STAURASTRUM. 85 



Length 17-5-23 p ; breadth 21-27 fi ; breadth of isth- 

 mus 6-7'5fjL. 



WALES. Capel Curig, Carnarvonshire ! 

 SCOTLAND. Loch Dawan, Aberdeen (Roy & Biss.). 

 IRELAND. Adrigole, Co. Cork ! 

 Geogr. Distribution. Sweden. Finland. United States. 



Var. undulatum var. nov. (PI. CXLI, fig. 13.) 



X/. h'icillarc var. 11 ml itlntii.ni \\ . & (',. S. \Vestin manuscript. 



Cells rather larger and relatively longer than in the 

 type, processes long and slender, more divergent, and 

 with their outlines gently undulate. Vertical view 

 triangular with very concave sides. 



Length, without processes, 18 \i ; with processes, 44 \L ; 

 breadth 37 \L ; breadth of isthmus 8'5 [/.. 



SCOTLAND.- -Rhiconich, Sutherland ! 



St. bacillare is a very rare Desmid, and only occurs in bogs 

 on the older paleozoic rocks in the western parts of the 

 British Isles. It is very variable in form, and scarcely any of 

 the figures yet published agree exactly with the figures of Ralfs. 

 Lagerheim (' La nuova Xotarisia,' 1892, p. 29) would make definite 

 varieties of the forms figured by both West (< Alg. X. Wales,' 1890, 

 t. 5, f. 4) and Wolle (' Fresh w." Alg. U.S.' 1887, t, 57, f. 5-6). 



103. Staurastrum franconicum Keinsch. 

 (PI. CXLII, figs. 9, 10.) 



St. franconicum Reinsch in Rabenhorst, Alg. Eur. no. 1899, f. 1-3, 1860; 

 Spec. Gen. Alg. 1867, p. 124, t. 4, B ; Lund. Desm. Suec. 1871, p. 5i 

 De Toni, Syll. Alg. 1889, p. 1213 ; Roy & Biss. Scott, Desm. 1893, p. 182. 



Didymidium (Staurastrum) franconicum Reinsch, Algenfl. Frank, 

 p. 158, t. 12, f. 3. 



Cells small, about as long as broad, excluding the 

 processes, or a little longer ; body of cell nearly rect- 

 angular in form ; sinus almost wanting, consisting of a 

 minute excavation in the middle ; semicells short and 

 rectangular, apex and lateral margins concave or nearly 

 straight, upper angles of semicell produced to form short 



