174 BRITISH DESMIDIACE^E. 



1893, p. 563 ; West & G. S. West, Alg. S. England, 1897, p. 493 ; Comerc, 



Desm. cle France, 1901, p. 165, t. 13, f. 21 ; West & G. S. West, Brit. 



Kreshw. Phytoplankton, 1909, p. 203. 



I >',(!)/ in iili /i in (Staurastrum) spinosum Reinsch, Alg. Frank. 1867, p. 168. 

 tStau rast rum furcatum var. armigerum Cooke, Brit. Desm. 1887, p. 146, 



t. 51, f. 1. 



>V. conmbiense Benn. Alg. N. Cornwall, 1887, p. 11, t. 4, f. 24. 

 ,SV. De Tonii Eichler & Gutw. Nonn. Spec. alg. nov. 1894, p. 18, t. 5, f. 51. 



Cells small, about as long as broad (including the 

 processes), or sometimes slightly longer or shorter than 

 broad, deeply constricted, sinus acute and open ; semi- 

 -cells subelliptical or subglobose, dorsal and ventral 

 margins almost equally convex, lateral angles produced 

 to form short, stout, nearly horizontal processes, with 

 bifid apices, the two teeth lying in the same vertical 

 plane ; apical margin of each face of the semicell with 

 two short bifid processes, which are nearly erect ; cell- 

 wall smooth, or very minutely punctate. Vertical view 

 triangular, angles scarcely produced, ending in a spine, 

 sides straight or very slightly concave, with 2 short 

 bifid processes projecting from each lateral margin. 



Zygospore globose, with numerous spines bifid at the 

 apex (Rolfs}. 



Length, including processes, 25-33 \L ; breadth, in- 

 cluding processes, 20-40^ ; breadth of isthmus 6-10^ ; 

 diam. zygosp., without processes, 33 \i ; including pro- 

 cesses 57 '5 {A. 



ENGLAND. Cumberland ! Westmoreland ! Strensall 

 Common ! (W. B. Turner) and Pilmoor ! N. Yorks ! 

 Leicestershire (Roy}. War wicks (Wills). Surrey ! (Rolfs}. 

 Dartmoor, Devon (Harris}. Cornwall ! 



WALES.- -Fairly general! (at 2200 feet on Glyder 

 Each). In the plankton ! 



SCOTLAND. General ! (Roy & Biss.}. In the plankton ! 



IRELAND. Donegal ! Mayo ! Galway ! Kerry ! 

 Dublin and Wicklow (Arch.). 



Geogr. Distribution.- -France. Germany. Switzerland. 

 Galicia and Austria. Hungary. Turkey. Norway. 

 Sweden. Denmark. Bornholm. Finland. Poland. 

 N. and S. Russia. Iceland. Japan. India. Australia. 

 United States. 



