STAURASTEUM. 149 



Var. inerme Wille. 



St. brevispinum var. inerme Wille, Ferskv. Alg. Nov. Sonilj. 1879, p. 52, 

 t. 13, f . 62. 



Cells larger, sinus more open with a rounded 

 extremity, isthmus wider ; sides of vertical view less 

 retuse; angles of semicells destitute of a papilla or 

 mucro. 



Length 73 ^ ; breadth GO JJL ; breadth of isthmus 



24 ? 



ENGLAND.- -\Voodbury Common, Devonshire ! (R. 

 Morgan) . 



Geogr. Distribution. XovaZembla. United States (?). 



It is possible that this variety should be relegated else- 

 where. The rounded sinus and the entire absence of the 

 small mucros are characters which separate it somewhat 

 widely from all other known forms of St. brevispinum. 



15. Staurastrum lanceolatum Arch. 

 (PL CXXI, figs. 3-6.) 



Staurastntm lanceolatum Arch. Descript. New Cosm. etc. 1862, p. 79, t. 2, 

 f. 16-22 ; Kabenh. Flor. Europ. Alg. Ill, 1868, p. 202 ; Nordst. Desm. 

 Spetsb. 1872, p. 38 ; Desm. Arctose, 1875, p. 33 [forms] ; Wille, Ferskv. 

 Alg-. Nov. Semlj. 1879, p. 51 ; Cooke, Brit. Desm. 1887, p. 158, t. 54, f . 2 ; 

 De Toni, Syll. Alg. 1889, p. 1182 ; West, Alg. N. Wales, 1890, p. 293 ; 

 Alg. W. Ireland, 1892, p. 178 j Koy & Biss. Scott. Desm. 1893, p. 22 

 (sep.) ; Nordst. Index Desm. 1896, p. 155; W. & GK S. West, Alg. S. 

 England, 1897, p. 493 ; Larsen, Ferskvandsalg. Vest-Gronl. 1907, p. 350. 



Cells very small, about as long as broad, very 

 deeply constricted, sinus open and acute-angled, sides 

 of sinus almost straight; semicells elliptic-lanceolate, 

 dorsal margin more convex than the ventral margin, 

 lateral angles acute and minutely apiculate (although 

 the apiculus is sometimes difficult to detect). Vertical 

 view triangular (or more rarely quadrangular), angles 

 very slightly inflated and minutely apiculate, sides 

 concave in the middle. Cell- wall smooth. 



Zygospore globose, furnished with numerous, 

 slender, acute spines. 



Length 15-29^; breadth lo-28/x; breadth of 



