188 GUIDE TO THE STUDY OF LICHENS. 



1. Lecothecium nigrum. Thallus crustose, granular, 

 indistinctly areolate, nearly black. Apothecia small, 

 somewhat raised above the thallus. Disk black. Spores 

 oblong, colorless, indistinctly once to thrice septate, 

 bearing oil-droplets, 13/x X 5/i,. 



This lichen is also known as Collema nigrum. It 

 forms inky-black stains upon the rock on which it 

 grows. 



2. Lecothecium corallinoides. Thallus crustose to 

 minutely scaly, scales ascending, dark-brown. Apo- 

 thecia sessile, somewhat immersed. Disk flattened, 

 dark-brown. Spores few, elliptical, 14/x X '^/w,. 



This species is generally described as Pannaria 



microphyllum. 



3. Lichina. 



Thallus crustose, minute, branching, dark, some- 

 what resembling that of Ephehe, but differs in that the 

 fungal symbiont forms the greater bulk of the struct- 

 ure and the protective tissue. The algse are Rivularia 

 nitida, hence blue-green and in chains. No cortical tis- 

 sue is present. 



The apothecia are small, terminal, globose, appear- 

 ing as small nodular enlargements of the ends of some 

 branches. They are dark. Spores are simple, ellipti- 

 cal, colorless. The hypothecium is colorless. 



Only a few species are known, they occur upon 

 rock in moist places and are found in the tropics 

 as well AS in the far north. 



1. Lichina conjinis. Thallus minute, branching, 

 lobes rigid and erect, dark. Apothecia terminal, 

 globose, dark. Spores colorless, simple, elliptical. 



