140 BKIT1SH DESM1DIACEJS. 



143. Cosmarium monomazum Lund. 

 (PL LXXVI, fig. 12.) 



Cosmarium monomazum Lund. Desm. Suec. 1871, p. 32, t. 3, f. 11 ; Cooke, 

 Brit. Desm. 1887, p. 99, t. 37, f . 19 ; De Toni, Syll. Alg. 1889, p. 1015 ; 

 West, Alg. Engl. Lake Distr. 1892, p. 726 ; Nordst. Index Desm. 1896, 

 p. 175; West & GK S. West, Alga-fl. Yorks. 1900, p. 69. 



Ursinella monomaza Kuntze, Eevis. gen. plant. 1891, p. 925. 



Cells somewhat small, about as long as broad, deeply 

 constricted, sinus narrowly linear; semicells subsemi- 

 circular from an angular base, basal angles rounded 



o o 



but somewhat obliquely truncate, with a minute tooth 

 at the entrance to the sinus, apex slightly .flattened, 

 maro-in of semicell furnished with about 1(3 very 



O e/ 



slightly emarginate flattened warts, centre of semicell 

 with a single large granule. Side View of semicell 

 circular, with a large granule at the middle on each 

 side and on each side of the apex, and with two 

 diverging 1 series of emarginate warts extending 1 from 



o o o o 



the base upwards to the apical granules. Vertical 

 view elliptic, with subtruncate poles, ratio of axes 

 about 1 : 1*5, with a large granule at the middle on 

 each side and a smaller one at each side of the poles, 

 and with a series of emaroinate warts extending from 



o o 



pole to pole just within each lateral margin. 



Zygospore unknown. 



Length 38 //, ; breadth 34 ^ ; breadth of isthmus 

 11*5 /u; thickness 22 p. 



ENGLAND.- -Blea Tarn, Westmoreland ! Penyo-heiit, 

 W. Yorks ! 



Geogr. Distribution.- -Saxony (var.). Sweden. 

 United States (var.). 



Var. polymazum Nordst. (PL LXXVI, figs. 13, 14.) 



C. monomazum Lund. var. polymazum Nordst. Norg-es Desm. 1873, p. 14, 

 1. 1, f. 3 ; West, Alg. W. Ireland, 1892, p. 151 ; Eoy & Biss. Scott. Desm. 

 1894, p. 169; Nordst. Index Desm. 1896, p. 175; West & O. S. West, 

 Alga-fl. Yorks. 1900, p. 70 ; Alg. N. Ireland, 1902, p. 38. 



C. polymazum (Nordst.) Wolle, Desm. U. S. 1884, p. 70, t. 16, f. 38-40. 



Semicells with the basal angles more rounded, and 

 with 16-20 flat emarginate warts immediately within 

 the margin ; with three large granules (the middle one 



