174 BRITISH DESMIDIACE^]. 



(1870), p. 18 ; Freshw. Alg. N. Ainer. 1874, p. 129, t. 21, f. 9; Wolle, 

 Desm. U. S. 1884, p. 78, t. 24, f . 24 ; De Toni, Syll. Alg. 1889, p. 999. 



C. binoduliim Reinsch, Contrib. Alg. et Fungi, 1875, p. 83, t. 18, f . 5 ; De 

 Toni, Syll. Alg. 1889, p. 1034. 



Ursinella binodula Kuntze, Revis. gen. plant. 1891, p. 924. 



U. isthmochondra Kuntze, 1. c. p. 925. 



? U. suborbicularis Kuntze, 1. c. p. 925. 



Cells small, about 1-g- times as long as broad, deeply 

 constricted, sinus narrowly linear; semicells semi- 

 circular-elliptic, basal angles obtuse and furnished 

 with a papilla, sides convex and furnished with 4 or 5 

 acute granules, apex subtruncate (very slightly convex) 

 and smooth, with a single series of 4 minute granules 

 within each lateral margin and two larger granules 

 within the median part of the apex, with a large 

 granule immediately above the isthmus, and with one 

 or two scrobiculations in the centre of the semicell. 

 Side view of semicell circular, with a granule on each 

 side of the apex and one just above the isthmus on 

 each side. Vertical view elliptic, sides granulate, 

 with two larger granules at the middle on each side, 

 poles somewhat pointed. Chloroplasts axile, each 

 with two pyrenoids. 



Zygospore unknown. 



Length 30-35 /A; breadth 27-30 /x; breadth of isth- 

 mus 7*5-1 1 fj. ; thickness 18-19 p,. 



ENGLAND.- -Near Bowness, Westmoreland (Bissett). 

 Near Keighley and Cautley Spout, W. Yorks ! Near 

 Jervaulx Abbey and Pilmoor, N. Yorks ! 



WALES.- -Capel Curig, Carnarvonshire! 



SCOTLAND.- -Loch Ruthven, Inverness ; Aberdeen ; 

 Bishop's Dam in Strachan, Kincardine ; Tannadice 

 and Clova Tableland, Forfar ; Durdie and near Fowlis 

 Wester, Perth ; Glen Coe, Argyll (Eoij $ Bissett). 



IRELAND.- -Lough Machugh, Donegal ! 



Geogr. Distribution. - - Norway. Sweden. Mada- 

 gascar (var.). Brazil (var.). Paraguay (var.). 



Var. pergranulatum West & G. S. West. 

 (PL LXXXI, fig. 8.) 



C. isthmocliondrum Nordst. var. pergranulatum West & G. S. West, 

 Freshw. Alg. Orkneys and Shetlands, 1905, p. 21, t, 1, f. 20. 



