116 GUIDE TO THE STUDY OF LICHENS. 



11. Megalospora. 



This genus has also been included under Heterothe- 

 cium. Its general characters are like those of Gatil- 

 laria; the apothecia are somewhat larger and the 

 disk more convex. The thallus presents almost the 

 same external appearance as to color and general con- 

 formation ; the algae are, however, Protococcus instead 

 of Pleicrococcus. The hypothecium is black or blue- 

 black. Each spore-sac contains one, rarely two, large 

 simple spores. The spore-wall consists of two layers, 

 of which the outer one is quite thick and gelatin- 

 ous. 



1. Megalospora sanguinaria. Thallus light-gray. 

 Apothecia comparatively large. Disk convex. Spores 

 large, simple, colorless, outer spore-wall (exosporium) 

 thick, 103^ X 4:0/x. 



The above is the only species which came to my no- 

 tice. It is not very common and occurs upon trees. It 

 seems to be northern in its range. 



12. Lopadium. 



This genus is also taken from the conglomerate 

 group Heterothecium. The thallus is crustose and uni- 

 formly spreading. The algae are Chroolepus umhrina. 

 Soralia are common. The apothecia are of medium 

 size, loosely sessile upon the thallus, discoid. A red- 

 dish-brown or nearly black color pervades almost the 

 entire apothecial structure. The spores are multiloc- 

 ular, large, and vary from colorless to brown and red- 

 dish-brown. 



A few species are reported which seem to be 



