Knowlics — The Maritime mid Marine Lichens of'Howth. 105 



morpha ou page 100, and those of Rhizocarpon alhoatntiii, page 101. All 

 three seem to be abundant round the peninsula. 



Epiphijfes. — Leciograplia parasitica was noted in one or two places on the 

 Broad Strand growing on Plnjscia parietina, and in almost every specimen of 

 L. prosechoides that was examined from all parts of the coast the apothecia 

 were found to be infested with Arthonia varians. 



(8) The Lichina Vegetation. 



Though Lichina confinis belongs to the semi-marine lichens and L.pygmaea 

 to the marine group, I have followed A. D. Cotton (3) in considering 

 them together. Both species are widespread on the Howth coasts, 

 L. confinia usually occurring along the inner fringe of high-tide mark 

 between the orange lichens and Verrucaria maura, and slightly overlapping 

 both these belts, Lichina pygmaea at a lower level below Verrucaria inaura 

 and usually defining the lower limits of this lichen, but in certain situations 

 extending down as far as low neap-tide. Tlie seaweed Pelvetia may be taken 

 as forming tlie upper limit of L- pygmaea and tlie lowest level at wliieh 

 L. confinis grows on these shores. Both species are found in sheltered and 

 in exposed situations, but L. pygmaea is absent from the most sheltered parts 

 of the south coast, and neither species was seen on the exposed and outer face 

 of the Needles. 



Vigorous growths of the Lichina vegetation occur on the south-west 

 coast between Red Rocks and the Needles. At Old Boat-house Lichina 

 confinis covers a fairly wide area ou the top of a rough rocky plateau, 

 L. piygmaea forming irregular patclies on the sea-faces of the same rocks. 

 On steep rocks with an easterly aspect in tJiis same locality L. confinis forms 

 a narrow zone of about 4 inches wide between a broad band of Lecanora 

 prosechoides and Verrucaria maura, whilst others facing west showed the 

 following lichen and algal zones from top to bottom : — 



Placodium lobulatum (spotted with a few tufts of Lichina confinis). 



Verrucaria maura. 



Pelvetia cananiculatus. 



Lichina pygmcea and Verrucaria striatula f. conlinua. 



Verrucaria mucosa. 



Barnacles on which Arthopyrenia foveolata was abundant. 



Fucus sp. 

 The three upper bands were narrow ones. 



On the western and weather side of Druraleck Point Lichina confinis 

 grows thinly on tlie top of the cliff amongst a poor growth of Bamalina 



q2 



