ARTHOXIACEAE. 533 



Order 3. GRAPHIDALES. 



Apothecia without an exciple. Fam. 1. Arthoxiaceae. 

 Apothecia with an exciple. 

 Thallus without a cortex. 



Apothecia solitary. Fam. 2. Graphidaceai;. 



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



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



Family 1. ARTHONIACEAE. 

 1. ARTHONIA Ach. 



Spores two to many-celled. 1. Arthonia. 



Spores muriform-multilocular. 2. Arthothelium. 



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. chiodertrlla. 



Spores with end-cell enlarged. 3. .1. 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. inter duct a. 



Spores eight- to sixteen-celled. 

 Spores 22-32 x7-ll M . 



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



Apothecia chestnut, 0.30.5 mm. wide. 8. A. septiscpta. 



Spores 50-75 x 14-23 . 



Apothecia orbicular. 0. A. platygraphidea. 



Apothecia linear and branched. 10. A.atrata. 



1. Arthonia gregaria (Weig.) Koerb. Syst. Lich. 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 Xyl. Flora 52: 125. 1869. 



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



3. Arthonia cinereopruinosa Schaer. Ennm. Lieh. 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 Tinder's Point : widely distributed in tropical and 

 subtropical America and in New Zealand. 



6. Arthonia interducta Xyl. Act. Soc. Sci. 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 Xyl. Flora 68: 447. 18S5. 



On bark, Great Bahama, near Rolletown : Florida. 



8. Arthonia septisepta Xvl. Flora 69: 104. Hyponym. 1886. Xyl. apiul Willey, 



Synops. Arth. 11. 1890. 



On bark, New Providence: Florida; Cuba. 



This species is very closely related to tho common Arthonia conferta (Pfie) Nyl., 

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

 celled instead of six-celled. 



