138 BRITISH 



Length 38-45 p ; breadth 38-45 p. ; breadth of 

 isthmus 11-12 p.. 



ENGLAND. Puttenham Common, Surrey ! Keston 



eJ 



Common, Kent ! New Forest, Hants ! 



IRELAND.- -Near Westport, Mayo ! Ballynahinch, 

 Loughs Nacoogarrow, Shannacloontippen. and Derry- 

 clare, Galway ! Lough Guitane, Kerry ! Adrigole and 

 Glen gar iff, Cork ! 



G-eoyi'. Distribution. --Germany. Austria. Norway 

 (Lappmark). Greenland. Samoa. Australia. 



8. Staurastrum ellipticum West. 

 (PL CXIX, fig. 7.) 



Staurastrum ellipticum West, Alg. Engl. Lake Distr. 1892, p. 731, t. 9, 

 f. 28; Nordst. Index Desm. 1896, p. 117 Lemm. Beitr. Kenntnis 

 Planktonalg-. XXVI, 1910, p. 295. 



St. muticum Breb. var. subsphxricum Borg. Ferskv. alg. Ostgronl. 1894, 

 p. 24, t, 2, f . 18. 



Cells small, about 1^ times longer than broad, fairly 

 deeply constricted, sinus open and acute-angled ; 

 semicells somewhat broadly elliptic. Vertical view 

 trigonal, with broadly rounded angles and straight or 

 slightly convex sides, or tetragonal with broadly 

 rounded angles and slightly concave sides. Cell- wall 

 smooth. 



Zygospore unknown. 



Length 42 '5-46 p ; breadth 29-30 p. ; breadth of 

 isthmus 13-15 p.. 



ENGLAND.- -Borrowdale, Cumberland ! 



fji'. Distribution. --Greenland. Paraguay. 



This species is nearest to St. vesiculatum Wolle (' Freslnv. 

 Alg. U.S./ 1887, p. 42, t. 54, f. 6, 7), from which it differs in 

 its broader sinus and elliptical semicells. It should also be com- 

 pared with St. muticum Breb. from which it is distinguished 

 by the proportionately greater length, the different shape of 

 the semicells, and the form of the vertical view. The axile 

 chloroplast in each semicell possesses a particularly large 

 central pyrenoid. 



