30 Fink: Problems of North American Lichenology 



them without seeing the specimens listed. Finally, in default 

 of a new manual of North American lichens, a compilation of 

 descriptions of post-Tuckermanian new species would be well 

 worth while. This, in turn, can be done only after one has at 

 hand as reliable a bibliography as can be made. 



A labor less distinctly American is that of typifying lichen 

 genera. This problem may become distinctly one for Americans 

 through failure of European lichenists to attack it. Our present 

 knowledge of lichen genera is far from complete. Recent at- 

 tempts to typify genera of American lichens has proven to the 

 writer that all lists of lichen genera, Krempelhuber's* not excepted, 

 fall far short of being complete. Krempelhuber gives approxi- 

 mately 750 lichen genera, and there are fully 250 more, some 

 of which he either ignored in his compilation or did not know, 

 while others have been proposed since 1870. An approximately 

 complete list of lichen genera is to be had only by working 

 over a vast amount of botanical literature, searching in obscure 

 places as well as in publications better known. This involves 

 an enormous amount of difficult literary work, besides thousands 

 of critical examinations of specimens. Some examples of diffi- 

 culties may be drawn from the writer's attempts to typify our 

 lichen genera. However, before giving these instances of diffi- 

 culties arising in attempts to typify genera according to the first 

 species rule, the writer wishes to disavow any settled conviction 

 on his part that this is the best method, nor does he care to be 

 interpreted as being certain that it is best to abandon well estab- 

 lished generic names in the interests of priority ; he prefers to 

 reserve judgment for the present. The illustrations are as 

 follows : * 



Type species, Amphiloma elegans (Link) Fr. Korb. Syst. Lich. 

 no. 1855. But this is our Placoalium elegans, and the name 

 Amphiloma is invalid. Type species, Pyrenula verrucosa Ach. 

 Lich. Univ. 314. pi. 15. f. 1. 1810. But this plant is a Verru- 

 caria, and Pyrenula would be invalid, were not V errucaria, in 

 our present conception of the genus, invalid. But we have as 



* Krempelhuber, A. von. Geschichte und Litteratur der Lichenologie i : 

 i-xv. 1-616. 1867; 2: i-viii. 1-776. 1869; 3: i-xvi. 1-261. 1872. Munchen, 

 C. Wolf & Sohn. 



