IULM. GO 



ENGLAND. Thursley Common, Surrey ! 

 Geo<ji'. Distribution. Germany. Galicia in Austria, 

 Bornholm. 



C. Jielcangulare is allied to C. Norimbergense, but is at once 

 distinguished by the straight sides of the semicells and the 



/ 



upwardly produced superior angles. 



90. Cosmarium coarctatum West. 

 (PL LXXI, fig. 8.) 



Cosmarium coarctatum West, Alg\ Engl. Lake Distr. 1892, p. 724, t. 9, 

 f. 11; Norclst. Index Desm. 1896, p. 76. 



Cells small, a little longer than broad, moderately 

 constricted, sinus somewhat open and obtuse; semi- 

 cells obtrapeziform, lateral margins almost straight 

 and slightly diverging upwards, apex broadly truncate, 

 straight, angles slightly rounded. Side view of semi- 

 cell subcircular from a flattened base, apex subtruncate. 

 Vertical view elliptic, ratio of axes about 1 : lv. 

 Cell-wall smooth, somewhat thickened at each apex. 

 , ^ Zygospore unknown. 



Length 16 ^ ; breadth at base of semicells 12-12-5 ^ 

 at apex 13*5-14'4 />t; breadth of isthmus 7/x; thick- 

 ness 8 JLC. 



ENGLAND.- -Borrowclale, Cumberland ! 



This species is closely related to C. contraction var. craco- 

 viense Eacib., but is much smaller,, has more truncate apices, 

 a relatively wider isthmus, and a different side view. 



91. Cosmarium protuberans Lund. 

 (PI. LXXI, fig. 9.) 



Cosmarium protuberans Lund. Desm. Suec. 1871, p. 37, t. 3, f. 17; De 

 Toni, Syll. Alg. 1889, p. 1006; Eoy & Biss. Scott. Desm. 1894, p. 172; 

 Nordst. Index Desm. 1896, p. 207. 



Cells small, a little longer than broad, deeply con- 

 stricted, sinus narrow and linear ; semicells subtrapezi- 

 form, sides diverging upwards, lower angles obtuse, 

 upper angles rounded, apex convex, with a finely and 



