DIRISA.] 



LECAXO-LECIDEEI. 



491 



red with iodine. Spermogones tuberculoso-immersed, with simple 

 sterigmata and acicular, arcuate spermatia. 



A small genus closely allied to Leca- 

 norn, from which it differs chiefly in the 

 character of the hypothecium. In this 

 respect, as also in their form, the apo- 

 thecia resemble those of Roccella. 



1. D. repanda Nyl. Mem. Soc. 

 Cherb. v. (.1857) p. 116. Thallus 

 determinate, thick, tartareo- farinose, 

 tuberculoso-unequal, subeffigurate at 

 the circumference, white (Kt' + yellow, 

 CaCl +- red) ; bypothallus white. 

 Apothecia elevated, piano-depressed, 

 at first closed, then expanded and di- 

 lated, black, caesio- or white-pruinose ; 

 the thalline margin thick, obtuse, 

 more or less inflexed ; spores often 

 slightly curved, 0,027-30 mm. long, 

 about 0,004 mm. thick. Cromb. 

 Journ.Bot. 1871 , p. 178 ; Leight. Lich. 

 Fl. p. 235, ed. 3, p. 22(5. Par melia 

 repanda Fr. Lich. Eur. (1831) 

 p. 177. 



Dirina repanda Nyl. a. A theca 

 and paraphysis, X 350. b. 

 Three spores, X 500. c. Ste- 

 rigmata and spermatia, X 500. 



A plant chiefly of S. Europe and N. Africa which finds its way to a 

 few localities in our Islands. The peculiar apothecia are numerous, at 

 times crowded and dift'orm with the thalline margin then flexuose. In 

 sterile specimens the spermogoues are abundant, with sterigmata 0,010 mm. 

 long, 0,001 mm. thick. The corticolous form (Lecanora Ceratonice Ach. 

 Lich. Univ. p. 36], t. 7. f. 5) does not occur with us. 



Hob. On rocks in maritime districts. Distr. Only sparingly in the 

 Channel Islands, S.W. England, and N. Wales. B. M. : La Coupe and 

 Rozel, Island of Jersey. Portland Island, Dorsetshire; Great Orma'a 

 Head, Carnarvonshire. 



Subtribe III. PERTUSARIEI Xyl. Lich. Scand. (1861) p. 177. 



Thallus variously crustaceous, continuous ; gonidial layer con- 

 taining typical eugonidia. Apothecia more or less inclosed in 

 thalline verrucge, punctiibrm or with the disc expanded and leca- 

 noroid ; spores variable in number, simple. Spermogones with 

 simple sterigmata. 



Arranged by many authors among the Pyrenocarpei from the fruit of 

 both being frequently subsimilar. As, however, the more developed 

 forms of the apothecia in Pertusariei resemble those of many Lecanorei, 

 its two genera are more appropriately included in this tribe. 



62. PERTUSARIA DC. Fl. Fr. ii. (1805) p. 139 ; Nyl. Mem. 



