FAMILIES AND GENERA 333 



Thallus with Gloeocapsa gonidia. 

 Thallus crustaceous. 



Spores simple I. Pyrenopsis Nyl. 



Spores i-septate 2. *Cryptothele Forss. 



Thallus shortly fruticose 3. Synalissa Fr. 



Thallus lobate, centrally attached 4. *Phylliscidium Forss. 



Thallus with Chroococcus gonidia. 



Thallus crustaceous 5. Pyrenopsidium Forss. 



Thallus lobate, centrally attached 6. *Phylliscum Nyl. 



Thallus with Xanthocapsa gonidia. 

 Thallus crustaceous. 

 Thallus non-corticate. 

 Spores simple. 



Apothecia open, asci 8-spored 7. Psorotichia Forss. 



Apothecia covered, asci many-spored 8. *Gonohymenia Stein. 



Spores i -septate. 



Apothecia closed 9. *Collemopsidium Nyl. 



Thallus with plectenchymatous cortex 10. *Forssellia A. Zahlbr. 



Thallus lobate, centrally attached. 

 Spores simple. 



Thallus plectenchymatous throughout u. *Anema Nyl. 



Thalline tissue of loose hyphae 12. *Thyrea Massal. 



Cortex of upright parallel hyphae 13. *Jenmania Wacht. 



Spores i -septate. 



Thalline tissue of loose hyphae 14. *Paulia Fe"e. 



Thallus fruticose. 



Thallus without a cortex 15. *Peccania Forss. 



Thallus with cortex of parallel hyphae 16. *Phloeopeccania Stein. 



XXXVIII. LlCHINACEAE 



The only family of lichens associated with Rivularia gonidia, the 

 trichomes of which retain their filamentous form to some extent in the 

 more highly developed genera; they lie parallel to the long axis of the 

 squamule or of the frond except in Lichinella in which genus they are 

 vertical to the surface. The thallus may be crustaceous, or minutely foliose, 

 or fruticose; in all cases it is dark-brown in colour, and the gelatinous 

 character is evident in the moist condition. The best known British genus 

 is Lichina which grows on rocks by the sea. 



The apothecia are more or less immersed in the tissue; in Pterygium and 

 Steinera they are open and superficial (the latter monotypic genus confined 

 to Kerguelen). They are also open in Lichinella and Homopsella, both very 

 rare genera. The spores are colourless and simple except in' Pterygium arid 

 Steinera where they are elongate, and i-3-septate. 



Thallus crustaceous squamulose. 



Apothecia immersed in thalline warts I. *Calothricopsis Wain. 



Apothecia superficial, with thalline margin 2. *Steinera A. Zahlbr. 



Apothecia superficial, without a thalline margin 3. Pterygium Nyl. 



