340 SYSTEMATIC 



Thallus strap-shaped. 

 Structure dorsiventral. 



Greyish-green above I. Evernia Ach. 



Whitish-yellow above 2. *Everniopsis Nyl. 



Structure radiate alike on both surfaces. 



Fronds grey ; medulla of loose hyphae 3. Ramalina Ach. 



Fronds yellow ; medulla traversed by strands 4. *Letharia A. Zahlbr. 



Thallus filamentous. 



Medulla a strong "chondroid" strand 5. Usnea Dill. 



Medulla of loose hyphae. 



Spores simple 6. Alectoria Ach. 



Spores muriform, brown 7. *Oropogon Fr. 



Thallus of upright podetia-like fronds. 



Fronds rather long (about two inches), tapering,) 8. Thamnolia Ach. (Cerania 



white I S. F. Gray). 



Fronds shorter, blunt 



Medulla solid 9. *Siphula Fr. 



Medulla partly or entirely hollow. 



Fronds swollen and tall (about two inches) 10. *Dactylina Nyl. 



Fronds coralloid, entangled u. *Endocena Cromb. 



Fronds short, upright 12. *Dufourea Nyl. 



XLVIII. CALOPLACACEAE 



In this family Zahlbruckner has included the squamulose or crustaceous 

 lichens with colourless polarilocular spores, relegating those with more 

 highly developed thallus or with brown spores to other families. He has 

 also substituted the name Caloplaca for the older Placodium, the latter being, 

 as he considers, less well defined. 



Algal cells are Protococcaceae. The thallus is mostly light-coloured, 

 generally some shade of yellow, and, with few exceptions, contains parietin, 

 which gives a purple colour on the application of potash. The squamulose 

 forms are closely appressed to the substratum, and have often a definite 

 rounded outline (effigurate). The spores have a thick median septum with 

 a loculus at each end and a connecting canal 1 . 



In Blastema the outer thalline margin is obscure or absent though 

 gonidia are frequently present below the hymenium. Caloplacaceae occur 

 all over the globe ; they are among the most brilliantly coloured of all 

 lichens. Polycauliona Hue 2 possibly belongs here: though based on thalline 

 rather than on spore characters, one species at least has polarilocular spores. 



Apothecia with a distinct thalline margin I. Caloplaca Th. Fr. 



Apothecia without a thalline margin 2. Blastenia Th. Fr. 



1 See p. 188. s Hue 1908. 



