CTiOSTElliUM. 149 



Var. angolense A\ r est & G. S. West. (PL XVIII, 



fig. 6.) 



Cl. acerosuni var. nn/iiilensc West & (Jr. S. West, Welw. Al'ric. Freshw. 

 Alg. 1897, p. 79 ; G. S. West, Alga-fl. Cambr. 1899, p. 111. 



Colls larger than in the typical form, with the 

 lateral margins parallel, attenuated near each extremity 

 to the apices, which are rounded ; cell-wall smooth 

 and colourless. 



Length 7 73-780 ft; breadth 30-38 /x. 



ENGLAND. Near Ely, Cambridge ! 



Geot/r. Distribution. W. Africa. 



27. Closterium lanceolatum Kiitz. 

 (PI. XVII, figs. 9, 10; PL XVIII, fig. 7.) 



l<nii-a.tl,itnm Kiitz. Phycol. germ. 1845, p. 1:50; Kali's, Brit. 

 Desm. 1848, p. 164-, t. 28, f. 1 ; Arch, in Pi-itch. Infus. 1861, p. 747 ; 

 Eabenh. Flor. Europ. Algar. Ill, 1868, p. 129 ; Wolle, Desm. U.S. 1884, 

 p. 39, t. 8, f. 14; Cooke, Brit. Desm. 1886, p. 21, t. 9, f. 2 ; De Toni, 

 Syll. Alg. 1889, p. 826; Eoy & Biss. Scott. Desm. 1884, p. 245 ; West 

 A: G. S. West, New and Int. Fivslnv. Alg. 1896, p. 150; Nordst. Index 

 Desm. 1896, p. 155 ; West & G. S. West, Alg. S. England, 1897, p. 481 ; 

 Alga-fl. Yorks. 1902, p. 52. 



Cl. accrosum (Selirank) Ehrenb. D. ? lanceolatum Eeinsch, Algeufl. Frank. 

 1867, p. 187. 



Cl. ccc rojiiOR b. lanceolatum Klebs, Desm. Ostpreuss, 1879, p. 7. 



Arthrodia lanceolata Kiintze, Eevis. gen. plant. 1891, p. 883. 



Cells large, 5-10 times longer than their diameter, 

 sublanceolate, almost straight, outer margin slightly 

 curved, about 30-3(> of arc, inner margin straight or 

 slightly convex, gradually narrowed towards the apices, 

 wh it'll are acutely rounded; cell- wall smooth and 

 colourless; chloroplasts with about eight ridges and a 

 single central series of G or 7 pyrenoids; terminal 

 vacuoles with a number of moving granules. 



Zygospore subglobose or oblong-ellipsoid, smooth. 



Length 2 34-3 70 /A; breadth 3 2-7 2 ft; diam. zygosp. 

 81-1 04 ft. 



ENGLAND. Cumberland ! Westmoreland ! (fialfx). 

 W., N., and E. Yorks ! Essex (zygosp. from Epping 

 Forest)! Cambridge! Gloucester f Middlesex ! Surrey"! 

 Kent ! 



WALES. Capel Curig, and near Dolbadarn Castle, 

 Carnarvonshire ! Bodorgan, Anglesey ! 



