BRITISH MARINE ALGjE. 



115 



Porphyra laciniata. Spring to autumn. Very common 

 on rocks and stones. 



Porphyra miniata. Summer. Appin. 



Porphyra vulgaris. Spring to autumn. Very common 

 on rocks and stones. 



Ptilota plumosa. Summer and autumn. On the stems 

 of Laminariae. On the northern and western coasts 

 of Great Britain and Treland. 



Ptilota sericea. Summer and autumn. On rocks. 

 Bovisand ; Mount Batten ; Whitsand Bay ; Tor- 

 quay ; Exmouth. 



Punctaria latifolia. Spring. Firestone Bay ; Sid- 

 mouth ; Torquay. Near Belfast. 



Punctaria plantaginea. Summer. Firestone Bay ; 

 Torquay ; Exmouth ; Ilfracombe ; Falmouth. 



Punctaria tenuissima. Summer. Firestone Bay, &c, 

 growing on Zostera marina. 



Pycnophycus tuberculatus. Summer and autumn. 

 Devon and Cornwall. Common. 



Ralfsia verrucosa. Winter. On rocks between tide- 

 marks. Common. 



Rhizoclonium Casparyi. Summer. On sand-covered 

 rocks near high-water mark. Not uncommon. 



Rhizoclonium riparium. Summer. With the preced- 

 ing. 



