HYSTEEIACEAE. 21 



the ascophore gaping widely at maturity, and thus exposing 

 the whole of the elongated, narrow disc. 



The species are all minute, and mostly gregarious ; all are 

 saprophytes, growing on old wood, bark, and also on dry- 

 leaves. 



ANALYSIS OF TEE GENERA. 

 A. — Spores coloured. 



Farlowia. Spores continuous. 



Mytilidion. Spores 3-7-septate; ascophoro vertical, 

 mussel-shaped. 



Hysterium. Spores 3-7-septate; asoophore not mussel- 

 shaped. 



Ostreion. Spores muriform ; ascophore vertical, oyster- 

 shaped. 



Hysterographium. Spores muriform; ascophore not 

 ojster-shaped. 



B. — Spores hyaline. 



Actidium. Spores 1-septate; ascophore stellately branched. 



Aulographum. Spores 1-septate; ascophore not stel- 

 late, membranaceous. 



Glonium. Spores 1-septate ; ascophore not stellate, car- 

 bonaceous. 



Hypoderma. Spores elongated, narrowly cylindrical or 

 fusiform ; ascophore membranaceous. 



liOphium. Spores needle-shaped, nearly as long as the 

 ascus ; ascophore vertical, mussel-shaped. 



Lophodermium. Spores needle-shaped, nearly as long 

 as the ascus ; ascophore not mussel-shaped. 



Gloniopsis. Sjiores muriform. 



Dichaena. Asci sessile, broadest at the base ; asoophores 

 densely gregarious. 



