FINK—THE LICHENS OF MINNESOTA. 69 
Thallus not plainly granular. 
Thallus becoming more or less distinctly are- 
olate. 
Apothecia usually immersed. 
Hypothecium pale.................. 20. L. cyanea. 
Hypothecium dark. 
Thallus widely spread; apothecia 
small..........-.------------- 19. L. lapicida.4 
Thallus usually covering quite 
limited rounded or irregular 
areas; apothecia middle-sized, 23, L. lactea, 
Apothecia not usually immersed. 
Apothecia adnate or somewhat im- 
mersed, commonly somewhat 
pruinose..........---------+------- 25. L. albocaerulescens. 
Apothecia sessile or adnate, rarely 
somewhat pruinose.......-....---- 27. L. platycarpa. 
Thallus becoming chinky but not areolate, 
rarely subareolate. 
Hypothecium pale; apothecia small, 
blackish, rarely pruinose..........-..-- 21. L. lithophila. 
Hypothecium dark. 
Disk flat, with persistent exciple, 
black...........-.-.-.---------- .. 22. L. contigua. 
Disk convex, exciple disappearing.. 22a. L. contigua con- 
verella. 
On trees or old wood (rarely on rocks). 
Thallus rather thick, rough and verrucose; apothecia 
middle-sized, adnate, very black...........-..-.-- 29. L. melancheima. 
Thallus thinner, smooth or becoming areolate or ver- 
rucose. 
Thallus pale yellowish, verrucose.....----------- 28a. L. enteroleuca theio- 
placa. 
Thallus sea-green, ashy, or whitish. 
Thallus becoming chinky, areolate, or ver- 
rucose. 
Thallus becoming chinky or areolate..... 28. L. enteroleuca. 
Thallus becoming verrucose or verru- 
cose-areolate. 
Thallus rather thick at first but often 
disappearing..........-....--...--. 28d. L. enteroleuca pilu- 
laris. 
Thallus at first thin, becoming 
thicker.............-------------- 28b. L. enteroleuca achris- 
ta. 
Thallus not usually becoming areolate or 
verrucose. 
Thallus thin and smoothish, variegated 
by black lines...........--------------- 28c. L. enteroleuca _fla- 
vida. 
Thallus thin and smoothish, not varie- 
gated by black lines..........-.-.----- 28e. L. enteroleuca am- 
bigua. 
aSee also 19a. L. lapicida orydata. 
