20 BRITISH CHAROPHYTA. 



appressed or slightly spreading, variable in length, stout, 

 more or less obtuse, often papiUiform. Whorls of 7-9 

 branchlets. Stipulodes of both series well-developed, 

 usually equal short stout and more or less obtuse. 

 Branchlets incurved, spreading or recurved, of 6-8 

 segments, of which 2-3 are usually ecorticate. Bract- 

 cells usually 5, of which one or two pairs are usually 

 elongated, extremely variable in length, the anterior 

 pair often much exceeding the oogonium, the posterior 

 1-3 rudimentary, sometimes all bract-cells developed, 

 the posterior much the shorter. Bracteoles similar to 

 the anterior bract-cells, sometimes exceeding them 

 in length. Oogonia and antheridia almost always 

 solitary produced at the 3-4 lowest nodes. Oogo- 

 nium varying from broadly ellipsoid to cylindrical- 

 ellipsoid, but usually tapering slightly upwards, usually 

 c. 525-800 (A long (excl. coronula), 350-475 t^ broad ; 

 spiral-cells showing 14-16 convolutions ; coronula very 

 variable in size and shape, 75-125 [x high, 200-325 (x 

 broad, usually more or less spreading. Oospore ellipsoid 

 or ellipsoid-cylindrical, c. 425-675 fx long (excl. cage), 

 c. 225-400 (i. broad, pale golden brown to dark brown, 

 showing about 12-15 low thin ridges, often prolonged 

 downwards into a cage* ; outer membrane thin, flexible," 

 very translucent light yellow-brown, sometimes con- 

 spicuously, sometimes obscurely granulated, granules 

 non-contiguous, varjong in size and prominence. Anthe- 

 ridium c. 325-500 \± in diameter. 



Habitat. — In lakes, ponds, pools, pits and ditches, 

 distributed all over the British Isles, but less common 

 in Scotland and Wales. 



Distribution. — England : Recorded from all coun- 

 ties except the Isle of Man. 



Wales : Glamorgan, Carmarthen, Pembroke, Cardi- 

 gan, Carnarvon, Flint, Anglesea. 



* It would seem that prolongation of the ridges of the oospore to form a 

 cage takes place in the strongly developed fruits. We have referred to their 

 presence in species where we have observed them, but they may well occur 

 in others. 



