SECT. iv. ANGIOCARPEI. 309 



tropical America, though a few species occur in the 

 frigid and temperate zones of both hemispheres. 



The order Glyphidei has no true excipulum ; the 

 coloured discs are at first immersed in the medullary 

 stratum of a crustaceous thallus, the crust then rises 

 into distinct expansions, in the centre of which the 

 coloured discs are set like gems in a mosaic. ' There is 

 in fact no true border to the disc, the perithecium being 

 reduced to a thick conical base, from which proceed 

 immediately the asci and paraphjses; each individual 

 hymenium being surrounded by the intervening medul- 

 lary matter injected, as it were, into the interstices.' 

 The whole surface of Chiodecton monostichum is pro- 

 ductive, and in that genus M. Tulasne found vessels in 

 the form of little scattered perithecia, containing filiform 

 curved fertilizing particles. The species of this order 

 are almost wholly tropical, though the Chiodecton myr- 

 ticola has been found in Ireland. 



The order Caliciei consists of horizontal lichens, with 

 generally an ill-developed crust; the discs, which are 

 at first covered by a veil, are contained in a stalked, or 

 more rarely sessile, excipulum, looking like little flat- 

 headed pins stuck into the crust; the veil at length 

 vanishes, and exposes a pulverulent mass of spores, 

 which adhere so loosely in the Calicium inquinans, that 

 they soil the finger if touched ; in other cases they come 

 out of their ascus like little necklaces. The species of 

 these lichens are almost entirely confined to Europe 

 and North America. 



In the second division of Lichenacese, the ANGIO- 

 CAEPEI, the discs are enclosed in an excipulum, which 

 projects from the surface of the plant, and ultimately 

 discharges the spores from a rupture or pore in its 

 surface. Besides the fructification consisting of peri- 

 thecia containing paraphyses and asci with their en- 



