STAURASTRUM. 51 



76. Staurastrum Picum W. & G. S. West. 



(PL CXXXVII, fig. 8.) 



'Staurastrum Picum West & G. S. West, Xew and Int. Freslr.v. Alg. 1896, 

 p. 159, t. 4, f. 49 ; Brit, Fresh w. Phytoplankton, 1909, p. 202. 



Cells small, a little broader than long, deeply con- 

 stricted, sinus open and subacuminate ; semicells 

 elliptic-fusiform, angles somewhat inflexed and subcapi- 

 tate, each with a single strong spine, slightly curved 

 and strongly inflexed ; dorsal margin provided with 

 about 6 paired spines which are short and curved ; 

 vertical view triangular, angles obtuse and subcapitate, 

 sides slightly concave, with about 6 paired spines along 

 each ; cell-wall smooth. 



Zygospore unknown. 



Length, without spines, 20 IJL ; with spines, 25 IJL ; 

 breadth without spines, 23-26 u. ; with spines, 29-34 M, ; 

 breadth of isthmus 8 \L . 



IRELAND. Glen Caragh, Co. Kerry ! 



77. Staurastrum horametrum Koy Biss. 



(PL CXXXIX, fig. 4.) 



St. Itoraniftruni Roy & Biss. Scott. Desni. 1893, p. 21, t. 3, f. 2 ; Gutvr. 

 Norm. Alg. Nov. 1896, p. GO. t. 7, f. 72. 



Cells medium sized, a little longer than broad, " hour- 

 glass ' ' shaped, constriction opening rectangularly, sides 

 about straight ; semicells widem'ng upwards, angles sub- 

 acute, ends flatly convex ; angles with 3 or 4 rows of 

 crowded, short, simple, acute, stout spines ; end view 

 triangular or quadrangular, sides slightly concave, angles 

 acutely rounded, very spiny, 2 or 3 rows of spines 

 across the angles, and a circle of 15 spines around the 

 centre in the triangular form, and of 20 in the quadran- 

 gular. Isthmus about half the thickness of the semicell. 

 Membrane smooth (Roy & Biss.). 



Zygospore unknown. 



Length about 57-65 ^ ; breadth 48-59 y. ; breadth of 

 isthmus 18-24[i. 



