148 HERRE 



PANNARIACE^E. 



Thallus crustaceous, granular, uniform or marginally lobed; or 

 squamulose, passing into foliaceous forms; hypothallus and rhizoids 

 usually well developed; the upper side with a cortex of pseudopar- 

 enchymatous tissue composed of hyphae arranged perpendicularly, 

 irregularly, or horizontally; lower side with or without a cortex; 

 algae Nostoc, Scytonema, or in two genera, Pleurococcus. 



Apothecia circular, marginal or scattered over the surface, lec- 

 anorine or biatorine, or occasionally lecideine; paraphyses simple; 

 spores colorless, simple, or 2-4 celled. 



A difficult group, nearly related to the Stictas and the Peltigeras, 

 and also the Heppias, with features intermediate between the lec- 

 anorine and the lecideine types of lichens. 



Following the arrangement of Dr. Zahlbruckner, we have 3 of his 

 ten genera, though the present author feels that some of the genera 

 are hardly separable. 



KEY TO GENERA. 



A. Apothecia lecanorine; spores i -celled XXXVII. Pannaria 



AA. Apothecia biatorine or lecideine. 



B. Spores i-celled XXXV. Parmeliella 



BB. Spores 2-8 locular XXXVI. Placynthium 



XXXV. Parmeliella Mull. Arg. 



Parmeliella Mull. Arg., 



Parmeliella A. Zahlbr. Ascolichenes, 181. 1907. 



Thallus of small scales, lobed at the margin, or nearly foliaceous, 

 usually with a well-developed dark hypothallus; alga Nostoc. Cor- 

 tex present on upper side but not on lower. 



Apothecia biatorine, scattered over the surface; margin of stel- 

 lately arranged, septate hyphae, not enclosing algae; spores simple, 

 colorless, elongate or ellipsoid. 



About 15 species, on rocks, earth, and bark of trees, often difficult 

 of determination. 



