15 148 Proceedings of the Royal Irish Academy. 



In England it is only known from the south coast ; but it has been found in 

 all the provinces of Ireland except Ulster, and is very common in the Clare 

 Island district. It is, usually attached to Coralliha officinalis, and occurs in 

 pools and in the low-littoral region. 



Var. agariciformis Foslie. — Batters, following Foslie, regards M. ayarioi- 

 formis Harv. as a variety of this species ; and Madame Lemoine, to whom I 

 sent for anatomical examination a fragment of a lloundstone specimen 

 (probably collected by McCalla) , writes that there is no doubt whatever that 

 Foslie was correct. The variety is evidently exceedingly rare, as no trace of 

 such a form was found by me on any of the Lithothamnium banks of Clew 

 Bay or Roundstone. 



Distribution. — A southern species. S. and W. Ireland, S. England, N. and W- 

 France, N. Spain, Mediterranean, Morocco. 

 Var. agariciformis. Roundstone Bay. 



L. fasciculatum Fosl. 



This species is known only from the west of Ireland, and is thus one of 

 the most interesting algae of the Irish flora. It is known locally as " Wild 

 Coral," and is plentiful in Clew Bay, occurring in patches mixed with 

 Lithothamnium calcarevm. It is also common at Roundstone (see p. 70). 



Foslie distinguished several forms of the present species ('09). The 

 plant was accidentally omitted (or rather unintentionally united with another 

 species) in Batters' Catalogue, as explained by me last year (Journ. Bot., 

 p. 115). 



Distribution. — Clew Bay ! Roundstone ! Fahy Bay ! Schull and Ballina- 

 courty (teste Johnson). 



Lithothamnium calcareum Aresch. 



The dominant species of the fruticulose Lithothamnium association of 

 Clew Bay and Roundstone (see p. 09). It occurs in great diversity of 

 form, but it seems clear that varieties compressa McCalla, squamulosa Fosl., 

 crassa Lem., subvalida Fosl., and mbsimplex Batters, as described and figured 

 by Lemoine ('10), are the most common in the district. Reference should be 

 made to that paper for details as to biology and ecology. Mannin Bay, 

 where L. calcareum occurs abundantly, is worthy of further investigation, 

 and should be compared with Roscoff and Concarneau, which have been 

 investigated by French botanists. 



Distribution. — British Isles, N. and W. France, Norway, Denmark, 

 Portugal, Morocco, Algeria, Mediterranean (Naples, Adriatic). 



