W. WEST AND G. S. west: ALGA-FLORA OF YORKSHIRE. I4I 



The cells are bright blue-green in colour, subglobose, and 

 contain many large distinct granules; the heterocysts are also 

 subglobose, single or occasionally in pairs, and are of a pale 

 straw colour. 



This species has not previously been recorded for the British 



Isles. 



Family NOSTOCE^. 

 Genus NOSTOC Vauch., 1803. 



694. Nostoc piscinale Kiitz., 1843. 

 S.W.— Near Bradford. 



695. Nostoc muscorum Ag., 1812. 



Mid W. — Near Ingleton. Heseltine Gill, on the eastern slope 

 of Penyghent, and several gills on the western slope. Cowside 

 Beck, Arncliffe. 



N.W.— Lund's Fell. 



N. E. — Strensall. 



Var. tenax Thur., 1880. 



Mid W. — Cowside Beck, Arncliffe. 



696. Nostoc humifusum Carm., 1883. 

 S.W. — CuUingworth. 



N.W.— Mickle Fell. 



697. Nostoc commune Vauch., 1803. 



S.W. — Wentbridge (H. F. Parsons). Manningham. 



Mid W.— Ripon {Y. A. Lees). Knaresborough (W. B. 

 Turner). Wetherby (F. A. Lees). Arncliffe. Sherburn (F. A. 

 Lees). Near Jennett's Cave, Malham (C. P. Hobkirk). 



698. Nostoc macrosporum Menegh., 1843. 

 Mid W.— Heseltine Gill, Penyghent. 



N.W.— Deep Dale, Dent (iii. 1893). 



699. Nostoc microscopicum Carm., iSt,^ [Syn. JVos foe 

 rupestre Kiitz., 1850; N. hyalinuin Benn., 1886; 

 N. opaliimm Benn.]. 



S.W.— Halifax. 



Mid W. — Ligleborough. Ciapham. Malham. Ribblehead. 

 Whernside. Old Cote Moor. 



