STAURASTRUM. 23 



Var. protuberans W. & G. S. West, (PL CXXXII, 



fig. 12.) 



Staurastrum aristiferum var. protuberans West & G. S. West, Scott. Freshw. 

 Plankton, I, 1903, p. 544, t. 14, f. 5. 



Apex of semicell strongly convex in the middle 

 portion ; vertical view triangular with the lateral margins 

 verv convex in the middle. 



/ 



Length, without spines, 23-27 \L ; breadth, without 

 spines, 24-27 \L ; length of spines 13'5-17 \L ; breadth of 

 isthmus 9*7 JJL. 



SCOTLAND.- -Plankton of Loch nan Eun, N. Uist, 

 Outer Hebrides ! 



54. Staurastrum cuspidatum Breb. 

 (PL CXXXII, figs. 13-15.) 



tricnxp'ulttta Breb. Alg. Falaise, 1835, p. 57, t. 8. 

 />'. cuspidala Bivb. in Clieval. mirrnsr. ct usa'_ r c, Is.'J'.i. p. '2"! "2. 

 xt'tiirastrum cumpiil'ifntti Breb. in Alenegh. Synops. Desm. 1840, p. '2-('< ; 



Ralfs, Brit. Desm. 1848, p. 122, t. 22, f. 1, anil t. 33, f. 10 : Arch, in Pritch. 



Infus. 1861, p. 737, t. 1, f. 31-34 ; Rabenh. Krypt. Fl. Sachs. 1863, p. 189 ; 



Wittr. Gotl. f)l. sotv. 1872, p. 54 ; Delp. iVsm. Subalp. 1877, p. 136, t. 



10, f. 26-33 ; Kirchn. Alg. Sdiles. 1878, p. 169; Wolle, Desm. U. S. 1884, 



p. 123, t. 40, f. 23-25 ; Cooke, Brit. Desm. 1887, p. 141, t. 49, f. 5 ; Hansg. 



Prodr. Algenfl. Bohm. 1888, p. 211 ; De Toni, Syll. Al.-r. 1889, p. 1140 ; 



Pvoy & \>\. Smtt. Dostn. 1S94, p. 19; Schmidle, Lappm. Siisswasser- 



algen, 1898, p. 49 : ComtVe, Desm. de France, 1901, p. 163, t. 13, f. 24 ; 



Schroder, Gallertbildung Alg. 1902, p. 168, t. 7, f. 15 ; Wot & G. S. West, 



Alga-fl. Yorks. 1902, p. 97 : Alg. X. Ireland, 1902, p. 44 : Freshw. Alg. 



Orkneys and Shetlands, 1905, p. 24; Phytoplankton Engl. Lake Distr. 



1909, p. 289 ; Hustedt, Desm. Bacill. aus Tirol, 1911, p. 339. 

 Phycastrum cuspidatum Kiitz. Phyc. Germ. 1845, p. 138 ; Spec. Alg. 1849, 



p. 179. 

 Ph. spinulosum Xag. Gatt. einz. Alg. 1849, p. 126, t. SA, f. 2. 



Cells small, about as long as broad, or a little longer, 

 not including the spines, very deeply and broadly con- 

 stricted, with a long cylindrical sinus about as long as 

 a single semicell, sinus broad and obtuse, widening out- 

 wards ; semicells fusiform, ventral margin more convex 

 than the dorsal, lateral angles terminating in a stout 

 spine, either parallel or converging. Vertical view 

 usually triangular, rarely quadrangular, sides concave, 

 angles inflated, each with a spine. 



