20 BRITISH DESMIDIACE.E. 



WALES. In the Plankton of Llynau Dywaunedd, 

 Carnarvonshire ! 



SCOTLAND.- -Khiconich, Sutherland ! 



In this form the semicells are much more rounded than 

 usual, and the hollow granules are similar to those of C. suli- 

 latum Novdst. and C. Pardalis Colin. 



232. Cosmarium ftuadrum Lund. 

 (PI. C, figs. 3-6.) 



Cosmarium Quadrum Lund. Desm. Snee. 1871, p. 25, t. 2, f. 11 ; Boldt, 

 Siber. Chlorophy. 1885, p. 107 ; Cooke, Brit. Desm. 1887, p. 102, t. 42, 

 f . 1 ; Boldt, Desmid. Gronland, 1888, p. 26 ; De Toni, Syll. Alg-. 1889, 

 p. 985 ; Anderss. Sverig. Chlor. 1890, p. 14 ; West, Alg. Engi. Lake 

 Distr. 1892, p. 726 ; Eoy & Biss. Scott, Desm. 1894, p. 173 ; Nordst. 

 Index Desm. 1896, p. 218 ; Schmidle, Lappmark Siisswasseralgen, 1898,. 

 p. 34; ? Ost-Afrika Desmid. 1898, p. 26; Borge, Trop. u. subtrop. 

 Siissw.-Chlor. 1899, p. 20 : W. & G-. S. West, Alga-fl. Yorks. 1900, p. 88; 

 Fresh w. Alg. Ceylon, 1902, p. 170 [forma] ; Borg-e, Beitrage Alg\ 

 Schweden, 1906, p. 30 ; G. S. West, Alg-. Third Tanganyika Expedit. 

 1907, p. 122 [forma] . 



C. conspersum Ralfs c. Quadrum Racib. Nonn. Desm. Poloii. 1885, p. 75. 



Ursinella Quadrum Ktintze, Eevis. gen. plant. 1891, p. 925. 



Cells of medium size, in general outline quadrate, 

 about as long as broad or slightly longer, deeply con- 

 stricted, sinns narrowly linear, with a slightly dilated 

 extremity; semicells subrectanemlar, basal ang'les 



i> * O O 



rounded, superior angles broadly rounded, sides slightly 

 convex (sometimes almost straight), apex generally 

 very slightly retuse, sometimes straight. Side view of 

 semicell snbcirciilar. Vertical view oblong-elliptic, 

 with straight parallel sides. Cell-wall densely granu- 

 late ; granules solid, arranged in decussating oblique 

 series and in somewhat less distinct vertical series, from 

 34 to 37 showing at the margin of a semicell, and 

 slightly reduced in size in the middle of the apex. 

 Chloroplasts axile, with two pyrenoids in each semicell. 



Zygospore unknown. 



Length 60-83 ^ ; breadth 54-74 ^ ; breadth of 

 isthmus 1S-29//,; thickness 27-40 /*. 



ENGLAND.- -Brant Fell and near Bowness, Westmore- 

 land ! Cullingworth, T\ r . Yorks ! 



WALES. --Capel Curig, Carnarvonshire ! 



SCOTLAND.- -Loch Inver, Sutherland ; Pittellachie 



