Marine Algce of the Orkney Island'^. 805 



TJLVA, Linn. 



13. XJlva lactuca, Linn. (Ulva latissima, Harv.) 



Common on rocks and stones, and epiphytic on Algte, in pools 

 between tide marks. All the year. In best condition in May. 

 June, and July. 



Family.— CONFERYACE.E. 

 CH 7RT0M0RPHA, Kiitz. 



14. Chaetomorpha implexa (Dillw.), Kutz. {Conferva implcxa, Dillw.) 

 On rocks, and epiphytic on Algce, in pools between tide marks. 



Annual. Found by Mr PoUexfen. 



15. ChsBtomorpha tortuosa (Dillw. ), Kiitz. (CoK/crra torizfosa, Dillw.) 



On rocks, and epiphytic on Algae, in pools at about half-tide 

 level. Always submerged. Annual. May to October. Plants 

 sometimes last tlirough the winter. Spores escape towards the end 

 of July. Papa-Westray, in pools ; Carness, opposite Hellyar Holm, 

 in pools. 



16. Chsetomorplia Uttorea (Harv.), Kiitz. (Conferva littorea, Harv.) 

 Usually on muddy sea-shores between tide marks. Ajinual. 



Summer. Found by Harvey in Orkney. 



17. Chsetomorplia arenosa (Carm.), Kiitz. {Conferva arenosa, Carm.) 

 In shallow pools between tide marks. " Peerie Sea," Kirkwall, 



and Scapa ; 1887 (G. ^Y. T.). Corroborated by E. M. Holmes. 



18. Chsetomorpha cannabina (Kiitz. ), Aresch. 



Kirkwall, in the " Peerie Sea," 1887 (G. W. T.). Xew to Britain. 

 Identified by Prof. Kjellman of Upsala. 



19. Chsetomorpha Limira (Roth.), Kiitz. {Conferva Linum, Roth.) 

 Usually occurs in muddy pools between tide marks. Always 



submerged. Annual. Summer and autumn. In the Loch of 

 Stenness, PoUexfen; in the "Peerie Sea," Kirkwall, 1887 

 (G. W. T.). 



20. Chsetomorpha serea (DUlw.), Kiitz. {Conferva oerea, DUlw.) 



At the Bay of Carness, in pools opposite Hellvar Hohn, 1887 

 (G. W. T.). Certified by Prof. Kjellman of Upsala. Annual. 

 Summer. Found also at Skaill according to ilr PoUexfen. 



21. Chsetomorpha Melagonium ("Web. and Mohr). Kiitz. {Conferva 



Mclagonium, Web. and Mohr.) 



In pools near low-water mark. Always submerged. Perennial. 

 Fruit in summer. Near Hoy Mouth, Rev. C. Clouston ; Carness, 

 in pools opposite HeUyar Holm, &c. Common. 



ULOTHRIX, Kiitz. 



22. XJlothrix flacca (Dillw.), Thur. {Lyngbya flacca, Harv.) 



On rocks, and epiphytic on Algae, near high-water mark ; usually 

 in the shade ; often associated with Ulotlirix isogona. Annual. 



TRAXS. BOT. SOC. VOL. XVIII. 2 L 



