STAUEASTRUM. 195 



process arising from the base of each lower process ; 

 processes of upper and lower whorls rarely exactly 

 superimposed, the upper whorl being twisted very 

 slightly in one direction. Chloroplast axile with a 

 pyrenoid in each angle and a pair of lobes stretching 

 into the base of each process. 



Zygospore unknown. 



Length, without processes, 44-60 [j, ; with processes, 

 74-1 00 pi ; breadth, without processes, about 43-54 y. ; 

 with processes, 84-1 20 [/. ; breadth of isthmus 13-22 ji. 



ENGLAND.- -Plankton of Ennerdale Water, Cumber- 

 land ! 



WALES. Capel Ctirig, Carnarvonshire! (Cooke & 

 Wills). In the plankton ! 



SCOTLAND. --Near Brin, Inverness (Roy & Biss.) 

 Rhiconich and in the plankton of Lochs nan Cuinne 

 and Shin, Sutherland ! Plankton of Loch near Cearna- 

 bahl and Lochs an Sgath, an Tomain, Langabhat, 

 Stranabhat and Fadaghoda, Lewis, Outer Hebrides ! 



IRELAND. Connemara, Gal way (Arch.). Plankton of 

 Galway and Kerry ! 



Geogr. Distribution.- -France. Germany. Norway. 

 Sweden. Finland. Siberia. Central China. Japan. 

 India. Ceylon. Burma. Singapore. Java. Australia. 

 New Zealand. 



This species differs from St. furcigerum Breb., which is the 

 only other British, species having a pair of vertically placed 

 processes at each angle, in the different shape of its semicells, 

 its more open sinus, and in the distinctly lateral insertion of all 

 its considerably longer processes. It is not an uncommon 

 species in the plankton of some lakes in the western parts of the 

 British Isles, but is otherwise very rare. 



Var. supernumerarium W. & G. S. West. (PL CLVII, 



fig. 4.) 



St. sexangidare var. supernumerarium West & G. S. West, Scott. Freshw. 

 Plankton, I, 1903, p. 551, t. 18, f. 8. 



This variety has an extra small process placed between 

 each upper and lower process. 



