LECANACTIS] LECANACTACE^ 201 



LECANACTACEJE. 



Thallus crustaceous. Algal cells, Trenteyohlia. Apothecia 

 roundish or oblong, immersed or sessile, immarginate or with a 

 proper margin only ; spores elongate, pluriseptate ; paraphyses 

 branched, confluent. 



This order has affinities with the Lecideei as well as with the 

 Graphidei; to the latter it is more closely related by the algal 

 symbionts, and by the form of the apothecia. There are two British 

 genera : — 



Apothecia with a proper margin 81. Lecanaetis. 



Apothecia without a proper margin ... 82. Platygrapha. 



81. LECANACTIS Eschw. Syst. Lich. p. 14 (1824) emend.; 

 Koerb. Syst. Lich. Germ. p. 275 (1855). Schismatomma Plot. 

 & Koerb. ex Massal. Ric. Lich. p. 55 (1852); Mudd Man. 

 p. 222. (PI. 18.) 



Thallus crustaceous. Apothecia roundish with a cupular 

 carbonaceous proper margin ; hypothecium carbonaceous ; ascus 

 clavate, 8-spored ; spores fusiform or acicular, 3- or 5-septate, 

 colourless. Spermogones with cylindrical spermatia. 



1. L. premnea Weddell in Mem. Soc. Sci. Nat. Cherb. xix. 

 p. 295 (1875). — Thallus effuse, thin, dark-greyish or -greenish or 

 evanescent (K — , CaCl — ). Apothecia moderate in size, black, 

 naked or dark-greenish-pruinose, with a thin prominent flexuose 

 proper margin ; hypothecium black, paraphyses lax, blackish- 

 brown at the tips ; spores oblong-fusiform, straight or slightly 

 curved, 5-septate, 0,018-25 mm. long, 0,005-7 mm. thick ; 

 hymenial gelatine yellowish-red with iodine. — Lichen ahiethms 

 Sm. Engl. Bot. t. 1682 (1807) (non Ach.); Leight. Angioc. Lich. 

 p. 66, t. 28, f. 3 (1851). Lecidea premnea Ach. Lich. Univ. p. 173 

 (1810) ; Tayl. in Mackay Fl. Hib. ii. p. 119 ; Hook, in Sm. Engl. 

 Fl. V. p. 176 ; Cromb. Lich. Brit. p. 90 ; Leight. Lich. Fl. p. 337 ; 

 ed. 3, p. 364. Schismatomma premneum Mudd Man. p. 222 (1861). 



Exsicc. Bohl. n. 101 ; Carroll Lich. Hib. n. 15 ; Mudd n. 197 ; 

 Leight. n 124. 



Sometimes confused with Biatorina premnea, which is externally 

 very similar, but has larger apothecia. The pruina when visible is 

 always darker than in the following species, which is further dis- 

 tinguished by the size and septation of the spores. 



Hah. On old trunks of trees. — JDistr. Not uncommon in England 

 and S. and W. Ireland, rare in Scotland. — B. M. Near Saltram, 

 Bovey Tracey, Lustleigh and Lynmouth, Devon; Shanklin, I. of 

 Wight ; New Forest, Hants ; Fletching, Hassock's Gate and Parham 

 Park, Sussex ; Penshurst, Kent ; Hainault Forest, Thorndon Hall, 

 Langford and Danbury Park, Essex ; near Purton, Gloucestershire ; 

 Moccas Court and Brampton Bryan Park, Herefordshire; Norton, 



