FAMILIES AND GENERA 327 



XXVIII. EcrOLECHIACEAE 



A family of tropical epiphyllous lichens that are associated with Proto- 

 coccaceous gonidia. The thallus is primitive in character, mostly a weft of 

 hyphae with intermingled algal cells, described as homoiomerous. 



The apothecia are without a thalline margin, and with a scarcely 

 developed proper margin : their affinity is with the Lecideaceae, though in 

 two genera, Lecaniella and Arthotheliopsis, there are gonidia belovv the 

 hypothecium, a character of Lecanoraceae. The genera are nearly all 

 monotypic ; in Sporopodium has been included Lecidea phyllocharis Wainio 

 (Sect. Gonothecimri), which is distinguished by hymenial gonidia. 



Apothecia at first covered by a "veil." 



Spores elongate, colourless, septate i. *Asterothyrium Miill.-Arg. 



Apothecia uncovered from the first. 

 Gonidia not present below the hypotheciunn. 

 Paraphyses unbranched, free. 



Spores muriform 2. *Lopadiopsis Wain. 



Paraphyses branched. 



Spores i-septate 3. *Actinoplaca Miill.-.Arg. 



Spores elongate, multi-septate 4. *Tapellaria Miill.-.Arg. 



Spores muriform 5. *Sporopodium Mont. 



Gonidia present below the hypothecium. 



Spores elongate, 2-septate 6. *Lecaniella Wain. 



Spores muriform 7. *Arthotheliopsis Wain. 



XXIX. Gyalectaceae 



The algal cells in this family are filamentous; either My.xophyceae 

 {Scytonemd) or Chlorophyceae ( Trentepohlia or Phyllactidium). The thallus 

 is crustaceous, and in some cases homoiomerous, as in Petractis, where the 

 alga, Scytonema, penetrates the substratum as deeply as the hyphae. Mono- 

 phiale, a tropical genus, possesses two kinds of gonidia : the species that 

 grow on bark or mosses are associated with Trentepohlia; others that have 

 invaded the surface of leathery evergreen leaves resemble most epiphyllous 

 lichens in being associated with the leaf alga Phyllactidium {Phycopeltis). 

 Some species of Trentepohlia exhale when moist an odour of violets. This 

 scent is retained in at least one genus, Jonaspis. 



The apothecia are superficial, and are soft, waxy and bright-coloured, 

 with prominent margins which are however entirely hyphal ; the affinity is 

 therefore with Lecideaceae. In one genus, Sagiolechia, the fruit is carbona- 

 ceous and dark coloured. The spores of all the genera are colourless. 



Apothecia waxy, bright-coloured. 

 Thallus with Scytonema gonidia. 



Spores elongate, 3-septate i. Petractis Fr. 



