STAURASTRUM. 61 



Cells small, about lj to li times longer than broad y 

 deeply constricted, sinus narrow and acute ; semicells 

 elliptic-oblong, dorsal margin somewhat flattened, 

 angles very bluntly rounded, with 2 or 3 scattered 

 spines and about 6 or 8 others arranged in a circle just 

 beneath. Vertical view triangular, rarely quadrangular, 

 lateral margins slightly concave, angles obtusely rounded; 

 spines confined to the region of the angles. Cell-wall 

 smooth. 



Zygospore unknown. 



Length, without spines, 25 (j. ; breadth, without spines, 

 21 (JL ; breadth of isthmus 6'5 JJL ; length of spines 3-4 [i. 



ENGLAND.- -Brother's Water, Westmoreland ! Ditton 

 Common, near DeviFs Jumps, and Thursley Common, 

 Surrey ! Xear Storrington, Sussex (Rolfs). Dartmoor, 

 Devon (PI arris). 



WALES. Capel Curig, Carnarvonshire ! Dolgelly, 

 Merioneth (Ralfs). 



SCOTLAND. Sutherland, Inverness, Aberdeen, For far, 

 Perth, Argyle, Arran (Roy & Biss.). Near Balallan, 

 Lewis, and Tarbert, Harris, Outer Hebrides ! 



IRELAND.- -Ballynahinch, Galway ! Leinster (Adams). 

 Dublin and Wicklow (Arch.). 



Geogr. Distribution.- -France. C4ermany. Switzerland. 

 Austria (var.). Hungary. Norway. Sweden. Poland. 

 United States. Brazil. 



This species is very similar to St. teliferum Ealfs, but is 

 readily distinguished from that species not only by its smaller 

 size and the more restricted arrangement of the spines, but also 

 in the form of the semicells, which are elliptic oblong and more 

 depressed than those of St. teliferum. 



86. Staurastrum Brebissonii Arch. 

 (PL CXXXVII, figs. 4, 5.) 



Staurastruni jjilosiini Breb. Liste Desm. 1856, p. 141, t. 2, f. 49; Cleve, 



Sverig. Desm. 1863, p. 490, t. 4, f. 3. 

 St. Brebissonii Arch, in Pritch. Inf. 1861, p. 739 ; Lund. Desni. Suec. 1871, 



p. 63 ; Xorclst. Desm. Spetsb. 1872, p. 133 ; Desm. Arctose, 1875, p. 34 ; 



Wolle, Desm. U.S. 1884, p. 141, t. 45, f . 5, 6 ; Cooke, Brit. Desm. 1887, 



