219 



bearing numerous " sperm agonia, pycnidia," or perhaps true par- 

 asitic fungi. 



THE CONTINENTAL RANGE OF THE LICHEN GENERA OCCUR- 

 RING IN THE NORTHEASTERN UNITED STATES. 



Lichens are more widely distributed than any other class of the 

 thallophytes. They are enabled to thrive where neither alga or fun- 

 gus could exist alone. They occur plentifully in the tropics as well 

 as in the extreme northern regions ; in the valleys as well as upon 

 the highest mountain peaks. The majority occur at sea level, while 

 some thrive most luxuriantly at high altitudes as Cladonia, Cetraria, 

 Umbilican'a, some species of Lccanora, etc. 



The following table gives the general continental range of the 

 lichen genera represented in the northeastern United States. Some 

 of the representatives are not sufficiently known to indicate their true 

 range ; such are marked with an *. Those given under " territory" 

 are about uniformly distributed throughout the region. 



