FAMILIES AND GENERA 315 



The gonidia are bright-green Protococcaceae (according to Chodat, Cocco- 

 botrys in Dermaiocarpon). In Endocarpon they appear in the hymenium. 



The least developed in structure is Normandina : the thallus of the 

 single species consists of delicate shell-like squamules which are non- 

 corticate above and below. In the other genera there is a cortex of 

 plectenchyma. 



The perithecia are almost wholly immersed, and open above by a straight 

 ostiole. The fructification of Dacatnpia is considered by some lichenologists 

 to be only a parasite on the white thickish squamulose thallus with which 

 it is associated. 



Hymenial gonidia present. 



Spores muriforra i. Endocarpon Hedw. 



Hymenial gonidia absent. 



Thallus non-corticate 2. Normandina Wain. 



Thallus corticate. 



Spores simple, colourless 3. Dermatocarpon Eschw. 



Spores simple, brown 4. *Anapyrenium Mull.-Arg. 



Spores elongate-septate, colourless 5. *Placidiopsis Beltr. 



Spores elongate-septate, brown 6. *Heterocarpon Miill.-Arg. 



Spores muriform, colourless 7. *Psoroglaena Miill.-Arg. 



Spores muriform, brown 8. Dacampia Massal. 



V. Pyrbnothamniaceae 



Thallus more or less fruticose and corticate on both surfaces. Algal 

 cells Protococcaceae. 



Only two genera are included in this family : Nylanderiella with one 

 species from New Zealand, with a small laciniate thallus up to 15 mm. in 

 height, partly upright, partly decumbent, and attached to the substratum by 

 basal rhizinae ; the other small. genus, Pyrenothamnia, belongs to N. America ; 

 the thallus has a short rounded stalk which expands above to an irregular 

 frond. The perithecia are immersed in the fronds. 



Spores colourless, i-septate i. *Nylanderiella Hue^ 



Spores brown, muriform 2. *Pyrenothamnia Tuckerm. 



VI. Mastoids ACE AE 



A family containing one genus and one species, with a wide distribution, 

 having been found in Siberia, on the Antarctic continent (Graham's Land), 

 as also in Tierra del Fuego, South Georgia, South Shetland Islands and 

 Kerguelen. The thallus is foliose, of small thin lobes, and without rhizinae. 

 Algal cells Prasiola"^. The perithecia are globose and partly project from 

 the thallus; the asci are 8-spored; the paraphyses are mucilaginous and 

 partly dissolving. 



Spores elongate-fusiform, simple, colourless ...i. *Mastoidea Hook, and Harv. 

 ^ Hue 1914. ^ Hue 1909. 



