LECANORA.] 



LECANO-LECIDEEI. 



349 



A large genus comprising several subgenera, formerly ranking as 

 distinct genera, but not sufficiently differing to warrant this arrangement. 

 Indeed, so intimately are they related that Nylander seems at times in- 

 clined to regard them as only leading sections. Some of these with bia- 

 toroid apothecia have sometimes been arranged under the Lecideei ; but 

 in most cases the apothecia are, at least in a young state, lecanorine, with 

 the margin containing gonidia. In other instances the character of the 

 spermogones indicates their true relation. 



Subgenus 1. PSOROMA Nyl. Not. Sallsk. pro F. et Fl. F. Forh. 

 v. (1886) p. 125. Thallns squamulose or subgranulose, internally 

 cellular. Apothecia lecanorine ; spores 8nae, ellipsoid, simple ; 

 hymenial gelatine bluish, then wine-red with iodine. Spermogones 

 with jointed sterigmata and short cylindrical spermatia slightly 

 thickened at either apex. Psoroma Ach. Prodr, (1798) p. 91 pro 

 minima parte ; Nyl. Mem. Soc. Cherb. iii. (1885) p. 322. 



At once distinguished by the entirely cellular structure of the thallua. 

 Most of the species are exotic, and of the few which are European, only 

 one occurs in this country. 



Fig. 58. 



Lecanora (Psoroma) hypnorum Ach. a. Vertical section of thallus, x200. 

 b. Spores, X5CK). c. Sterigmata and spermatia, X500. 



1. L. hypnorum A.ch. Syn. (1814) p. 193; Nyl. Not. Sallsk. pro 

 F. et Fl. F. Forh. v. (1866) p. 125. Thallus indeterminate, squa- 

 muloso-granulate, yellowish-brown or tawny-yellow ; squamules 

 minute, crenate or granulate (K ). Apothecia moderate or some- 

 what large, at first urceolate, then plane, red or brownish, the thai- 

 line margin granuloso-crcnate ; spores often somewhat acute at 

 either apex, 0,016-21 mm. long, 0,008-11 mm. thick; hymenial 

 gelatine bluish, then wine-red with iodine. Cromb. Grevillea, xii. 

 p. 60 ; Hook. Fl. Scot, ii. p. 51 ; Tayl. in Mack. Fl. Hib. ii. p. 139. 



