i73 



layer, which always extend in a longitudinal direction and which 

 perhaps indicate the beginnings of mechanical bundles, similar to 

 those in Evemia. 



The apothecia are small to medium and occur upon the upper sur- 

 face of the thallus, along the margin or sometimes terminal ; the disk 

 is flattened, convex or concave ; the excipular margin is entire, with- 

 out cilia or thalloid fringes ; the hypotheciuro is colorless, consisting 

 of much interwoven hyphae ; the two layers are rather indistinct. 

 The paraphyses and spore-sacs are somewhat longer than in Ever- 

 nia and Cetraria. The thecium is usually light-brown or almost of 

 the same color with the thallus. 



The spores are quite small, colorless, two-celled, elliptical, some- 

 times somewhat curved. 



The representatives of this genus are southern and western in 

 their distribution, occurring upon trees, rocks and sandy soil. Some 

 of the tree forms attain an enormous size (i?. reticulata, R. linearis). 

 Only comparatively few of the species occur in the territory, and of 

 these R. calicaris is most frequent. 



PLATE 47. 



Ramalina calicaris (L.) Ft. 



1. Natural size. 



2. Portion of thallus with apothecia. 



3. Section of apothecium. 



4. Longitudinal section of thallus. 



5. Paraphyses and spore-sac. 



6. Spores. 



7. Algae. 



10. Alectoria Ach. Lich. Univ. 120. 1810. 



This genus differs from the foregoing in its cylindrical radially 

 built thallus, and its large spores with thick walls. 



The thallus is in all cases typically fruticose, never showing any 

 foliose tendency. Branching is frequent and more or less distinctly 

 dichotomous, with a gradual decrease in the size of the branches in 

 an acropetal direction. At the points of branching the thallus is 

 somewhat flattened for the purpose of supplying mechanical sup- 

 port. 



In this group the mechanical (and protective) tissue is highly 

 developed and specially adapted to resist lateral tensions, that is 



