NEW ENGLAND LICHENS 



51 



and in my experience, rock growing examples are as a rule 

 the ones that develop apothecia, and a confusion with the 

 somewhat like colored apothecia of Parmelia conspersa is 

 therefore likely to be made. If Parmelia caperata fruited 

 commonly throughout the northern portion of its range — it 

 might suggest that in this latitude the colder rock substratum, 

 as compared with the warmer vegetable, had the effect to 

 equalize latitude. ... 



FIGURE 4. — A disintegrated specimen, lacking symmetry on 

 account of its rough bark substratum (Fraxinus.) 



Another distracting feature in the ready determination 

 of this species, Is n-ot only due, as I have suggested, to the 

 character of the surface of the substratum, nor to Its vege- 

 table or mineral character, but to the position of the plant's 

 growth. The corlaclous thallus often shows the effect of 

 gravity. If the attachment of the Lichen is discontinuous or 

 weak, it shows the tendency, when growing in a vertical 



