STATJBASTRUM. ,;7 



where, the basal margin being almost straight, and the sinus 

 in consequence quite narrow. Some forms with shorter spines 

 are very similar to St. muricatum Breb., and it is often difficult 

 to draw a sharp line between the two species. St. muricaim 

 is usually larger than St. hirsutum, and its spines are much 

 shorter. 



89. Staurastrum muricatum Breb. 

 (PI. CXXXVIII, fig. 9; PL CXXXIX, figs. 1, 2.) 



BiiiattUa muricatum Breb. Alg. Falaise, 1835, p. 2(39. 



Staurastrum muricatum Breb. in Menegh. Synops. Desm. 1840, p. 22(i (in 



part) ; Ralfs, Brit. Desm. 1848, p. 126, t/22, f. 2 ; Arch, in Pritch. Inf. 



1801, p. 740; Rabenh. Krypt.-fl. Sachs. 1863, p. 190; De Not. Desm. 



Desm. U.S. 1884, p. 127, t. 42, f. 3, 4; Cooke, Brit. Desm. 1887, p. l.V., 

 t. .14, f. 5; De Toni, Syll. Alg. 1889, p. 1189; Heimerl, Desm. Alp. 

 1891, p. (505 ; Liitkem. Desm. Attersees, 1893, p. 566 ; Roy & Bi<s. 

 Scott. Desm. 1893, p. 22 ; West & G. S. West, Alg. S. England, 1897, 

 p. 494 ; Comere, Desm. de France, 1901, p. 175, t. 12, f. 7 ; West & 

 O. S. West, Alga-fl. Yorks. 1902, p. 102 ; Alg. N. Ireland, 1902, p. 50 ; 

 Gutw. Alg. Mont. Tatrensium, 1909, p. 472 ; Borge, Botan. Xotis. 1913, 

 p. 29. 



Xanthidium deltoideum Corda, Aim. de Carlsbad, 1840, p. 214, t. 5, f. 38, 39. 



tloniocystis (Trigonocystis) muricata /3 rugosa Hass. 1845, p. 19, t. 84, f. 10. 



titaurastrum muricata /3 Ralfs in Ann. Mag. Nat. Hist. 1845, p. 154, t. 11, 

 f. 1, d and e. 



Phycastrum muricatum Kiitz. Spec. Alg. 1849, p. 182. 



Phycastrum (Amblyactinium) muricatum Xag. Gatt. einz. Alg. 1849, p. 125. 



Cells of medium size, about 1-J times longer than broad, 

 rarely Ij times longer, deeply constricted, sinus narrow, 

 but opening more widely; semicells subeUiptical or 

 reniform, sometimes truncate-pyramidate, dorsal margin 

 much more convex than the ventral, angles obtusely 

 rounded . Cell- wall covered with minute conical granules 

 arranged in close concentric series round the angles 

 Vertical view triangular, sides straight or very slightly 

 convex, angles obtusely rounded, granules in the centre 

 of the apex often reduced or wanting. Chloroplast 

 axile, with a single pyrenoid in the centre of each semi- 

 cell, and a pair of lobes extending into each angle. 



Zygospore unknown. 



