STAURASTRUM. 35 



are very mucli reduced and the apex of the semicell is 

 often nob so convex. 



Length 80-90 JJL ; breadth, without spines, 75-85 y. ; 

 length of spines 7-10 p ; breadth of isthmus 30-35 [/.. 



ENGLAND.- -Plankton of Ennerdale Water, Cumber- 

 land ! 



WALES.- -In the plankton ! 



SCOTLAND. Glen Coe, Argyle, 1878 (Roy < Biss.). 

 Khiconich, Sutherland ! Plankton of Lochs Fadaghoda 

 and an Sgath, Lewis, Loch Diracleet, Harris, and Loch 

 nan Etm, N. L T ist, Outer Hebrides ! 



Geogr. Distribution. Switzerland. Sweden. United 

 States. 



64. Staurastrum Brasiliense Nordst. 

 (PL CXXXY, fig. 11.) 



m Brasiliense Xordst. Desm. Brasil. 1869, p. 227, t. 4, f. 39 ; 

 Wolle, Freshw. Alg. U.S. 1887, p. 46, t. 60, f. 39, 40 ; De Toni, Syll. Alg. 

 1889, p. 1200 ; Cushraan in lihodora, vol. 7, 1905, p. 262. 



Cells large, about Ij times longer than broad, deeply 

 constricted with a broad sinus ; semicells shortlv 



/ 



cuneate, broadening towards the apex which is truncate 

 or slightly retuse, lateral margins concave ; upper 

 angles each terminating in 3 stout diverging spines ; 

 cell- wall punctate ; isthmus about one-half the diameter 

 of the cell. Vertical view 4- (-5-) angled, angles termi- 

 nating in 3 diverging spines (on one occasion 4 have 

 been observed) ; lateral margins concave. 



Zygospore unknown. 



Length, not including the spines ; 43-51 JJL ; with 

 spines, 56-77 [i ; breadth, not including the spines, 

 25-37 (JL ; with spines 65-99 JJL. 



Geogr. Distribution.- -IN oiw&y. Abyssinia. United 

 States. Brazil. 



Var. Lundellii W. & G. S. West. (PI. CXXXV, 



figs. 12, 13.) 



St. Brasiliense forma Lund. Desm. Suec. 1871, p. 73, t. 5, f. 2 ; Cooke, Brit. 

 Desm. 1887, p. 165, t. 56, f. 2 ; Wolle, Desm. U. S. 1884, p. 146, t. 48, 

 f. 1-3. 



