104 YORKSHIRE NATURALISTS UNION. 



487. Staurastrum laeve Ralfs. 



N.E.— Strensall (\V. B. Turner). Pilmoor, near Thirsk, 

 abundant (vi. 1898, with zygospores). 



Zygospores globose, furnished with spines which are very 

 slightly enlarged at the base and doubly bifid at the apex. 

 Diameter of zygospore without spines 20 n, with spines 33-35 p. 



488. Staurastrum irregulare West. 

 X.E.— Pilmoor, near Thirsk (vii. 1897). 



489. Staurastrum tetracerum Ralfs. 



Mid W. — Roundhay Park, Leeds. Cocket Moss, near 

 Giggleswick. 



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

 S.E. — Riccall and Skipwith Commons. 



490. Staurastrum hexacerum (Ehrenb.) Witir., 1872. 

 [Syn. Difsmidt'ro/i ? hexaceros Ehrenb., 1835; Stau- 

 rastrum tricoriie Ralfs, 1848]. 



S.W. — Denholme. Cullingworth. 



Mid W.— Adel Bog. Bolton Woods. Malham Tarn. Ribble- 

 head. 



N.W. — Mickle Fell. Cotterdale. Lund's Fell. Snaizeholme 

 Fell. 



N.E. — Gormire (W. B. Turner). Strensall. 

 S.E. — Riccall Common. 



^'ar. /3 Ralfs. 

 S.W.— Cullingworth. 

 N.E.— Strensall. 



Var. semicirculare ^Vittr. 

 Mid W. — Baildon Moor. Roundhay Park, Leeds. 

 491- Staurastrum pseudotetracerum (Nordst.) West 

 it G. S. \^'est. [Syn. ^9. contortum Delp. var. pseudo- 

 tetracerum Nordst.]. 

 S.E. — Skipwith Common. 



492. — Staurastrum cyrtocerum Breb. 

 N.E. — Pilmoor, near Thirsk. Scarborough Mere. 

 S.E. — Riccall and Skipwith Commons. 



Trans. V.N.U., 1899 (pub. July 1901). Hot. Series, \o\. 5. 



