Dictydium. 69 



almost colourless when empty and furnished with 12 darker 

 coloured ribs giving off lateral, free, not anastomosing branches ; 

 stem elongated, flexuous, brownish. 



Dictydium venosum, Schrader, Nov. Gen., p. 14, pi. iii., fig. 6 ; 

 Sacc., Syll, v. 7, pt. I., no. 1412 ? 



On rotten prostrate trunks of pine. Germany. 



It is doubtful whether the species described by Berlese in 

 Sacc., Syll., 1. c., is the species intended by Schrader. 



COLUMELLIFERAE. - 



The most pronounced features of the present section are the 

 presence of a central columella, which in most instances is a 

 direct continuation of the stem within the peridium, and the 

 absence of lime from every part. The two sub-sections as 

 defined appear distinct, but this, as usual, is only true of the 

 two poles, and curiously enough, transitions have been met 

 with where they would have been least expected. In the 

 Lamprodermeae, characterized by the capillitium springing from 

 the apex of the columella, we find this character fairly satis- 

 factory in the typical genus Lamproderma, and yet more rigidly 

 carried out in Encrthcnema, where the copious capillitium 

 originates entirely from a peltate disc springing from the apex 

 of the columella after the latter has passed quite through the 

 sporangium; yet we find in the genus Ancyropliorus all the 

 characteristics presented by the genus Enerthenema, plus a few 

 scattered branches springing from various points of the columella 

 throughout its length, in addition to the main bulk of the 

 capillitium which originates from the apical disc as in Ener- 

 thenema. The branches of the capillitium springing from the 

 columella are again broken up into smaller and smaller branch- 

 lets, which usually combine to form an irregular network. The 

 sporangial wall is always very thin and blackish in colour and 

 remarkable for its brilliant metallic tints, and also for its 

 ephemeral nature, disappearing entirely or in part as the spores 

 approach maturity, or as in the genus Orthotrichia being absent 



