W. WEST AND n. S. WEST: ALGA-FLORA OF YORKSHIRE. II7 



N.E. — Strensall ! (W. B. Turner). Pilraoor, near Thirsk. 

 Scarborough Mere. 



560. Pediastrum gracile Ralfs. 

 Mid W.— Markington ! (Rev. J. S. Tute). 

 S.E. — Riccall Common. 



561. Pediastrum biradiatum Meyen, 1829. 



[Syn. r. Rohda (Ehrenb,, 1838) A. Br., 1855]. 

 N.E. — Scarborough Mere ! (G. Massee). 



562. Pediastrum bidentulum A. Br. 



Mid W. — Malham Tarn Bog (viii. 1896). 



563. Pediastrum tetras (Ehrenb.), Ralfs. 



[Syn. P. Ehnnbeigii (Corda), A. Br.]. 

 Forma a. Dispositio cellularum 4. 

 Mid W.— Adel. Ribblehead. 



N.E. — Near Rievaulx Abbey. Pihnoor, near Thirsk. Scar- 

 borough Mere. 



S.E. — Riccall Common. 



Forma b. Dispositio cellularum i -f- 7. 

 S.W.— Rawcliffe Common (H. F. Parsons). 

 Mid W. — Malham Tarn Bog. 



N.E. —Strensall ! (W. B. Turner). Pilmoor, near Thirsk. 

 Terrington. Stokesley. Scarborough Mere. 

 S.E. — Skipwith Common. 



Forma c. Dispositio cellularum 4-1-11. 

 Mid W. — Malham Tarn Bog. 



564. Pediastrum integrum Nag. 



Mid W.— Staveley Dam, near Knaresborough. 

 N.E.— Pilmoor, near Thirsk. 



Genus CRUCIGENIA Morren, 1830. 



565. Crucigenia rectangularis Nag. 



[Syn. Staurogenia rectangularis (Nag.), A. Br., 1855]. 

 Mid W.— Staveley Dam, near Knaresborougli. 

 N.W.— Lund's Fell. 



Hot. s-H 



