7i milTlsH DESMIDIACEJE. 



Cells -mall, as long as broad, or sometimes a little 

 longer ilmn l>n>ad, broadly oval or circular in outline, 

 di'cplv constricted, sinus very narrow and linear; semi- 

 ells nearly .-emicircular or subpyramidate-truncate, 

 ventral margin straight, dorsal margin somewhat flat- 

 tened on the apex, lateral margins with about 4 emar- 

 i:inate verruca?, which are seen when the angle is viewed 

 from ih<' front as a series of broad complicated verrucas 

 extending from the apex to the base of the semicell ; 

 upper margin of faces with an apical series of verrucas. 

 Yertiral view triangular, lateral margins concave, angles 

 luoadly truncate and tricrenate, with two or three series 

 oi verrucas just within the truncate angles, and another 

 series just within the concave margins. 



/VIM s] x >re unknown. 



Lt-n-tli 33-42 IJL ; breadth 30-35 (i ; breadth of isth- 

 mus Ilia. 



K x < ; i , A x i ) . Xear Bowness, Westmoreland (Bissett) . 



SCOTLAND.- -Powlair, Rosehill Loch, Craigendinnie, 

 Ms of Logic, Loch Da wan, Aberdeen; Craithes, Kin- 

 eanline ; near Tobermory in Mull, Argyle (Roy & Biss.). 

 Moidart. Inverness ! 



1 1 : K LA N i > . -Ballynahinch ! , Derryclare Lough ! , plank- 

 t-n <>f Loti'Ji Corrib! and near Maam (Archer), Gal way. 

 . Co. Cork ! 



Dixtrihntitni- Norway. Sweden. Finland. 

 United States. 



>7. Staurastrum spongiosum Breb. 

 (PI. CXL, fig. 14.) 



'mil, II, i .v/;//f//,.sv/ lin'-l>. in Cheva]. inirroscop. et usage, 1839, p. 272. 



'tauraatrum .II<>,,,/;<,U,H Breb. in Halts, Brit. l)e.sm. 1848. p. 141, t. 23, f. 4 ; 



\><h. in IVit.-h. Int. 1X01, j). 739, t. 3, t. 22, 23; Rabenh. Krypt.-fl. 



Sachs. lsi;:{, ,,. |'.i;{ : n. \ ()t . ivsni. Ital. lS(i7, p. 48; Rabenh. Flor. 



Km. Alg. 1868, ]>. 2)7 ; Lund. De.-sin. Suer. 1871, p. (35; Nordst. Norges 



1873, |.. 32 ; Kirclm. Alir. Scliles. 1878, p. 100; Turn. New Rare 



85, p. f.. t. l.\ L 22 ; ( 'onke, Brit. Desm. 1887, p. 153, t. 53, f. 1 ; 



Desm. Cn.nland, 1888, p. 3i> ; West, Desm. Massach. 1889, p. G, 



I'- Toni, S\ll. Al.u. 1889, p. 1174; Racib. Desm. Ciaston. 1892, 



AI.L'. \\. Ireland, 1N92. p. 175; Roy & Biss. Scott. Desm. 



26; \\ esl & G. S. \V<-st, Alir. S. tlngland, 1897, p. 494; Schmidle, 



