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



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

 Scarborough Mere. 



560. Pediastrum gracile Ralfs. 

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

 S.E. — Riccall Common. 



561. Pediastrum biradiatum Meyen, 1829. 



[Syn. P. Rotula (Ehrenb., 1838) .A. Br., 1S55]. 

 N.E. — Scarborough ATere ! (G. Mas.see). 



562. Pediastrum bidentulum A. Br. 



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



563. Pediastrum tetras (Ehrenb.), Ralfs. 



[Syn. P. E/irc/ibergn (Corda), A. Br.]. 

 Forma a. Dispositio cellularuni 4. 

 Mid W.— Adek Ribblehead. 



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

 borough Mere. 



S.E. — Riccall Conmion. 



Forma b. Dispositio cellularum 1 + 7. 

 S.VV. — 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 1. 

 Mid W. — Malham Tarn Bog. 



564. Pediastrum integrum Niig. 



Mid W. — Staveley Dam, near Knaresborough. 

 N.E. — Pilmoor, near Thirsk. 



Genus CRUCIGENIA Morreii, 1830. 



565. Crucigenia rectangularis Nag. 



[Syn. Staiirogenia rechi/ignhiris (Nag.), A. Br., 1855]. 

 Mid W. — Staveley Dam, near Knaresborough. 

 N.W.— Lund's Fell. 



«ot. 5-H 



