60 BRITISH DESMIDIACE^E. 



SCOTLAND. General, occasionally with zygospores 

 (Roy & Biss.}. Rare in the plankton ! Lewis and 

 Harris, Outer Hebrides ! Orkneys and Shetlands, and 

 in the plankton ! 



IRELAND. General ; zygospores from near Round- 

 stone, Co. Galway ! Clare Island ! 



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

 Galicia and Austria. Servia. Roumania. Italy. Norway. 

 Sweden. Denmark. Bornholm. Finland. N. and S. 

 Russia. Faeroes. Iceland. Greenland. Siberia. Central 

 China (var.). Japan. Burma. Azores. United States. 

 Brazil. 



This is one of the most widely distributed of the British 



*/ 



Desmids, and is frequent in nearly all bog collections. The 

 form described by Bennett (' Alg. Engl. Lakes.' 1886, p. 11, 

 t. 2, f. 21 and 22) as St. teliferum var. convex-urn does not belong 

 to this species, but is more probably a form of St. polytriclium 

 Perty. 



Forma obtusa West. (PL CXXXVI, fig. 7.) 



St. teliferum forma obtusa West, Alg. W. Ireland, 1892, p. 175, t. 24, f. 6. 



A form in which the spines are reduced to very short 

 obtuse nodules. 



Length, without spines, 45 (x ; with spines, 50 ^ ; 

 breadth, without spines, 39 [*. ; with spines, 45 ^ ; 

 breadth of isthmus 12 '5 p. 



IKELAND. Small Lakes, Clifden to Roundstone, Co. 

 Galway ! 



85. Staurastrum Hystrix Ralfs. 

 (PI. CXXXVI, fig. 1.) 



>7. Hystrix Ralfs, Brit. Desm. 1848, p. 128, t. 22, f. 5 ; Arch, in Pritch. Infus. 



1861, p. 739; Rabenh. Flor. Europ. Alg. 1868, p. 213; Wolle, Desm. 



U. S. 1884, p. 142, t. 45, f. 14-16 ; Cooke, Brit. Desm. 1887, p. 151, t. 52, 



f. 3; De Toni, Syll. Alg. 1889, p. 1167; West, Alg. Engl. Lake Distr. 



1892, p. 19 ; Roy & Biss. Scott. Desm. 1893, p. 21 : Schmidle, Beitr. 



Alp. Alg. 1895, p. 31 ; West & G. S. West, Alg. 8. England, 1897, p. 493 ; 



Comere, Desm. de France. 1901, p. 171, t. 13, f. 9: Espenscheid, Alg. 



berg. Landes, 1903, p. 103, t. 2, f. 20. 

 Didymidium (Staurastrum) Hystrix A. minus a trigonum Reinsch. Algenfl. 



Frank. 1867, p. 171. 



