PARMELIACEAE— PHYSCIACEAE 83 



(2) Cyphellae or pseudocyphellae absent ; cephalodia usually present 



(a) Apothecia with thalline exciple 



*Phycodiscis 188 



(b) Apothecia with proper exciple only 



Lobarina 188 

 b. Thallus scaly to small-leafy, sometimes crustose, exceptionally large-leafy, 

 without cyphellae, etc. Subfamily Pannariae 178 



(1) Lower surface of thallus scarcely or not at all veined; spores 1-2-celled 



(a) Upper cortex well-developed; distinct 



x. Upper cortex with hyphae perpendicular to it 

 (x) Upper cortex hairy or pilose 



Erioderma 183 

 (y) Upper cortex not hairy 

 m. Apothecia with thalline exciple 

 (m) Spores i-celled; algae Nostoc 



Pannaria 181 

 (n) Spores 2-celled ; algae Scytonema 



Massalongia 183 

 n. Apothecia with proper exciple only 



(m) Spores i-celled Parmeliella 181 



(n) Spores 2-many-celled Placynthium 181 

 y. Upper cortex of horizontal hyphae 



Coccocarpia 184 



(b) Upper cortex indistinct; algae occupying nearly the whole width of 



the thallus Lepidocellema 180 



(2) Lower surface of thallus with distinct forked veins ; spores 4-celled 



Hydrothyria 184 



Family 43. PHYSCIACEAE 



Zahlbruckner 226-234 



Thallus crustose, foliose or f ruticose, as in Parmeliaceae ; apothecia mostly 

 lecanorin, sometimes with proper exciple alone ; spores normally 2-celled, with more 

 or less thickened cross-wall, often traversed by a line-like canal, or exceptionally 

 i-many-celled or muriform 

 I. Spores 2-celled 



1. Spores clear 



a. Thallus without cortex, uniform or crustose 



(1) Apothecia with thalline exciple Caloplaca 227 



(2) Apothecia with proper exciple only 



Blastenia 226 



b. Thallus with cortex, foliose or fruticose 



(1) Thallus foliose, horizontal or ascending, dorsiventral, with rhizoids, cor- 



tex pseudoparenchymatic on both sides 



Xanthoria 229 



(2) Thallus fruticose, erect, radial, cortex of conglutinate longitudinal hyphae 



Theloschistes 230 



2. Spores dark or brown 



a. Thallus without cortex, uniform or crustose 



