Didymium. 241 



thin, colourless, repeatedly forked and joined laterally to form 

 a loose, irregular net ; spores globose, dingy lilac, very minutely 

 verruculose, 8 10 JJL diameter: 



Didymium obrusseum, B. and C., Grev. (1873), vol. ii., p. 53. 



Physarum obrusseum (B. and C.), Sacc., Syll., 1195 (in part). 

 ' (Type in Herb., Kew.) 



Exsicc. Fung. Cubenses Wrightiani, 532. 



On twigs, leaves, &c. Cuba ; United States. 



Gregarious, stem flaccid, irregular and flattened below, very 

 thin above, about 2 mm. long, hypothallus very thin and 

 shining. 



Didymium pertusum, Ber^^V? 



Scattered. Sporangium globose or depressed, generally more 

 or less umbilicate, white, frosted with minute crystals of lime ; 

 stem elongated, slightly attenuated upwards, rufous; columella 

 entirely absent ; threads of capillitium very thin, colourless, vari- 

 ously branched and combined to form a net; spores globose, 

 dirty lilac, verruculose, 10 13 //. diameter. 



Didymium pertusum, Berk., Eng. Fl., vol. v., p. 313 ; Cooke, 

 Myx. Brit., p. 35 ; Sacc., Syll., 1317. 



(Type in Herb. Berk.) 



On dead herbaceous stems. Appin, N. B. 



Scattered, varying from 2'5 3 mm. high. There is no trace 

 of a columella, although after dehiscence the basal persistent 

 portion of the sporangial wall falls down, and this under a 

 pocket-lens might be mistaken for a columella. The threads 

 of the capillitium anastomose freely and form a very irregular, 

 scanty network. The stem is more or less longitudinally 

 rugulose, and filled with amorphous particles of lime. 



Didymium eximium, Peck. 



Sporangia subglobose, slightly or not at all umbilicate below, 

 grey, frosted with stellate crystals of lime ; stem elongated, erect 

 or slightly curved above, almost eqiijol, slender, pale yelloivish- 

 brown, darker towards the base, which expands into a minute 

 hypothallus, slightly rugulose, filled with amorphous particles 



