i39 



The thallus is crustaceous and quite uniformly spreading. There 

 is no cortical tissue proper; the upper part of the thallus consists 

 of a thin layer of agglutinate hyphae with much gelatinized cell- 

 walls (protective covering). Below this is found the algal layer, 

 consisting of the algae ( Ckroolepus umbrina) enclosed by a network 

 of rather slender hyphae. The rhizoidal hyphae are quite numerous 

 and extend into the substratum to a considerable depth. It must also 

 be mentioned that groups of Poly coccus functiformis frequently occur 

 in different parts of the thallus and at the base of the apothecia (con- 

 tingent symbiosis) . Soredial patches (soralia) are frequently present. 



The apothecia are of medium size, distinctly discoid and loosely 

 sessile upon the thallus, to which they are attached by hyphal bundles. 

 A reddish brown or a black coloration pervades nearly the entire 

 apothecial structure. This coloration is principally due to a deposit 

 in and upon the hyphal cell-walls of some lichen acid. The para- 

 physes are simple and quite distinct. The spores are multilocular 

 and vary from colorless to brown and reddish brown. 



The species are southern, occurring upon the bark of trees and 

 on mosses. 



PLATE 34. 

 Lopadiuji pezizoideum (Ach.) Kbr. 



1. Natural size; a, apothecia. 



2. Section through the thallus and margin of the apothecium. 



a, thecium ; b and c, hypothecium ; d, excipular layer ; e, hyphae 

 connecting the apothecium with the thallus (f and g) . 



3. Section of thallus. 



4. Paraphyses and spore-sac with spore. 



5. Spores; a, earlier stage of development ; b, mature spore. 



13. GyalectaAcIi. Lich. Univ. 151. 1810. 



This genus of lichens is so little understood that it is practically 

 impossible to give its limitations, most of its representatives being 

 included by authors in other lichen-genera. The following are the 

 generic characters as far as they can be determined. 



The thallus is crustaceous in the majority of species ; in the 

 higher forms it consists of minute foliose lobes with upper and lower 

 cortical layers. In the majority of species it is usually quite dark, 

 above and below. The algae are apparently Cystococcus humicola 

 in all the species examined ; incidentally Polycoccus -punctiformis 



