130 IJIMTISH PESMIIHACK.l-:. 



Yar. elongatum Tiny & Biss. 



<?. jitiiriilitiii \-;ir. i-li'injittinn Roy & Biss. Scott. Desm. 1894, p. 21-5. 



('ells rather large, .ibont :>(> times longer than their 

 diameter. 



Length 355-400 /A; breadth 11'2/z. 

 SCOTLAND. G-eneral (7A>// cj- 7>/.vsv//). 



We have never seen this variety from any part of the 

 British Islands, although lioy appears to have found it fre- 

 (jiientlv in Scotland. 



Section ]>. 



14. Closterium Dianse Ehrenb. 

 (PI. XV, figs. 1-0.) 



? Closterium ruf leaps Ehrenb. Entwick. Lebends. d. Infus. 1832, p. 07. 

 Cl. Diana- Ehrenb. Infus. 1838, p. 92, t. 5, f. xvii, 1-6 ; Menegh. Synops. 



Desm. 1840, p. 2:52; Ilass. Brit. Freshw. Alg. 1845, p. 371, t. 84, f. 5 ; 



Ralfs, Brit. Desm. 184S, p. 108, t. 28, f. 5 ; Arch, in Pritch. Infus. 1801, 



p. 748 ; Rabenh. Flor. Europ. Alg. Ill, 18(58, p. 133 ; Cooke, Brit. Desm. 



1880, p. 28, t. 13, f. 3; ? West, Alg. W. livl.nnl. ls'.2, p. 122; Roy \ 



Biss. Scott. Desm. 1894, p. 244; Nordst. Index Desm. 1896, p. 104; 



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



U.S. 1898, p. 284; Alga-fl. Yorks/1900, p. 48; Alg. N. Ireland, 19(>2, 



p. 23. 

 Cl. acuminatum Kiitz. Phyc. germ. 1845, p. 130 ; Rabenh. Flor. Euro]). 



Algar. Ill, 1808, p. 133; Wittr. Gotl. Ul. sotv. Alg. 1872, p. 04, t. 4, 



f. 18 ; Wolle, Desm. U.S. 1884, p. 44 ; De Toni, SyD. Alg. 1889, p. 840. 

 Cl. Dianx a. typicum Klebs, Desm. Ostpreuss. 1879, p. 11, t. 1, f. 10 a, 



f. 13 h. 



Arlhrtxliii Dianie Kuntze, Revis. gen. plant. 1S91, p. 883. 

 A. iinnniinif.it Kuntze, I.e. 



Cells of medium si/e, usually 10-12 times longer 

 than their diamctci 1 , strongly curved, outer margin 

 about 112 130 of arc, inner margin scarcely or very 

 slightly tumid, gradually and gracefully attenuated 

 towards the apices, which are obtusely rounded ; dorsal 

 margin at each apex obliquely truncate and thickened; 

 cell-wall smooth and of a reddish-brown colour ; cliloro- 

 plasts obscurely ridged, containing a single .series of 

 five or six pyrenoicls ; terminal vacuoles with many 

 moving granules. 



o o 



Zygospore globose and smooth. 



Distance between apices 270-380 ^; breadth 1C-36/A; 

 breadth of apices about f> //, ; diam. /ygosp. oG-52 /z. 



