DIDYMIUM.] DIDYMIACE^. 95 



Mass., Mon., p. 212 ; Blytt, Bidr. K. ISTorg., Sop. iii. (1892), p. 6. 

 Bidymiwrn, Libertianum de Bary, Mycetozoa, p. 124. Diderma 

 Uceoides, Fr., Syst. Myc, iii., p. 107. Licea macrospora Schwein., 

 in Trans. Am. Phil. Soc. (1834), p. 258. Chondrioderma Uceoides 

 Kost., Mon., App., p. 17 ; Mass., Mon., p. 215. 



Plate XXXVII., A. — a. sporangia, x 20 ; J. capillitium attached to the 

 sporangium-wall, which shows the thickened margin of the base passing into 

 the membranous upper wall, x 280 ; o. portion of the crystalline crust of 

 Ume, X 280 ; d. delicate capillitium, x 280 ; e. spore, x 600 (England). 



This species is removed from Ohondrioderma, where it was placed 

 hy Rostaflnski, on account of the crystalline character of the lime 

 forming the outer crust of the sporangium- wall. It is to be regretted 

 that there is no type of C. calcareum Eost. in Strassb. Herb., for the 

 description in Rostafinski's Monograph answers well for the forms 

 of D. difforme with well developed capillitium ; as the latter species is 

 given by Rostaflnski as being almost destitute of capillitium, it is 

 possible that C. calcareum is not entitled to specific rank. The type 

 specimen of Chondrioderma Uceoides Rost. (K. 1206) from the Schweinitz 

 Herb., marked Licea macrospora by Schweinitz, is Didymium difforme ; 

 the structure of the sporangium-wall and the characters of the capil- 

 litium and spores are quite typical. 



Hah, On dead leaves and herbaceous stems. — Wanstead, Essex 

 (L:B.M.71) ; "Welshpool, Montgomery (B. M. 1062) ; Prance (K. 386) ; 

 Germany (B. M. 507, 521, 524, 529) ; Belgium (K. 401) ; Italy 

 (B. M. 527) ; India (K. 1466) ; Seychelles (K. 1467) ; Carolina (K. 1206). 



2. D. dubium Eost., Mon., p. 152 (1875). Plasmodium watery 

 white, among dead leaves. Sporangia rounded or irregular plas- 

 modiocarps, depressed, solitary, 1 to 12 mm. broad, 0-13 mm. 

 thick ; sporangium-waU of two layers, the outer consisting of 

 large stellate crystals combined to form a fragile uneven crust, 

 more or less attached to the delicate membranous inner layer. 

 Columella none. Capillitium of profuse, rigid, erect, dark purplish- 

 brown threads, anastomosing chiefly above and below, and at- 

 tached at either end by colourless slender branches to the 

 sporangium-wall. Spores violet-grey, spinulose or nearly smooth, 

 8 to 15 /i diam. — Cooke, Myx. Brit., fig. 167 ; Lister, in Journ. 

 Bot. (1891), p. 261 ; Mass., Mon., p. 246. Bidymiwrn Listeri 

 Mass., Mon., p. 244. 



Plate XXXVII., B.— a. sporangia, x 20 ; J, e, d, e. various forms of 

 capillitium, and spores, x 280 ; /. fragment of sporangium-wall, showing 

 the crystalline outer layer, x 280 ; g. spore, x 600 (England). 



This species is abundant at Lyme Regis, where it presents consider- 

 able variation. In many gatherings the spores are nearly smooth, 

 measuring 8 to 10 ^i diam., in others spinulose, 12 to 15 ;u diam. ; the 

 capillitium may differ from the usual form in being flexuose with 

 bead-hke or irregular thickenings and with short free branches. Speci- 

 mens submitted to Rostaflnski are pronounced by him to be distinct 

 from the original Hauenstein gathering in having smoother spores and 

 more slender capillitium without thickenings ; considering the varia- 

 tion mentioned above, these distinctions cannot be accepted as sufficient 

 to mark the Lyme Regis form as a distinct species. 



Hah, On dead leaves. — Lyme Regis, Dorset (L:B.M.72) 



