Fink: LICHENS OF THE NORTHERN BOUNDARY. 175 



Placodium cinnabarrinum (Acn.) ANZ. 



Placodium citrinum (HOFFM.) LIGHT. 



Placodium cerinum (HEDW.) NAEG. and HEPP. var. sideritis 

 TUCK. 



Placodium aurantiacum (LIGHT.) NAEG. and HEPP. 



Placodium vitellinum (EHRH.) NAEG. and HEPP. var. aurel- 

 lum ACH. 



Lecanora rubina (VILL.) ACH. 



Lecanora rubina (VILL.) ACH. var. heteromorpha ACH. 



Lecanora muralis (SCHREB.) SCHAER. var. saxicola SCHAER. 



Lecanora frustulosa (DICKS.) MASS. 



Lecanora varia (EHRH.) NYL. 



Lecanora cinerea (L.) SOMMERF. 



Lecanora cinerea (L.) SOMMERF. var. laevata FR. 



Lecanora fuscata (SCHRAD.) Th. FR. 



Rinodina oreina (Acn.) MASS. 



Rinodina lecanorina MASS. 



Urceolaria scruposa (L.) NYL. 



Lecidea lapicida FR. 



Buellia concreta (KBR.) ECK. 



Buellia petraea (FLK.) TUCK. 



Buellia petraea (FLK.) TUCK. var. montagnaei TUCK. 



Similar formations were found well developed in other places, 

 as on Oak island, at Kettle falls, and at Tower, where they were 

 especially well represented. Turning to the similar formation 

 recorded for Granite falls in the fifth paper of this series, it 

 appears that there is the usual marked resemblance in the for- 

 mations of the similar substrata in remotely separate portions of 

 the state. The genera are the same practically and the species 

 remarkably near so, except for the presence in the above for- 

 mation of a few more northern forms of Lecidea and Buellia. 

 By adding Biatora rufonigra Tuck, from the similar formation 

 at Kettle falls and the JSndocarpon from the one at Emo, the 

 genera would be identical in the two formations. However, it 

 would be accidental rather than otherwise if exactly the same 

 forms existed in two distinct formations even when much less 

 remote. The northern Buellia obscurata (Ach.) Eck. occurs in 

 the like formation at Kettle falls, and passing to the Oak island 

 region, where were met more arctic and subarctic lichens than 

 anywhere else on account of more northern location, and yet 

 more because of the influence of the larger Lake of the Woods, 



