IX 



GLOSSARY. 



Antagonistic symbiosis, a form of symbiosis in which one of the sym- 

 bionts is benefited at the expense of the other; usually known as parasitism. 

 Apothecium (Apothecia), the spore-bearing structure of lichens, in- 

 cluding epithecium, thecium, hypothecium and exciple. 



Areolate, a term referring to a crustaceous thallus which is marked off 

 into minute, usually polygonal areas. 



Breathing pores, intercellular canals in the cortical layers leading from 

 the interior of the thallus to the exterior. 



Cephalodium (Cephalodia), usually a globular, flattened or irregular 

 outgrowth from the upper or lower surface of the thallus, induced by for- 

 eign algae and bearing them. 



Contingent symbiosis, a form of symbiosis which is not constant in 

 its occurrence. (Incipient symbiosis. Raumparasitismus. ) 

 Cortex, see Cortical. 



Cortical layers, pseudo-parenchymatous tissue (upper and lower) of 

 the thallus of the higher lichens. 



Crustaceous thallus, a firmly adherent thallus of lichens devoid of 

 distinctly cortical layers. 

 Cuticle, see Epidermis. 



Cyphella (Cyphellae), a pit or depression in the under surface of the 

 thallus of most Stictei ( Sticta and Stictina). They are neoformations anal- 

 ogous to lenticels. 



Endospore, the inner coat of the spore-wall. 



Epidermis, the thin horizontal scaly layer on the upper surface of the 

 higher foliose lichens. 



Epilithic. a term applied to the parts of lichens occurring on and above 

 the surfaces of rocks. 



Epiphloeodal, occurring on the surface of the bark. 

 Epispore, see Exospore. 



Epithecium, the upper colored structureless coating of the thecium. 

 Exciple or Excipulum, the outer covering of the apothecium; when 

 formed by the thallus and bearing algae it is known as thalloid exciple ; 

 when formed by the perithecium and not bearing algae it is known as 

 proper exciple. 



Exospore, the outer coat of the spore-wall. 



Fibril or Cilium, a slender filament, consisting of united hyphae, 

 usually occurring on the margin of the thallus. 



Foliose thallus, an expanded entire or lobed thallus, having one or 

 two cortical layers, usually attached by rhizoids. Also known as foli- 

 aceous or frondose thallus. 



