243 
P. saxatilis var. panniformis (Ach.) Schr. 
P. saxatilis var. sulcata Ny. 
P. saxatilis {. furfurascens Schr. Thallus very furfuraceous. 
P. saxatilis var. omphaloides Fr. 
P. fraudans Ny}. 
This has been regarded as a subspecies of P. saxatilis and fre- 
quently taken for that species, but has distinctions worthy of 
specific rank. 
P. physodes (U..) Ach. 
Var. vittata (L.) Ach. 
Var. enteromorpha Tuck. 
Var. odscurata Ach. 
P. encausta (Sm.) Nyl. 
P. encausta var. alpicola Ny). 
P. colpodes (Ach.) Nyl. 
P. olivacea (L.) Ach. 
P. olivacea var. aspidota Ach. 
P. olivacea var. panniformis Nyl. 
P. olivacea var. sorediata (Ach.) Nyl. 
P. lanata (L.) Wallr. 
P. stygia (L.) Ach. 
P. conspersa (Ehrh.) Ach. 
P. leucochlora Tuck. 
P. centrifuga (L.) Ach. 
P. incurva (Pers.) Fr. 
P. ambigua (Wulf.) Ach. 
Var. albescens Wahl. (P. hyperopta Ach.). 
Puyscia DC. 
P. hypoleuca (Mull.) Tuck. 
P. comosa Esch. (P. galactophylla Willd). 
P. leucomela (L.) Michx. 
P. ciliaris (L.) D. C. 
P. ciliaris var. crinalis Schr. 
P. aquila var. detonsa Tuck. 
P. pulverulenta (Schreb.) Nyl. 
P. pulverulenta var. leucoleiptes Tuck. 
P. pulverulenta £. muscigena Auct. 
