MARINE ALGAL VEGETATION 59 



Rh o do p hy ce ae. 



Ceratocolax Hartzii. Cruoria arctica. 



Turnerella Pennyi. Lithothamnion flavescens. 



Delesseria Baerii corymbosa. L. foecundum. 



Polysiphonia arctica. 



Phseophyceae. 



Omphalophyllum ulvaceum. Laminaria nigripes. 



Dictyosiphon corymbosus. 



C h 1 o r o p h } r c e 36. 

 Monostroma groenlandicum. 



B. The Subarctic Group. 



Subdivision I. 



The species of this subdivision are common in the Arctic Sea, 

 and are rather common in the cold-boreal area of the Atlantic Ocean 

 as far south as the Faeroes and Nordland; some of them occur, 

 although rarely, as far south as England. 



Rhodophycese. 



Rhodophyllis dichotoma. Peyssonellia Rosenvingii. 



Halosaccion ramentaceum. Lithothamnion tophiforme. 



Ptilota pectinata. L. laeve. 



Rhodochorton penicilliforme. Clathromorphum compactum. 



Phaeophyceae. 



Lithoderma fatiscens. Chaetopteris plumosa. 



Ralfsia ovata. Coilodesme bulligera. 



R. deusta. Saccorrhiza dermatodea. 



Myrioncma globosum. Laminaria fseroensis. 



M. Laminarias. L. digitata. 



Streblonema secidioides. Alaria Pylaii. 

 Sphacelaria britannica. 



Chlorophyceae. 



Chlorochytrium Schmitzii. U. pseudoflacca. 



Monostroma undulatum. Acrochaete parasitica. 



M. fuscum. Urospora Hartzii. 



Ulothrix consociata v. islandica. Acrosiphonia hystrix. 



U. subflaccida. A. penicilliforme. 



Subdivision II. 



This subdivision includes species, which are either common 

 in the Arctic Sea and the North Atlantic from western France- 

 England northward, or which, if not common, are at least all 

 equally frequent. 



