28 BRITISH CHAEOPHYTA. 



the anterior usually shorter than the fruit ; bracteoles 

 usually longer. Oogonia and antheridia solitary, pro- 

 duced at the lowest 3-4 nodes. Oogonium (excl. cor.) 

 c. 900-1000 jji long, 625-700 fi. broad, spiral-cells show- 

 ing about 13-14 convolutions, coronula spreading c. 

 180 [i. high, 350 [l broad. Oospore c. 675-750 [i long 

 (excl. basal appendage), 425-450 (x broad, rich chestnut- 

 brown, showing about 12-13 fine ridges, prolonged 

 downwards into a cage ; outer membrane thin, flexible, 

 translucent, light rich chestnut-brown faintly and finely 

 granulated. Antheridium 400-500 [x in diameter. 



Habitat. — Usually occurring in lakes, but occasion- 

 ally in running water, rare in England ; known from one 

 county only of Wales ; in several counties of Scotland ; 

 much more widely distributed in Ireland. 



Distribution. — England: Cambridge, Salop, Lanes, 

 W., Yorks, N.E., Durham. 



Wales : Anglesea. 



Scotland : Roxburgh, Haddington, Fife, Perth, E., 

 Elgin, Easterness, Main Argyll, Orkney. 



Ireland : Tipperary, S., Limerick, Clare, Tipperary, 

 N., Kilkenny, Queen's Co., Galway, S.E., W. and N.E., 

 King's Co., Kildare, Wicklow, Dublin, Meath, West- 

 meath, Longford, Roscommon, Mayo, E. & W., Sligo, 

 Cavan, Monaghan, Fermanagh, Donegal. E., Armagh, 

 Down. 



First record : (as variety of C. hispida) ' Journ. Bot.' 

 1880. 



Outside the British Isles C. rudis is recorded from 

 Sweden, Russia, Denmark, Belgium, Holland, Germany, 

 Austria, Hungary, Switzerland. 



A large plant often 3 feet lugh, with moderately stout stem 

 and long branchlets, usually much incrusted. It resembles the 

 more common C. Jiispida, of whicli it is often regarded as a 

 subspecies, but differs from it in having a more slender stem 

 and branchlets, much larger secondary cortical-cells, often twice 

 the diameter of the primary cells, almost hiding the latter, and 

 in having a considerable proportion of the spine-cells geminate. 



