COSMARIUM. 257 



The following variety is much better known than Kirchner's 

 Silesian form : 



Var. ^QUATORIENSE Nordst. in Wittr. & Nordst. Alg. Exsic. 

 1893, no. 1116; in Botan. Notis. 1893, p. 196. Euastrum 

 hexagonum West & G. S. West, Alg. Centr. Africa, 1896, 

 p. 378, t. 361, f. 10. Very slightly larger than the type, apex 

 decidedly retuse or retuse-einaro-inate, o-ranulation more 



C_} f CD 



restricted, grannies in somewhat irregular clusters at and 

 within the lobes (especially within, the basal angles), central 

 tumour rather smaller and with fewer granules than in the 

 type; vertical view less tumid at the middle on each side. 

 Leno-th 44-53 /n breadth 38-46 ILL ; breadth of isthmus 

 9-5-13 ju j thickness 21-24 ^ (PL XC, fig. 8.) 



Geoyr. Distribution. Central Africa. Ecuador. 



There is another variety of G. alatum var. gostyniense 

 Racib. which appears to be distinguished by its wider cells 

 and its more numerous and densely crowded granules (vide 

 Racib. <Xonn. Desm. Polon/ 1885, p. 73, t. 11, f. 17). 



C. alatum var. sub oblong um West & Gr. S. West (' Welw. 

 Afric. Freshw. Alg/ 1897, p. 122, t. 370, f. 18-19) should be 

 known as G. subalatum var. suboblongnm nob. 



G. alatum var. indicum Turn. (' Freshw. Alg. E. India/ 

 1893, p. 57, t. 8, if. 36, 57) has 110 relationship with G. alatum 

 Kirchn., but the figures may possibly be very inaccurate 

 representations of forms of C. subalatum. The latter is known 

 to occur in Burma. 



215. Cosmarium hexalobum Nordst. 

 (PL XC, fig. 4.) 



Cosmarium hexalobum Nordst. Desm. Spetsb. 1872, p. 33, t. 7, f. 16 ; Cooke, 

 Brit, Desm. 1887, p. 116, t, 40, f. 10 "figure bad]; Boldt, Desm. Gron- 

 land, 1888, p. 24 ; De Toni, Syll. Alg. 1889, p. 1053 ; West, Alg. 

 X. Wales, 1890, p. 290; Borge, Siissw. Clilor. Archang. 1894, p. 30 

 [forma]; Eoy & Biss. Scott. Desm. 1894, p. 103; Borg. Ferskv. Alg. 

 Ostgronl. 1894, p. 15 ; Nordst, Index Desm. 1896, p. 139 ; West & G-. S. 

 West, Alga-fl. Yorks. 1900, p. 85 ; Larsen, Freshw. Alg. E. Greenland, 

 1904, p. 85. 



Ursinella hexaloba Knntze, Revis. gen. plant. 1891, p. 924. 



Cells somewhat small, about 1J times as long as 

 broad, subhexagonal in outline, moderately constricted, 

 with a narrowly linear sinus ; semicells trapeziform, 

 very gradually attenuated from a straight base to a 

 broad apex, basal angles obtuse or obliquely sub- 



YOL. III. 17 



