98 BRITISH CHAKOPHYTA. 



chestnut-brown, showing about 6 very prominent 

 sharp-flanged ridges ; outer membrane semi-rigid and 

 translucent, yellow-brown, decorated with minute 

 non-contiguous rounded tubercles (PI. IV, figs. 1, 2). 

 Antheridium large, c. 600 /x in diameter. 



DISTRIBUTION.- -Cambridgeshire, Sutton Gault, in a 

 ditch some 50 yards long, near the Old Bedford River, 

 where it was discovered in 1885 by the late Alfred 

 Fryer of Chatteris. 



Outside the British Isles N. capillaris is recorded 

 from Norway, Sweden, Denmark, Spain, France, 

 Belgium, Germany, Switzerland, Austria, Hungary, 

 Italy, Serbia, and Greece ; also from North Africa, 

 Asia, and North America. 



A slender elegant species, ahout 20-30 era. in height, 

 usually light-green and often with conspicuous annular in- 

 crustation. 



From N. opaca it is distinguished by the gelatinous envelop- 

 ment of the oogonia and antheridia, the more strongly and 

 acutely flanged ridges of the oospore, and the finely tubercled 

 membrane. It is also usually more slender, has somewhat 

 more sharply pointed secondary rays, of which on the barren 

 branchlets there are often 3 and sometimes 4. The fruits are 

 also usually clustered. 



Nordstedt, in his ' De Algis et Characeis/ has the following 

 observation on N. capitata : "Membrane thickly covered with 

 little scattered warts which change to small prickles. Prickles 

 about 1'5 fji thick, about 3-4 /u long, generally hyaline; in 

 surface view of the membrane they are not quite rounded, 

 but more or less angular, which probably induced de Bary 

 to describe the membrane of this species as furrowed in a 

 net-work ' ' (translated) . 



Although the small dyke in which it was originally found, 

 and where it continued to flourish, is connected by a small 

 channel with the Old Bedford River, the plant seems to have 

 spread but little. A few isolated specimens have been collected 

 in this old river-cut, but it does not appear to have established 

 itself in any new locality, in spite of the freedom with which 

 it fruits. The oogonia ripen early in June. 



Specimens previously collected in Kent (Stowting), Car- 

 narvonshire (Lake Idwal), and Kerry (Killarney) were 

 referred by Braun to this species, but we do not feel satisfied 



