162 GUIDE TO THE STUDY OF LICHENS. 



6. JRamalina rigida. Thallus long and much 

 branched ; lobes very slender, flattened, gray. Apo- 

 thecia rather small, lateral, not cup-shaped. Disk 

 somewhat convex, color of thallus. Spores typical, 

 oblong, not curved, 21/x X 4/x. 



7. Bamalina reticulata. Thallus very long (sev- 

 eral feet), pendulous, much branched ; lobes slender, 

 flattened, reticulately perforate. Apothecia lateral, 

 small. Disk convex and of the same color as the 

 thallus. Spores typical, curved, 14/x X 7/x. 



This lichen is at once recognized by the reticulate 

 perforations of some of the lobes, or perhaps more cor- 

 rectly the reticulate branching of certain portions. It 

 is southern and occurs upon trees. 



9. Rocella. 



This is a typically fruticose genus. The thallus is 

 sparingly branched, lobes flattened, rigid, thick, not 

 canaliculate ; edges rounded. Color gray to some- 

 what purplish. Large discoid soralia frequently 

 occur along the margin of the lobes. The apothecia 

 are small, marginal, not terminal, and characterized by 

 a black hypothecium, a characteristic not found in any 

 other genera of the family. Disk flattened, dark to 

 black. The algae are Chroolepus. These two characters 

 are in contrast to the other generic groups of the fam- 

 ily and seem to indicate that the genus is perhaps mis- 

 placed. As has already been indicated, Reinke and 

 others place the group with the Graphidacece. The 

 gross characters, however, indicate a relationship to 

 Ramalina* 



