Clare Island Survey — Marine Algae. 15 57 



large masses of Lynglya majuscula. The more open parts of the bay show, 

 with the exception of Dictyosiphon and Cyanophyceae, which are rare or 

 absent, the same epiphytes (see also p. 25). 



For the comparison of the present association with that of other countries, 

 see p. 26. 



The Lichina Association (sheltered). 



Locally distributed on sheltered and semi-sheltered localities (Clew Bay, 

 Achill Sound, Bellacragher Bay). See notes on p. 26. 



Porphyra Association (sheltered coasts). 



The growth of Porphyra found in many sheltered places, though not noted 

 by previous writers, is very characteristic and worthy of record. It is found 

 on two types of shore, viz. (1) gently sloping beaches of low rocks and stones, 

 and (2) sandy bays where half-buried rocks are present. The growth 

 occurs more or less throughout the year, though it appears to be more abundant 

 in spring and autumn than in summer. On both shores it is usually 

 accompanied by various forms of Enteromorplia intestinalis and E. linza. 



On beaches composed of stones and flat rocks the association usually fills 

 up the gaps between Fucus. The latter is confined to the larger rocks, whilst 

 Porphyra, which extends from below F. spiralis down to low-water mark, 

 occupies the smaller stones and rocks, though it also occurs epiphytically on 

 Fucus. The amount of growth noted varied considerably on different occasions, 

 as did also the size and form of the plants. In summer it is mostly confined 

 to the lower levels, where it may form a distinct belt. This type of growth is 

 well seen at Louisburgh (immediately east of the Bunowen Eiver), also on the 

 inner side of Bartraw and on Annagh Island, where wave-action is entirety 

 absent. Other parts of Clew Bay, which appeared equally suitable, were entirely 

 devoid of Porphyra. In the localities named a strong current runs along the 

 shore, so that the conditions though quiet are not by any means stagnant, and 

 this fact may in part explain the vigorous growth, and its absence elsewhere. 



The second type of growth referred to, namely that on rocks in sandy bays, 

 is somewhat remarkable, because the expanded membranaceous thalli have to 

 endure the constant friction of the sand. In spite of this, however, a very 

 vigorous and characteristic vegetation is found. The growth is most notice- 

 able at the sides of low bare rocks or those crowned with a mass of Fucus. 

 It may be seen thus in many spots in our area, and has been noticed in other 

 parts of the British Isles. But in addition to this, Porphyra occurs on rocks 

 more or less hidden by sand, so that at first sight the growth might be taken 

 for loose fronds that have become embedded. The plants are in reality 



B.I. A. PROC, VOL. XXXI. H 15 



