LEPIDODERMA.] DIDYMIACE.E. 105 



of the sporangia or continued into the capillitium threads. 

 Spores dull purple, strongly spinulous, 10 to 13 /x diarn. Host., 

 Mon., p. 191 ; Cooke, Myx. Brit., p. 45 ; Blytt., Bidr. K. Norg., 

 Sop. iii. (1892), p. 7; Macbride, in Bull. Nat. Hist. Iowa, ii., 

 p. 144. Reticularia alba Bull., Champ., p. 92, t. 326 (1791). 



Plate XLL, A. a. gethaliuni, x 2 ; b. cluster of sporangia from an 

 sethalium ; in three places they are broken and show the hollow columellfe, 

 x 20 ; c. capillitium and spores, x 280 ; d. crystals from the investing 

 covering of lime, x 280 ; e. spore, x 600 (England). 



Allied to Didymium through D. crustaceum, but separated by its 

 aethalial habit. 



Hal). On grass, dead leaves, etc. Common in Europe. Highgate, 

 Middlesex (B. M. 161) ; Batheaston, Somerset (B. M. 171) : Oxford- 

 shire (B. M. 1083, 1084, 1085) ; Cromarty, Scotland (B. M. 1088) ; 

 Ireland (K. 584) ; France (B. M. 997) ; Belgium (B. M. 594) ; Germany 

 (B. M. 599) ; Finland (B. M. 597) ; Poland (Strassb. Herb.), Ohio 

 (L:B.M.79); Iowa (L:B.M.79). 



The description of Spumaria Micheneri Berk., in Grev., vol. ii., p. 52, 

 is too brief in the absence of the type to be of value. 



Genus 14. LEPIDODERMA de Bary, in Eost., Versuch, p. 13 

 (1873). Sporangia stalked, sessile, or plasmocliocarps ; sporangium- 

 wall cartilaginous, beset with superficial crystalline scales ; capil- 

 litium profuse, without linae. 



KEY TO THE SPECIES OF LEPIDODERMA. 



Sporangia subglobose . . . . L. tigrinum. 

 Sporangia forming plasmodiocarps . L. Carestianum. 



1. L. tigrinum Host., Versuch., p. 13 (1873). Plasmodium 

 yellow (teste Schroeter). Sporangia subglobose, flattened and 

 umbilicate beneath, stipitate or sessile, scattered, 1 to 1*5 mm. 

 diam., olive- or purplish-grey, glossy, more or less closely beset 

 with rounded or angular crystalline scales of lime, which are 

 sometimes wanting; sporangium- wall cartilaginous, of two 

 closely combined layers, orange-yellow. Stalk stout, cylindrical 

 0'2 to 04 mm. thick, furrowed, orange-brown, of a spongy texture 

 within, containing deposits of lime ; rising from a hypothallus 

 which is either vein-like, or effused and of a loose reticulated 

 structure. Columella hemispherical, brown, of the same texture 

 as the stalk, containing deposits of lime in rounded nodules. 

 Capillitium profuse, of straight or flexuose threads, sparingly 

 branched, dark purple-brown or grey. Spores dark purplish- 

 grey, minutely and closely spinulose, 8 to 13 /x diam. Mon., 

 p. 187; Cooke, Myx. Brit,, p. 44; Blytt, Bidr. K. Norg., 

 Sop. iii., 1892, p. 7 ; Mass., Mon., p. 253. Didymium tigrinum 

 Schrad., Nov. Gen. PL, p. 22 (1797). Lepidodermafulvum Mass., 

 Mon., p. 253. 



Plate XLL, B. a. sporangium, x 20 ; b. fragment of sporangium- wall 

 with crystalline discs, x 50 ; c. capillitium and spores, x 280 ; d. spore, 

 x 600 (Germany). 



