42 CONTRIBUTIONS FROM THE NATIONAL 
Branches flattened. 
Spores hyaline, simple. 
Thallus sea-green, not conspicuously chan- 
neled................22222220222----- 
Thallus pale or darker brown, conspicu- 
ously channeled....-... One species .of 
Spores 2-celled. . 
‘Spores brown; thallus usually sea-green. 
One species of 
Spores hyaline. 
Cells of spores proximate; thallus usually 
sea-green or grayish. .........-..-- 
Cells of spores polar; thallus more or less 
yellowish. .........2.0..020..2.-.-. 
Thallus crustose. 
Apothecia unknown; thallus rudimentary and sore- 
diate......0.....0.2 202 
Apothecia well known and usually present. 
Proper exciple produced into a perithecium; thal- 
loid exciple absent or uncertain. 
Apothecia immersed in the thallus and the peri- 
thecium poorly developed or not discernible, 
being usually replaced by an amphithecium. 
Apothecia usually grouped in verruce; spores 
Apothecia occurring singly. 
Spores simple, minute and many in each as- 
cus, hyaline; thallus strictly crustose, 
granular, greenish...................-. 
Spores muriform, hyaline or brown, large and 
few in each ascus; thallus showing a cor- 
tex in section.............-.-..-------- 
Apothecia partially or rarely entirely immersed 
in the substratum or the thallus, but the peri- 
thecium always well developed. 
Spores hyaline, never muriform. 
Spores simple; thallus well developed, ver- 
rucose or areolate, the apothecia not 
often completely immersed............- 
Spores not simple. 
Spores 2 to several-celled, ellipsoid to lin- 
ear-oblong; thallus and  apothecia 
partly or mainly in the substratum. .. 
Spores 4 to several-celled, fusiform toacicu- 
lar; thallus and apothecia as in Artho- 
pyrenia..........2.------22----+----- 
Spores brown or muriform, or both. 
Spores brown, 2 toseveral-celled; thallus and 
apothecia partly or mainly in the sub- 
stratum.........2...-2---------2-------- 
Spores muriform, brown or rarely hyaline; 
thallus conspicuous on the substratum 
and the apothecia immersed more or less 
IM it... 2. ee eee eee ee eee eee ee 
HERBARIUM. 
EVERNIA (p. 202). 
CETRARIA (p. 199). 
Puyscia (p. 224). 
RAMALINA (p. 208). 
TELOSCHISTES (p. 217). 
AMPHILOMA (p. 247). 
PERTUSARIA (p. 187). 
THELOCARPON (p. 241). 
ENDOCARPON (p. 244). 
VERRUCARIA (p. 233). 
ARTHOPYRENIA (p. 236). 
SAGEDIA (p. 235). 
PYRENULA (p. 238). 
STAUROTHELE (p. 246). 
