104 STNOP8I8 of British si:awkeds. 



more or less Incrassated, and, especially when dry. of a 

 brownish-red. Jt differs from others of the genus, not 

 merely in being more membranaceous, bu1 in its fructifica- 

 tion, the tetraspores being divided by transverse zones, 

 like those of Plocamium, of CatencUa, and of some other 

 Alga>; while in Rhodymenia proper they are of the more 

 common tripartite kind. 



178. laciniata {The jagged Rhodymenia) ; frond thickish, sub- 

 cartilaginous, opaque, bright-red, more or less palmate or 

 flabellilbrm, cleft into numerous, broad, wedge-shaped seg- 

 ments, which are again divided in a subdichotomous man- 

 ner : the apiees obtuse ; the margin, when in fructification, 

 curled and fringed with minute cilia, in which the tub. 



are imbedded, Qrev. Alg. Brit. p. 86. (Atlas, PL XXXIX. 

 Fig. 179.) 

 Delesseria laciniata, Qrev. D. ciliaris, Lamour. Calophyllis la- 

 ciniata, Ktz. Halymenia ciliaris, Gaill. Sphserococcus laci- 

 niatus, Lyngb. Fucus laciniatus, lluds. F. crispatus, Stack. 

 F. miniatus, Fl. Dan. F. crispus, Esp. 

 Hah. Atlantic shores of Britain. On rocks and stones in the sea, 

 and on Laminarice ; rarely within tide-mark. Biennial. 

 January to July. Frequent. 

 This species is subject to very considerable variation in 

 form, in size, and in the relative proportion of its different 

 parts, and yet there is so much that is common to every 

 variety, that it is rarely mistaken for anything else, al- 

 though in the earlier days of marine botany its synonymy 

 was very much confused. The structure of the frond in 

 Rhodymenia laciniata is considerably different from that 

 of the typical species, and at a future time it may become 

 the type, as already proposed by Kiitzing, of a new group, 

 to which, probably, several exotic species may belong. The 

 large empty spaces, or lacuna?, with which the substance is 

 permeated, which do not appear to be enlarged cells, but 

 rather cavities, are not found in true Pliodymenice ; and it 

 is these, seen through the surface cellules, which give the 

 appearance of areolation, noticed by Mr. Turner, when the 

 plant is examined with a pocket lens, and which is lost if 

 the frond be subjected to a higher magnifier. 



179. Palmetta {The little-palm Rhodymenia) ; stem cylindrical, 

 sub-simple, expanding into a fan-shaped, rose-red frond, 

 which is more or less deeply cleft in a dichotomous manner ; 

 segments linear-wedge-shaped, with broad, rounded inter- 

 stices, and a very entire, flat margin ; apices, according to 



