Clare Island Survey — Marine Algae. 15 149 



Lithothamnium norvegicum Kjellm. 



L. hdrvegic'inn is an addition to the published list of our flora. It has been, 

 however, sent out recently by Holmes in his " Algae Britannicae Eariores " 

 (No. 264) ; he obtained specimens from Arran (Scotland). The species 

 resembles in form a small, much-branched specimen of L. calcarcum ; but the 

 branches are more slender and the whole plant more compact. The structure 

 also is distinct (see Lemoine, '11, p. 108). It has doubtless been mistaken 

 for L. calcareum in the past, and is probably not uncommon on our shores. 

 In Clew Bay it occurred sparsely scattered amongst other species. 



Distribution. — Clew Bay, Eoundstone, W. Scotland (Arran) ; Norway, 

 Denmark, America (N. Atlantic coast). 



L. laevigatum Fosl. 

 (Phjmatolithon laevigatum Fosl., Batt. Cat., p. 98). 



A sub-littoral species, but found occasionally in caves. It was dredged off 

 The Bills in about 15 fathoms, and was found on limpets in a cave on Clare 

 Island. 



Distribution. — England (Berwick), Ireland (Gola Island, Larne), Faeroes, 

 S. Norway, Denmark, Atlantic coast of N. America (Rhode Island, Maine, 

 Newfoundland). 



L. polymorphum Aresch. 

 (Phymatolithon polymorph mil Fosl., Batt. Cat., p. 98). 



Common on exposed coasts in our area, and forming a band below 

 L. incrustans, as explained on p. 41. For taxonomy see Lemoine ('11), p. 63. 



Distribution. — British Isles (common), Norway, Sweden, Denmark, Faeroes, 

 Iceland, Heligoland, N., W. and S. France, Tangier, Mediterranean, Adriatic. 



L. compactum Kjellm. 

 (L. circumscriptum Strdmfelt; Clathromorphuin circumscriptum Fosl., Batt. Cat., 



p. 97). 



Foslie at first regarded L. compactum and L. circumscriptum as distinct, but 

 subsequently referred them to the same species. Kjellman's name antedates 

 Stromfelt's by three years, and must be adopted (see Lemoine, '11, p. 98). The 

 plant was dredged twice, in 5 fathoms between the outer islands of Clew Bay, 

 and in 7 fathoms off Mulranny. It is listed by Johnson and Hensman ('99), 

 but no locality is given, and it has not been found in England or Scotland. 



Distribution. — Ireland (Mayo), Faeroes, Iceland, Norway, Spitzbergen, 

 Nova Zembla, Greenland, Atlantic coast of N. America (Maine, Newfoundland, 

 Nova Scotia;, and Pacific Coast (Alaskaj. 



