38 THE CHICAGO ACADEMY OF SCIENCES. 



Arthonia, are not found in our territory, but inhabit Florida. 

 We have several species of Arthonia, two so abundant as to 

 be easily identified. 



102. A, lecideella, Nyl. Thallus green, uneven, effuse; apothecia 

 abundant, small, round, plain, pruinose. Spores oblong- 

 ovoid. Nyl. En. 337. Tuck. Gen. 221. Willey, Syn. 16. 

 On hickories and Crataegus throughout our territory. 



103. A. spectabilis, Fl. Thallus thin, white; apothecia black, 

 difform, angulate, plain or convex, often bordered by the 

 thallus. A. dispersa, Duf. A. polymorpha, of Muhl. Catal. 

 i8i8. Willey, Syn. 51. 



On maples at Glencoe, Riverside and elsewhere. It is also 

 found on other trees. Synonyms numerous. 



104. A. diffusa, Nyl. Thallus white, effuse or wanting; apothecia 

 round or difform, plane or convex, pruinose. A. willeyi. 

 Tuck, in litt. Willey, Syn. 36. 



On hickories and maples in Will County; not common. 



105. A, pyirhuliza, Nyl. Thallus white, thin; apothecia reddish, 

 slender, much divided, ramose, Willey, Syn. 15. 



On oaks in Will County; rare. Was once considered the A. 

 medusaea of Tuckerman. May occur on Cratsgus, in which 

 case it is more likely to be noticed. 



106. A radiata, (Pers.) Th. Fr. Thallus whitish, darkening, or 

 obsolete; apothecia dark-brown, stellate, difform or ramulose, 

 erumpent. Opegrapha, Pers. (1794). Arthonia, Th. Fr. 

 Arctic. 240. A. astroidea, Ach. Syn. 6. Willey, Syn. 44. 

 Has many synonyms, and until lately was known as A. astro- 

 idea, Ach. Found on oaks near Elgin and elsewhere. The 

 variety swartziana, Nyl. should also occur within our 



* limits. 



107. A. taediosa, Nyl. Thallus indeterminate; apothecia erumpent, 

 linear, heaped, few branched and sometimes round. 



On maples in the Desplaines valley; also found on oaks. The 



name is very applicable, its habit, as to form, ma}- be called 



sportive. 



Note— Tribe i, including the genera Siphula, Spha^rophorus, Acroscvplius, 

 Acolium, Calieium and Coniocybe, have not been found in our territory. Tlie two 

 latter genera are possibilities. 



