Ser. RHoposPERME#. Fam. Nemastomee. 
PLATE LXXXVIII. 
CATENELLA OPUNTIA, Grev. 
Gen. Cuar. Frond dull-purple, membranaceous, filiform, constricted at 
intervals; its axis composed of a lax net-work of anastomosing, lon- 
gitudinal filaments; its periphery of densely compacted, dichotomous, 
moniliform filaments. Fructification of two kinds, on distinct indivi- 
duals ; 1, spherical masses of spores (favellidia), contained in external 
capsular bodies (abortive ramuli, resembling ceramidia); 2, solitary 
oblong, transversely parted ¢e¢raspores, surrounded with a limbus, and 
formed from the filaments of the periphery, in which they are im- 
mersed. CaTENELLA (Grev.),—a little chain, “in allusion to the 
chain, or necklace-like form of the frond.” 
CaTENELLA opuntia; fronds rising from a mass of creeping fibres, vaguely 
branched ; pseudo-articulations lanceolate or elliptical, about four times 
as long as broad. 
CATENELLA opuntia, Grev. Alg. Brit. p. 166.t.17. Hook. Br. Fl. vol. ii. 
p- 309. Harv. in Mack. Fl. Hib. part 3. p. 188. Harv. Man. p. 51. 
Wyatt, Alg. Danm. no. 126. J. Ag. Alg. Medit. p.89. Endl. 3rd Suppl. 
p.37. Kitz. Phyc. Gen. p. 394. t. 76. f. 4. 
CHorparia opuntia, Spreng. Syst. Veg. vol. iv. p. 330. 
LoMENTARIA opuntia, Gill. Dict. Hist. Nat. v.53. p. 367. 
HALYMENIA? opuntia, 4g. Sp. Alg. vol.i. p.217. Syst. p. 245. 
CHONDRIA opuntia, Hook. Fl. Scot. part 2. p.106. Grev. Fl. Edin. p. 292. 
GIGARTINA opuntia, Lamour. Ess. p. 49. 
Gicartina pilosa, Lamour. 1. c. p. 49 (see Ay.). 
RivuLaRia opuntia, Gm. Eng. Bot. t. 1868. 
Fucus opuntia, Good. and Woodw. in Linn. Trans. vol. iii. p. 219. Stack. 
Ner. Brit. p.104. t.16. Turn. Syn. Fue. vol. ii. p. 387. Turn. Hist. t. 107. 
Fucus repens, Lightf. Fl. Scot. vol. ii. p. 961. With. vol. iv. p. 91. 
Fucus cespitosus, Stack. Ner. Brit. p. 59. t. 12. 
Utva articulata 8. Huds. Fl. Angl. p. 569. 
Has. On submarine rocks, piles, &c., near high-water mark. Perennial. 
Not uncommon on the shores of England, Ireland, Scotland, and the 
Orkney Islands. Rarely found in fruit. 
Geogr. Distr. Atlantic shores of France and Spain. Mediterranean Sea. New 
Zealand, Dr. Hooker. 
Descr. Root, a mass of creeping, irregularly branched fibres. Fronds springing 
from the creeping fibres, erect, densely tufted, and forming patches two or 
more inches in diameter, spreading over any substance which they en- 
counter, half an inch to nearly an inch in height, sparingly branched, con- 
stricted at intervals into a string of oblong or lanceolate pseudo-articulations. 
Branches similar to the main stem, alternate or opposite, simple or forked, 
their terminal joints acute. Substance membranaceous. Struetwre: the 
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