440 Rev. W. A. Leighton on the British Gia])liide2e. 



subradiate shapes ; disk black, plane, jcracked ; sporidia in asci, 

 eight, broadly obovate, 3-septate. 



Arthonia Swartziana, Ach. Schrad. Journ. Bot. 1.3. p. 13. t. 4. f. 1 (1806) ; 



Sm. E. Bot. 2079 ; Ach. L. Univ. 142 ; «. Syn. 6 ; Mart. Fl. Erlang. 



285 ; Fingerh. FL Eiffl. 25; Johnst. ! Fl. Berw. 101 ; Hook. Br. Fl. 2. 



143; Tayl. Fl. Hib. pt. 2. 104 ; Leight. Licli. Brit. Exsic. 70 ! 

 Arthonia vulgaris, /3. Swartziana, Schaer. Spicil. 246 (1823-1836). 

 Opegrapha atra, X. Swartziana, Schaer. Spicil. 326 ; Exsic. 462 ! ; Enum. 



155. 



atra, y. macularis, Tuckerm. N. Amer. Lich. 75 (1848). 



Arthonia microscopica, jS. artho^rapta, Wallr. Crypt. Germ. 322 (1831). 



> On ash, near the Retreat, Berwickshire ! Dr. G. Johnston. On 

 smooth bark of trees. Shropshire, generally ! 



Thallus forming small subdeterminate patches, of an irregular 

 round or oblong shape, pale yellow or cream-colour with a tinge 

 of ashy-gray, or altogether ashy-gray, thin and scaling off here 

 and there. Ardellce numerous, closely approximate, of a very 

 irregular shape, with a substellate or radiate outline, arising as 

 it were from the apparent confluence of many ardellse into one 

 dark blotch of a full dull black colour. Disk flat or convex, 

 cracked irregularly. Sporidia of a very broad obovate form, 

 3-septate, pale yellow, eight in each ascus. 



Plate VIII. fig. 33. Opegrapha atra, X. Swartziana, Schajr. Exs. 462 : 

 a, vertical section of ardella and thallus ; h, sporidia. — Shropshire 

 specimens of Arthonia Swartziana, Ach. : a', vertical section of 

 thallus and ardella ; b', sporidia. 



5. Arthonia impolita, Borr. Thallus thin, subtartareous^ 

 cracked, indeterminate ; ardellse immersed, roundish or irre- 

 gularly oblong ; disk flat or slightly convex, brownish or lead- 

 coloured, rough, pruinose ; sporidia in asci, eight, obovato-linear, 

 rounded at the extremities, 3-, 4- or 5 -septate. 



Verrucaria impolita, Hoffm. Fl. Germ. 2. 172 (fide Ach.). 



Lichen impolitus, Ehrh. Crypt. 274 (fide Ach. et Schaer.). 



Patellaria pruinata, Pers. in Ust. Ann. st. 7- p- 28 (1794). 



Lichen pruinatns, Pers. in Ust. Ann. st. 11. p. 19 (1797)- 



Parmelia impolita, Ach. Meth. 160 (1803). 



Arthonia pruinosa, Ach. L. Univ. 147. t. 1. f. 3 (1810); Syn. 7; Wallr. 



Crypt. Germ. 321 ; Moug. & Nestl. Stirpes, 1159 ! 

 Arthonia impolita, Borr. in E. Bot. Suppl. 2692. fig. 1 (1831); Hook. Br. 



Fl. 2. 143 ; Tavl. Fl. Hib. pt. 2. 1 04 ; Schar. Enum. 242 ; Exsic. 506 ! ; 



Leight. Lich. Brit. Exsic. 131 ! 

 Parmelia impolita b*. Fries, L. Reform. 183 (1831 ). 

 Lecanactis impolita. Fries, Summa Veg. Scand. 118 (1846); Tuckerm. N. 



Amer. Lich. 77- 



On ivy. Kenilvvorth Castle, Warwickshire ! On oak. Hen- 

 field, Sussex ! On worked timber, Livermore, Suffolk ! all in 

 herb. Borrer. Oswestry, Shropshire ! Rev. T. Salwey. On oak. 



