30 THE CHICAGO ACADEMY OF SCIENCES. 



Pertusafiai D C. Thallus crustaceous, continuous, smooth or 

 verrucose; apothecia globular, difform, closed; enclosed in 

 thalline verrucas, .opening by pores (ostioles); explanate, 

 lecanoroid. Spores generally large, ellipsoid. 



67. P, velata, (Turn.) Nyl. Thallus white, glaucescent, rugose, 

 chinky, rimose, radiate near the circumference; apothecia 

 small, adnate, pale yellowish, white powdery; the thalline 

 margin disappearing in the fruit. Muhl. Br. L, 274. Tuck. 

 Syn. 212. 



On rocks and trees. 



68. P, multipuncta, (Turner.) Nyl. Thallus ash colored, rugose, 

 verrucose, zonate at the circumference; apothecia small, in 

 verrucae — 2-4; lecanoroid, finally elevated; disk becoming 

 black, soon excluding the thalline margin and often forming 

 powdery heaps. P. faginea, Tuck. Syn. N. E. 64. 



On oaks and hickories; not rare. 



69. P. communis, D C. Thallus glaucescent^ smooth, chinky or 

 rugose-verrucose, may become zonate at the circumference; 

 apothecia small, adnate, depressed, sub-globose, difform, 

 closed, the numerous ostioles sunken and black. Spores gen- 

 erally in twos, sometimes solitary. Porina pertusa, (L.) Ach. 

 Syn. L. 109, etc. 



Common on oaks everywhere in our territory. 



70. P, leioplaca, (Ach.) Schaer. Thallus whitish or more com- 

 monly pale-yellowish; apothecia medium size, globular and 

 difform, often crowded together; depressed ostioles indistinct, 

 often blackening. Nyl. Scand. 181. Tuck. Syn. 215. 



On oaks near Elgin and elsewhere. 



71. P, pustulata, (Ach.) Nyl. Thallus greenish or whitish; chinky, 

 or verruculose; apothecia very small, hemispherical and 

 difform, globular or confluent; ostioles black. Spores in twos. 

 Porina, Ach. L. U. 309. Tuck. Syn. 21.5. 



On trees; general in distribution here and elsewhere. 



Conotfema, Tuckerm. Thallus crustaceous, uniform; apothecia 

 urceolate, truncate-conoid. Spores cylindraceous, pluri- 

 locular. 



