( xvi ) 



wide separation of Bceomyces and Cladonia from Biatora, be- 

 tween all of which there are direct transitions the difficulties 

 of the multiplicity, and unequal, now very uncertain values of 

 the points of view 'the salient characters of all parts of lichens' 

 are, for us, insuperable. The resulting complex of series and 

 tribes belongs indeed to, and illustrates brilliantly, with the au- 

 thor's unequalled knowledge of particulars, the Natural Method; 

 but the complex is, in very consequence of the extreme extent 

 of this particularism, perplexing to the student (*), who finds 

 himself entangled anew in the meshes of nature, from which 

 meshes nature, with whatever devotion he seek her help, is pow- 

 erless to release him. What wonder then, if escaping at length, 

 by his own deliberate act, from the inordinate multifariousness 

 and accidentality of the natural affinities, and unable to accept 

 the thallus as a sufficient guide, he turn now to his only remain- 

 ing choice, the apothecium the flower and fruit, and highest 

 that we know of our plants : the principle of construction of 

 Persoon, Acharius, Wahlenberg, and Fries. We are here con- 

 sidering only system, and it may be permitted to me to add, 

 that much, and invaluable, and not yet to be fully estimated, as 

 are the acquisitions of the improved methods of study of the 

 last thirty years, the whole movement took its start from the 



(*) And in view of the importance of this consideration, it is proper 

 to be more explicit. The genus Lecidea, as understood by Nylander, 

 while constituted of a now no little strained association of not less than 

 six, (by some prominent writers broken into many more) generic types 

 accepted by the great majority of modern lichenologists, two of these 

 types indicating groups of vast extent, Fries's distinction of which has 

 proved an invaluable boon to study, is yet further and to the last degree 

 embarrassed, in the two great and difficult groups named, by crowds, 

 ever increasing, of lichens called new, but neither sufficiently charac- 

 terized, nor, for the most part, illustrated by any sufficient explanation ; 

 and has thus, in the great bulk of the genus, become, what we have no 

 better word for than a wilderness of obscure forms, into the intricacies 

 of which only the author can presumably possess any trustworthy clew. 



