W. WEST AND G. S. WEST : ALGA-FLORA OF YORKSHIRE. 53 



This variety has not previously been recorded for the British 

 Isles. 



209. Closterium sigmoideum Lagerh. & Nordst. 

 Mid W.^Eldwick, abundant. 



From the dorsal view this species possesses a regular and 

 well-marked sigmoid curvature. It is nearest to CI. Lunula but 

 is not so robust, and the apices though possessing the slight but 

 characteristic recurvature of the latter species, are narrower. 

 The number of moving corpuscles in each apical locellus was 

 usually about twenty, but sometimes they were as few as five at 

 one pole though normal at the other. There were eight to ten 

 pyrenoids in each semicell. Length 310 — 330/*; breadth 



35—44 ^ 



This species has only previously been seen from Brazil. 



Forma major. 

 Length 482 — 552 ^i; breadth 47 — 58/i. 

 Mid W. — Eldwick, with the typical form, but more abundant. 



210. Closterium peracerosum Gay. 

 S.W. — Rawcliffe Common. 



211. Closterium littorale Gay. 

 N.W. — Masham. 



N.E. — In stream, Rievaulx Abbey. Stokesley. 



212. Closterium tumidum Johnson 1895. 



[Syn. CI. Cornu Wille non Ehrenb.]. 

 Mid W. — Near Norwood Hall, above Lindley Reservoir. 

 Ribblehead. 



213. Closterium Cornu Ehrenb. 



S.W. — Greetland, near Halifax. Cullingworth. 

 Mid W.— Adel Bog (J. Abbott). Eldwick. Ilkley (W. H. 

 Dikes). Cocket Moss, near Giggleswick. Moughton Fell. 

 Ribblehead. 



N.W.— Mickle Fell. Lund's Fell. 

 N.E.— Gormire (W. B. Turner). 



314. Closterium didymotocum Corda. 



rSyn. C. antiacerosum DeNot.]. 



Bot. 5— p 



