38 BRITISH CHAEOPHYTA. 



anterior bract-cells. Oogonia and antheridia solitary, 

 produced at the lowest 2-4 branchlet-nodes. Oogonium , 

 c. 650-975 [i. long (excl. cor.), c. 500-575 |i, broad ; 

 spiral-cells stowing 13-15 convolutions ; coronula 125- 

 190 [X bigh, 260-360 (x broad, spreading. Oospore ellip- 

 soid to cylindrical-ellipsoid, c. 525-725 fx long, 375-425 [x 

 broad, black, showing about 11-14 fine ridges; prolonged 

 downwards into a cage ; outer membrane thin, semi-rigid, 

 translucent, yellow-brown or cold-brown, granulated, 

 with granules varying in size and prominence. Antheri- 

 dium c. 800-450 (x in diameter. 



Habitat. — In lakes, ponds, canals, peat-pits, etc., 

 widely distributed, but not common except in Ireland. 



Distribution. — England : Devon, S. & N., Dorset, 

 Surrey, Berks, Oxon, Suffolk, E. & W., Norfolk, E. & W., 

 Cambs, Beds, Hunts, Northants, Warwicks, Salop, 

 Leicestersh., Cheshire, Lanes, S. & W., Yorks, M.-W., 

 Westmorland. 



Wales : Glamorgan, Anglesea. 



Scotland : Haddington, Fife, Forfar, Ebudes, S.M. & 

 N., Caithness, Orkney, Shetland. 



Ireland : Kerry, S., Tipperary, N., Carlow, Queen's 

 Co., Galway, S.E., W. & N.B., King's Co., Kildare, 

 Dublin, Meath, Westmeath, Longford, Eosconmion, 

 Mayo, E. & W., Sligo, Leitrim, Cavan, Monaghan. 

 Donegal, E. & W., Armagh, Down, Londonderry. 



First record : ' Journ. Bot.,' 1881. 



Outside the British Isles C. contraria occurs in Nor- 

 way, Sweden, Denmark, Belgium, Holland, Spain, 

 France, Germany, Switzerland, Austria-Hungary, Italy, - 

 and Russia, also in Asia, N. Africa, N. & S. Afr ica .' 

 and Australia. 



Usually a rather small to medium-sized plant, and much 

 incrusted, varying considerably in habit. In its more ordinary 

 forms it resembles the much commoner species, C. vulgaris, from 

 which it is to be distinguished by the greater relative size and 

 prominence of the primary cortical-cells. This difference 



