Marine Algce of the Orkney Islands. 321 



In repiard to this species Mr Pollexfen writes to me as follows :— 

 " The first specimen of this seaweed found in this country was 

 gathered by me floating in a rocky pool at Skaill Bay. The 

 description of the species as given by Agardh did not enable 

 Harvey to recognise the plant, which was young, but in perfect 

 condition, and he considered it a new species, and so named it. 

 He afterwards, however, discovered that it had been previously 

 figured in the Flora Danica, and, of course, the old name was 

 restored. It has since been found at Skaill by Mrs Mofl'at." 



127. Antithamnion plumula (Ellis), Thur. {Callithamnion plumula 

 (Ellis), Lyiigb.) 



In deep water in quiet places, coral bottoms. Annual. 

 Summer. Fruit, July, August. Skaill Bay, West Mainland ; 

 Kirkwall Bay, dredged by Mr Pollexfen. 



CALLITHAMNION, Lyngb. 



128. Callithamnion Borreri {Eng. Bot. ), Ag. 



Found by Mr Pollexfen in Kirkwall Bay, but very rare. Identi- 

 fied by Mr Batters. " In quiet places " according to Dr M'Bain. 

 Annual. Summer. 



129. Callithamnion thuyoideum {Eng. Bot. ), Harv. 



Usually on rocks near low-water mark. Annual. Spring and 

 summer. Dredged by Mr Pollexfen in Kirkwall Bay. Identified 

 by INIrs Griffiths, and recently by Mr Batters. 



130. Callithamnion roseum (Roth), Lyngb. 



Occurs in quiet bays, 4 fathoms, coral bottoms. Annual. 

 Summer. Kirkwall Bay. 



131. Callithamnion polyspermum, Ag. 



Occurs at about half-tide level on shaded vertical rocks, and 

 epiphytic on Algaj. Always in places which are uncovered by the 

 tide for several hours daily. Annual. March to October. Fruit, 

 May, June, July. Spores usually escape towards the end of July. 

 Rousay; Eday ; Skaill Bay, West Mainland ; in Kirkwall Bay, and 

 on Kirkwall Pier, &c. One of the Orkney specimens Harvey 

 describes as " a beautiful variety." 



132. Callithamnion Hookeri (Dillw.), Ag. 



Epiphytic on Algae from about half-tide level to near low-water 

 mark. Usually at places which are uncovered by the tide, and 

 exposed to the light for several hours daily. Annual. March to 

 October. Fruit from May to August. Papa-Westray ; Skaill, 

 West Mainland ; also in the Pentland Firth. The variety lanosum 

 of Harvey also occurs. 



133. Callithamnion Brodieei, Harv. 



On rocks in the shade near low-water mark. Usually uncovered 

 by the tide for some hours daily. Annual. May to October. 

 Skaill Bay, West Mainland, very fine. 



TRANS. BOT. SOC. VOL. XVIII. 2 M 



