108 



Mycologia 



tilaginous, innate-marginate, periphery entire, or fimbrio-ciliate 

 (oregana) , disk concolorous or discolorous, rarely pruinose. 

 Asci clavate, containing 2 to 8 spores ; paraphyses gelatinous, 

 filamentous. Spores monoblast, hyaline or colorate, muriform or 

 emuriform. Spermagones immersed or papilliform, apices 

 slightly incrassate. Soralia* white, pale virescent or yellow. 

 Soredia unobserved. Cephalodia unobserved. Cyphella occasion- 

 ally present. Thallus erect, prostrate, or pendulous, branched, 

 tortulous, terete, subterete, or compressed; glabrous, nitidous, 

 canescent, sulciform or foveolate ; pale stramineous, virescent 

 sulphureous, cinereous or brown-; cortex cartilaginous, contigu- 

 ous ; gonidia " Protococcus " (Cystococcus humicola (Nseg.) ; 

 medulla loosely cottonous, arachnoid or absent. 



Though I have examined an immense amount of material and 

 placed it under the following species with as much accuracy as 

 possible, judging it with the enlightenment of a long and critical 

 study, I am not ready to claim that the distribution of specimens 

 has been either faultless or the reason always apparent. The 

 genus Alectoria presents a most complex and difficult problem, 

 due to the enormous variation found in filamentous lichens, and, 

 after years of study, it seems to me that we must keep the 

 broadest view of species and allow the two extremes of varia- 

 tion to stand far apart. To narrow our limits, and name con- 

 tingent phases that present themselves in legion, we at once 

 destroy the discrimination which is possible toi one after long 

 study of much material. 



The only determinations that I am absolutely sure of are of 

 those specimens which I myself have gathered in the field, or that 

 have been collected in such entirety, accompanied by careful field 

 notes, that I can not only judge of the plant, but of its particular 

 environs. It is a common experience of lichenists to find that a 

 plant which has long been an absolute puzzle after the examina- 

 tion of much herbarium material, will be at once understood if 

 met and studied in the field. Alectoria diver gens with Cetraria 

 aculeata, Alectoria chalybeiformis and its northern limit of distri- 

 bution, and Alectoria ochroleuca Cincinnati and crinalis, are 

 examples of puzzles that only an extensive field study can 

 thoroughly solve. Exactitude can never be gained by narrowing 



* Bitter, Hedwigia 40: 171. 1901. 



