68 BKITISH DESMIDIACEJE. 







Turner has described a ' forma major' of this variety from 

 northern India. 



Var. Iseve Scbmidle. (PI. CIX, fig. 3.) 



X. antilopssum var. Ixve Schmidle, Beitr. Algenfl. Schwarzwald. 11. Rlieineb. 

 1893, p. 94, t. 4, f. 7 ; W. & G. S. West, Further Contrib. Freshw. 

 Plankton Scott. Lochs, 1905, p. 485 ; Brit. Freshw. Phytoplankton, etc., 

 1909, p. 180. 



A rather large variety in which the semicells are 

 entirely destitute of a thickened or scrobiculated 

 central area. Cell-wall sometimes perfectly smooth, 

 at other times finely punctate. 



Length without spines 79-90 /*, with spines 96- 

 121ja; breadth without spines 62-79 /x, with spines 

 88-116 ju; breadth of isthmus 20-35 /x. 



SCOTLAND.- -Plankton of Loch Fadaghoda, Lewis, 

 Outer Hebrides ! 



IRELAND.- -Bog W. of Lough Neagh, Londonderry ! 



Geogr. Distribution. Germany. 



A form of this variety with a more or less irregular 

 disposition of the spines was abundant in Derrycrow Bog, 

 near Lurgan, in the north-east of Ireland. This we have 

 named ' forma IRREGULARIS ' (W. & G. S. West, ( New Brit. 

 Freshw. Alg. ' 1894, p. 8, t. 1, f. 44) ; length without spines 

 80-82 fjL, with spines 105-115 JJL breadth without spines 62-63 /u, 

 with spines 85-100 M ; breadth of isthmus 21-25 /u. (PL CIX,, 



fig- 4.) 



The form described by Liitkemuller (' Desm. Attersees/ 

 1893^ p. 548) as "var. fasciculoides forma inevolutum 3 is 

 probably one of the forms of this variety. 



Var. oligacanthum Schmidle. (PL CIX, fig. 5.) 



X. antilopseum var. nligacanthum Schmidle, Chlorophy.-Fl. Torfsticlie 

 Vimheim, 1S94, p. i'.O, t. 7, f. 10. 



Semicells more elliptical than in the type, with 

 only one spine at each of the upper angles, and with 

 no differentiated central area. 



Length without spines 46-50 /x; breadth without 

 spines -46-58 /x. 



Geogr. Distribution. Grermany. 



