230 A Monogi'a2)1i of the My,wgastres. 



f. fasciculatnm. Three to five sporangia confluent, supported 

 on a common stem. 



On wood, leaves, moss, &c. Cuba ; N. Zealand ; Ceylon. 



Remarkable for the circular, sharply limited hypothallus 

 with prominent, regularly radiating ribs, resembling the hy- 

 menium of a small agaric. Resembling superficially some forms 

 oi Didymium sqummdosum, var. costatum. 



Didymium clavus, Rost. (figs. 53, 54). 



Sporangia very 'much depressed, slightly convex above, plane 

 below, lime sprinkled in tine crystals on the surface of the dark 

 membrane ; stem short, Uacldsh-hroivn, more or less longitudinally 

 rugulose ; columella absent ; mass of spores blackish ; threads of 

 capillitium 3 — 4 fx thick at base, slightly tapering, sparingly 

 forked at acute angles, and sometimes laterally connected and 

 furnished with small ring-lilce dark-coloured thicl'enings, pale 

 brown to dirty violet ; spores globose, smooth, dingy lilac, 6 — 8 fx 

 diameter. 



Didymium clavus, Rost., Mon., p. 153; Cooke, Hdbk., p. 3U ; 

 Raunk., p. 87; Schroeter, p. 121 ; Sacc, Syll., 1299. 



On twigs, leaves, &c. Britain (Wey bridge, Kew, Otton Wood, 

 Leicester ; Epping Forest, Forden, Linlithgow) ; France ; Bel- 

 gium ; Germany ; United States ; Canada ; Egypt ; Ceylon. 



Sporangia scattered, 1 — 1*5 mm. across wlien circular, some- 

 times irregular and larger. Remarkable for the much flattened, 

 pileus-shaped sporangia. 



(Rostafinski's Synonyms.) 



lieticularia hemisphcrica, Bull., t. 446, f 2 (1791). 

 Physarum clavios, A. and S., t. 2, f. 2 (1805). 

 Didymium melanop^ts, j8. clavus, Fr., S. M., iii., 114 (1829); 

 B. and Br., Ann. N. H., No. 110 ; Cooke, Hdbk., No. 1118, /3. 

 Didymium hemiq)hericum, Wallr., Fl. Germ., 2192 (1833). 

 Didymium clavus, Rabh., Fl. Crypt., 2282 (1844). 

 Didymium clavus, Berk., Eng. FL, v., p. 314. 



