COSMAEIUM. 229 



1888, p. 196 ; De Toni, SyU. Alg. 1889, p. 1000 ; West, Alg. X. Wales, 

 1890, p. 290; Borge, Bidr. Siber. Chlor. 1891, p. 11; West, Alg. W. 

 Ireland, 1892, p. 150 ; Borg. Ferskv. Alg. Ostgronl. 1894, p. 14 ; Gntw. 

 Flor. Glon. Okolic Tarnapola, 1894, p. 95 ; Eoy & Biss. Scott. Desm. 

 1894, p. 175 ; Nordst. Index Desm. 1896, p. 244 ; West & G. S. West, 

 Alg. S. England, 1896, p. 488 ; Some Desni. U. S. 1898, p. 304 ; Schmidle, 

 Lappmark Siisswasseralgen, 1898, p. 36: West & G. S. West, Alga-fl. 

 Yorks. 1900, p. 70 ; Borg. Freshw. Alg. Fseroes, 1901, p. 227 ; West & 

 G. S. West, Alg. N. Ireland, 1902, p. 37; Larsen, Freshw. Alg. E. 

 Greenland, 1904, p. 89 ; West & G. S. West, Freshw. Alg. Orkneys and 

 Shetlands, 1905, p. 18 ; Borge, Beitrage Algen Schweden, 1906, p. 34. 



Ursinella subcrenata Kuntze, Revis. gen. plant. 1891, p. 925. 



Cosmarium costatum Nordst., forma Gutw. Flor. glonow Galic. 1892, p. 130, 

 t. 3, f. 12. 



C. Boldtianum Gntw. Flor. Glon. Okolic Tarnapola, 1894, p. 100, t. 3, 

 f. 36. 



C. subreniforme Nordst. forma ? Schmidle, Lappmark Siisswasseralgen, 

 1898, p. 41, t, 2, f. 9. 



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

 stricted, sinus narrowly linear: semicells subsemicir- 

 cular with a truncate apex, basal angles more or less 

 subrectangular, sides 4-6 (commonly 5)-crenate 3 upper 

 crenations slightly larger than lower crenations, apex 

 4 (more rarely 5)-crenate, generally with minute 

 binate granules immediately within each crenation 

 (except the one or two basal ones), and within these 

 with one or two series of minute granules disposed 



both radially and concentrically, with a broad flattened 





 tumour in the centre above the isthmus furnished with 



5-7 vertical series of granules (3-6 granules in each 

 series). Side view of semicell ovate from a broad base, 

 apex truncate, upper parts of sides retuse. Vertical 

 view elliptic, with a broad tumour on each side fur- 

 nished with about 5 very distinct granules, poles 

 rounded or truncate. Chloroplasts axile, one in each 

 semicell with a single central pyrenoid. 



o 1 / 



Zygospore globose, furnished with short, scattered 

 spines, each arising from a conical base, and with an 

 emarginate or slightly furcate apex. 



Length 23-37 p.; breadth 18-30 /x; breadth of isth- 

 mus 8-14 /x; thickness 12-19 p.; cliam. zygosp. without 

 spines 32-35 ju; length of spines 8-10 p.. 



ENGLAND. W. and X. Yorks ! Essex ! Middlesex 1 

 Surrey! Hants (P oij). Cornwall! 



