Arcyria. 169 



Arcyria fuliginea, Cke. and Mass. (fig. 113). 



Sporangia (?), mass of capillitium and spores smoky-olive, 

 threads round, 6 7 jw. diameter, thicldy and equally covered with 

 slender spines 3 4 JA long, combined to form a dense, irregular 

 network ; spores globose, smooth, 8 fx diameter. 



Hemiarcyria fuliginea, Cke. and Mass., Grev., vol. xvi., p. 74. 



On living leaves. Mount Wilson, N. S. Wales. 



Nothing is known of the sporangium, which had been com- 

 pletely crushed and lost; capillitium forming a large mass 

 spreading over the leaves. May possibly prove to be a broadly 

 effused, plasmodiocarp form of an Ophiotheca. 



Sub-sect. TRICHEAE. 

 OLIGONEMA, Host. 4 



Wall of sporangium single, dehiscing irregularly ; capillitium 

 scanty, composed of free, simple or branched elaters, furnished 

 with ring-like thickenings, or a single very diffuse, rudimentary 

 spiral, tips obtuse. 



Oligonema, Host., Mon., p. 291 ; Cooke, Myx. Brit., p. 77 ; 

 Sacc., Syll., p. 436 ; Mass., Rev. Trich., p. 21. 



Agreeing with the genus Trichia in having the elaters per- 

 fectly free, but readily distinguished by the rudimentary mark- 

 ings on their walls, never having more than a single, indistinct, 

 very open spiral, which may be present on one portion of an 

 elater and absent on another part, or not unfrequently altogether 

 absent from all the elaters of one sporangium, and present 

 on some of those from another sporangium taken from the 

 same group. A second type of ornamentation on the walls 

 of the elaters in the present genus consists of annular or 

 ring-like thickenings, which present the appearance of thin, 

 flat discs, rather larger than the diameter of the elater, and 

 placed at right angles to its long axis. These ring-like thicken- 

 ings are very unequally distributed, five or six being sometimes 

 met with at unequal distances on an elater, whereas they may 



