rolysiphonia.] ALO^E RHODOSPERME^E. 205 



A. Main filaments inarticulate. 



1. P. fruticulosa, Grev. Shrubby Polysiphonia. Stems dif- 

 fuse, branched from the base ; branches divaricating, pinnato- 

 dichotomous, much divided, inarticulate, set in the lower part 

 with short, horizontal, multifid ramuli ; in the upper more or 

 less distinctly pinnate, with larger, similarly divided branchlets ; 

 axils rounded ; articulations of the ramuli shorter than broad ; 

 dissepiments opaque ; veins anastomosing. Hutchinsia Wul- 



feniij dg." Sp. Alg. v. ii. p. 95. Fucus frutic. Turn. Hist, 

 t. 227. El Bat. t. 1686. P. fruticulosa. Harv. in Hook. Br. 

 Fl. v. ii. p. 327. fin part.} 



Bantry bay ; Miss Hutchins. Black rocks, Portrush ; Mr. D. 

 Moore. In the British Flora I confounded the two following under 

 this species, and the " Miltown Malbay" station, given in that work, 

 belongs to P. thuyoides. The true P. fruticulosa is readily distin- 

 guished by its diffuse growth, different ramification, and by the hori- 

 zontal multifid ramuli which clothe the stems. 



2. P. thuyoides, Harv. MSS. Arbor-Vita Polysiphonia. 

 Stems tufted, rising from creeping filaments, erect, terete ; be- 

 low simple, and set with short spine-like ramuli ; above, much 

 and fasciculately branched ; branches crowded round the apices, 

 very erect, bipinnate ; pinnae pinnato-multifid ; axils rounded ; 

 articulations of the ramuli shorter than broad; dissepiments 

 opaque ; veins anastomosing. P. fruticulosa^ Harv. in Hook. 

 Br. Fl. I. c. (in part.) 



Rocky shores. Very abundant at Miltown Malbay. Portrush bay; 

 Mr. D. Moore. 3 4 inches high, dull brown. Capsules very rare. 

 Granules and antheridia very frequently produced. The habit of this 

 is very different from that of the preceding'; indeed, at first sight, it 

 might readily be mistaken for P. nigrescens, a plant of a totally dif- 

 ferent structure. I am not aware that it has been previously described. 



3. P. cristata, Harv. MSS. Crested Polysiphonia. Stem 

 erect, compressed, subsimple below, decomposite above ; 

 branches erecto-patent, more or less regularly bipinnate (as is 

 also the stem to the base) ; lower pinnae very short, their pin- 

 nules simple and broadly subulate ; upper longer, with pinnato- 

 multifid pinnules ; axils all acute ; ramuli, as well as branches, 

 inarticulate, reticulated with veins. Fucus cristatus- 7. Miss 

 Hutchins in Herb, (not of Turner.) 



Very rare. Bantry bay ; Miss Hutchins. If specimens, which I 

 possess through the kindness of Dr. Hooker, be correctly named, 

 (which I have no reason to doubt,) this is not the var. y. of Turner's 

 Fucus cristatus ( Rhodomenia cristata, Grev.) ; and, consequently, 

 not the Rytiphlcca complanata of Agardh. Indeed, if the genus 

 Rytiphlaa be characterized by a transversely striate frond, this has no 

 claims to admission into it. This species is alluded to in the British 

 Flora, under P. fruticulosa, as a beautiful variety of that species, 

 found at Whitsand bay by Mr. Walter Arnott. 



