Didymium. 229 



(?) Physarum alatum, Fr., 1. c., iii., p. 132 (1829). 

 Didymium costatum, Fckl., Sym. Myc. I., Nach., p. 339. 



Didymium discoideum, Rost. 



Sporangia discoid, almost sessile, umbilicate, inferior part of 

 wall violet, superior spotted, with irregular pellucid veins, 

 breaking away after maturity in small patches ; stem from its 

 shortness scarcely apparent, hid in the umbilicus, dilated at the 

 base into a circular hypothallus ; columella discoid or hemi- 

 spherical, like the stem yellowish flesh-colour ; threads of capil- 

 litium flexuous, rarely forking, bay, tips colourless; spores 

 strongly warted, blackish-violet, 11 13 /u, diameter. 



Didymium discoideum, Rost., Mon., p. 162; Sacc., Syll., no. 

 1305. 



Germany. 



* * Spores smooth. 



Didymium radiatum, B. and C. (figs. 68 72). ti. 



Scattered, sporangia vertically compressed, not umbilicate, but 

 sometimes slightly depressed below, dark grey, with crowded, 

 small, white, innate patches of lime, dehiscing irregularly ; 

 stem longer than height of sporangium, slightly attenuated 

 upwards, white or pale grey, expanding into a small, circular 

 hypothallus, longitudinally costate, the ribs passing in a radiate 

 manner into the hypothallus; columella brownish, much com- 

 pressed ; capillitium abundant, radiating from the columella to 

 the wall of the sporangium, threads thin, brownish-lilac, some- 

 times forked; spores globose, lilac, smooth, 8 10 jot diameter. 



Didymium radiatum, B. and C., Journ. Linn, Soc., vol. x, 

 p. 348 ; Sacc., Syll., n. 1328. 



(Type in Herb. Berk., Kew, no. 10765.) 



Didymium commutabile, B. and Br., Journ. Linn. Soc., v. xiv., 

 p. 83; Sacc., Syll., n. 1300; Rost., App., p. 21. 



(Type in Herb. Berk, n. 10766.) . 



Didymium lotryoides, Berk, in Herb. 



/. gcnuinum. Simple, scattered ; stem usually longer than 

 sporangium. 



