98 BEITISH DESMIDIACE^l. 



IN". Yorks ! Skip with Common, E. Yorks ! Surrey! 

 Hants ! Tintagel and "Witliiel, Cornwall ! 



WALES. Grlyder Each (at 2200 ft.) and Llyn Gleirio- 

 nedd, Carnarvonshire ! 



SCOTLAND.- -Moidart, Inverness ! Loch Cuthaig and 

 Loch Fadaghoda, Lewis, Outer Hebrides ! Orkneys ! 

 Shetland ! 



IRELAND. Grlenties, Loughs Anna and Machu;h, 



o " 



Donegal ! Plankton of the lakes in Kerry ! 



Geogr. Distribution.- -Germany. Austria. Italy. 

 . Sweden. Australia. 



This variety is almost as generally distributed as the 

 typical form. It is distinguished by the form of its semicells 

 and by the greater number of scrobiculations in the trans- 

 verse rows. 



- 



112. Cosmarium Clepsydra Nordst. 

 (PI. LXXIII, figs. 6, 7.) 



Cosmarium Clepsydra Nordst. Desm. Brasil. 1870,, p. 212, t. 3, f. 29; Lund. 



Desm. Suec. 1871, p. 37 ; De Toni, Syll. Alg. 1889, p. 1046 ; West, Alg. 



Engl. Lake Distr. 1892, p. 724, t. 9, f . 30 [figure not good] ; Nordst. 



Index Desm. 1896, p. 74 ; Borge, Alg. erst. Regnell. Exped., II. Desmid. 



1903, p. 102 [forma major']. 

 C. Bicardia Eeinsch, Coiitrib. Alg. et Fung. 1875, p. 83, t. 16, f . 15 [figure 



not good] ; Nordst. Bornliolm. Desm. 1888, p. 201 ; De Toni, Syll. Alg. 



1889, p. 1007; Borge, Siissw. Chlor, Archang. 1894, p. 31, t. 3, f. 33; 



Roy & Biss. Scott. Desm. 1894, p. 42 ; Borge, Beitriige Alg. Schweden, 



1906, p. 43, t. 3, f. 34 [forma]. 



Ursinella Clepsydra Kuiitze, Eevis. gen. plant. 1S91, p. 924. 

 U. Bicardia Kuiitze, 1. c. p. 924. 



Cells small, about as long as broad, subpolygonal, 

 very deeply constricted, sinus narrowly linear with a 

 slightly dilated apex ; semicells somewhat angularly 

 subsemicircular or broadly subtriangular, inferior 

 angles obliquely bevelled to an obtuse angle, upper part 

 of sides slightly convex or almost straight, apex 

 obtusely pointed. Side view of semicell widely ob- 

 cuneate, upper angles somewhat obliquely truncate, 

 apex rounded-truncate. Vertical view rhomboidal 

 with concave sides and obtuse angles, ratio of axes 

 about 1 : 1'G. Cell- wall smooth. Chloroplasts one in 

 each semicell, axile, with a central pyrenoid. 



