CHARA DELICATULA. 67 



Distribution. — Distributed almost throughout the 

 British Isles. We have seen specimens from more than 

 half the English and Welsh counties, from Cornwall and 

 the I. of Wight northwards, from the Channel I., from 

 more than three-quarters of the Scottish, and two- 

 thirds of the Irish, counties, and it occurs probably in 

 most of the others. 



We have not as yet been able to work out the separate 

 distribution of C. delicatula, outside the British Isles. 

 It is apparently much less generally distributed than 

 C. fragilis, but we have seen specimens from many parts 

 of Europe, from Asia Minor and Japan, S. Africa, and 

 North America. 



Closely allied to C. fragilis, of which it has been regarded as a 

 variety or subspecies. It is usually a smaller, firmer and neater 

 plant than the ordinary forms, and never attains to the size of 

 the larger forms of that species. It can usually be readily dis- 

 tinguished by the appreciably larger and more prominent 

 primary cortical-cells, sometimes giving the stem a distinctly 

 ribbed appearance, by the spine-ceUs being apparent, tbough 

 often quite small, and by one series at least of the stipulodes 

 being elongated ; the bract-cells and bracteoles also are longer. 

 The coronula, which is usually connivent, varies considerably in 

 height. The cells are usually long ; on a plant from Biddulph, 

 Staffs (Coll. R. F. & F. P. Thompson), some of them measure as 

 much as 300 /n. Occasionally they are quite short ; on a plant 

 from Cringla Fiold, Orkney (Coll. H. H. Johnston), they are less 

 than 100 ,u long, while in one from Clonbrock, Galway (Coll. 

 R. LI. Praeger), they are still shorter. The branchlets are usually 

 rather short and firm, but, in extreme states, they are elongated 

 and almost as slender and flexuous as those of C. fragifera. 

 Kuczewski (l. c.) has made a histological study of C. delicatula, 

 especially of the bulbilliferous form. We have followed Braun 

 as regards the name and authority for this species, but the position 

 is an ambiguous one. The name G. delicatula was first given by 

 Desvaux (' Journ. Bot.' p. 137, 1810) to a plant which, according 

 to Braim, was G. aspera. Agardh quotes Desvaux as the autho- 

 rity and would appear to be merely following BruzeHus, but 

 presumably Braun had seen the plants described by both authors. 

 Neither Desvaux's, BruzeUus's nor Agardh's description is 

 alone sufficient for identification. 



