h
37. Usnea Dill. Thallus filamentose, internally with ohondroid
axis : apotheoia terminal or lateral, th e margin often ramuloso-
ciliate, concolorous, w ith simple sp o re s; spermogones with simplish
sterigmata and stra ig h t spermatia.
Tribe X I. ALECTOEIEI Nyl. Thallus much branched, rounded
or compressed, with woolly medulla : apotheoia parmelioid, soutelli-
form.
38. Alectoria Ach. Thallus usually filamentose and intricately
b ran ch ed ; medulla arachnoid or laounose: apotheoia term in al or
pseudo-terminal, diseolorous, with simple or very ra re ly murali-
dividod spores; spermogones with pauci-artieulate sterigmata and
acioular stra ig h t spermatia.
Tribe X I I . CETRAEIEI Nyl. ThaUus frutioulose or foliaceous,
with w hite wooUy meduUa : apotheoia parmelioid, marginal, obliquely
afiixod.
39. Cetraria Ach. ThaUus frutioulose, laciniose, rarely fistulöse :
apotheoia subooncolorous, w ith simple sp o re s; spermogones with
simple sterigmata and cylindrioal spermatia.
40. Platysma Nyl. Thallus frutioulose or membranaceo-lobed;
apotheoia diseolorous, w ith simple sporos; spermogones w ith simplish
or pauoi-articulate sterigmata, and various (not cylindrical) spermatia.
Series IV. P H Y L L O D E I Nyl. ThaUus foliaceous, usually
depressed, lo h a te : apotheoia generaUy parmelioid or lecanorine,
diseolorous.
Tribe X I I I . PARMELIEI Nyl. ThaUus frondosely dUated, or
lohate, or laciniate, w ith woolly, ra re ly solid meduUa: apotheoia
parmeleine rarely leoanorine.
41. Evernia Ach. ThaUus laciniose or much branched, fiaooid ;
meduUa arachnoid or p a rtly ohondroid : apotheoia late ra l with simple
spores; spermogones with pauoi-articulate sterigmata and acioular
stra ig h t spermatia.
42. Parmelia Ach. Thallus variously lohed or laciniate, usuaUy
fibrilloso-rhizinose, rarely glabrous b e n e a th ; medulla woolly, l a x :
apotheoia superficial, with simple spores ; spermogones w ith pauci-
artioulate sterigmata and acioular apioaUy fusiformi-incrassate
spermatia.
43. Parmeliopsis Nyl. ThaUus steUato-laciniate, sparingly rhizi-
noso b e n e a th ; meduUa woolly, l a x ; apotheoia superficial, with simple
spores ; spermogones w ith simple sterigmata and oyhndrical arcuate
spermatia.
Tribe XIV. STICTEI Nyl. Thallus large, membranaceo-lobed,
cyphellate or Goyphellate b e n e a th ; gonidial layer containing gonimia
or tru e gonidia; medulla wooUy: apotheoia leoanoroid or
parmeleine.
Subtribe I . ST ICT INE I Nyl.
mia in plurilooular nodules.
Gonidial layer consisting of goni-
44. Stictina Nyl. Thallus rhizinoso-tomentose and cypheUate
beneath ; apotheoia leoanoroid, rarely parmeleine, usually with
septate spores ; spermogones innate, with jointed sterigmata and
apioaUy incrassate spermatia.
45. Loharina Nyl. ThaUus scrobicnlose, eoyphellato beneath:
apotheoia leoanoroid, with 3-septate spores; spermogones as in
Stictina.
Suhtribe I I . EUSTICTEI Nyl.
Gonidial layer consisting of
gonidia or gonidimia (in Ricasolia).
46. Loharia Hoffm. ThaUus sorobioulose, eoyphellate b en ea th :
apotheoia leoanoroid, with 1-3-sep tate sp o re s; spermogones innate,
w ith jointed sterigmata and apioaUy incrassate spermatia.
47. Sticta Sohreh. ThaUus rhizinoso-tomentose and cypheUate
beneath : apotheoia leoanoroid, raroly parmeleine, w ith variously
septate spores; spermogones as in Loharia.
48. Ricasolia De Not. ThaUus often entirely glabrous and very
rarely cypheUate beneath: apotheoia parmeleine, w ith septate spores;
spermogones in mastoid prominences, with jointed sterigmata and
apioaUy thickish spermatia.
Tribo XV. PELTIGEREI Nyl. ThaUus frondosely dilated,
frag ile ; cortical layer usuaUy w anting on th e lower surface ; gonidial
s tra tum consisting either of gonidimia or usuaUy of gonimia:
apotheoia peltiform.
Subtribe I . P E L T ID E I Nyl. ThaUus bearing oephalodia;
gonidial layer consisting of g o nidim ia: apotheoia variously situated.
49. Peltidea Ach. ThaUus with the cortical layer not continuous
on th e u n d e rsid e : apotheoia marginal on the upper surface,
with septate spores ; spermogones unknown.
50. Solorina Ach. ThaUus with th e cortical layer n o t continuous
on th e underside: apotheoia scattered and innate on the
upper surface of the thaUus, with biloonlar spores ; spermogones
unknown.
Subtrihe I I . P E L T IG E E IN E I Nyl. Thallus destitute of oephalodia;
gonidial layer consisting of gonimia: apotheoia variously
situated.