94 
ENDOSPORE^. 
[didymium. 
superficial crystals of lime either scattered over the surface or 
combined into a separable crust ; capillitium of branching threads 
which are often thickened at intervals with dark calyciform 
nodes, without lime-knots. 
KEY TO THE SPECIES OF DIDYMIUM. 
A . Superficial crystals closely combined to form a thin shell-like 
crust : — 
Capillitium scanty, usually broad at the base. 
1. D. difforme 
Capillitium profuse, slender at the extremities. 
2. D. dubium 
B. Superficial crystals scattered or loosely combined : — 
A. Plasmodiocarps, capillitium associated with large, olive- 
coloured vesicles. 3. D. Serpula 
B. Sporangia usually stalked, capillitium without large 
vesicles — 
a. Sporangia disc-shaped, columella absent. 4. D. Clavm 
h. Sporangia subglobose — 
Stalk and columella dark brown, stalk opaque and 
granular. 5. D. fcw'inaceum 
Stalk olive-brown or orange, hornclear. 
6. D. nigrij^es 
Stalk and columella white ; crystals on sporangium- 
wall scattered or forming a wrinkled crust. 
7. D. effusum 
Columella nearly white, stalk when present mem- 
branous ; crystals on sporangium-wall forming 
a smooth, thick, deciduous envelope enclosing the 
pale membranous stalk. 8. D. crustaceum 
1. D. difforme Duby, Bot. GaU.,ii.,p. 858 (1830). Plasmodium 
colourless or pale yellow. Sporangia pulvinate on a broad base 
or irregularly elongated and forming plasmodiocarps, scattered, 
0*4 to 2 mm. or more long, smooth, white; sporangium-wall of 
two layers, the outer a thin crust of densely combined minute 
crystals of lime, separating from the iridescent membranous 
inner layer, which is purplish or nearly colourless above, stout 
and yellowish-brown at the base, thickened at the margin. 
Columella none. Capillitium often very scanty, of coarse or 
delicate, purple or colourless, flattened threads, usually broad at 
the base, branching dichotomously and slender above. Spores 
dark purple-brown, faintly warted, 11 to 14 /a diam. — Diderma 
difforme Pers., Disp. Meth., p. 9 (1797). Chondrioderma difforme 
Post., in Puckel, Symb., Nachtr., p. 73; Mon., p. 177; Cooke, 
Myx. Brit., p. 39 ; Lister, in Ann. Bot., vol. iv., No. xiv., p. 282 
