AKTHONIACEAE. 533 



Order 3. GRAPHIDALES. 



Apothecia without an exciple. Fam. 1. ARTHONIACEAE. 

 Apothecia with an exciple. 

 Thallus without a cortex. 



Apothecia solitary. Fam. 2. GRAPHIDACEAE. 



Apothecia typically imbedded in a stroma. Fam. 3. CHIODECTONACEAE. 



Thallus with an upper cortex. Fam. 4. DIRINACEAE. 



Family 1. ARTHONIACEAE. 



Spores two to many-celled. 1. Arthonia. 



Spores muriform-multilocular. 2. Arthothelium. 



1. ARTHONIA Ach. 



Spores four- to six-celled. 



Apothecia some shade of red. 1. A. gregaria. 



Apothecia brown or black. 



Apothecia orbicular or difform. 



Apothecia about 0.3 mm. in diameter. 



Spores with cells of equal size. 2. A. chiodectella. 



Spores with end-cell enlarged. 3. A. cinereopruinosa. 



Apothecia over 0.6 mm. in diameter. 



Spores with cells of equal size. 4. A. polymorpha. 



Spores with one or both end-cells enlarged. 5. A. complanata. 



Apothecia linear, more or less branched. 6. A. interducta. 



Spores eight- to sixteen-celled. 

 Spores 22-32 x 7-11 #. 



Apothecia fulvous, 0.1 mm. wide. 7. A, fissurinea. 



Apothecia chestnut, 0.3-0.5 mm. wide. 8. A. septiscpta. 



Spores 50-75 x 14-23 #,. 



Apothecia orbicular. 9. A. platygraphidea. 



Apothecia linear and branched. 10. A. atrata. 



1. Arthonia gregaria (Weig.) Koerb. Syst. Lien. Germ. 291. 1855. 



Sphaeria gregaria Weig. Obs. Bot. 43, pi. 2, f. 10. 1772. 

 Arthonia cinnabarina Wallr. Crypt. Germ. 1: 320. 1831. 

 On bark, Stocking Island, Exuma Chain : cosmopolitan. 



2. Arthonia chiodectella Nyl. Flora 52: 125. 1860. 



On bark, New Providence : Florida ; Louisiana ; Texas. 



3. Arthonia cinereopruinosa Schaer. Enum. Lich. 243. 1850. 



On bark, New Providence : North America ; Europe. 



4. Arthonia polymorpha Ach. Syn. Lich. 7. 1814. 



On bark, Great Bahama, New Providence, Great Exuma : widely distributed in 

 tropical regions of both hemispheres. 



5. Arthonia complanata Fee, Essai Crypt. 54. 1824. 



On bark, Great Bahama, at Finder's Point : widely distributed in tropical and 

 subtropical America and in New ..Zealand. 



6. Arthonia interducta Nyl. Act. Soc. Sd. Fenn. 7: 496. 1863. 



On bark, Stocking Island, and Cay north of Wide Opening, Exuma Chain : 

 Florida ; Anegada Island ; Nicaragua ; Brazil ; Hawaiian Islands. 



7. Arthonia fissurinea Nyl. Flora 68 : 447. 1885. 



On bark, Great Bahama, near Rolletown : Florida. 



8. Arthonia septisepta Nyl. Flora 69: 104. Hyponym. 1886. Nyl. apud Willey, 



Synops. Arth. 11. 1890. 



On bark, New Providence : Florida ; Cuba. 



This species is very closely related to the common Arthonia conferta (F6e) Nyl., 

 differing only in having the apothecia spuriously margined and the spores eight- 

 celled instead of six-celled. 



