62 H. JOXSSOX 



Ectocarpus fasciculatus. Castagnea virescens. 



E. Hinksiae. Laminaria saccharina. 



Sphacelaria radicans. L. hyperborea. 



S. olivacea. Fucus spiralis. 



Phyllitis zosterifolia. F. serratus. 



Dictyosiphon Ekmani. Pelvetia canaliculata. 



D. Mesogloia. Alaria esculenta. 

 D. Chordaria. 



Chlorophyceae. 



Codiolum Petrocelidis. Entoderma \Yittrockii. 



C. pusillum. Acrochaete repens. 



Enteromorpha aureola. Ochlochaete ferox. 



Prasiola polyrrhiza. Acrosiphonia albescens. 



P. furfuracea A. flabelliformis. 



P. stipitata. Cladophora glaucescens. 



Cyanophy ceae. 



Plectonema norvegicum. 



E. The Warm-Boreal Group. 



The majority of the species referred to this group extend at least 

 as far south as the Mediterranean and the Atlantic coast of North 

 Africa. According to the different distribution northward the group 

 is divided into three parts of which only the one reaches as far 

 north as S. Iceland. 



1. Species extending as far north as S. Iceland, the Faroes and 

 Northern Norway, and at least as far south as the Mediterranean 



/ > 



and North Africa. 



Rhodophyceae. 



Chondrus crispus. Callithamnion scopulorum. 



Lomentaria clavellosa. Ceramium arborescens. 



Plocamium coccineum. Cruoria pellita. 



Bonnemaisonia asparagoides. 

 Pterosiphonia parasitica. 



Phseophyceae. 

 Desmarestia ligulata. Leathesia difformis. 



Chlorophyceae. 

 Enteromorpha Linza. 



C y a n o p h y c e ae. 



Phormidium autumnale. 



According to the above the number of species in the groups is 

 as follows: 



