FINK—THE LICHENS OF MINNESOTA. 
FAMILY TELOSCHISTACEAE (p. 211). 
Placodium. Teloschistes. 
Famity PHYSscIAcEAE (p. 219). 
Rinodina. Pyxine. 
Physcia. Urceolaria. 
SUBORDER PYRENOCARPINEAE. 
39 
The thallus varies from undifferentiated and mainly hypophloodal or hypolithic 
erustose conditions to well developed foliose or fruticose forms. The algal symbiont 
is either Chroolepus or Pleurococcus, The fungal symbionts belong to the Sphae- 
riaceae or to closely related fungi. The apothecia are furnished with a perithecium, 
which entirely incloses the hymenium, except for the apical ostiole, and are more 
or less immersed in the thallus or the substratum. Within the perithecium is found 
the amphithecium, a less heavy layer. Or the perithecium may be almost entirely 
wanting, when the amphithecium alone is seen about the hymenium. 
FamiILy VERRUCARIACEAE (p, 232). 
Verrucaria, 
Famity PyrENULACEAE (p. 239). 
Sagedia. Arthopyrenia. 
Pyrenula. 
FamiIty DERMATOCARPACEAE (p. 241). 
Thelocarpon. Dermatocarpon, 
Famity ENpDOCARPACEAE (p. 244). 
Endocarpon, StaurotLele. 
FamiLy LEPRARIACEAE (p. 247). 
Amphiloma. 
ARTIFICIAL KEY TO THE GENERA. 
Thallus foliose (or squamulose). 
Thallus of the modified foliose form known as squamu- 
lose. : 
Algal cells blue-green (probably Polycoccus); spores 
hyaline or pale, simple to 4-celled.......-.-.--- PANNARIA (p. 150). 
Algal cells bright green (Cystococcus). . 
Spores simple, hyaline, ellipsoid......--..---.---- Psora (p. 101). 
Spores hyaline, ellipsoid, 4 to 8-celled..........-- Toninia (p. 104). 
Thallus plainly foliose. 
Algal cells bright green (Cystococcus or Pleurococ- 
cus). 
Spores simple, hyaline (sometimes slightly col- 
ored in Gyrophora). 
Thallus attached by an umbilicus. 
Apothecia scattered and immersed. ...--- DERMATOCARPON (p. 242). 
Apothecia clustered ona very short pedicel . GYROPHORA (p. 166). 
Thallus not attached by an umbilicus. 
Thallus small, closely adnate (scarcely 
plainly foliose). ..-.-. Higher species of Lecanora (p. 171). 
