304 Mr George Traill on the 



Class IL— CHLOROPHYCE^. 

 Order II.— CHLOROZOOSPORE^. 



Family.— ULVACE^. 



PBASIOLA, Suhr. 



4. Prasiola stipitata, Suhr. 



At Scapa, near the burn, on large stones at about the high-water 

 mark of neap tides, 1887 (G. W. T.) Left uncovered by the tide, 

 and exposed to the light for many hours daily. All the year. 

 Usually in best condition in winter and spring, and poor in summer 

 and autumn. Fruit in February and March. New to Orkney. 



MONOSTROMA, Thur. 



5. Monostroma Grevillei (Thur.), Wittr. (Ulva lacttica,' Harv. non 



Liun. ) 



At above half-tide level, chiefly where there are fresh-water 

 streams. Epiphytic on Algse. Annual. March to June. 



ENTEROMORPHA, Link. 



6. Enteromorpha percursa ( Ag. ), Hook. 



In pools near high-water mark. Annual. Spring and summer. 

 "Peerie Sea," Kirkwall; Scapa; July 1887 (G. W. T.). Corro- 

 borated by E. M. Holmes. 



7. Enteromorpha erecta (Lyngb. ), Hook. 



In rock pools at about half-tide level. Fine specimens in deep 

 water in Kirkwall Bay. Annual. Spring and summer. 



8. Enteromorpha clathrata (Roth), Grev. 



In pools at about half-tide level. Annual. April to September. 

 Corroborated by E. M. Holmes. 



9. Enteromorpha compressa (Liun.), Grev. 



Common on rocks and stones, also epiphytic on Algae, between 

 tide marks. Vegetates at all seasons. Fruit in spring and summer. 



10. Enteromorpha liinza (Linn. ), J. Ag. (Ulva Linza, Linn.) 

 Common in pools at about half-tide level. Always submerged. 



Annual. May to September. Fine in Damsay Bay. 



11. Enteromorpha intestinalis (Linn. ), Link. 



Common, chiefly in brackish water. Always submerged. 

 Annual April to September. 



12. Enteromorpha cornucopise, Hook. 



In brackish pools, Marwick Head, Ac. Mr Pollexfen is under 

 the impression that this should be included under Monostroma 

 Grevillei. 



