114 BRITISH DESMIDIAOEJE. 



the terminal vacuoles and in the striated cell-wall. It also 

 differs in its curvature from Cl. Jenneri and CL Venus, and it 

 is relatively broader than Cl. parni! n m. 



Var. curvatissimum West & Gr. S. West, (PI. XI, 



fig. 4.) 



('1. Cynthia var. curvatissimum West & Cl. S. West, Scott. Freshw. 

 Plankton, I, 1903, p. 537, t. 14, f. 3. 



A variety with the cells much elongated and the 

 apices correspondingly incurved; each chloroplast with 

 6 pyrenoids ; curvature 210 of arc. 



Distance between apices 88 JJL ; breadth 12' 5 p. 



SCOTLAND. Plankton of Loch a Bhursta, Benbecnla, 

 Outer Hebrides ! 



The curvature of this plant, which occupies 210 of arc, is 

 the greatest curvature known to exist in the genus. A dis- 

 tance of 102 [i can he measured along the curvature, although 

 the apices are only 88 /.t apart. 



2. 



Closterium Lagoense Nordst. 

 (PI. XI, figs. 5-7.) 



Closterium Lagoense Nordst. Desm. Brasil. 1870, p. 203, t. 2, f. 2 ; Arch, in 

 Qiiart. Journ. Micr. Sci. 1873, p. 213; Cooke, Brit. Desm. issti. p. 1's, 

 t. 12, f. 5; West & G-. S. West, Desm. Singapore, 1897, p. 159; Nordst. 

 Index Desm. 1896, p. 154. 



Arthrodia Lagoense Kxmtze, Rev. gen. plant. 1891, p. 883. 



Cells small, 6-7-J- times longer than their diameter, 

 strongly curved, outer margin 1 20- 1 50 of arc, inner 

 margin not tumid but sometimes straight in its median 



o o 



portion, gradually narrowed to the apices, which are 

 slightly dilated, obtuse, and suddenly attenuated ; cell- 

 wall finely striate, about 16 stria? visible across the 

 cell, pale yellow or becoming brown in colour ; each 

 chloroplast with about 5 pyrenoids in an axile series. 



Zygospore unknown. 



Distance between apices 1 38-194 /A; breadth, 25-28/x. 



ENGLAND. Enbridge Lake, Hants (livi/). 



IRELAND. Galway (Archer). 



Groi/r. 'Dixfi-ihiifiuit. Singapore. Java(var.). Mada- 

 gascar (var. ). Brazil. 



