STAURASTRUM. Oo 



SCOTLAND. Glen Coe, Argyle (Arch.). Rhiconich, 

 Sutherland ! Xear Tarbert, Harris, Outer Hebrides ! 



IRELAND.- -Dublin and Wicklow (Arch.). 



Geogr. Distribution.- -France. Norway. Sweden. Fin- 

 land. Poland. Central Africa. United States. N. W. 

 Canada. Brazil. Paraguay. 



St. setigerum is distinguished from all other spiny species of 

 Staurastnun by the possession of two distinct kinds of spines, 

 the stout angular spines contrasting strongly with those on the 

 laces of the semicell. which are much more delicate. 



79. Staurastrum polytrichum (Perty) Rabenh. 

 (PL CXXXVI, figs. 8-10.) 



Phyca6tnini palytrirlnuii Perty, Kleinst. Lebeiisf. 1852, p. 210, t. 10, f. 24. 

 Staurastrum Pringsheimii Reinsch, Spec. Gen. Alg. 1867, p. 22, t. 5, A, B, 



f. 1-8; Arch, in Journ. Bot. 1874, p. 93; R.-ins.-h, C.mtr. Alg. Fung. 



1875, p. 90, t. 10, f. 4: Cooke, Brit. Desm. 1887, p. 152, t. 52, f. 4; 



Espensch. Desm. berg. Landes, 1903, p. 103, t. 2, f. 19. 

 >7. polytricltuHi Rabenh. Flor. Europ. Alg. 18(38, p. 214; Lund. Desm. 



Suec. 1871, p. 63; Xordst. Xorges Desm. 1873, p. 30; De Toni, Syll. 



Alg. 1889, p. 1169; Racib. Desmidyja Ciastonia, 1892, p. 389; West, 



Alg. W. Ireland, 1892. p. 175, t. 22, f/18 ; Roy & Biss. Scott. Desm. 1893, 



p. 23, t. 3, f. 8 ; Turn. Freshw. Alg. E. India, 1893, p. 113. t. 13, f. 16 ; 



West & G. S. West, Alg. 8. England, 1897, p. 494 : Gutw. \Vvkaz Glonow 



Wadow.-Makow. 1897, p. 158 ; Schmidle, Lappmark Siisswasseralgen, 



1898, p. 54 ; Liitkem. Desm. Millstattersees, 1900. p. 23 ; West & G. S. 



West, Alga-fl. Yorks. 1902, p. 99 ; Alg. X. Ireland, 1902. p. 48 ; Scott. 



Freshw. Plankt. I, 1903, p. 529 : Him, Desm. Finnland, 1903, p. 22 : 



G. 8. West, Brit. Freshw. Alsr. 1904, p. 172, f. 65 D : ('ushman in Bull. 



Torr. Bot, Club, 1905, p. 228, t. 8, f. 18 (var.). 

 St. Pringsheimii var. clupln-tndjor Turn. Xew Rare Desm. 1885, p. 939, 



t. 16, f. 24. 

 St. teliferum var. convexuni Benn. Alg. Ensd. Lake Distr. l.ssi.i. p. 11, t. 2, 



f. 21-23. 



Cells of medium size, about lj times longer than 



* ^t ^3 



broad, deeply constricted, sinus acute and sometimes 

 fairly open ; semicells elliptical or subelliptical, cell- wall 

 covered with fairly long acute spines, arranged in 

 obscure circles round the angles, and sometimes visible 

 as longitudinal rows on the faces. Vertical view tri- 

 angular, sides straight or almost imperceptibly concave, 

 angles somewhat obtusely rounded, spines becoming 

 shorter towards the centre of the apex, which is quite 

 smooth. 



