140 Scientific Proceedings^ Royal Dublin Society. 



associated witli Lichina pygmaea and Verrucaria striatula. A. leptotera 

 also occurs both on the Broad Strand and at Balseadden Bay associated 

 with Verrucaria aquatilis on rocks over which fresh water frequently 

 flows. This species is distinguished from tlie other marine Arthopyrenias 

 by the dark gelatinous thallus ; the very minute perithecia, which are 

 thickly scattered on the surface ; by the dimidiate perithecial wall and by 

 the narrow spores, which, in the Howth specimens, are of an almost 

 uniform widtli throughout, and measure 15-17ju x 5ju. 



*A, halodytes Oliv. — Frequent all round the coast on the silieious rocks 

 Not seen on the limestones. 



* var. tenuiscula Wedd. — Witli the species on hard smooth quartzites, 



Lion's Head. 



*A. halizoa A. L. Sm. — Limestone rocks, Balseadden. 



'A. marina A. L. Sm. — East end of Broad Strand with A. leptotera. The 

 narrow three-septate spores of this species are very distinct, and easily 

 separate it from the other marine Arthopyrenias. In the Howth 

 specimens the thallus is less developed than that of A. leptotera, with 

 which it is sometimes associated. 



tPorina chlorotica Wainio. — On the Nose of Howth with V. maiira; frequent 

 on moist shady quartzites on the east coast ; occasional on the Broad 

 Strand. 



Pyrenula nitida Ach. — On Blackthorns, Earlscliffe ; rare. 



IV. Bibliography. 

 Adams, J. : 



1. The Distribution of Lichens in Ireland. Proc. Roy. Irish Acad., xxvii, 



B, No. 10, July, 1909. 



BORGESEN, F. : 



2. The Algae- Vegetation of the Faeroese Coasts. Botany of the Faeroes, 



part iii, 1908. 

 Cotton, A. D. : 



3. Marine Algae, Clare Island Survey, part xv, Proc. Roy. Irish Acad., 



vol xxxi, 1912. 

 Crombie, M. : 



4. A Monograph of Lichens found in Britain, being a descriptive 



Catalogue, &c. Part I. 1894. 

 Geological Survey of Ireland, Memoirs : 



5. The Geology of the Country around Dublin. Explanation of sheet 112. 



1903. 



