GEOLOGY OF LA SALLE COUNTY. 139 



pertusa, L., Ach. Common on oaks everywhere. 

 P. leioplaca, Ach., Schser. Thallus whitish or 

 more commonly pale yellowish, apothecia medi- 

 um size, o-lobular and diiform, often crowded 

 together, depressed ostioles indistinct, often 

 blackenino-. Nyl. Scand. 181. Tuck. Syn. 215. 

 On oaks. 



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. Po- 

 rina, Ach. L. U. 309. On trees, general in 

 distribution. 



CONOTREMA, Tuckerm. Thallus crustaceous, uni- 

 form, apothecia urceolate, truncate-conoid. 

 Spores cylindraceous, plurilocular. 

 C. urceolatum, Ach., Tuckerm. Thallus smooth, 

 becoming chinky and rugged, whitish, apothecia 

 small, urceolate, from black to pruinose, promi- 

 nent, elevated. Lecidea, Ach., L. U. 671. 

 Gyrostomum, Fr. Tuck. Gen. L. 129. Cono- 

 trema. Tuck. Syn. 217. This, the only species 

 of the genus, has a wide distribution. Found 

 on maples and poplars along the Vermillion and 

 elsewhere. 



URCEOLARIA, Ach.. Flotow. Thallus crustace- 

 ous, uniform, apothecia urceolate. Spores ovoid- 

 ellipsoid, muriform, pluri-locular, fuscescent. 

 U. scruposa, L., Nyl. Thallus tartareous, rugose- 

 plicate, glaucous, ash-colored or white, apothe- 

 cia immersed, but emerging, urceolate, large, 

 black, disk somewhat cinereous, margin denticu- 

 late, hidden by the thalline one, if present. Nyl. 

 Scand. 176. Found on dead cedars along the 

 banks of the Illinois, below Ottawa. . ■ 



