Clare Island Survey — Marine Algae. 15 7t 



published an account of his trip ('99). He found L. fasciculatum still 

 plentiful, as it was also in September, 1911. The dominance of L. calcareum 

 in both Eoundstone and Clew Bay is normal for the British Isles. 



The remarkable " coral beaches " at Mannin Bay and Ballyconneely Bay 

 (Co. Galway) are due to the presence of extensive Lithothamnium associations 

 in the neighbourhood. When driving from Clifden to Eoundstone in 

 September, 1911, the former spot was examined; but time did not permit of 

 exploration by dredging. It was evident, however, that the material washed 

 up is L. calcareum, and that the beach, a fairly wide one, is composed almost 

 entirely of broken particles of this species. The photographs on Plate IV, 

 kindly taken by Dr. Gr. H. Pethybridge, show two views of the beaches in 

 Mannin Bay. A few low rocks occur in part of the bay as shown in the 

 lower illustration, but elsewhere there are stretches of pure " coral sand." 

 The greater part of the sand is composed of small particles (see Plate V, 

 fig. 1) ; but at high-water line and in certain other places coarser 

 pieces and knolls accumulate, with a certain quantity of broken shells. 

 Dr. Pethybridge informs me that at low-water mark the particles are 

 exceedingly fine and resemble ordinary sand ; but it is probable that they have 

 the same origin. The Lithothamnium fronds are completely bleached, and 

 the beach is thus dazzlingly white in the sun. .Though the coral sand is 

 carted for use as manure, fresh supplies are constantly washed up, so that it 

 is evident that the bank outside is extensive. A similar. beach is said to exist 

 in Ban try Bay. 1 



In the British Isles L. calcareum is certainly the dominant fruticulose 

 species, beds being known from several localities (Studland and Falmouth in 

 the south of England, and Bute in Scotland), and under certain conditions it 

 is washed ashore in quantities. A fine bed in 14 fathoms was once dredged 

 by me off Fowey (Cornwall). Another species, L. racemus, appears to exist as 

 an association at Falmouth, since it is washed ashore in plenty ; but this is 

 the only station for the plant in England, and records of Lithothamnium banks 

 in England or France formed by species other than L. calcareum require 

 verification. 



Comparison with other countries. — L. calcareum is also frequent in France. 

 It is abundant in Normandy, and in Brittany as far south as Croisic. Lemoine 

 ('11) states that it is known from Denmark, Portugal, Naples, Morocco, and 

 Algeria. In all these localities it probably occurs in associations similar to 



1 Several other remarkable beaches occur in the west of Ireland. A shore consisting exclusively 

 of broken shells is found at Knockboy (Co. Galway), which, like the coral-sand beaches, is 

 exploited for manure (Johnson and Hensman, '99) ; whilst Dog's Bay, near Eoundstone, is famous 

 for its beautiful sands, composed almost entirely (up to 90 per cent.) of Foraminifera. 



