LICHENES IMPERFECTI OR FALSE LICHENS. 



Formerly various lichens and parts of lichens were 

 classed as Pseudolichens or Lichenes imperfecti. Of 

 these six generic groups were recognized: Isidium 

 Ach., Variolaria Ach., Lepra Hall., Pulveraria Ach., 

 Spilonema Ach., Pyrenothea Fr. Isidium included 

 the peculiar warty and isidioid outgrowths quite fre- 

 quent on the upper surface of foliose thalli ; it also 

 comprised various sterile warty crustose lichens. Un- 

 der Variolaria were included sterile forms of Pertusa- 

 ria communis, P. lactea, besides other sterile crustose 

 lichens of a gray or whitish color, especially those 

 bearing numerous soredia. Lepra included the pseudo- 

 lichen L. viridis as well as sterile forms of Placodium 

 and perhaps Rinodina. Under Pulveraria were evi- 

 dently included incipient primary thalli of Cladonia 

 as well as sterile forms of Calicium, etc. The char- 

 acters of Spilonema are very uncertain, referring, per- 

 haps, to sterile forms of Graphis, Arthonia, etc. The 

 term Pyrenothea referred, no doubt, to low forms of 

 lichens (perhaps old, dying plants) bearing numerous 

 8permagonia, pycnidia, or perhaps parasitic fungi. 



