STAURASTRUM. 191 



ENGLAND.- -Bowness and Loughrigg, Westmoreland ! 

 New Forest, Hants ! Dartmoor, Devon (Harris). In 

 the plankton ! 



WALES. Capel Curig and Llyn Ogwen, Carnarvon- 

 shire ! In the plankton ! 



SCOTLAND. Spital of Glen Shee, Perth ! 



IRELAND.- -In lakes, Clifden to Roundstone, and 

 Ballynahinch, Galway ! Glen Caragh, Kerry ! 



Geogr. Distribution. Germany. New Zealand. United 

 States. 



The lower whorl of processes in forma eustephana do not seem, 

 at any rate in British specimens, to have so many or as acute 

 denticulations as in the type form. Furthermore the margins 

 of the upper whorl of processes seem to be practically smooth. 



It has been pointed out by G. S. West (' Variation Desm.' 1899, 

 p. 396) that this form was correctly placed by Nordstedt as a 

 form of St. furcigerum, since specimens have been observed in 

 which one semicell was typical, and the other of the form 

 eustephanum. Further, the zygospore figured on PL CLVI, 

 fig. 8 shows the conjugation of a typical specimen of St. furci- 

 gerum with one of forma eustephana. This is an additional proof 

 that the two forms are really the same species. Cushman 

 ( ; Bull. Torr. Bot. Club,' 1905, t. 8, f. 19) also figures the zygospore 

 of forma eustephana. His specimen shows rather more compli- 

 cated appendages than the example figured above. 



Forma armigera (Breb.) Nordst. (PI. CLVI, fig. 10.) 



Stan rast rum armigerum Breb. Liste Desm. 1856, p. 136, t. 1, f. 22 ; Roy & 



Biss. Scott. Desm. 1893, p. 17, t. 3, f. 12. 

 St. pseudof urc iger um Reinsch, Spec. Gen. Alg. 1867, p. 20, t. 4 C, f. I ; Alg. 



Frank. 1867, p. 169, t. 11, f. 2 ; Wills, Alg. X. Wales, 1881, t, 5, f. 10 ; 



Cooke, Brit. Desm. 1887, p. 147, t. 61, f. 4 ; Hansgirg, Prodr. Alg. Bohm. 



1888, p. 215. 

 St. furcigerum forma armigera Nordst. Desm. Boniholm 1888, p. 207 ; 



West & G. S. West, Alga-fl. Yorks. 1902, p. 98 ; Further Contrib. Plank- 

 ton Scott. Lochs, 1905, p. 487. 

 St. furcatum var. armigerum West, Alg. X. Wales, 1890, p. 16; Alg. Engl. 



Lake Distr. 1892 ; p. 19 ; Alg. W. Ireland, 1892, p. 174. 



Cells in form similar to the type, but with the lower 

 whorl of processes somewhat longer than usual, and 

 with an apical whorl of 6 accessory processes (in the 

 usual triradiate form). All the processes are consider- 



