320 SYSTEMATIC 



XVI. CYPHELIACEAE 



Thallus crustaceous. Algal cells Protococcaceae or Trentepohlia. Apo- 

 thecia sessile, more widely open than in the previous family; in some genera 

 the thallus forms an outer apothecial margin. The genera Farriola from 

 Norway and Tylophorella from New Granada are monotypic. The British 

 genus Cyphelium has been known as Trachylia. 



Thallus with Protococcaceae. 



Spores colourless, simple I. *Farriola Norm. 



Spores brown, i-3-septate (rarely simple or muriform) ...2. Cyphelium Th. Fr. 

 Thallus with Trentepohlia. 



Spores simple, many in the ascus 3. *Tylophorella Wainio. 



Spores 8 in the ascus. 



Apothecia with a thalline margin 4. *Tylophoron Nyl. 



Apothecia without a thalline margin 5. *Pyrgillus Nyl. 



XVII. SPHAEROPHORACEAE 



The most highly evolved family of the subseries, as regards the thallus. 

 Algal cells Protococcaceae. In Tholurna, a small lichen endemic in Scan- 

 dinavia, there is a double thallus : one of horizontal much-divided squa- 

 mules, the other swollen, upright, terminating in the capitulum. The fruit 

 is lateral in Calycidium, a squamulose form from New Zealand, and in 

 Pleurocybe from Madagascar, with stiff strap-shaped fronds. All the genera 

 are monotypic except Sphaerophorus, of which genus ten species are recorded, 

 some of them with a world-wide distribution. The spores are brown and 

 simple or i -septate. 



Thallus squamulose and upright I. *Tholurna Norm. 



Thallus wholly squamulose 2. *Calycidium Stirton. 



Thallus fruticose. 



Fronds hollow in the centre 3. *Pleurocybe Miill.-Arg. 



Fronds not hollow. 



Fruit without a thalline margin 4. *Acroscyphus Lev. 



Fruit inclosed in the tip of the fronds 5. Sphaerophorus Pers. 



SUBSERIES 2. Graphidineae 



In this subseries are included five families that differ rather widely from 

 each other both in thallus and apothecia; the latter are more or less 

 carbonaceous and mostly with a proper margin only. Families and genera 

 are widely distributed, though most abundant in warm regions. Algal cells 

 mostly Trentepohlia. 



A comprehensive study of the apothecia of this series by Bioret 1 gives 

 some interesting results in regard to the paraphyses: in Arthonia they are 

 irregular in direction and much-branched ; in Opegrapha, the paraphyses 

 are vertical and parallel with more regular branching ; Stigmatidium (Entero- 



1 Bioret 1914. 



