Didymium. 247 



eating threads are present, but in most sporangia there is no 

 trace of a capillitium. 



Didymium flavidum, Peck. K c \ tri n c \ 



Sporangia globose, or broadly obovate, sessile on a broad or 

 narrow base, wall brittle with lime, rugulose, sulphur-yellow, 

 sometimes with a tinge of orange, becoming irregularly ruptured 

 at the apex, or the apical portion breaking away in an irregu- 

 larly circumscissile manner, basal half persistent ; mass of spores 

 blackish-violet, spores globose, dingy lilac, very minutely ver- 

 ruculose, 10 12 p. diameter. 



Didymium flavidum, Peck, 28th Report State Mus., N. Y., 

 p. 54. 



Physarum flavidum, Peck, Berl., Sacc., Syll., n. 1215. 

 (Authentic specimen from Peck, in Herb., Kew.) 



On wood. United States. 



Scattered or gregarious, about '5 mm. diam., springing from 

 a very thin hypothallus; capillitium consisting of a few scat- 

 tered, very thin, bifurcating threads, or most frequently entirely 

 absent. 



Owing to imperfect diagnoses and absence of type specimens, the 

 following cannot be arranged in their respective sections. 



Didymium tenerrimum, B. and C. var. o\>r\>t*euv 



Sporangium globose, white, venulose, umbilicate below ; hypo- 

 thallus obsolete ; stem elongated, thickened below, pallid, hyaline; 

 threads of capillitium colourless ; spores black. 



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

 p. 348. 



Didymium obmsseum, Sacc., Syll., n. 1195 (in part). 



On leaves of grass, nearly allied to D. obrusseicm, B. and C. 

 Cuba. 



The present species is given as a synonym of D. olrusseum, 

 B. and C., in Saccardo's Sylloge, but as the authors considered 

 the two species to be distinct,' and as no specimen exists in 

 Berkeley's Herbarium, I have considered it advisable not to 



