Knowles — The Maritime and Marine Lichens of Howth. 129 



fli. crenulata Nyl. — Here and tliere on rough quartzites. 



fL. Hageni Ach. — Frequent and general round the coast on stones lying 



level with tlie soil, and on rocks at the base of the eartli-banks, sometimes 



also on the ground associated with BiieUia myriocarpa and L. epixantha. 



f. calcigena Nyl. — On rocks on the shore, Broad Strand ; frequent. 



This form seems to grow nearer the sea than the species. 



fL. prosechoides Nyl. — Abundant on rocks splashed by the sea at high tide. 

 The tliallus varies a good deal in the Howth plant, being smooth, con- 

 tinuous, and much expanded on steep rock-faces, but more dispersed and 

 unequal on low-lying flat rocks, where it is more often associated with 

 other lichens. The apotliecia also vary a good deal in size and colour. 

 In a note about the species Crombie remarks that it is sometimes the 

 host of Arthonia rarians. On the Howth coast A. varians is almost 

 invariably present on the apothecia. Hardly a specimen was gathered 

 on which the parasite was not detected. Sandstede (24), in his account of 

 the lichens of the German islands in the North Sea, mentions a three- 

 septate parasite as occurring on L. prosechoides, which is very probably 

 A. varians, but he does not give it a name. 



* var. aeruginosa Wedd. — On quartz rocks near Needles, associated 



with the species. 



* var. melacarpoides Nyl.— With Rhizocarpon alboatrum on the top of 



the sea-wall, Sutton. 

 *L. prosechoidiza Nyl. — At various places on the south-west coast in 

 situations similar fo those in which L. prosechoides grows, and on 

 calcareous rocks at Balsoadden. L. prosechoidiza seems to be closely 

 related to L. prosechoides, and may be only a state of that plant. The 

 main characters which distinguish it from L. prosechoides are tlie greyer 

 thallus, the eonglutinate paraphyses, and the different reaction with 

 iodine. It is much less common than L. prosechoides. 

 *L. conferta Nyl. — On quartzites, Sutton shore, and on the Harbour wall, 

 Howth; rare. 

 L. sulphurea Ach. — Only seen on steep, rather shady rocks at the west end 

 of Broad Strand. 

 fL. epanora Ach. — On slate rocks ; rare. 

 L. varia Ach. — On Blackthorns, EarlsclifEe, and on dead twigs lying on the 

 ground ; common. 

 fL. symmictera Nyl. — On Blackthorns, Earlscliffe ; rare. 

 tl". polytropa Schaer. All round the coast ; frequent. 

 L. atra Ach. — General all round the coast in the Ramalina belt, but nowhere 



abundant. 



T 2 



