127 



cium and upper ends of the simple paraphyses present two prevailing 

 colors, brown and bright scarlet ; in fact most authors separate the 

 Cladoniae into two groups based on these color differences ; the 

 hypothecium is colorless, showing a marked cortical tendency. 



The spores are simple, colorless, elliptical and of such uniformity 

 in size and form that no specific distinctions can be based upon their 

 characters. It must also be borne in mind that a number of species 

 are quite constantly sterile, but in spite of this fact soredia are defi- 

 cient. Special means of propagation and reproduction are not nec- 

 essary, since the majority of Cladoniae are endowed with almost 

 eternal life. 



The Cladoniae are widely distributed, though some are typically 

 northern ; they occur upon the soil, old tree-trunks, old fences, and 

 rocks. 



PLATE 13. 



CLADONIA PYXIDATA Fr. 



1. Plants natural size. 



a and c, sterile pocletia ; b, apothecia borne upon apothecial branches, 

 e; d, horizontal (primary) thalli. 



2. Diagramatic section of the cup of podetium showing the arrange- 



ment of the mechanical tissue (b). 



3. Section of apothecium. 



4. Vertical section of primary thallus. 



=;. Spore-sac with spores and paraphyses. 



6. Spores. 



7. Algae. 



8. Portion of spermagonium. 



a, sterigmata bearing spermatia ; b, hyphal network below the sterig- 

 mata continuous with the tissue (c) enclosing the entire sperma- 

 gonium. 



9. Spermatia. 



(See also Plate 14.) 



5. THAMNOLIA Ach. ; Schaer. Lich. Helv. Spec. 44. 1823. 



This genus is represented by only one species, T. vermicularis ; 

 which has probably been derived from some species of Cladonia. 



The horizontal thallus is wanting. The vertical thallus is mor- 

 phologically more highly developed than that of the Cladoniac, the 

 outer layer, though thin, being for the most part cortical ; the algal 



