134 BRITISH CHAROPHYTA. 



Monoecious. Stem very stout, often solitary, much 

 branched. Sterile whorls of about 6-20, simple 3-5- 

 celled, often very unequal branchlets, the cells diminish- 

 ing gradually in length and thickness towards the 

 apex, apical cell rather bluntly conical. Fertile whorls 

 usually in large densely crowded heads. Branchlets 

 once or twice divided, with usually 3 lateral rays and 

 one central ray, which is either elongated or again 

 divided with a central elongated ray. Ultimate rays 3- 

 5-celled, the cells usually much diminishing in length 

 and breadth towards the apex ; ultimate cell conical, 

 acute or acuminate, sometimes rather blunt. Oogonia 

 and antheridia at the nodes ot the branchlets and at 

 the base of the whorl. Oogonia ellipsoid-biconical, 

 c. 500-560/A long, 400-450 ju, thick; spiral-cells show- 

 ing 1 1-12 convolutions; coronula prominent, persistent, 

 c. 60 fji high, 65 ju, broad, the cells of the upper tier 

 much the longer. Oospore amber to dull brown, globose- 

 ellipsoid, 330-400 )u, long, 250-330 ju, thick, showing 

 about 9 very thin prominent often winged ridges ; 

 outer membrane very thin and flexible, light yellow and 

 translucent, undecorated. Antheridia usually sessile, 

 c. 300 )u, in diameter. 



Habitat. — Rivers, canals, and ditches, usually in 

 rather shallow, slowly-flowing water ; rare. 



Distribution. — England: Sussex, W., Henfiield {W. 

 Borrer, 1827), Amberley {T. Hilton), South Stoke 

 (/. O.) ; Sussex, E., near Eastbourne {TEL. T. Mennell) ; 

 Berks, E. Isis, near Oxford {G. G. Bruce) ; Oxon, Kid- 

 lington {G. B. B.-W.) ; Norfolk, E., near Beccles 

 {G. B. B.-W.), Martham (G. E. Salmon); Norfolk, 

 W., near Brandon Creek {G. B. B.-W.) ; Cambs, Ely 

 {G. B. B.-W.), Ben wick {A. Fryer), Stretham Ferry 

 (G. B. B.-W.); Hunts, Ramsey St. Mary {A. Fryer), 

 Stirtloe (E. F. Linton) ; North ants, Rockingham 

 {T. B. Blow), Yelvertoft (iJ. N. Dixon); Lines, S., 

 Deeping Fen {W. H. Beehy); Lanes, W., canal 

 between Lancaster and Preston, at Cabus and Brock, 

 near G-arstang, etc. {A. Wilson and J. A. Wheldon). 



