FINK—THE LICHENS OF MINNESOTA, 41 
Spores brown or brownish, commonly 
4-celled; thallus larger and usually 
brownish....................... 
Thallus without well-developed lower cor- 
tex, 
Thallus large, no lower cortex; spores 
long and slender, with 4 to 8 or more 
Thallus sometimes showing a rudimen- 
tary lower cortex, smaller; spores 
commonly 2-celled............2.... 
Thallus wholly or partly fruticose or crustose, 
Thallus fruticose, or else 2-fold, in part fruticose and in 
part foliose or crustose. 
Thallus 2-fold, consisting of a fruticose portion and a 
foliose (squamulose) or a crustose portion, 
Thallus consisting of a fruticose portion (the pode- 
tium) and a foliose (squamulose) or rarely 
crustose portion, the latter frequently evanes- 
Thallus consisting of a fruticose portion (the stipe, 
strictly part of the fruit) and a crustose portion. 
Stipes well developed, very small and rarely 
branched. 
Spores spherical or subspherical. 
Spores colorless or only slightly colored... . 
Spores brown or brownish................... 
Spores oblong or ellipsoid. 
Spores simple and hyaline.................. 
Spores brown and usually 2-celled.......... 
Stipes very short and seldom evident: 
Spores hyaline, 2 to 4-celled............ Lesa 
Spores brown and 2-celled............2...... 
Thallus consisting of a fruticose portion only, or (Pi- 
lophorus and Stereocaulon) also of an evanescent, 
horizontal portion rarely seen. 
Podetia present, clothed more or less with phyllo- 
cladia. 
Thallus small and rarely branched............. 
Thallus larger and much branched............. 
Podetia wanting. 
Algal symbiont, Sirosiphon, determining the form 
of the thallus and giving it a dark color .... 
Algal symbiont, Cystocoecus, not determining the 
form or color. 
Branches cylindrical or compressed-cylin- 
drical. 
Grayish to sea-green, or rarely reddish, rarely 
angular..........222-..0.022222220-0-- 
Commonly brownish to blackish, rarely sea- 
QTCCN.. 2... eee eee eee eee eee eee 
7920— 10——4 
NEPHROMA (p. 164). 
PELTIGERA (p. 159). 
SOLORINA (p. 158). 
CLADONIA (p. 107). 
CONIOCYBE (p. 45). 
CHAENOTHECA (p. 48), 
BAEOMYCES (p. 105). 
CALICIUM (p. 45), 
ICMADOPHILA (p. 106). 
Acouium (p. 51). 
PrLopHorus (p. 132). 
STEREOCAULON (p. 130). 
EPHEBE (p. 146). 
UsneEa (p. 207). 
ALECTORIA (p. 206). 
