2l8 



unknown whether the hyphae develop apothecia under any circum- 

 stances or not ; they evidently do not develop them as lichens. 



Amfhiloma lanuginosum (Ach.), which has been classed as 

 Pannaria lanuginosa by Koerber, is another doubtful structure. E. 

 Fries is the only investigator who is reported to have found apothe- 

 cia, but the report is, however, so doubtful that no reliance can be 

 placed upon it ; all of the European and American specimens which 

 came under my observation showed no trace of an apothecial struc- 

 ture. As compared with Lepra it is a much higher structure ; it pre- 

 sents essentially the characters of a lichen-thallus ; it has a radial 

 growth with definite marginal outline which spreads slowly while the 

 central portion dies away ; the entire thallus is very friable, almost 

 mealy in nature ; the upper surface is light grey tinged with green ; 

 no cortical structure is present ; the upper portion of the thallus is 

 soredioid in nature ; in fact the entire thallus may be looked upon 

 as a mass of soredia loosely held together by hyphal threads ; the 

 lower surface is somewhat smoother, white or light grey and bears 

 numerous darker rhizoids which usually occur in bunches.' 



As already indicated, the majority of algae occur in the soredioid 

 association. Haustoria, both ectotrophic and endotrophic, are very 

 numerous ; the algae, which are undoubtedly Cystococcus hnmicola 

 Nag., are somewhat smaller and paler green than* in Parmelia and 

 Physcia. 



Formerly various lichens and parts of lichens were classed 

 under Pseudolichenes or Lichenes imferfecti. Of these, six generic 

 groups were recognized: Isidium Ach., Variolaria Ach., Lefra 

 Hall., Pulveraria Ach., Sfilonema Ach., Pyrenothea Fr. Isidium 

 included the peculiar warty and isidioid outgrowths quite frequent 

 on the upper surface of foliose thalli ; it also comprised various 

 sterile warty crustaceous lichens. Under Variolaria were included 

 sterile forms of Pertusaria communis, P. lactea, besides other sterile 

 crustaceous lichens of a grey or whitish color, especially those bear- 

 ing numerous soredia. Lefra included the above described true pseu- 

 do-lichen L. viridis as well as sterile forms of Placodhmi and perhaps 

 Rinodina. Under Pulveraria were evidently included incipient 

 primary thalli of Cladonia as well as sterile forms of Calicium, etc. 

 The characters of Sfilonema are very uncertain, referring, perhaps, 

 to sterile forms of Graf his, Arthonia, etc. The term Pyrenothea 

 referred, no doubt, to low forms of lichens (perhaps old dying plants) 



