FAMILIES AND GENERA 335 



XL. HEPPIACEAE 



A family belonging to the "blue-green" series as it is associated with 

 a gelatinous alga, Scytonema, but is of almost entirely cellular structure and 

 is non-gelatinous. The thallus is squamulose or minutely foliose, or is formed 

 of narrow almost fruticose lobes; the apothecia are semi-immersed; the asci 

 are 4-many-spored. 



Heppia is a wide-spread genus both in northern and tropical regions 

 with about forty species that live on soil or rock. So far, no representative 

 has been recorded in our Islands. 



Spores simple, colourless, globose or ellipsoid i. *Heppia Naeg. 



Spores muriform, colourless, ellipsoid 2. *Amphidium 1 Nyl. 



XLI. PANNARIACEAE 



The members of this family are also non-gelatinous, though for the most 



^part associated with blue-green gelatinous algae, Nostoc or Scytonema. The 



gonidia are bright-green in the genera Psoroma and Psoromaria, the former 



often included under Lecanora, but too closely resembling Pannaria to be 



dissociated from that genus. 



The thallus varies from being crustaceous to squamulose or foliose, and 

 has a cortex .of plectenchyma on the upper and sometimes also on the 

 lower surface. The apothecia are superficial or lateral and with or without 

 a thalline margin (lecanorine or biatorine), the spores are colourless. 



Zahlbruckner has included Hydrothyria in this family. It is a monotypic 

 aquatic genus found in North America and very closely allied to Peltigera. 

 The British species of the genus, familiarly known as Coccocarpia, have 

 been placed under Parmeliella, the former name being restricted to the 

 tropical or subtropical species first assigned to Coccocarpia and distinguished 

 by the cortex, the hyphae forming it lying parallel with the surface though 

 forming a regular plectenchyma. 



An Antarctic lichen Thelidea corrngata with Palmetto, gonidia is doubt- 

 fully included : the thallus is foliose, the apothecia biatorine with colourless 

 i -septate spores. 



Thallus with bright-green gonidia. 



With Palmella i. *Thelidea Hue. 



With Protococcaceae. 



Apothecia non-marginate (biatorine) 2. *Psoromaria Nyl. 



Apothecia marginate 3. Psoroma Nyl. 



Thallus with Scytonema gonidia. 



Apothecia marginate, spores i-septate 4. Massalongia Koerb. 



Apothecia non-marginate ; spores simple. 



Upper surface smooth 5. *Coccocarpia Pers. 



Upper surface felted 6. *Erioderma Fe'e. 



1 A. Zahlbruckner, in Oesterr. hot. Zeiischr. 1919, p. 163. 



