170 Mr George W. Ti-aill on tJte [sess. lii. 



lowest level of spring tides. Perennial. Fruit in 

 July and August. 

 1-41. Polysiplionia dongdla, Harv. 



" Near low water," according to Dr M'Bain. 



142. Polysiplionia fastigiata, Grev. 



Usually epiphytic on Fuci; sometimes growing on 

 rocks. Perennial. Fiuit from June to September. 



143. T'olysijyhonia fibrata, Harv. 



At 3, 7, &c., on damp, exposed rocks, and on Algae, 

 in the shade, a little below half-tide level; some- 

 times in pools. Annual, summer and autumn. 

 Fruit from June to September inclusive. 



144. Poh/siphonia fibrUlom, Grev. 



Chiefly at 7 and 8, on rocks, and on CladostejoJms 

 spongiosus, in clear sunny pools, usually a little 

 above half-tide level. Very fine, and often 

 abundant in pools a little to the east of the 

 " crooked skerry." Perennial. Fruit in July, 

 August, and September. 



145. Polysiphonia nigrescens, Grev. 



Common on rocks, especially at 2, and on Corcdlina 

 officinalis in pools between tide marks. Perennial, 

 but usual duration from March to October, 

 Young shoots on old plants generally appear in 

 January. Fruit from June to September. The 

 form affinis also occurs. 



146. Polysijjhonia paradtica, Grev. 



At 2 and 7, on rocks in shaded pools between tide 

 marks ; also cast ashore epiphytic on Laminaria 

 Cloustoni. Always submerged. Annual, April to 

 October. Fruit in July and August. 



147. Polysiphonia itrccolata, Grev. 



On rocks and Algte at G, between tide marks, usually 

 in po(jls. Usual duration from March to October, 

 Ijut ])laiits sometimes survive the winter. Fruit in 

 July and August. The variety 'patens also occurs. 



148. Porphyra laciniata, Ag. 



Common on exposed rocks, and on Alga;, usually 

 between half-tide level and high-water mark. All 

 the year. Fruit Ijcst in September. 



