112 BRITISH CHAROPHYTA. 







Aberdeen, S., Easterness, Westerness, M., Sutherland, 

 E., Caithness (fide Ar. Bennett), Hebrides, Shetland. 



Ireland: Kerry, S. & N., Cork, W., M., & E., 

 Galway, W., Mayo, W., Donegal, E. & W., Armagh, 

 Down, Antrim, Londonderry. 



Channel Isles : Guernsey. 



First record : Flora Britannica, 1804. 



Outside the British Isles N. translucens is recorded 

 from Sweden, Denmark, Portugal, Spain, France, 

 Belgium, Holland, Germany, Austria, and Italy ; also 

 from North Africa (Algiers). 



The largest and one of the most distinctive of our Nitellas 

 with a firm stout stem, often attaining a height of 70 cm. 

 The only British species with which this can be confounded 

 is N. flexilis, in its larger forms, and from this it can be 

 readily distinguished by all or nearly all the secondary rays 

 of the sterile branchlets being extremely minute, as well as 

 by the important structural character of the two-celled ulti- 

 mate rays. The secondary rays of the sterile branchlets are 

 usually so inconspicuous that the latter appear simple, and 

 were so described by some of the earlier authors. In deep 

 water it attains a considerable height, the internodes of the 

 stem being sometimes 20 cm. or more in length and the 

 branchlets as much as 11 cm. 



One of the shortest and stoutest forms we have seen was 

 collected in a swiftly-running stream. 



The branching is often irregular, the branches not being: 

 invariably produced in the axils of whorls. The upper 

 branches often run out into long whip-like ends, producing 

 distant minute whorls. When dried the stems and branches 

 present a remarkably brilliant glazed appearance, by which it 

 may be immediately recognized. It is sometimes annularly 

 incrusted. The fertile whorls have usually very short 

 branchlets and the internodes are short, so that they form 

 dense heads, sometimes of considerable size. 



A plant collected by Gr. R. B.-W. in Etang de Cazau 

 (Grironde) possessed large composite root-bulbils, but we have 

 not met with these in any other specimens. 



One variety only has been described, f . confervoides Migula, 

 having more slender stem and branchlets than in the type, 

 and long secondary rays perceptible to the naked eye. The 



