MICEASTEEIAS. 91 



7. Micrasterias papillifera Breb. 

 (PI. XLIY, figs. 1, 2, 7.) 



Micrasterias papillifera Breb. in Ealfs' Brit. Desm. 1848, p. 72, t. 9, f . 1 ; 

 Arch, in Pritch. Infus. 1861, p. 727, 1. 1, f. 18, 19 ; Eabenh. Flor. Europ- 

 Alg. Ill, 1868, p. 194 ; Delp. Desm. snbalp. 1873, p. 86, t. 4, f . 5, 6 ; 

 Kirchn. Alg. Schles. 1878, p. 163 ; Wolle, Desm. U. S. 1884, p. 109, 

 [t. 32, f . 8, 9 ?] ; Cooke, Brit. Desin. 1886, p. 60, t. 27, f . 2 ; Hansg. Prodr. 

 Algenfl. Bohm. 1888, p. 210 ; De Toni, Syll. Alg. 1889, p. 1132 ; West, 

 Alg. N. Wales, 1890, p. 287 ; Alg. W. Ireland, 1892, p. 135 ; Alg. Eng. 

 Lake Distr. 1892, p. 722; Eoy & Biss. Scott. Desm. 1893, p. 174; 

 Nordst. Index Desm. 1896, p. 194 ; West & G. S. West, Alg. S. England, 

 1897, p. 484 ; Alga-fl. Yorks. 1900, p. 66 ; Alg. N. Ireland, 1902, p. 30. 



Didymidium (Micrasterias} papHliferum Eeinsch, Algenfl. Frank. 1867, 

 p. 146. 



Helierella papillifera Knntze, Eevis. gen. plant. 1891, p. 899. 



Cells of moderate size, usually a little longer than 

 broad, subelliptic or subcircular, deeply constricted, 

 sinus very narrowly linear ; semicells 5-lobed, with the 

 lobes and lobules usually almost approximate, inter- 

 lobular incisions linear ; polar lobe cuneate with con- 

 cave sides, apex concave with a slight median notch, 

 each angle slightly produced and furcato-emarginate, 

 with a pair of small teeth on each side of the median 

 notch ; lateral lobes cuneate, of almost equal breadth, 

 each divided by a moderately deep incision into two 

 lobules, lobules again divided, the four ultimate divi- 

 sions of each lobe being emargmate (or rarely tridenti- 

 culate). Side view of semicell elliptic-oblong, with a 

 tricuspidate apex. Vertical view narrowly oblong 

 with subacute poles. Cell-wall generally minutely 

 punctate, with a row of acute granules or denticula- 

 tions on each side of the sinus and the interlobular 

 incisions ; in both side and vertical views these 

 granules or small teeth are marginal. 



Zygospore globose, furnished with strong processes, 

 each of which is doubly furcate at the apex, the ulti- 

 mate divisions being small but widely spreading ; the 

 processes are one-third the diameter of the zygospore 

 in length. 



Length 1 18-145 ^; breadth 108-145 ^ ; breadth of 

 polar lobe 35-44 ^ ; breadth of isthmus 15-22/*; 

 thickness 21-24 /i; diam. zygosp. without processes 



