Marine Ahjca of the Orkney Islands. 313 



71. Sphacelaria cirrhosa (Rotli), Ag. 



Epiphytic on ^Vlgfe in pools at and above half-tide level. All 

 the year. Fruit in June and July. Propagula in July. Carness 

 in pools ; Shapausey ; Rousay, &c. 



72. Sphacelaria plumigera (Lyngb.), Holmes, i Splmcclaria iilumosa, 



Harv.) 



Doubtful as an Orkney species ; and probably (Jlise.topteris 

 plunwsa, Kiitz, has been confounded with it. 



CHTRTOPTEBIS, Kiitz. 



73. Chaetopteris plumosa (Lyngb.), Kiitz. 



In bays, 7 fathoms, coral bottoms. Pierowall, Kirkwall, Linga 

 Sound, &c. Perennial. Fruit in winter. 



CLADOSTEPHUS, Ag. 



74. Cladostephus spongiosus (Lightf.), Ag. 



Common on rocks and in pools near low-water mark. Perennial. 

 Fruit in winter. 



75. Cladostephus verticillatus (Lightf.), Ag. 



Submerged in bays on rocks and stones; also epiphytic on Cordl- 

 lina officinalis. Perennial. Fruit in winter. Occurs at Eday, 

 Widefirth, &c. 



Family. — EALFSI ACE.E. 



RALFSIA, Berk. 

 76.^Ralfsia verrucosa, Aresch. {Balfsia deusta, Berk.) 



In shallow pools between high-water mark and half-tide level, 

 incrusting rocks and stones ; also on exposed rocks in damp places. 

 Perennial. Fruit in winter. 



Family.— ]\IYRI0XEMACE.E. 



MYRIONEMA, Grev. 

 77. Myrionema vulgare, Thur. {Myrionema strawjidans, Grev.) 



At about half-tide level. Left uncovered by the tide, and exposed 

 to the light for some hours daily. Annual. Summer and autumn. 

 Fruit in July and August. Epiphytic on Ceramium nihrum, 

 "Westray ; on Enteromorpha compressa at Broch, Eousay. 



77a. Myrionenaa v~ulgare, var. putictiforme (Harv. ), Batters. {Myri&iiema 



puadifonne, Harv.) 



At about half-tide level. Annual. Summer and autumn. 

 Fruit in July and August. At Skaill, Rousay, epiphytic on 

 Porphyra laciniata, var. vulgaris. At Kirkwall Bay on Ceramium 

 ruhritm. 



