Ser. MelanospermejE. Fam. Chordariea. 



Plate XVII. 



CHORDARIA DIVARICATA, Ay. 



Gen. Char. Frond filiform, much branched, cartilaginous, solid. Axis 

 composed of densely packed, longitudinal, interlaced, cylindrical fila- 

 ments ; the periphery, of simple, club-shaped, horizontal, whorled 

 filaments, and long, byssoid, gelatinous fibres. Fructification obovate 

 spores, seated among the filaments of the periphery. Chordaria — 

 from chorda, a cord-, because the branches resemble small cords. 



Chordaria divaricata', frond irregularly divided; branches divaricate, 

 subdichotomous, nexuous, furnished toward the apices with short, 

 very patent, mostly forked ramuli ; filaments of the periphery capitate. 



Chordaria divaricata, Ag. Syn. p. 12. Sp. Alg. vol. i. p. 165. Syst. p. 256. 



Fndl. 3rd Suppl. p. 23. 

 Mesogloia divaricata, Kiitz. Pliyc. Gen. p. 332. 



Hab. Annual. Autumn. Thrown up from deep water, at Carrickfergus, 



near Belfast, Mr. Mc'Calla. Oct. 1845. 

 Geogr. Distr. Baltic Sea, Agardh. Belfast Lough. 



Descr. Frond 1-3 feet long, not a line in diameter, forming globular tufts, 

 the branches spreading in all directions from a centre; very irregularly 

 divided. Some specimens are nearly dichotomous from the base, with 

 distant forkings, four or five inches asunder, naked, or having a few short 

 ramuli near the tips. Others have a short leading stem, furnished with 

 very numerous, divaricating, lateral, secund or alternate branches, which 

 are more or less regularly dichotomous, and beset with short, patent, forked 

 ramuli. Others again, as our figure represents, have a much longer leading 

 stem, giving birth to excessively numerous branches spreading at right 

 angles, and furnished throughout with equally spreading lesser branches 

 and ramuli. The surface of the whole frond is slimy, and clothed with 

 long, byssoid, gelatinous fibres, which spread in all directions, and, when 

 the plant is floating in the water, add greatly to its apparent diameter-. 

 These are imperfectly preserved in a dry state. Colour olive, much paler 

 than in C.Jlagelliformis. The filaments composing the periphery are slender, 

 scarcely clavate, the articulations, all but the terminal one, which is \n\ 

 large and globose, being nearly cylindrical. Sport* affixed to the bases 

 of the filaments of the periphery, obovate, bright olive, plentiful on our 

 specimens. 



Chordaria divaricata was first described by the elder Agardh 

 in 1817, and until its recent discovery on the Irish coast was only 

 known 1o inhabit the Baltic Sea, and even there was considered a 

 rarity. Mr. Mc'Calla i<> whom we owe the Irish locality, found 

 it thrown up in great plenty, last October, along the shores of 



