188 ALG^E RHODOSPERME^E. [Halymenia. 



numerous branches, contracted, as if jointed, in a moniliform 

 manner, composed internally of branched filaments radiating 

 from the centre. Fruct. unknown. Grev. Name ; catenella, 

 a little chain, which its fronds resemble. A genus of a 

 very questionable character, which I adopt entirely in de- 

 ference to Dr. Greville, though by no means convinced of 

 the propriety of so doing. 



1. C. Opuntia, Grev. Opuntia-like Catenella. Grev. Alg. 

 p. 166. t. 17. Hook. Br. Fl. v. ii. p. 309. Fucus Opuntia. 

 Turn. t. 107. Eivularia Opuntia. E. Bot. t. 1868. 



Marine rocks, near high-water mark. Fronds tufted from half an 

 inch to an inch and half in height, dull purple. 



31. DUMONTIA. Lamour. Dumontia. 



Frond cylindrical, simple or branched, membranaceous, tubu- 

 lar, gelatinous within, of a red or purplish-red colour. Fruct. : 

 globules of seeds, attached to the inner surface of the mem- 

 brane of the frond. Grev. Named in honour of M. Dumont, 

 a French Naturalist. 



1. D. Jiliformis, Grev. Filiform Dumontia. Frond tender, 

 membranaceous, cylindrical, pinnated with long simple branches, 

 which are attenuated at each extremity. Hook. Br. FL v. ii. 

 p. 308. U. purpurascensj E. Bot. #.641. p. crispata ; frond 

 compressed, waved, curled, or twisted. Grev. Crypt, t. 240. 



Rocks and stones in the sea, common. 3 12 inches long, dull 

 purple. 



32. HALYMENIA. Ag. Halymenia. 



Frond cylindrical, compressed or flat, gelatinoso-membrana- 

 ceous, of a pinky red colour, subdichotomously branched. 

 Fruct.: globules of seeds, imbedded in the central substance of 

 the frond. Name ; Xs, aXts, the sea, and v/wp, a membrane ; 

 sea-membrane. 



1. H. ligulata, Ag. Ligulate Halymenia. Frond gelati- 

 noso-membranaceous, compressed or flat, irregularly dichoto- 

 mous or palmate, the segments attenuated, often proliferous at 

 the margin. Hook. Br. Fl. v. ii. p. 308. Ulva ligulata. E. 

 Bot. t. 429. U. rubra, Huds.fB. latifolia ; frond very broad, 

 palmate, dark-red, quite flat, membranaceous. 



Sea- shores, rare. Bantry bay ; Miss Hutchins.&. at Miltown 

 Malbay and Kilkee, County of Clare ; W. H. Harvey. Very vari- 

 able in size, in the breadth and thickness of the frond, and in the rami- 

 fication. Sometimes it is nearly filiform and cylindrical. . is a truly 

 remarkable variety, which, at one time, I felt disposed to regard as a 

 distinct species ; but after comparing many varieties from the South of 

 England, kindly furnished by my valued friends Mrs. Griffiths and 



