Iridaa.] ALGM RHODOSPERME^E. 189 



Miss Cutler, with my Irish specimens, I have feared that the distin- 

 guishing characters are too variable to be depended on. The frond in 

 my largest specimen is about 18 inches long, and 4 5 inches wide in 

 the broadest part ; cloven into three principal segments, with a palmate 

 outline. When fresh, it had a soft feel like fine kid leather ; and was 

 not thicker than the membrane of Rhodomenia reniformis, perfectly 

 flat, and with a darker colour than in the more common variety. 



2. H. furcellata, Ag. Forked Halymenia. Frond tender, 

 gelatinoso-membranaceous, cylindrical, uniformly dichotomous, 

 the segments obtuse. Hook. Br. FL v. ii. p. 308. Ulva fur- 

 cellata. E. Bot. #.1881. 



Very rare on our coasts ; Bantry Bay ; Miss Hutchins. Quilty 

 Strand, Miltown, Malbay ; W. H. Harvey. Distinguished from the 

 preceding by the regular dichotomous frond. Miss Hutchins's spe- 

 cimens are remarkable for possessing a more or less distinct midrib : in 

 one specimen this is so fully developed, that, were there not interme- 

 diate states from the strongest to the most imperfectly ribbed, I might 

 have mistaken it for a distinct species. The branches (particularly in 

 these Bantry specimens) are frequently constricted, so as in some in- 

 stances to form regular septa at the strictures. 



33. IRIDAA. Bory. Iridaea. 



Frond flat, expanded, carnose, more or less of a purple-red 

 colour. Fruct. : globules of roundish seeds, imbedded be- 

 tween the two coats of the frond, or contained in little pedi- 

 cillated processes. Named from the iridescent hues of some 

 of the species when recent. 

 1. I. edulis, Bory. Esculent Iridcea. Frond simple, obo- 



vate or cuneiform, rounded at the apex, attenuated at the base 



into a short stipes. Hook. Br. FL v. ii. p. 380. F. edulis. E. 



Bot. t 1307. 



Sea-shores, abundant. 2 18 inches long ; dark purple. 



TRIBE X. SPONGIOCARPE^E. 



Marine plants, of a dull dark-purple colour ; of a cartilagin- 

 ous or carnose substance, and fibrous structure. Frond cylindri- 

 cal, dichotomous ; the central part composed of very slender, 

 closely packed, longitudinal fibres ; the circumference formed of 

 radiating dichotomous filaments. Root scutate. Fructification 

 double (?) ; 1. naked spongy warts, composed of radiating fila- 

 ments, among which are imbedded globules of red seeds ; 2. mi- 

 nute granules immersed in the substance of the slightly swollen 

 tipper ramuli. 



