Didymium. 231 



Didymium neglectum, Mass. (nov. sp.) ; (fig. 207). ' 



Sporangia globose or slightly depressed, flattened or some- 

 times slightly umbilicate below, stipitate ; wall single, at first 

 with a continuous, rugose, white crust of lime, which at maturity 

 becomes broken up into minute, persistent particles; stem 

 equal to or longer than height of sporangium, erect, slightly 

 attenuated upwards, black, longitudinally wrinkled, expanding 

 at the base into a small hypothallus; columella circular in 

 outline, much depressed, placentiform, with a distinct margin, 

 covering the base of the sporangium, ruguloee, pale brownish- 

 lilac, capillitium dense, threads radiating from the columella, 

 lilac-brown, becoming colourless towards the tips, bifurcating, 

 now and then anasmosing laterally; spores globose, smooth, 

 1 9 //. diameter. 



On wood. Fairmount Park, Philadelphia, U. S. 



Solitary or in scattered clusters of 2 6 specimens, about 



1 mm. high; superficially resembling Didymium farinaceum, 

 but quite distinct in the smooth spores, which only show vague 

 indications of roughness when magnified 1200 diameters. The 

 columella is very characteristic, being broad and flattened with 

 a distinct margin ; at maturity the sporangium falls away 

 except a minute frill round the lower edge of the columella, 

 which, with the stem, in this condition resembles a little table. 

 The original specimens were found mixed with specimens of 

 Tilmadochc oblonga, communicated by Mr. Harold Wingate, of 

 Philadelphia. 



Didymium Barter!, Mass. (n. sp.). V 



Gregarious ; sporangia spherico-depressed, slightly umbilicate 

 below, stipitate, cretaceo^(,s layer pure white, rugulose, for a long 

 time persistent, then breaking away in small granules; stem 

 elongated, slender, attenuated upwards, pure white, strongly 

 wrinkled longitudinally ; columella small, globose, white ; mass 

 of spores blackish-purple; capillitium copious, threads about 



2 i*. thick, equal, sometimes flexuous, forked at an acute angle 



