Didymium. 237 



slender, erect, snow-white, very slightly attenuated upwards, 

 almost smooth, expanding at the base into a small, circular, 

 white hypothallus; columella absent ; capillitium well-developed, 

 threads very thin, colourless, branching and anastomosing irregu- 

 larly to form a network, nodes usually triangular; spores 

 globose, dingy lilac, smooth, 8 10 jot diameter. 



(Type in Herb. Berk., Kew, with Tilmadoche nutans.} 



On bark and wood. Britain (Yorks) ; Lower Carolina. 



A very distinct species, characterized by its snow-white colour 

 throughout, 2*5 3 mm, high, sporangium very small. Spores 

 perfectly smooth under a T V objective. 



Didymium Mvellum, Mass. (n. sp.) (fig. 232). D.\M(\rip 



Sporangia spherical,' very little or not at all umbilicate, 

 stipitate, outer cretaceous coat pure white, composed of minute 

 granules which fall away in the form of powder, inner wall with- 

 out lime, rather tough, bright fulvous ; stem slender, elongated, 

 straight or slightly curved above, attenuated upwards, same 

 colour as inner wall of sporangium, much wrinkled longitudin- 

 ally, expanding at the base into a similarly coloured circular 

 hypothallus ; columella brown, not very prominent ; mass of 

 spores blackish with a purple tinge ; capillitium copious, threads 

 repeatedly forked, 2 3 /u, thick, rather broader at the base of 

 each bifurcation, combined laterally to form an irregular net- 

 work, colourless ; spores globose, smooth, pale dirty lilac, 8 10 p. 

 diameter. 



On fallen oak leaves; scattered or gregarious. 



United States. 



(Type in Herb., Kew.) 



Sporangium 1 mm. diameter, stem about 2 mm. high. 



Didymium australis, Mass. (fig. 208). 7ricW*^ViDva. yez'x.o<W3 



Sporangium globose or slightly flattened above and below, 

 slightly umbilicate, at first with a thick, white layer of crystals 

 which soon breaks up into large, persistent, irregular patches; 

 stem thin, bright brown, slightly attenuated upwards, often bend- 



