7. D. effusum Link, Obs., ii., p. 42 (1816). Plasmodmm 

 greyish-white, among dead leaves. Total height 0'5 to 1 mm. 

 Sporangia subgiobose, or hemispherical, umbilicate beneath, 

 stipitate, or sessile, or effused plasmodiocarps, gregarious, snow- 

 white from abundant stellate crystals, which often form a 

 wrinkled, deciduous, scaly, outer crust, or grey when the crystals 

 are more scanty ; in the plasmocliocarp forms the crystals are 

 sparsely distributed ; sporangium-wall membranous, sometimes 

 mottled with red-brown towards the base. Stalk white, cylindrical, 

 deeply furrowed, opaque and granular from deposits of lime, as 

 long as the sporangium, or very short or wanting. Columella 

 white, hemispherical ; wanting in effused plasmodiocarps. Capil- 

 litium variable, of delicate or coarse threads, almost simple, or 

 branching at an acute angle, usually with dark or pale calyciform 

 thickenings ; colourless, violet, or purplish-brown. Spores violet- 

 brown spinulose, 8 to 11 ft diam. Rost., Mon., p. 163; Mass., 

 Mon., p. 236. D. squamulosum Fries, Symb. Gast., p. 19 (1818); 

 Host., Mon., p. 159; Cooke, Myx. Brit., p. 33; Mass., Mon., 

 p. 223; Blytt, Bidr. K. Norg., Sop. iii., 1892, p. 6. Diderma 

 squamulosum Alb. & Schw. , Consp. Fung., p. 88 (1805). Didymium 

 leucopus Fries, Syst. Myc., iii., p. 121. D. costatum Fries, I.e., p. 118. 

 D. confluens Rost., Mon., App., p. 22. D. macrospermum Rost., 

 Mon., p. 161; Mass., Mon., p. 228. D. Fuckelianum Rost., 

 Mon., p. 161; Mass., Mon., p. 222. D. prcecox de Bary, in 

 Rab. Fung. Eur., No. 367; Rost., Mon., p. 163; Mass., Mon., 

 p. 223. D. radiatum Berk. & Curt., in Journ. Linn. Soc., x., 

 p. 348; Mass., Mon., p. 229 (in part). Chondrioderma Alexan- 

 dra wiczii Rost., Mon., p. 169. Didi/mium Alexandroiviczii Mass., 

 Mon., p. 232. Chondrioderma Cookei Rost., Mon., App., p. 17. 



