30 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 
discoid, sessile upon or immersed in the thallus and thalline warts, or occurring dis- 
tinctly pedicellate; exciple (outer covering or margin) well developed, though want- 
ing in a few genera; apothecium either biatorine (the exciple soft in texture and pallid 
in color), lecideine (the exciple dark, black, and brittle, horny, or carbonaceous), or 
lecanorine (the exciple surrounded by a margin having the characters of the thallus); 
hypothecium (a continuation of the proper margin beneath the thecium or hymenium) 
partaking of the character of the margins in the forms of apothecia mentioned; 
paraphyses simple or branched, free or reticulately connected, without or with septa, 
their tops often thickened and colored, or the paraphyses closely adglutinated by 
hymenial gelatine; asci permanent, 1 to many-spored; spores 1-celled (simple), or 
variously partitioned, bilocular, polari-bilocular (a form of the bilocular, with the 
loculi (cells) more or less separated, being situated mostly at the poles of the spore 
and connected by a central tube (isthmus), this, however, sometimes absent), or 
muriform-multilocular, colorless or brown; sterigma variously formed, endobasidial 
or exobasidial. \ 
KEY TO FAMILIES. 
Spores bilocular or polarilocular, colorless or brown. 
Spores colorless, polarilocular. 
Thallus crustaceous, uniform or lobed at pe- 
riphery.......-..--+.+-0-+eee- wee eee eeee CALOPLACACEAE (p. 110). 
Thallus foliaceous or fruticulose............... TELOSCHISTACEAE (p. 116). 
Spores brown, 2 to 4-locular or muriform. 
Thallus crustaceous, uniform or lobate at pe- 
riphery......------.eeeeeee eee wee e eens BUELLIACEAE (p. 1158). 
Thallus foliaceous or fruticose.................. PHYSCIACEAE (p. 127). 
Spores simple, several locular or muriform, rarely 
colored. 
Thallus gelatinous when moist, homoémerous, 
the alge blue green. 
Gonidia Scytonema or Stigonema algw......... EPHEBACEAE (p. 70). 
Gonidia Nostoc algee, apothecia discoid. ....... COLLEMACEAE (p. 71). 
Gonidia Gloeocapsa alge; apothecia  urn- 
shaped or discoid.......-.....2.......... PYRENOPSIDACEAE (p. 68). 
Thallus not gelatinous when moist. 
Thallus terete, more or less erect or pendent.... USNEACEAE (p. 105). 
Thallus not terete. 
Thallus crustaceous, uniform or lobed. 
Gonidia Protococcus...........--2------ DIPLOSCHISTACEAE (p. 33). 
Gonidia Chroolepus or Phyllactidium 
a LECANACTIDACEAE (p. 31). 
Gonidia bright yellow green Pleurococcus 
or Palmella alge. 
Asci 1 to 8-spored, seldom 16 or more 
spored; apothecial margin pale and 
soft or dark and brittle. ; 
Apothecia with lecanorine margin.... LECANORACEAE (p. 85). 
Apothecia not lecanorine. 
Not sunken in thallus. 
Sessile. .......22..2.052-0022200.. LECIDEACEAE (p. 34). 
Pedicellate................... .. CLADONIACEAE (p. 57). 
Sunken in thallus ................ PERTUSARIACEAE (p. 84). 
Asci many-spored; apothecia lecanorine, 
biatorine, or lecideine.............. ACAROSPORACEAE (p. 62). 
