132 GEOIvOGY OF LA SALLE COUNTY. 



P. nigra, Huds., Nyl. Thallus squamulose, minute, 

 lead-colored, and mostly merg-ed into a granu- 

 loid crust, apothecia small, biatorine, sessile, 

 disk black, marg-in entire. On calcareous rocks 

 at the old Lowell Mill, Bailey's Falls and else- 

 where. 



P. lanug-inosa, Ach., Koerb. Thallus whitish, 

 powdery, apothecia seldom developed. Covell 

 Creek, etc., on shaded rocks. 



COLLEMEI. 



PYRENOPSIS, Nyl. Thallus coralloid, apothecia 

 g-lobose, depressed. On rocks. 

 P. scha^reri, Moss, Nyl. Apothecia sm.all, disk 

 reddish. On black slate and calcareous rock. 

 Clark's Ravine, Baldwin Farm, Deer Park. 

 Rare and fine. 



OMPHAL-ARIA, Dur. & Mont. Thallus foliaceous, 

 attachea to substrate at one point, apothecia 

 immersed. Synalissa, Fr. 

 O. pulvinata, Nyl. Thallus foliaceous, blackish, 

 of closely clustered lobes, apothecia at the 

 edg-es. On calcareous rocks. Eton's Mill only. 

 Curious and rare. 



COLLEMA, Hoffm., Fr. Thallus greenish, cortical 

 layer obsolete, g-onimia in chains, apothecia very 

 small to middle size, scutellsform. Spores vari- 

 ously shaped. 

 C. pycnocarpum, Nyl. Thallus small, pale, g^reen, 

 sub-orbicular, lobes radiate, narrowed, fene- 

 strate, ribbed, the marginal lobules densely 

 fruited, apothecia small, disk reddish, excluding- 

 marg-in. Spores ovoid ellipsoid, bilocular, decol- 

 orate. Nyl. Syn., 115. On elm, Illinois 

 timber. 



