312 Mr George Traill on the 



64. Ectocarpus Hincksiae, Harv, 



Epipliytic on A/aria esculenta, west of Broch in Rousay, July, 

 1887 {G. W. T.). Corroborated by E. M. Holmes. Annual. .Summer. 

 Epiphytic on Laminaria digitata (M'Bain). 



65. Ectocarpus granulosus {Eng. BoL), Ag. 



On rocks in pools near low-water mark, and at a greater depth. 

 Annual. April to October. Fruit from May to September. Calf 

 Sound, 7 fathoms ; Kirkwall Bay. 



66. Ectocarpus longifructus, Harv. 



Epiphytic on Algae in pools between tide marks. Annual. 

 Summer. Discovered by Mrs jNloffat at Skaill, West Mainland. 



ISTHMOPLEA, KjeUman. 



67. Isthmoplea sphseropliora (Harv.), Kjellm. {Ectocarpus sphoero- 



'phorius, Carm.) 



In caverns, also on exposed rocks between tide marks, epiphytic 

 on Algge. Usually left dry by the tide, in the shade, for several 

 hours daily. Annual. April to September. Fruit from May to 

 August. In a dark narrow chasm, east side of Eday, epiphytic on 

 Ptilota elegaris and CladopJwra rupestris. Found also in Kirkwall 

 Bay, &c. 



PYLAIELLA, Bory. 



68. Pylaiella Uttoralis (Linn.), Kjellm. {Ectocarpus littoralis, Lyngb.) 

 Common on fuci in pools between tide marks ; also on exposed 



rocks. At all seasons. Fruit in summer. 



TILOPTERIS. 



69. Tilopteris Mertensii (£'nf7. Bat.), Kiitz. {Ectocarpus Mcrtcnsii, Ag.) 



Usually on mud-covered rocks and stones near low-water mark, 

 and at a greater depth. Sometimes occurs where fresh-water streams 

 enter the sea. Annual. Spring. Skaill Bay, West Mainland. 



Family.— SPHACELARIACE.^.. 



SPHACELARIA, Lyngb. 



70. Sphacelaria radicans (Dillw.), Harv. 



On sand-covered rocks between tide marks at the east side of 

 Kirkwall Bay. All the year. Fruit in winter. Uncovered by the 

 tide, and exposed to the light for some hours daily. 



70a. Sphacelaria radicans (Dillw.), Harv., var. oUvacca (Dillw.), Batters. 

 Usually in velvety patches on rocks near high-water mark, 

 accompanying Rhodocliorton Rotliii. Uncovered by the tide, and 

 exposed to the light for many hours daily. All the year. Uni- 

 locular pedicellate sporangia in winter. Harvey mentions that 

 Messrs Hooker and Borrer collected this species in Orkney ; but the 

 locality is not known. 



