Arcyriae. 113 



Sub-sect. ARCYRIAE. 



Elaters attached to wall of sporangium only slightly branched 

 or forming a network. 



PROTOTRICHIA. Elaters fixed by one end to base of spor- 

 angium, tips free. 



PERICHAENA. Sporangial wall with a layer of lime granules 

 inside ; capillitium scanty. 



Ophiotheca. Threads of capillitium usually spiny, of equal 

 thickness, forming a net with numerous blunt, free arms. 



ffeterotrichia. Threads of capillitium of two distinct thick- 

 nesses, forming a net, outer network with numerous free, 

 pointed arms. 



Lachnobolus. Threads of capillitium forming a network 

 attached at numerous points to wall of sporangium. 



ARCYRIA. Threads of capillitium forming a network usually 

 elastically protruded at maturity. 



LYCOGALA. Cortex containing numerous cells filled with 

 protoplasm, capillitium tubes thick. 



Sub-sect. ARCYRIAE. 



PERICHAENA, Fries. 



Sporangia sessile, gregarious, dehiscing irregularly or in a 

 circumscissile manner, wall usually double, the outer often 

 containing granules of lime or a layer of granules of organic 

 matter ; capillitium variously developed, in some species form- 

 ing an irregular network attached at various points to the upper 

 portion of sporangial wall, in other species almost obsolete, 

 threads of the capillitium without definite markings, either 

 quite smooth or with a few scattered, rudimentary spinules or 

 notch-like constrictions ; spores globose. 



Perichaena, Fries, Gast., p. 12; Rost., Mon., p. 292; Cooke, 

 Myx. Brit., p. 77 ; opf, p. 169 ; Sacc., Syll., vii. pt. I., p. 420. 



The most prominent generic features are the circumscissile 

 dehiscence of the sporangium, which however is not universal, 

 the layer of amorphous particles of lime or of organic matter 



