104 YORKSHIRE NATURALISTS' UNION. 



487. Staurastrum laeve Ralfs. 



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

 abundant (vi. 1898, with zygcspores). 



Zygospores globose, furnished with spines which are very 

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

 Diameter of zygospore without spines 20 ,u, with spines 33-35 /^. 



488. Staurastrum irregulare West. 

 N.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 Skipw-ith Commons. 



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



[Syn. Desviidinin ? liexaceros Ehrenb., 1835 : Stau- 

 rastrum tricorne Ralfs, 1848]. 

 S.W. — Denholme. Cuilingworth. 



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 Conmion. 



Var. /3 Ralfs. 

 S.W. — Cuilingworth. 

 N.E.— Strensall. 



Var. semicirculare Wittr. 

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



491. Staurastrum pseudotetracerum (Nordst.) West 

 iv Cj. S. A\'est. [Syn. .S". cofitortum Delp. S2iX. pseudo- 

 tetracerum Nordst.]. 



S.E. — Skii)with Common. 



492. — Staurastrum cyrtocerum Breb. 

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

 S.E. — Riccall and Skipwith Commons. 



Trans, Y.N.U., 1899 (pub. July 1901). Hot. .Series, Vol. 5. 



