curved towards the extremities, gradually but slightly 

 attenuated towards the apices, which are broad and 

 truncate; cell-wall smooth, colourless or straw-coloured ; 

 chloroplasts with about six ridges and containing a 

 central row of 4 or "> pyrenoids; terminal vacuoles \vii li 

 one large moving granule. 



Zygospore globose and smooth. 



Length 127-1 -30 /a; breadth 12-1-Vo/x; breadth of 

 apices 6-7 /x; diam. zygosp. 32 10 /A. 



ENGLAND. Cumberland ! Westmoreland ! W. and 

 N. Yorks ! Lancashire ! Surrey ! Hants ! Devon ! 

 Cornwall ! 



WALES.- -Y Foel Fras, Capel Curig, G-lyder Fach (at 

 2,000 ft.), Llyn-y-cwm-ffynon, and Llyn Gwynant, 

 Carnarvonshire ! 



SCOTLAND. Loch Minnoch, Kirkcudbright ! Loch 

 Macaterick, Ayr ! Near Lairg, Sutherland ! Achna- 

 sheen, Ross ! Moidart, Inverness ! Near Tarbert, 

 Harris and Balallan, Lewis, Outer Hebrides ! Hoy, 

 Orkneys ! Plankton of Loch Beosseter, Shetland* ! 



II.-ELAND. Near Glenties, Loughs Anna and Clogher, 

 and near Lough Magrath, Donegal ! Oughterard, 

 Gal way ! Shores of Lough Neagh ! 



Gcof/r. ])ixtri1>nti<m. Germany (form). Austria and 

 Galicia. Central Africa (form). United States. 

 Brazil. 



This is a well-marked species, some forms of which bear a 

 slio'lit resemblance to 67. tumid inn Johns., hut those are at 

 once distinguished by their stouter habit and broadly truuc;itc 

 apices. 



In outward form Cl. abrupt um resembles some of the small 

 forms of CL. intermedium llalfs, but can at once be distin- 

 guished by its smooth cell-wall. 



Forma punctata West. 



(.'I. a In- a i>t ti m fi>rm;i punctata West, Alg. Eng. Lake Distr. ls ( ,)2, p. 719. 



A form with the cell-wall irregularly punctate. In 

 other respects exactly similar to the type. 



KM;I,AXI>. Bog near Cockley Beck, Lancashire! 



