DIDYMIUM.] DIDYMIACE.E. 97 



the specimen? the upper wall is broken and the spores are shed, but 

 sufficient remains to indicate the discoid form of the sporangia ; the 

 sporangium- wall is faintly mottled with brown ; the capillitium is 

 delicate, the spores pale violet-brown, 5 to 6 /z diam. 



Bab. On dead leaves, etc. Batheaston, Somerset (B. M. 80) ; Lyme 

 Regis. Dorset (L:B.M.74) ; Wanstead, Essex (L:B.M.74) ;' Germany 

 (Strassb. Herb.) ; Ceylon (B. M. 537) ; Philadelphia (L:B.M.74). 



5. D. farinaceum Schrad., Nov. Gen. PI., p. 26 (1797). Plas- 

 modium grey, among dead leaves, on bark, etc. Total height 

 0*5 to 1 mm. Sporangia subglobose or hemispherical, deeply 

 umbilicate beneath, stipitate, gregarious, 0*6 to 1 mm. diam., or 

 nearly sessile and confluent, white or grey ; sporangium -wall firm, 

 mottled with purple-brown, beset with stellate crystals of lime. 

 Stalk cylindrical with a broad base, striate, dark brown, rarely 

 rufous, 0'2 to 0'7 nun. long, 0'05 to 0'2 mm. thick, opaque and 

 granular when mounted in glycerine. Columella large, hemi- 

 spherical, umbilicate, dark brown, chambered, containing coarse 

 granules of lime. Capillitium of stout or delicate, sparingly 

 branched or simple, more or less flexuose threads, colourless or 

 purplish-brown, with dark calyciform thickenings. Spores dark 

 purplish-brown or purplish-grey, with a thick spore-wall, nearly 

 smooth or spinose, 7 to 11 /x, diam. Host., Mon., p. 154; Cooke, 

 Myx. Brit., p. 31 ; Blytt, Bidr. K. Norg., Sop. iii. (1892), p. 7 ; 

 Macbricle, in Bull. Nat. Hist. Iowa, ii., p. 146 ; Mass., Mon., 

 p. 219. Spumaria physaroides Pers., Syn. Fung., p. 163. 

 ~Didymium physaroides Fr., Symb. Gast., p. 21 ; Host., Mon., 

 p. 158 ; Cooke, Myx. Brit., p. 33; Mass., Mon., p. 233. 



a. genuiimm: threads of capillitium 2 /x thick; spores 9 to 11 

 /A diam. 



(3. minus : threads of capillitium 1 /x thick ; spores 7 to 9 /x 

 diam. 



Plate XXXIX., A. a. sporangia a. genuinum, x 20; b. capillitium and 

 spores, with fragment of sporangium-wall and lime-crystal, x 280 ; c. spore, 

 x 600 (England) ; d. sporangia /3. minus, x 20 ; e. the same with heads 

 confluent ; /. capillitium and spores, x 280 (England). 



Intermediate varieties uniting vars. /3 and a are so frequent that 

 the former cannot be regarded as a distinct species. It is, however, 

 very constant in its characters from different parts of the world, being 

 marked by the smaller size and delicate capillitium. It often bears a 

 considerable resemblance to D. nigripes, and is named D. microcarpum 

 Host, in some specimens in Strassb. Herb. ; the opaque granular stalk 

 distinguishes it from that species and its allies. Rostafinski's specimen 

 of D. physaroides in Strassb. Herb, appears to be an imperfect develop- 

 ment of D. farinaceum, as indicated by the spores, many of which are 

 abnormal in shape and size, 15 to 50 p. long, combined in agglutinated 

 masses, and by the capillitium, which contains vesicular expansions 

 filled with lime-granules such as are not unfrequent in imperfect growths 

 of Didymium ; the sporangia are mostly clustered and confluent, but 

 in some cases they are solitary ; the columella is dark b .-own and 

 chambered, and the sporangium-wall is mottled with purple-brown. 



