CHAPTEE XVIII 



GAPING FUNGI HYSTEEIACEAE 



The ffysteriaceae are related on the one hand to the Pyreno- 

 mycetaceae, and on the other to the Discomyceteae, but perhaps 

 externally most strongly to the former, to which they approach 

 through the subfamily Lophiostomaceae, whilst their connection 

 with Discomyceteae must be through such genera as Colpoma 

 and Triblydium. As the Discomyceteae approach Lichens 

 through some of the Patellariaceae, so also do the ffysteriaceae 

 through Aulographum and Dichaena. In this family the 

 perithecia are erumpent and then superficial, with a flattened 

 base, and horizontally extended, either oblong or linear. In 

 substance they are occasionally membranaceous, but more 

 often coriaceous, or rather carbonaceous, but very rarely some- 

 what fleshy. They are for the most part black, and dehiscence 

 takes place by a long narrow fissure which extends the whole 

 length of the perithecium. The asci may be tetrasporous or 

 oetosporous, and sometimes polysporous, but the sporidia vary 

 in the different sections and genera, from simple and continuous 

 to multiseptate and muriform. The arrangement proposed by 

 Saccardo may be accepted as the best yet proposed. The only 

 objection which could be urged concerns the genera Schizo- 

 thyrium, Aulographum, and Lembosia, which from our point of 

 view seem to be scarcely generically distinct, since the differ- 

 ence lies only in the sporidia, which are respectively con- 

 tinuous, uniseptate, and hyaline, and uniseptate and coloured. 

 Great care needs to be exercised, for species of Aulographum 

 are at first continuous, as in Schizothyrium., and may ultimately 

 be faintly coloured, passing thus into Lembosia. 



The whole family is divided, carpologically, into nine sections, 



