COS MAR I CM. 79 



This minute species is nearest to C. Sinostegos Schaar. var. 

 obtusius Gutw., but is distinguished by its proportionately 

 greater length, by its rounder basal angles, which are also 

 more rectangular, and by the rounded poles of the vertical 

 view. It is very distinct from typical C. Sinostegos. 



100. Cosmarium Sinosteg-os Schaarschm. 

 (PI. LXXI, fig. 39.) 



Cosmai-ium Sinosteyos Schaarschm. Magyar. Desm. 1882, p. 266, t. 1, f. 12; 



De Toni, Syll. Alg. 1889, p. 1043 ; Xordst. Index Desm. 1896, p. 234. 

 U i-sinella, Sinostegos Kuutze, Revis. gen. plant. 1891, p. 925. 



Cells minute, about 1-J- times as broad as long, 

 deeply constricted, sinus widely open from a narrow 

 apex ; semicells subhexagonal, with the part bordering 

 on the sinus convex, lower angles produced upwards 

 and outwards, very acute, sides concave, upper angles 

 not rounded, apex broadly truncate and straight. Side 

 view of semicell circular-oblong, with truncate apices, 

 and a papilla in the middle of each side. Vertical 

 view elliptic-rhomboid, poles sharply acuminate, with 

 an acutely conical papilla at the middle on each side. 

 Cell- wall smooth. Chloroplasts axile with a central 

 small pyrenoid. 



Zygospore unknown. 



Length 10 /x; breadth 14 p.; breadth of isthmus 

 4'o JLC ; thickness (with papilla) 9 JJL. 

 Distribution. Huno-arv. 



The typical form of this species is not known to occur in 

 the British Islands. 



Var. obtusius Ghitw. (PI. LXXI, fig. 40.) 



C. Sinosteyos Schaarschm. var. obtusius Gutw. in Xuova Xotarisia, III, 1892, 

 p. 21 ; Flor. Glonow Galic. 1892, p. 131, t. 3, f. 13 ; West & G. S. West. 

 Alg-. Madag. 1893, p. 58, t. 6, f . 33 ; Some X. Amer. Desm. 1896, p. 247 ; 

 Xordst. Index Desm. 1896, p. 234 ; West & G. S. West, Welw. Afric. 

 Freshw. Alg-. 1897, p. 118; Alg. S. England, 1897, p. 4*7. 



Cells about 1 times as broad as long, lower angles 

 less acuminate, apex sometimes slightly depressed ; 

 vertical view elliptic with acute poles. 



Length 9-14 //, ; breadth 10'5-17/x; breadth of 

 isthmus 1'8-3'6/x; thickness 5*5-0 ft. 



