16 BTNOP8I8 OF BRITISH S] 



and south of Ireland. On i Low-watermark and in 



tide-pools; also to b-15 fathoms water. Perennial. Summer. 



This is the largest and finest of the British Cyst. ! 

 and when grown under circumstances favourable to it* full 

 development, it is a very handsome plant. From ( 



. with which only among British species it can he 

 confounded, C. fibrosa may always he known hj its more 

 slender branches, t]w large size of its air-vessels, and the 

 very long, filiform receptacles clothed with setaceous ra- 

 muli ; nor does it exhibit, when growing, those brilliant 

 rainbow-tints for which C. ericoides is so remarkable. It 

 is by no means so commonly clothed with animal parasites 

 as our other species, but is frequently infested with 

 Elachista flacctda, a plant which I believe to be peculiar 

 to it. 



IT. PYCXOPIIYCUS. 



9. tuberculatus [The tuberded Pycnophycus) ; root composed 

 of branching fibres ; frond cylindrical, dichotomous : air- 

 vessels, when present, innate, simple ; receptacles terminal, 

 cellular, pierced by numerous pores, which communicate 

 with immersed, spherical conceptacles, containing, in the 

 lower part of the receptacles, parietal, simple spores, and in 

 the upper, tufted antheridia, Kilt zing, Phye. Gen. p. 359. 

 (Atlas, PL III. Fig. 9.) 

 Cymaduse tuberculata, Due. Fucus tuberculatus, Huds. F. bi- 



furcatus, With, 

 Sab. In rock-pools left, on the recess of the tide, near low- 

 water mark ; never growing in places which are dry at low- 

 water. Perennial. Summer and autumn. 

 There is something so peculiar in the habit of this 

 species, so different from that of the other members of the 

 restricted genus Funis, that it seems, even at first sight, 

 to have claims to be regarded as belonging to another 

 genus. Its branching root and cylindrical frond are very 

 obvious distinctions, but they are not the only ones. When 

 we come to examine its receptacles more closely, we find 

 that not merely are they (so to speak) moncecious, each 

 receptacle containing the two kinds of conceptacles, while 

 in Fucus they are dioecious; but their cellular structure 

 is widely different, those of the present individuals agree- 

 ing much more nearly with the receptacles of Jfal/drys, 

 than of Fucus proper; and it is next to Hal i dry s that 

 Kiitzing has very properly placed it in his arrangement. 



