STAURASTRUM. 181 



processes, with more delicate spines, dorsal processes 

 shorter. 



Length, without processes, 25 y. ; breadth, including 

 spines, 40^ ; breadth of isthmus 14(ju 



IRELAND.- -Lough Guitane, Kerry ! 



166. Staurastrum subavicula W. & G. S. West. 



(PL CLY, fig. 10.) 



,S7. arcuatuni var. subavicula West, Alg. Engl. Lake Distr. 1892, p. 20, f. 25. 

 -SV. .siibiin'cuhi \Vest & G. S. West, New Brit, Alg. 1894, p. 12. 

 .s7. arcuatuni var. vastuni Schmidle, Alg. Bern. Alps, 1894, p. 94, t. 6, f. 7. 

 St. vastum Schmidle, Beitr. Alp. Alg. 1896, p. 31. 



Cells about as long as broad, or a little longer, includ- 

 ing the processes, deeply constricted, sinus open, almost 

 rectangular ; semicells subelliptical, or cuneate, apex 

 and lateral margins nearly straight or slightly convex : 



o / v 



upper angles scarcely produced, ending in two spines, 

 and with two series of granules just beneath, apex of 

 each face with a pair of short bifid processes. Vertical 

 view triangular, sides concave, angles rounded with two 

 spines, one beneath the other, apex with a circle of 

 6 bifurcate processes ; centre of apex smooth. 



Zygospore unknown. 



Length 32 \L ; breadth 32-32'o \L ; breadth of isth- 

 mus 9'5 fj.. 



ENGLAND.- -Harrop Tarn, Westmoreland ! 



WALES. Glyder Fawr, Carnarvonshire ! 



Geoyr. Distribution. Germany. Australia. 



167. Staurastrum amphidoxoii West. 

 (PL CLV, fig. 11.) 



stnuit ampludoxon West & G. S. West, New Brit. Freshw. Alg. 1894, 

 p. 10, t. 1, f. 17. 



Cells small, nearly twice as broad as long, deeply 

 constricted ; semicells subelliptical, rough with granules 

 arranged in concentric series round the angles, apex 

 nearly straight, ventral margin convex, angles produced 



