30 BRITISH DESMIDIACE^:. 



N/. lln i .^iliense var. Lundellii West & G. S. West, Some N. Amer. Desm. 



1896, p. 259 ; Notes Alg. II, 1900, p. 295 ; Scott. Freshw. Plankt. I, 



3903, p. 546; Further Contrib. Freshw. Plankt. Scott. Lochs, 1905, 



p. 480. 

 St. Brasiliense var. Lundellianum Schmidle, Lappmark Siisswasseralgen, 



1898, p. 58. 



Cells very large, about 1^ times longer than broad, 

 deeply constricted ; sinus broad, deeply excavated at its 

 apex; semicells cuneate, sides and apex nearly straight, 

 upper angles somewhat obliquely truncate, and provided 

 with 3 stout spines each, 2 of which lie in the same hori- 

 zontal plane, the third being inserted in a more dorsal 

 position and at an angle to the others. Vertical view 

 5-, rarely 6-angled, sides deeply concave, angles broad 

 and bifid, each lobe attenuated into a stout spine, and 

 with a third spine at each angle lying between the other 

 two, inserted on the apex. Chloroplast axile, with 

 numerous pyrenoids. 



Length, without spines, 75-80 \L ; with spines 120- 

 130(jL ; breadth, without spines, 63-80 [JL ; with spines, 

 120-140 [JL ; breadth of isthmus 28-34 p ; length of 

 spines 25-30 JJL. 



ENGLAND.- -Plankton of Ennerdale Water, Cumber- 

 land, and Easedale Tarn, Westmoreland ! 



WALES. Capel Curig, Carnarvonshire ! (Cooke & 

 Wills). In the plankton ! 



SCOTLAND. Plankton of Loch Shin, Sutherland ! L. 

 Shiel, Inverness ! Plankton of Loch Fadaghoda and L. 

 an Sgath, Lewis, and L. nan Eun, N. Uist, Outer 

 Hebrides. 



IRELAND.- -Foxford, Co. Mayo ! Arderrv Louo-h, and 



J / o 



in the plankton, Galway ! Cloonee Lough and in the 

 plankton, Kerry ! 



Geogr. Distribution.- -Norway . Sweden. Finland. 

 United States. Paraguay. 



This beautiful Desmid is a distinctly ' western "* type, and 

 is more frequent in plankton than in other situations, often 

 occurring in abundance. With its three stout angular spines 

 it is quite distinct from any other species. The cell-wall is 



* Vide p. 18 supra. 



