FAMILIES AND GENERA 341 



XLIX. Teloschistaceae 



Polarilocular colourless spores are the disting^uishing feature of this 

 family as of the Caloplacaceae. Algal cells Protococcaceae. The thallus 

 of Teloschistaceae is more highly developed, being either foliose or fruticose, 

 though never attaining to very large dimensions. The cortex of Xanthoria 

 (foliose) is plectenchymatous, that of Teloschistes (fruticose) is fibrous. The 

 species of both genera are yellow or greenish-yellow due to the presence of 

 the lichen-acid parietin. 



Both genera have a wide distribution over the globe, more especially in 

 maritime regions. 



Thallus foliose i. Xanthoria Th. Fr. 



Thallus fruticose 2. Teloschistes Norm. 



L. BuELLIACEAE 



A family of crustaceous lichens distinguished by the brown two-celled 

 spores. Algal cells Protococcaceae. Zahlbruckner has included here Buellia 

 and Rinodina; the former with a distinctly lecideine fruit and with thinly 

 septate spores; the latter lecanorine and with spores of the polarilocular 

 type, with a very wide central septum pierced in most of the species by 

 a canal which may or may not traverse the middle lamella of the wall. 

 Rinodina is closely allied to Physciaceae, while Buellia has more affinity 

 with Lecideaceae and is near to Rhizocarpon. 



Both genera are of world-wide distribution. 



Apothecia lecideine, without a thalline margin i. Buellia De Not. 



Apothecia lecanorine, with a thalline margin 2. Rinodina Massal. 



LI. Physciaceae 



Thallus foliose or partly fruticose, and generally attached by rhizinae. 

 Algal cells Protococcaceae. The spores resemble those of Rinodina, dark- 

 coloured with a thick septum and reduced cell-lumina. As in that species 

 there may be a second septum in each cell, giving a 3-septate spore; but 

 that is rare. 



Pyxine, a tropical or subtropical genus, is lecanorine only in the very 

 early stages; it soon loses the thalline margin. Anaptychia is differentiated 

 from Physcia by the subfruticose habit, though the species are nearly all 

 dorsiventral in structure, only a few of them being truly radiate and corticate 

 on both surfaces. The upper cortex of Anaptychia is fibrous, but that 

 character appears also in most species of Physcia either on the upper or the 

 lower side. Physcia and Anaptychia are widely distributed. 



Thalline margin absent in apothecia i. *Pyxine Nyl. 



Thalline margin present in apothecia. 



Thallus fohose 2. Physcia Schreb. 



Thallus fruticose 3- Anaptychia Koerb. 



