402 INTRODUCTION TO CRYPTOGAMIC BOTANY. 



as it were into the interstices. In some species, as Chiodecton 

 monostichum, there are scarcely any distinct fructifying spots, 

 the whole surface being productive. The spermatogonia of 

 Chiodecton are figured by Tulasne, in the form of little 

 scattered perithecia, which produce filiform, curved spermatia. 



439. The typical genus Glyphis* is distinguished from 

 Chiodecton by something like an excipulum extending up the 

 sides of the hymenium. In Medusula we have the elongated 

 form of Hysterium, to which there is an approach also in some 

 species of OlyiMs, accompanied by a radiating disposition, which 

 is repeated in Actinoglyphis, Mont. This is, however, dis- 

 tinguished by a double row of partial excipula along each disc. 

 Byssophytum is also placed in this tribe by Montague. The 

 apothecia of this curious plant are discoid and bordered by the 

 thallus, destitute of any proper excipulum, and enclosing a 

 byssoid parenchyma which gives rise to coloured pulveraceous 

 spores. This abnormal genus, of which I possess by the kindness 

 of Dr Montague the Tahiti species B. sul/urewm, appears to 

 me scarcely autonomous. A Lichen without asci would be a 

 complete anomaly, when productions like Pyrenothea are ex- 

 cluded. The species of Glyphidei are almost wholly tropical, 

 though one or two species occur rarely in Europe. Chiodecton 

 myrticola ascends as high as Ireland, where it was discovered 

 by Dr. Taylor. The coloured disc is characteristic of most of 

 the species, but the tint is sometimes obscured by a pulverulent 

 coat, or the surface blackened by age. 



8. Graphidei, .Fr. 



Disc linear, simple or branched. Excipulum carbonaceous, 

 various, superior, or lateral, sometimes absent. 



440. Exactly analogous to Hysterium and its allied genera, 

 the genera of this group afford a large mass of the truly cor- 

 tical species of Gymnocarpous, as the Verrucarioe do amongst 

 the Angiocarpous Lichens. A large number of the species are 

 readily referred to this tribe, being quite as perfect resem- 

 blances of letters as the mysterious marks upon the tree 

 described by Hue and Gabet, the counterpart of which was 



* The names of Olyphis and Chiodecton are transposed in EschweileVs 

 plate, 80 that the latter seems to have the more perfect organization. 



