STAURASTRUM. 37 



usually of some thickness, and is distinctly punctate. The 

 spines are hollow only at the extreme base. 



65. Staurastrum quadrangulare Breb. 

 (PL CXXXIV, fig. 5.) 



Staurastrum quadrangulare Breb. in Ralfs, Brit. Desm. 1848, p. 128, t. 2:2, 

 f. 7, t, 34, f. 11 ; Arch, in Pritch. Infus. 1861, p. 741, t. 3, f. 24, 25 ; 

 Rabenh. Flor. Europ. Alg. 1868, p. 215 ; Kirchn. Alg. Schles. 1878, p. 170 ; 

 \Volle, Desm. U. S. 1884, p. 145, t. 41, f. 1-4 ; Cooke, Brit, Desm. 1887, 

 p. 164, t, 55, f. 4 ; De Toni, Syll. Alg. 1889, p. 1199 ; AYest, Alg. Eng. 

 Lake Distr. 1892, p. 20 ; Roy & Biss. Scott. Desm. 1893, p. 24 ; Eichler, 

 Mat. Flor. Miedz. 1893, p. 62 ; and 1894, p. 131, t. 4, f. 46 : West & G. 8. 

 West, Some N. Amer. Desm. 1896, p. 257, t. 16, f. 16, 17 : Gutvr. Wykaz. 

 Glonow Wadow.-Makow. 1897, p. 161 ; Comere, Desm. de France, 1901, 

 p. 166, t. 12, f. 23 : Georgev. Desm. Macedonia, 1910, p. 244. 



Didymidium Hystrix, A. mi mis, p tetrayonum Reinsch, Algenfl. Frank. 

 1867, p. 171. 



^tnurastrum quadra mjulare f. major Cooke, Brit. Desm. 18S7. ]>. 164; Teo- 

 doresco, Mater. Flor. alg. Roumania, 1907, p. 186. 



Cells small, in general outline subrectangular, sinus 

 fairly deep and acute, almost linear ; semicells rect- 

 angular, dorsal margin straight, lateral margins straight 

 or slightly concave, ventral margin very slightly convex ; 

 angles of semicells provided typically with 4 spines each, 

 one pair towards the apex and another at the base; 

 spines conical and diverging, at times one or other of 

 them duplicated or wanting. Vertical view typically 

 4-angled ; rarely 3- or 5-angled, sides straight or very 

 slightly concave, angles broad and very slightly produced, 

 each bearing two superimposed pairs of spines. 



Zygospore unknown. 



Length 20-30 JJL ; breadth, including spines, 20-30 JJL ; 

 breadth of isthmus 8-10 a. 



ENGLAND. Ambleside (Ralfs) and Loughrigg, West- 

 moreland ! 



SCOTLAND. --Birsemore Loch, near Dinnet, and Dal- 

 bagie, Aberdeen (Roy & Biss.). Rhiconich, Sutherland ! 

 Tarbert, Harris ! 



IRELAND.- -Near Foxford, Co. Mayo! Dublin and 

 Wicklow (Arch.). 



Geoyr. Distribution- -France. Germany. Galicia in 



