318 Mr George Traill on the 



Class IV.— RHODOPHYCE^. 

 Order VII.— FLORIDE^. 

 Family.— PORPHYRACE^. 



PORPHYRA, Ag. 



106. Porphyra abyssicola, Kjellni. 



Some specimens from 8kaill Bay in Mrs Moffat's collection have 

 been attributed to this northern species ; and another from Rousay, 

 found by the late Mrs Traill of Wood\yick in 1839, appears to Mr 

 Batters, on a careful microscopic examination, to agree very well 

 with Kjellman's figure and description, and with Foslie's speci- 

 mens. 



107. Porphyra coccinea, J. Ag. ( = P. minima, Crn.). 



Dredged by Mr Pollexfen in Kirkwall Bay. Epiphytic on other 

 Algae. Identified by Mr Batters. New to Orkney. 



108. Porphyra laciniata (Lightf.), Ag. 



Common on exposed rocks, and epiphytic on Algte, usually 

 between half-tide level and high-water mark. Usually left dry by 

 the tide, and exposed to the light for many hours daily. All the 

 year. August and September are usually the best months for fruit. 



108a. Porphyra laciniata (Lightf.), Ag., var. fulgaris (Ag.), Le Jolis. 



Common on rocks, and epiphytic on Algse, in pools between tide 

 marks. Always submerged. Annual. jNIay to October. Fruit in 

 August and September. 



109. Porphyra leucosticta, Thur. 



Epiphytic on Algse from half-tide level to low-water mark. 

 Usually left uncovered by the tide, and exposed to the light for 

 several hours daily. Annual. May to October. September is 

 usually the best time for fruit. Skaill, in Rousay; Inganess Bay; 

 Deerness. 



110. Porphyra linearis, Grev. 



Usually on rocks at about the high-water mark of neap tides. 

 Annual. Winter and spring. Found at Skaill, West Mainland ; 

 at Kirkwall Bay ; and by Dr M'Bain at Calf Sound. 



111. Diploderma miniata, Kjelhn. 



A single and very large specimen of this plant was dredged in 

 Kirkwall Bay by Mr Pollexfen. Identified by Mr Batters. New 

 to Orkney. 



Family.— SQUAiMARIACE^. 



PETROCELIS, J. Ag. 



112. Petrocelis ci'uenta, J. Ag. {Oruoria pcllita, Fries.) 



On rocks between half-tide level and low-water mark. Usually 

 left uncovered by the tide, and exposed to the light fqi^' some hours 

 daily. Perennial. Fruit in winter. 



