THE LICHEN-FLORA OF CHICAGO AND VICINITY. 19 



10. P, perlata, (L.) Ach. Thallus greenish-glaucescent, or whitish; 

 dilated; lobes rounded, often sorediate, undulate; black be- 

 neath, with brown margins; apothecia small to large, rufous, 

 entire. Ach. L. U. 459, etc. 



Found throughout our territory on oaks and other trees, and 

 on boulders near Lemont. 



11. P, perforata, (Jacq. ) Ach. Thallus whitish, much dilated; cori- 



aceous, membranaceous, glaucescent, smooth, sinuate lobed; 

 beneath black or fuscous; fibrillose; apothecia very large, per- 

 forate, cyathiform; disk fuscuous or rufous. Spores ellipsoid. 

 Ach. L. U. 459, etc. 



On various trees in Cook and Will Counties. A common spe- 

 cies. 



12. P, crinita, Ach. Thallus dilated, membranaceous, surface 

 covered with minute granules and branchlets; black beneath 

 and fibrillose; lobes ciliate; apothecia ample, cyathiform; disk 

 chestnut. Fr. , L. E., 58. 



On oaks in Hanover Township; on detached rock near Le- 

 mont; not common. 



13. P, cetrata, Ach. Thallus greenish, dilated, rather thin, smooth; 



beneath black and hispid; the sinuate lobes sorediferous on 

 the margins, narrowed, soon prolonged; apothecia medium size, 

 chestnut. Ach. Syn. L,, 198, etc. 



On trees and stones near Lemont and westward. 



14. P, tiliacea, (Hoffm) Fl. Thallus smooth, closely aduate, much 



narrowed, membranaceous, margins crenate; lobes rounded, 

 sinuate-laciniate; apothecia medium size, few, margins crenu- 

 late. Fr. L. E. 59, etc. 



On oaks at Riverside, Lemont and Hanover, There are 

 varieties in the South. 



15. p. tiliacea, FL, var. sulphufosa, Tuck. Medullary layer sulphur- 

 yellow; otherwise like the species. Tuckerm, Syn. 1, 57. 



Found near Elgin on oak trees. Will probably be found else- 

 where. 



