20 THE CHICAGO ACADEMY OF SCIENCES. 



IG. P, borreri, Turner. Thallus cinereous, glaucescent; lobes large 

 or narrow, rugulose; beset with round soredia; membranace- 

 ous; pale brown beneath, fibrillose, dense; apothecia large, 

 badio-rufous, margin entire. Spores rounded. Turner. Linn. 

 Tr. 148. Ach. L. U. 461, etc. 

 Very common everywhere in our territory, especially on oaks. 



11. p. bofferi, Turn., var. fudecta, Tuckerm. Thallus isidioid. 

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



Occurs on oaks in the west part of Cook County, and at 

 Lemont and Joliet. 



18. P, saxatilis, (L.) Fr. Thallus glaucous-cinerascent, membran- 

 aceous, more or less lacunose, ramose; isidiophorous; beneath 

 black and densely fibrillose; lobes sinuate multifid, incised; 

 apothecia large, disk fuscous, or spadiceous, margin subcrenu- 

 late. Spores ellipsoid. Fr. L. E. 61. Nyl. Syn. 388. 



Found on trees in Cook County near Elgin and on recent sand- 

 stones and boulders at Lemont. 



19. P, saxatilis, Fr., var. sulcata, Nyl. On bluff boulders and 

 ^stones near Lemont, and in Will County. Very fine specimens 



may be gathered in LaSalle County. 



The very numerous soredia, which are round or oblong, con- 

 fluent and reticulate, mark the variety. Tuck. Syn. 58. 



20. p. physodes, (L.) Ach. Thallus loosely attached, substellate, 

 whitish, coriaceous, glaucous; beneath fuscous-black, no fibrils; 

 lobes many cleft, complicate, often with white soredia; apothe- 

 cia medium to large, badio-rufescent, margin nearly entire. 

 Spores subellipsoid. Ach. S. L. 218. Tuckerm. Syn. 59, etc. 

 Occurs on oaks in Cook and Du Page Counties, and elsewhere, 



There are several varieties in other States. 



21. P, caperata, (L. ) Ach. Thallus substramineous, dilated, cor- 

 iaceous, undulate-plicate, often sorediate; beneath black, 

 fibrillose; lobes sinuately-laciniate, rounded tips; apothecia 

 large, chestnut, margin subcrenulate, often sorediate. Ach. 

 S. L. 196, etc. 



Very common on oaks everywhere. The fruit is seldom seen 

 here, but the lichen is conspicuous for size and color. 



