CHAR A VULGARIS. 21 



Scotland : Wigton, Kirkcudbright, Selkirk, Roxburgli, 

 Haddington, Edinburgh, Fife, E., Perth, E., Forfar, 

 Aberdeen, N., Elgin, Easterness, Main Argyll, Clyde, S., 

 Ebudes, S. k M., Sutherland, W., Caithness, Hebrides, 

 Orkney, Shetland. 



Ireland : All counties except Waterford and Tyrone. 



Channel I. : Guernsey, Alderney, Sark, Herm. 



Outside the British Isles C. vulgaris has, next to C. 

 fragilis, the widest range, occurring practically all over 

 Europe except the extreme north, in Asia, North and 

 South Africa, North and South America, and Austral- 

 asia. 



First record : Probably Johnson's edition of "' Gerard's 

 Herbal,' 1633. 



A medium-sized plant, normal forms ranging from about 

 9-18 inclies in height, with moderately stout stem ; it is usually 

 conspicuously incrusted, but entirely unincrusted states occa- 

 sionally occur. We have seen no root-bulbils, and there is less 

 tendency towards thickened stem-nodes than in many species. 

 The coronula is extremely variable in size and shape, the cells 

 being sometimes almost spherical, sometimes so elongated as to 

 be twice as long as broad, and quite spreading. 



It may be distinguished from the other British species of the 

 section Aulacanihw by all the spine-cells being soKtary and obtuse, 

 by the short obtuse stipulodes, the bract-cells being more obtuse 

 and the back pair being but little developed, and by the smaller 

 fruits and antheridia. In facies it more closely resembles C. 

 contraria, from some forms of which it is not always easy to 

 distinguish it when the cortical-cells are of about equal pro- 

 minence. The points of difference will be discussed under 

 C. contraria. 



C. vulgaris is our most variable species, the forms and states 

 which it presents being almost unlimited in number. Many of 

 these have been described and named. In Dr. Migula's ' Die 

 Characeen ' no less than sixty-nine " forms " _are discriminated 

 by name, but most of these appear to us too trivial to be worth 

 distinguishing. The principal Hnes of variation, not including 

 var. crassicaulis, are well indicated in the following analysis by 

 Braun, in " Die Characeen Afrikas " (' Monatsb. Akad. Wiss. 

 Berl.' for 1867, pp. 911-2). 



