MICKASTERIAS. 87 



Cells rather large, about 1^ times as long as broad, 

 oblong-elliptic, deeply constricted, sinus narrowly 

 linear ; semicells 5-lobed, interlobular incisions narrow 

 and linear, not very deep, those below the polar lobe 

 deeper than the others ; lateral lobes somewhat cuneate 

 and slightly bilobuiate, each lobule retuse ; polar lobe 

 very widely cuneate, angles rounded, apex broadly 

 convex but retuse in the middle. Side view of semi- 

 cell oblong-elliptic. Vertical view oblong-fusiform, 

 with the sides in the middle subparallel, somewhat 

 suddenly attenuated to the poles, which are obtusely 

 rounded. Cell-wall densely covered with irregular 

 flattened granules of variable size, which are sometimes 

 much reduced. 



Zygospore unknown. 



Length 132-170 ^; breadth 82-125 p.; breadth of 

 polar lobe 60-81 //,; breadth of isthmus 24-33 p.. 



ENGLAND. Near Stickle Tarn, Westmoreland (very 

 abundant) ! Sutton Park, Warwick (Wills). Thurs- 

 ley Common, Surrey ! New Forest, Hants ! (Ealfs). 

 C orn wall (Ma rquan d) . 



WALES.- -Capel Curig, Carnarvonshire ! (Cooke 

 Wills). Dolgelly, Merioneth ! (Ealfs). 



SCOTLAND. Sutherland, Ross, Inverness !, Aberdeen, 

 Kincardine, Forfar, Perth, Argyll, and Arran (Roy $ 

 Bissett). Near Sligachan, Skye ! Plankton of Loch 

 Doon, Ayrshire. 



IRELAND. Near Foxford, Mayo ! Kylemore, G-al- 

 way ! Tyrone (Archer). Dublin and Wicklow (Archer). 

 Grlencar (Archer) and Carrantuohill !, Kerry. 



Geogr. Distribution. France. Germany. G-alicia in 



Austria. Norwav. Sweden. Denmark. New Zealand 



/ 



(var.). United States. 



This characteristic species is very uncommon. It occurs 

 principally in upland Sphagnum-aYe& and is sometimes found 

 in quantity in association with Micrasterias oscitans var. 

 mucronata, Euastrum insigne, Xanthidinm armatum, etc. 



The typical form is densely covered with flattened granules, 

 but the amount of roughness varies much in different specimens. 



