128 



GEOLOGY OF LA SALLE COUNTY. 



adnate, much narrowed, membranaceous, mar- 

 gins crenate, lobes rounded, sinuate-laciniate, 

 apothecia medium size, few, marg-ins crenulate. 

 Fr. Lf. E. 59, etc. Common on trees every- 

 where. 



P. tiliacea, FL, var. sulphurosa. Tuck. Medul- 

 lary layer sulphur yellow, otherwise like the 

 species. Deer Park. Rare. 



P. borreri. Turner. Thallus cinereous, glauces- 

 cent, lobes larg-e or narrow, rug-ulose, beset with 

 round soredia, membranaceous, pale brown be- 

 neath, fibrillose, dense, apothecia larg'e, badio- 

 rufous, marg-in entire. Spores rounded. Tur- 

 ner. Linn. Tr. 148. Very common every- 

 where in our county, especially on oaks. 



P. borreri. Turn., var. rudecta, Tuckerm. Thallus 

 isidioid. Ach. Syn. 197. Tuckerm. Syn. 58. 

 A mere variety found occasionally with the pre- 

 ceding*. 



P. saxatilis, L/., Fr. Thallus gflaucous-cinerascent, 

 membranaceous, more or less lacunose, ramose, 

 isidiophorous, beneath black and densely fibril- 

 lose, lobes sinuate multifid, incised, apothecia 

 larg'e, disk fuscous, or spadiceous, marg-in sub- 

 crenulate. Spores ellipsoid. Fr. L. E. 61. 

 Very common west of Ottawa on trees and sand- 

 stones. 



P. saxatilis, Fr., var. sulcata, Nyl. On bluff 

 boulders and stones, and along- Illinois river, 

 below Ottawa. 



P. physodes, L., Ach. Thallus loosely attached, 

 substellate, whitish, coriaceous, g-laucous, be- 

 neath fuscous-black, no fibrils, lobes many cleft, 

 complicate, often with white soredia, apothecia 



