GENERA AND SPECIES. 



169 



VII. VERR UCA RIA CE^. 



The representatives of this family are characterized 

 by small globose apothecia, which are either immersed 

 in the substratum (bark or rock) or in the thallus {Der- 

 matocarpon and Endocarpon). In the majority of 

 genera the thallus is crustose, even wholly hypophloeo- 

 dal or hypolithic. Another characteristic of the fam- 

 ily is the indistinct, slender, gelatinized paraphyses. 



With the exception of Endocarpon the members of 

 the family are insignificant in appearance; in fact, 

 some are very doubtful lichens, as, for example, most 

 of the Pyrenulas and some species of Trypethelium. 



Two algal types exist in this family: Ghroolepus 

 occurs in the genera from Trypethelium to Verrucaria, 

 Pleurococcus occurs in Verrucaria, Dermatocarpon 

 and Endocarpon. It must, however, be born in mind 

 that the algal symbiont may vary in different in- 

 dividuals of the same species. This change in sym- 

 bionts requires further study. 



KEY TO THE GENERA. 



Crustose thallus. , , ^ , 



Thallus scarcely visible, mostly hypophloeodal. < 

 Spores six to eight-celled, colorless . 1. Trypethelium. 



Spores four-celled, brown 2. Pyrenula. 



Spores many-celled, colorless . . . 3. Conotrema. 

 Spores multilocular, colorless. 



Spore-wall normal 4- Thelolrema. 



Spore-wall thick 5. G/postomum. 



Thallus visible, mostly epiphloeodal or epilithic. 

 Spores simple, colorless. 



Medium size ^- lerrucana. 



Very large ^- Pertusario. 



Foliose thallus.^ntiro ; spores colorless. 



Spores multilocular: thallus minute . S. Dermatocarpon. 

 Spores simple ; thallus large . . . . 9. Endocarpon, 



