100 BRITISH DESMIDIACEJE. 



IRELAND. Dublin and "\Yicklow (Archer}. Clough, 

 Antrim ! 



Geogr. Distribution. France. Belgium. Germany. 

 Galicia in Austria. Norway. Sweden. Denmark. 

 K". and S. Russia. United States. 



Var. fimbriata forma spinosa Bissett. (PI. XL VII, 



fig. 5.) 



M . fimbriata Ealfs var. spinosa Bissett in Roy & Biss. Scott. Desm. 1893, 

 p. 174, t. 4, f. 3. 



Cell-wall furnished with a row of minute spines 

 along each side of the principal incisions, three or four 

 close to the base of each semicell, and a row of about 

 four under the base of the polar lobe. 



Length 210 p. ; breadth 200 /x ; breadth of isthmus, 



^dO fJi. 



SCOTLAND. Slew drum, Loch Ullachie and marsh west 

 of it, Aberdeen (Roy fy Bissett). 



M. apiculata var. fimbriata, although a scarce Desmid, is 

 more often met with than any of the other forms of J/. apicu- 

 lata. It is exceedingly variable in the form of the lobules, 

 especially those of the inferior lateral lobes nearest the sinus, 

 which often project considerably beyond the general contour 

 of the cell. The polar lobe is also variable in the amount of 

 its exsertion, sometimes projecting considerably beyond the 

 superior lateral lobes, sometimes not projecting in the least 

 degree. The insertion of the marginal spines is precisely 

 similar to that in typical M. apiculata. Most forms of 

 M. apiculata var. fimbriata are usually destitute of surface- 

 spines, but many intermediate stages are met with between 

 such forms and the thickly-spined form of M. apiculata itself. 

 In some the surface-spines are scattered and few in number, 

 in others they are irregularly disposed in the neighbourhood 

 of the principal incisions, and in others they are more 

 numerous and more regularly arranged. The latter form was 

 named by Bissett "/. spinosa" 



The zygospore is recorded from Rochester, New Hampshire, 

 U.S.A., by Wolle. 



