237 



COSMA1I1UM. 29 



Cosmarium amoenum Brcb. 



(PI. Oil, figs. 1-4 ; PI. GUI, fig. 9.) 



amoenum Breb. in Kalfs' Brit. Desm. 1S4S, p. 102, t. 17, f. '! ; 

 Arch, in Priteh. Iiifus. 1861, p. 733; Eabenh. Flor. Europ. Alg. Ill, 

 1S68, p. 159; Lund. Desm. Suec. 1871, p. 46; Kirchn. Alg. Sclil<-~. 

 1S7S, p. 152 ; Wolle, Desm. U. S. 1884, p. 78, t. 14, f. 5, 6 [figures very 

 poor] ; Cooke, Brit. Desm. 1887, p. 110, t. 40, f.2 [figures poor J ; Boldt, 

 Desiiiid. Gronlaiid, 1888, p. 29 ; De Toiii, Syll. Alg. 1889, p. 988 ; Borg. 

 Desm. Brasil. 1890, p. 37 ; Anderss. Sverig. Chlor. 1890, p. 14 ; West, 

 Alg. X. Wales, 1890, p. 290; Alg. W. Ireland, 1892, p. 156 ; Alg. Engl. 

 Lake Distr. 1892; p. 728; Liitkem. Desm. Attersees, 1893, p. 558; Koy 

 & Biss. Scott. Desm. 1894, p. 41 ; Kordst. Index Desm. 1896, p. 43 ; 

 W. & Gr. S. West, Alg. S. England, 1897, p. 488 ; Schmidle, Lappmark 

 Siisswasseralgen, 1898, p. 35 ; W. & Gr. S. West, Alga-fl. Yorks. 1900, 

 p. 88 ; Liitkem. Desm. Millstattersees, 1900, p. 7 ; W. & G. S. West, Alg. 

 N. Ireland, 1902, p. 38 ; Borge, Beitrage Alg. Schweden, 1906, p. 29. 

 UrsitieUa amcena Kuntze, Eevis. gen. plant. 1891, p. 924. 



Cells somewhat small, almost twice as long as 

 broad, moderately constricted, sinus rather variable, 

 often slightly open and acute-angled (more rarely 

 sublinear) ; semicells rounded-quadrate with sides 

 and apex very slightly convex, sometimes semi-elliptic ; 

 cell-wall granulate, granules in more or less distinct 

 vertical series (from 6 to 9 of these series visible 

 across the face of a semicell), about 20-25 visible 

 round the margin of a semicell, granules at the base 

 of the semicell sometimes more or less regularly 

 disposed in vertical pairs. Side view of semicell 

 ovate-oblong or subelliptic-oblong. Vertical view 

 broadly elliptic, ratio of axes 1 : 1'2. Chloroplasts 

 axile, with two pyrenoids in each semicell. 



Zygospore unknown. 



Length 42*5-55 ju; breadth 23-30 /i; breadth of 

 isthmus 11-17 ju; thickness 20-24 ^. 



ENGLAND.- -Angle Tarn, Cumberland ! Westmore- 

 land ! (Ealfs). Cocket Moss, W. Yorks! Strensall 

 Common, N. Yorks ! (IF. B. Turner). Skip with 

 Common, E. Yorks ! (Rev. W. Fowler). Surrey ! 

 Wilts ! Cornwall ! (Marquand). 



WALES.- -Capel Curig, Llyn-y-cwm-ffynon, bog* 

 between Grlyder Each and the river Llugwy, and 

 Glycler Fawr, Carnarvonshire ! Dolgelly, Merioneth ! 



